Shapeable wood-based compositions and use thereof

Abstract

In one aspect, there is provided an article shaped from a composition comprising a waste particulate material (wood powder) and a binder. Furthermore, method of manufacturing the articles, such as by printing (3D printing) and casting are also provided.

Description

SHAPEABLE WOOD-BASED COMPOSITIONS AND USE THEREOF CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No.63 / 777,015, titled "SHAPEABLE WOOD-BASED COMPOSITIONS AND USE THEREOF", filed March 25, 2025. The content of which is incorporated herein by reference in their entirety.FIELD OF THE INVENTION

[0002] The invention relates to the field of mixtures used in the preparation of biodegradable articles and to methods for manufacturing biodegradable articles, such as by liquid modelling or by casting.BACKGROUND OF THE INVENTION

[0003] The building and construction sector is responsible for approximately 37% of global energy and process-related CO2 emissions, with building operations accounting for around 27% and the production of building materials contributing an additional 10%. Insulating materials, such as mineral wool, expanded polystyrene, extruded polystyrene, and polyurethane with ranging thermal conductivity of 0.030-0.046 W / m.K, play a vital role in energy efficiency by maintaining stable indoor temperatures with reduced energy consumption. However, these materials are often petroleum-based, posing challenges for disposal and contributing to higher CO2 emissions. In this context, adopting low-carbon insulation could reduce CO2 emissions from material production by over 80%. The market for bio-based insulation is expected to grow, reaching 2.3 billion euros by 2032, with an annual growth rate of 3% per year. A promising biobased insulation material is wood-based insulation that is influenced by the manufacturing process, binder content and the natural structure of wood. Strategies such as selecting lower density wood, smaller particle sizes, and lowering forming pressures have proven effective in achieving lower thermal conductivities. These strategies create small voids within the structure, increasing the complexity of the heat transfer path and thereby reducing thermal conductivity.

[0004] Additive Manufacturing (AM), still a relatively new and underexplored field in the building and construction sector, holds significant potential for contributing to energy efficiency initiatives. AM competes with traditional production methods by enabling complex designs with reduced tooling costs, optimized performance, minimal material wastage, a lower carbon footprint, and customizable geometries, making it a promising technology for sustainable construction.

[0005] Wood waste, including sawdust from various industrial processes, is an emerging material in the context of AM. Wood-based AM has demonstrated that it can recreate several physical properties of wood such as compressive, acoustic and insulative performance making it a promising technology. Wood combined with a binder creates an extrudable wood-based material that can be deposited layer by layer. Wood powders mixed with polymers, extrudable at plastic melting temperatures using Fused Filament Fabrication (FFF) or Fused Deposition Method (FDM), achieve good structural properties albeit at lower wood percentages, typically between 5% to 20%. In contrast, methods such as layer-by-layer binding, Direct Ink Writing (DIW), and Liquid Deposition Modeling (LDM) can incorporate higher wood percentages, from 60% to 100%, effectively leveraging more wood properties and increasing wood biomass usage. LDM is a promising method for AM that predominantly uses wood. To achieve sustainability, bio-based binders such as clay, gypsum and methyl cellulose mixed with wood powder have shown promising printability, exhibiting physical behaviors like wood in the final components.

[0006] However, physical properties such as thermal performance attributed to wood remain underexplored in LDM printing. Additionally, challenges associated with large-scale printing persist, including significant post-drying shrinkage, deformation and the need for efficient tool paths. To this end, there is a great need for scalable, eco-friendly wood-based composites which can be industrially shaped to obtain sustainable building materials.SUMMARY OF THE INVENTION

[0007] It is an object of the present invention to provide sustainable construction materials (i.e. articles disclosed herein) shaped from wood waste using 3D printing techniques, specifically LDM. These materials were developed using industrial wood waste combined with natural binders, specifically CMC, to ensure recyclability. The inventors successfully manufactured an exemplary article (a building block) measuring 200 mm high, 360 mm wide, and 220 mm deep, by 3D printing. Other molded articles (such as a cast board) were prepared by compression casting.

[0008] In one aspect, the present invention provides an article comprising a wood powder and a binder, wherein:

[0009] a ratio between the wood powder and the binder is between 10: 1 and 1.5:1;

[0010] a water content of the article is below 10%w / w;

[0011] the wood powder is characterized by mesh particle size between 10 and 10.000 micron;

[0012] and wherein the binder comprises any one of: carboxymethyl cellulose, starch, methyl cellulose, hydroxypropyl methylcellulose (HPMC), including any salt and any mixture thereof.

[0013] In one embodiment, the wood powder is derived from a soft wood, a hard wood, or a mixture thereof.

[0014] In one embodiment, the article is characterized by wood powder content of at least 60% by dry weight of the article.

[0015] In one embodiment, a ratio between the wood powder and the binder is between about 7:1 and about 2:1.

[0016] In one embodiment, the binder is CMC.

[0017] In one embodiment, the article is characterized by density between about 0.4 and about 0.6 g / cm3.

[0018] In one embodiment, the article is a 3D printed article.

[0019] In one embodiment, the 3D printed article has a height of at least 40 cm, or at least 50cm.

[0020] In one embodiment, the wood powder is characterized by mesh particle size between about 400 and about 3000 microns.

[0021] In one embodiment, the article is characterized by at least one of: compressive strength between about 0.6 to about 5 MPa and thermal conductivity between about 0.1 and 0.2 W / mK.

[0022] In another aspect, there is provided a method for manufacturing the article of the invention, comprising:

[0023] providing a shapeable composition comprising the wood powder, water and the binder, wherein a ratio between the wood powder and the binder is between 10:1 and 1.5:1; and a ratio between the wood powder and water is between 1:6 and 1:8;

[0024] shaping the shapeable composition by liquid modelling to obtain a wet article; and

[0025] drying the wet article, thereby obtaining the article.

[0026] In one embodiment, a w / w concentration of (i) the wood powder, (ii) the binder and (iii) water in the shapeable composition is between about 15 to about 25%, between about 5 and 15% and between about 60 and 75%, respectively.

[0027] In one embodiment, shaping comprises printing, and wherein the printing comprises applying extrusion force of at least 4 bar, at least 6 bar or between 4.5 and 8 bar and a temperature ranging between 1 and 200°C.

[0028] In one embodiment, drying is performed at a temperature between about 15 and 60°C; and wherein a ratio between the wood powder, and water in the shapeable composition is about 2:7.

[0029] In another aspect, there is provided an article comprising a wood powder and a binder, wherein:

[0030] a ratio between the wood powder and the binder is between 7 : 1 and 2:1;

[0031] a water content of the article is below 5%w / w;

[0032] the wood powder is characterized by mesh particle size between about 1000 and about 3000 micron;

[0033] and wherein the binder comprises any one of: carboxymethyl cellulose, starch, methyl cellulose, hydroxypropyl methylcellulose (HPMC), including any salt and any mixture thereof.

[0034] In one embodiment, the wood powder is derived from a soft wood, a hard wood, or a mixture thereof.

[0035] In one embodiment, the article is characterized by wood powder content of at least 70% or about 75% by dry weight of the article.

[0036] In one embodiment, a ratio between the wood powder and the binder is between about 4 : 1 and 5:1; and wherein the binder i s CMC .

[0037] In one embodiment, the article is characterized by density between about 0.4 and about 1.1 g / cm3.

[0038] In one embodiment, the article is a cast article.

[0039] In one embodiment, the cast article has a thickness of at most 5cm.

[0040] In one embodiment, the article is characterized by compressive strength between about 20 to about 60 MPa .

[0041] In another aspect, there is provided a method for manufacturing the cast article, comprising:

[0042] (i) providing wood particles having a mesh particle size between 5 and 15 mm (or more) and subjecting the wood particles to wet grinding to obtain wood powder having a mesh particle size between about 1000 and 3000 microns;

[0043] (ii) mixing the wood powder, water and the binder to obtain a shapeable composition, wherein a ratio between the wood powder and the binder in the shapeable composition is between 7:1 and 2:1; and a ratio between the wood powder and water in the shapeable composition is between 1 : 1 and 1 :2;

[0044] (iii) shaping the shapeable composition by casting to obtain a wet article; and

[0045] (iv) drying the wet article, thereby obtaining the article.

[0046] In one embodiment, step (i) further comprises drying the wood powder to obtain dry wood powder; and wherein step (ii) comprises mixing the dry wood powder, water and the binder to obtain a mixture, and grinding the mixture to obtain the shapeable composition comprising wood powder having a mesh particle size between 800 and 1200 microns.

[0047] In one embodiment, a w / w concentration of (i) the wood powder, (ii) the binder and (iii) water in the shapeable composition is between about 35 to about 50%, between about 5 and 15% and between about 40 and 55%, respectively.

[0048] In one embodiment, casting comprises any one of: compression casting, injection molding and vacuum molding; wherein the compression casting comprises applying pressure suitable for compression of the shapeable composition and a mold temperature ranging between 10 and 150°C.

[0049] In one embodiment, drying is performed at a temperature between about 30 and 100°C.

[0050] In one embodiment, a w / w ratio between the wood powder, and water in the shapeable composition is about 3:1.3.

[0051] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and / or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

[0052] Further embodiments and the full scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

[0053] In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the study of the following detailed description.BRIEF DESCRIPTION OF THE FIGURES

[0054] Figs. 1A-1H Initial sawdust of beech (a) and oak (e); Wood powder derived from beech (b, c, d) and oak (f, g, h), corresponding to Bl, B2, B3, and 01, 02, 03, respectively.

[0055] Fig.2 Wood-CMC wet paste formed into lumps before loading (B 1 formulation).

[0056] Figs. 3A-3B Image a: Custom 3D-printed nozzle designed for specimen fabrication. Image b: Specimen extraction process in progress: a. Partially sanded specimen being prepared for thermal conductivity testing, b. Specimen being prepared for compressive testing.

[0057] Figs. 4A-4C Specimens for compressive tests a.: Oak wood composites and b. beech wood composites, c. compressive test setup Instron ElectroPuls® E10000 Linear-Torsion press.

[0058] Figs. 5A-5C Specimens for thermal tests a. beech wood composites b. Oak wood composites, c. Hot Disk TPS setup for thermal conductivity tests.

[0059] Figs. 6A-6B Design schematics of large-scale 3D printed test blocks as a potential wall segment. First block (6A) having a single wall with a negative cantilever and a staggered infill pattern and a second block (6B) having a double wall without the cantilever design.

[0060] Fig. 7 Regression analysis between Thermal Conductivity and Compressive Strength of Wood Bio-Composite Specimens.

[0061] Figs. 8B1-8O3 Optical microscopy images showing the cross-section of dried 3D-printed oak and beech Wood-CMC specimens, highlighting particle distribution along the tool path.

[0062] Fig. 9 Optical microscopy images revealing interaction between Wood particles and CMC, the voids formed and CMC film coating (top: Bl specimen, bottom: B2 specimen).

[0063] Figs. 10A1-10C2 First and second blocks post printing stages: post printing wet state-first block (10A1) and second block (10A2); post printing deformation (side view) - first block (10B1) and second block (10B2); dried state (top view) - first block (10C1) and second block (10C2).

[0064] Fig. 11 post drying deformations in the block are illustrated in comparison to the wet state.

[0065] Fig. 12 illustrates a 3D printed block 2 using wood-CMC Beech formulation as a potential large scale wall segment unit with customizable infill geometries represented by tool paths.

[0066] Fig. 13 illustrates a representative 3D printed wall (a non-limiting non-hollow article disclosed herein) of 30 mm width using 16mm diameter nozzle; b) Dried and extracted specimen volume; c) Trimmed and shaped specimen for thermal testing; d) Trimmed and shaped specimen for compressive testing.

[0067] Fig. 14 illustrates corrugated-infill toolpath configurations with spacings of 0, 4, 8, 10, 12, and 14 mm (specimen width = 60 mm). The increasing offset allowed evaluation of air-gap formation and buildability prior to large-scale trials.

[0068] Figs. 15A-15C illustrate three gap configuration geometries of building blocks for buildability testing: overlapping (15 A), touching (15B) and separated (15C).

[0069] Figs. 16A-16C illustrate three geometries building blocks for thermal validation: overlapping (16A), touching (16B) and separated (16C).

[0070] Figs. 17A-17D illustrate building blocks and commercial Aircrete benchmark used for thermal testing. 17A: Aircrete block (benchmark), 17B: 14 mm gap geometry, 17C: 10 mm touching toolpath, and 17D: 4 mm overlap configuration.

[0071] Figs. 18A-18K include illustration of isometric views of building blocks with different peripheral walls and varying extending elements, according to some embodiments of the invention.

[0072] Fig.19 illustrates a flowchart for a method for manufacturing a building block, according to some embodiments of the invention.

[0073] Fig. 20 illustrates the custom SHB setup used for steady-state and transient thermal testing. The system consisted of a heated hot chamber and an ambient cold side separated by the test specimen. A PID-controlled electric heater and fan maintained uniform temperature distribution within the hot chamber. Nine K-type thermocouples recorded air, surface, and internal temperatures: two in the hot chamber (one connected to the PID controller), two on the hot surface of the block, two embedded within the block, two on the cold surface, and one in the ambient cold-side air. Temperature data were logged using a BTM-4208SD data logger for post-processing and analysis.

[0074] Fig.21 illustrates impact of toolpath spacing on geometric stability. Variable spacings (0-14 mm) demonstrate that the "touching" regime (8-10 mm) uniquely balances structural continuity with air retention, forming consistent vertical micro-gaps via controlled shrinkage, unlike the densified overlapping paths (0-4 mm) or unconnected separated paths (12-14 mm).

[0075] Fig. 22 illustrates shrinkage dynamics in the "touching" configuration (10 mm spacing). Schematic illustrating the transition from wet to dry state, where controlled lateral shrinkage (~5%) transforms initial proximity gaps (0.5-1 mm) into stable 2-2.5 mm vertical air channels, preserving internal porosity despite 10% vertical densification.

[0076] Fig. 23 is a graph showing average load-strain response of 3D printed geometries A (4 mm overlap), B (10 mm touching), and C (14 mm gap). Colored dots denote peak compressive strengths, revealing a performance hierarchy (A > B > C) driven by toolpath density. Geometry A achieves the highest strength (-3.82 MPa), while Geometry C exhibits progressive failure typical of porous configurations (-1.39 MPa).DETAILED DESCRIPTION OF THE INVENTION

[0077] The present invention is related, in some embodiments thereof, to an article comprising a wood powder and a binder, wherein a w / w ratio between the wood powder and the binder is between about 10:1 and about 1.5:1; a water content ofthe article is below 10%w / w; and wherein the wood powder is characterized by mesh particle size between 10 and 10.000 micron.

[0078] In some embodiments, w / w ratio between the wood powder and the binder is between about 10:1 and about 1.5:1, between 8:1 and 1.5:l,between7:l and 1.5:1, between 6:1 and 1.5:1, between 5:1 and 1.5:1, between 5:1 and 2:1, between 3:1 and 2:1, between 3:1 and 1.5:1, between about 10:1 and about 8:1, between about 8:1 and about 7:1, between about 7:1 and about 5:1, between about 10:1 and about 7:1, between about 10:1 and about6:l, between about 10:1 and about 5:1, between 10:1 and 2:1, between 10:1 and 2.5:1, between 10:1 and 3:1, between 8:1 and 2:1, between 8:1 and 3:1, between 7:1 and 3:1, between 7:1 and 2:1, between about 7:1 and about 3:1, including any range between. In some embodiments, the w / w ratio between the wood powder and the binder in the article is between 7:1 and 2:1, between 7:1 and 4:1, between 5:1 and 4:1, between 7:1 and 5:1, between 7:1 and 3:1, between 6:1 and 3:1, including any range between.

[0079] In some embodiments, water content of the article is below 10% w / w, below 8%w / w, below 5%w / w, below 3%w / w, below l%w / w, between 0.1% and 5%w / w, between 0.1% and 8%w / w, between 0.1% and 10%w / w, including any range between.

[0080] In some embodiments, the wood powder is characterized by mesh particle size between 10 and 10.000 micron, between 50 and 10.000 micron, between 100 and 10.000 micron, between 70 and 10.000 micron, between 10 and 5.000 micron, between 10 and 4.000 micron, between 10 and 3.500 micron, between 100 and 5.000 micron, between 200 and 5.000 micron, between 300 and 5.000 micron, between 500 and 5.000 micron, between 700 and 5.000 micron, between 900 and 5.000 micron, between 1.000 and 5.000 micron, between 1.000 and 4.000 micron, between 1.000 and 3.500 micron, between 1.000 and 3.000 micron, between 1.000 and 4.500 micron, between 1.000 and 6.000 micron, between 1.000 and 7.000 micron, between 1.000 and 8.000 micron, between 400 and 800 micron, between 800 and 1200 micron, between 500 and 4.000 micron, between 500 and 3.500 micron, between 700 and 4.000 micron, between 700 and 3500 micron, between 800 and 3.000 micron, between 1500 and 4.000 micron, between 1500 and 3500 micron, between 1500 and 3.000 micron, including any range between.

[0081] In some embodiments, the wood powder is characterized by mesh particle size below about 1500 micron, below about 1400 micron, below about 1300 micron, or below about 1200micron. In some embodiments, the wood powder is characterized by mesh particle size between about 200 and about 1500 micron, between about 300 and about 1500 micron, between about 300 and 1 about 300 micron, between about 300 and about 1200 micron, between about 400 and about 1200 micron, including any range between. In some embodiments, the mesh particle size refers to an average particle size (e.g. number average). In some embodiments, the mesh particle size refers to a particle size distribution of the wood powder. In some embodiments, the wood powder is derived from a soft wood; wherein at least 90%, at least 95% or at least 97% of the total number (or of the total weight) of particles have a mesh particle size distribution ranging between 400 and 1200 micron.

[0082] The term “Mesh particle size” may refer to the characteristic dimension of a particulate material as determined by passage through a standardized test sieve conforming to the requirements of ASTM El 1 or ISO 3310-1.

[0083] A particle is deemed to have a mesh particle size equal to the smallest sieve aperture, according to ASTM Ell or ISO 3310-1, through which all or substantially all of the particles pass under standard sieving conditions. Mesh particle size may also be specified as a range when particles are retained between two standardized sieve openings.

[0084] In some embodiments, the term “substantially all” encompasses at least 80%, at least 85%, at least 90%, at least 95%, at least 97% or at least 99% by weight or by number of the particles, including any range between.

[0085] In some embodiments, the wood powder is derived from a soft wood; wherein at least 90%, at least 95% or at least 97% of the total number (or of the total weight) of particles have a mesh particle size distribution ranging between 400 and 1200 micron, between 400 and 800 micron, or between 800 and 1200 micron.

[0086] In some embodiments, at least 80%, at least 85%, at least 90%, at least 95%, at least 97% or at least 99% or between 90 and 100%, between 95 and 100%, between 95 and 99% by weight of the article consists of the wood powder and the binder.

[0087] In some embodiments, the article of the invention consists essentially of the wood powder and the binder, and optionally of the natural fibers. In some embodiments, at least 80%, at least 90%, at least 95%, at least 97%, or between 80 and 99%, between 80 and 95%, between 90 and 95%, between 95 and 99%, between 90 and 97% of the article of the invention consists of the wood powder, the binder, and optionally of the natural fibers. In some embodiments, at least 80%, at least 90%, at least 95%, at least 97%, or between 80 and 99%, between 80 and 95%, between 90 and 95%, between 95 and 99%, between 90 and 97% of the article of theinvention consists of the wood powder and CMC, wherein the w / w ratio between the wood powder and CMC is as disclosed hereinabove.

[0088] In some embodiments, the binder is a cellulose-based polymer (e.g. comprising a cellulose backbone, and optionally further comprising chemically modified groups). In some embodiments, the binder is a chemically modified cellulose-based polymer.

[0089] In some embodiments, the chemically modified cellulose-based polymer is characterized by substitution degree between 0.2 and 3, between 0.5 and 3, between 0.5 and 2.5, between 0.5 and 2, between 0.5 and 1.5, between 0.5 and 1.3, between 0.5 and 1, between 0.7 and 1, between 0.7 and 0.9, between 0.7 and 1.5, between 0.7 and 2, including any range between.

[0090] In some embodiments, the binder is a chemically modified water-soluble cellulose-based polymer.

[0091] In some embodiments, the water solubility of the chemically modified water-soluble cellulose-based polymer is up to 20%, up to 15%, up to 10%, up to 8%, or between 1 and 10%, between 1 and 8%, between 1 and 6%, between 1 and 5%w / w, wherein water solubility is determined at 20°C in DDW.

[0092] In some embodiments, the binder comprises any one of: carboxymethyl cellulose (CMC), starch, methyl cellulose, hydroxypropyl methylcellulose (HPMC), including any salt and any mixture thereof. In some embodiments, the binder is or comprises CMC. In some embodiments, the CMC is characterized by weight average molecular weight (viscosity based, or as determined by GPC) between 100 and 500 kDa, between 100 and 400 kDa, between 100 and 350 kDa, between 100 and 300 kDa, including any range between.

[0093] In some embodiments, the CMC is characterized by viscosity of between about 300 and 600 cP (2% water solution, Brookfield, at 20°C) and by degree of substitution of 0.7-0.8.

[0094] In some embodiments, the article further comprises plant waste material. In some embodiments, the plant waste material comprises natural fibers. In some embodiments, the w / w concentration of the plant waste material in the article is between 1 and 20%, between 1 and 15%, between 1 and 10%, between 1 and 5%, including any range between.

[0095] In some embodiments, the natural fibers comprise cellulose-based fibers, lignocellulose fibers, polyphenol based fibers, lignin fibers, or any combination thereof. In some embodiments, the natural fibers are selected from water soluble fibers (e.g. psyllium husk fibers, flax fibers; mycelium, lignin fibers) and water-insoluble fibers (e.g. jute fibers, palm fibers, hay fibers, hemp, bagasse, stubble fibers, rice husk fibers, bamboo fibers, cotton fibers).

[0096] In some embodiments, the wood powder is derived from a soft wood, a hard wood, or a mixture thereof. The wood powder may be obtained from any processed wood material, such aswood part (e.g. stem, bark, branch, trunk) subjected to any wood processing such as cooking, delignification, humidification, drying, different types of grinding such as hammering, crushing, shredding / shearing, sawing; classification methods such as mesh sieving, sorting or any combination thereof.

[0097] In some embodiments, the article is characterized by wood content of at least 60%, at least 70%, at least 80%, at least 85%, or between 60 and 90%, between 70 and 90%, between 60 and 85% by dry weight of the article, including any range between.

[0098] In some embodiments, the article is a 3D printed article. In some embodiments, 3D printing comprises Liquid Deposition Modeling (LDM). In some embodiments, the article has a three-dimensional shape.

[0099] In another aspect, there is provided 3D printed article, comprising a wood powder and a binder, wherein a water content of said article is below 10%w / w; wherein the binder comprises any one of: carboxymethyl cellulose (CMC), starch, methyl cellulose, hydroxypropyl methylcellulose (HPMC), including any salt and any mixture thereof; the wood powder is derived from a soft wood; wherein at least 90% of the total number (or of the total weight) of the wood powder particles have a mesh particle size distribution ranging between 400 and 1200 micron and a w / w ratio between the wood powder and the binder is between about 5 : 1 and about 2: 1, or between 3 : 1 and 2: 1. In some embodiments, the 3D printed article is as disclosed herein, wherein the binder is or comprises CMC. In some embodiments, the 3D printed article is as disclosed herein, wherein the wood powder content thereof is between about 60% and about 80%, between about 60% and about 75%, between about 65% and about 75%, between about 65% and about 70%, between about 70% and about 80% by dry weight of the 3D printed article. In some embodiments, the 3D printed article is as disclosed herein, wherein the 3D printed article is characterized by density between about 0.3 and about 0.6 g / cm3, between about 0.3 and about 0.5 g / cm3, between about 0.4 and about 0.5 g / cm3, between about 0.5 and about 0.6 g / cm3, including any range between.

[0100] In some embodiments, the 3D printed article comprises at least one wall and is characterized by vertical (height) dimension of at least 30 cm, at least 40 cm, or at least 50cm or up to 70cm , up to 60 cm, up to 55 cm, including any range between. In some embodiments, the 3D printed article has a vertical buildability of up to about 60cm, up to 50cm, up to 55 cm, including any range between. In some embodiments, the at least one wall is a peripheral wall. In some embodiments, the peripheral wall has a curved shape or a polygon shape. In some embodiments, the 3D printed article is hollow (i.e. at least a portion of the article’s volume is void comprising macroscopic cavities, voids, or enclosed spaces that are separated from theexterior surface). In some embodiments, the 3D printed article is a non-hollow article (i.e. is a solid body whose internal volume is filled with material, such that the article does not contain internal cavities, voids, or enclosed spaces that are separated from the exterior surface). For purposes of this disclosure, ‘non-hollow’ means that the geometric interior volume is occupied by solid material, excluding incidental porosity or manufacturing-related micro-voids.

[0101] In some embodiments, the 3D printed article is further characterized by a minimum wall thickness of at least 10mm, at least 15mm, or between 5 and 30, between 5 and 20, between 10 and 30, between 10 and 20 or between 10 and 15 mm, including any range between.

[0102] In some embodiments, the 3D printed article is characterized by a compressive strength of at least 0.6 MPa, at least 1 MPa, at least 2 MPa, at least 3 MPa, at least 4 MPa, at least 5 MPa, including any range between.

[0103] In some embodiments, the 3D printed article is characterized by a compressive strength between about 0.6 to about 5 MPa, between about 1 to about 5 MPa, between about 2 to about 5 MPa, including any range between.

[0104] In some embodiments, the 3D printed article is characterized by a compressive strength as disclosed above and is further characterized by thermal conductivity between about 0.1 and 0.2 W / mK.

[0105] In some embodiments, the 3D printed article is a self-supporting article. In some embodiments, the 3D printed article is characterized by vertical shrinkage below 8%, below 7%, below 6%, below 5%, including any range between.

[0106] The 3D printed article of the invention comprises or consists of multiple alternating layers, which can be visualized microscopically, e.g. by SEM or by light microscopy. The thickness (e.g. average thickness) of each layer is uniform and may range from 0.1 to 10, or from 0.1 to 5, from 0.5 to 5, from 0.5 to 3, from 0.5 to 2, from 0.5 to 1, about 1mm, about 2mm or about 3mm including any range between.

[0107] In another aspect, there if provided a cast article comprising a wood powder and a binder, wherein a w / w ratio between the wood powder and the binder is between about 10:1 and 2: 1 or between about 10:1 and 5 : 1 ; a water content of the article is below 5%w / w; and the wood powder is characterized by mesh particle size below 400 microns. In some embodiments, the binder is as described above.

[0108] In some embodiments, the wood powder is of the cast article is derived from a soft wood and is characterized by mesh particle size between about 10 and about 400 microns, between about 100 and about 400 microns, between about 10 and below 400 microns, between about 10 and about 50 microns, between about 50 and about 100 microns, between about 50 and about400 microns, between about 100 and about 200 microns, between about 200 and about 400 microns, including any range between. In some embodiments, the wood powder is of the cast article is derived from a soft wood and wherein at least 90%, at least 95%, at least 97% of the total number (or total weight) of the wood powder particles have a mesh particle size distribution of below or ranging between 10 and 400 micron, between about 100 and about 400 microns, between about 10 and below 400 microns, between about 10 and about 50 microns, between about 50 and about 100 microns, between about 50 and about 400 microns, between about 100 and about 200 microns, between about 200 and about 400 microns including any range between.

[0109] In some embodiments, the cast article is characterized by wood powder content of at least 80%, at least 85%, or between about 80 and about 95%, between about 80 and about 94%, between about 80 and about 93%, between about 80 and about 91%, between about 80 and about 90%, between about 85 and about 90%, between 80 and 93%, between 80 and 85%, between 85 and 93%, between 85 and 92%, between 85 and 90%, between 88 and 93%, between 88 and 92%, between 88 and 90% by dry weight of the article, including any range between.

[0110] In some embodiments, the cast article is a homogenous single-layer article (i.e. no layers are visible microscopically).[Oil 1] In some embodiments, the cast article is characterized by athickness (width dimensions) of at most 10, at most 8, at most 5cm or between 0.1 and 5 cm, including any range between.

[0112] In some embodiments, the cast article is characterized by density of at least 0.65, at least 0.7, at least 0.8, between 0.4 and 1.1 g / cm3, between 0.4 and 0.6 g / cm3, between 0.4 and 0.65 g / cm3, between 0.6 and 1.1 g / cm3, between 0.65 and 1.1 g / cm3, between 0.7 and 1.1 g / cm3, between 0.75 and 1.1 g / cm3, between 0.8 and 1.1 g / cm3, between 0.9 and 1.1 g / cm3, between 0.9 and 1 g / cm3, between 0.65 and 0.8 g / cm3, between 0.65 and 0.9 g / cm3, between 0.65 and 0.7 g / cm3, between 0.7 and 0.9 g / cm3, between 0.7 and 0.8 g / cm3, between 0.7 and 1 g / cm3, between 0.8 and 0.9 g / cm3, including any range between.

[0113] In some embodiments, the cast article is further characterized by compressive strength of at least 1 MPa, at least 5 MPa, and up to 100 MPa, up to 90 MPa, up to 80 MPa, up to 70 MPa, up to 60 MPa, up to 50 MPa, including any range between.

[0114] In some embodiments, the article of the invention is devoid of a polymer which is not the binder disclosed herein.

[0115] In some embodiments, the article is biocompatible or bioerodible. In some embodiments, the article is at least partially degradable or biodegradable. In some embodiments, the article is at least partially erodible or bioerodible.Building block

[0116] Reference is now made to FIGS. 15A-15C and 17B-17D, which illustrate building blocks according to some embodiments. In some embodiments, a building block 100 may comprise a peripheral wall 10 and triangular extending elements 20 extending inward from an inner side of peripheral wall 10. As used herein, the inner side of the peripheral wall refers to the surface of the peripheral wall that faces the interior of the building block, as opposed to the outer side which faces outward from the building block.

[0117] Building block 100 may be fabricated using three-dimensional printing techniques, such as Liquid Deposition Modeling (LDM). Peripheral wall 10 forms an outer boundary of building block 100, while triangular extending elements 20 create internal structural patterns within building block 100.

[0118] In some embodiments, the material of peripheral wall 10 and triangular extending elements 20 comprises a wood powder and a binder. A ratio between the wood powder and the binder may be between 10:1 and 1.5:1. A water content of building block 100 may be below 10% w / w. The wood powder may be characterized by mesh particle size below 1200 micron. In some embodiments, the wood powder is derived from pine wood, which is a soft wood with favorable thermal characteristics.

[0119] With continued reference to FIGS. 15A-15C and 17B-17D, building block 100 may be configured with different toolpath (e.g., triangular extending elements 20) configurations that affect both structural integrity and thermal performance. In the nonlimiting example of Figs 15A-15C, a first configuration comprises an overlapping geometry with a 4 mm gap between adjacent triangular extending elements 20. In the overlapping geometry, triangular extending elements 20 are positioned close together, resulting in a dense, cohesive internal structure. A second configuration comprises a touching geometry with a 10 mm gap between adjacent triangular extending elements 20. In the touching geometry, triangular extending elements 20 are in near contact, forming narrow, stable vertical voids that trap air. A third configuration comprises a separated geometry with a 14 mm gap between adjacent triangular extending elements 20. In the separated geometry, triangular extending elements 20 have visible gaps between them, creating continuous hollow cores with higher porosity.

[0120] In some embodiments, building block 100 comprises corrugated infill geometries designed to maximize air entrapment and create discrete heat-flow breaks. Triangular extending elements 20 may be arranged in a zigzag pattern within the interior of peripheral wall 10, creating internal cavities and air gaps. The varying gap distances between triangular extending elements 20 in each geometry affect the thermal and structural properties of building block 100.

[0121] As further shown in the nonlimiting examples of FIGS. 15A-15C and 17B-17D, building block 100 may have a height of at least 40 cm, or at least 50 cm. In some embodiments, building block 100 achieves a maximum printable height of 445 mm using overlapping toolpath configurations. Building block 100 may have base dimensions of 250 mm by 100 mm. As should be understood by the one skilled in the art, the a height of, building block 100 may be any required height, for example, from 5 cm, 10 cm, 20 cm, 30 cm, 40 cm, 60 cm, 100 cm, 200 cm, or any value or range in between.

[0122] In some embodiments, building block 100 comprises shrinkage-induced micro-gaps between filament boundaries that enhance thermal resistance by introducing fine-scale air pockets. Building block 100 may exhibit lateral shrinkage of approximately 5% and vertical shrinkage of approximately 10% during drying. The shrinkage-induced micro-gaps may be uniformly distributed along the height of building block 100, producing a repeatable internal air network. In the touching geometry, filaments that are initially printed in near contact may undergo controlled dimensional reduction during drying, resulting in the formation of narrow, continuous vertical micro-gaps between adjacent extruded paths.

[0123] Reference is now made to FIGS. 16A-16C, which illustrate isometric views of nonlimiting examples of building block geometries according to some embodiments. FIG.16A shows Geometry A with an overlapping toolpath configuration having a 4 mm gap between adjacent triangular extending elements 20. FIG. 16B shows Geometry B with a touching toolpath configuration having a 10 mm gap between adjacent triangular extending elements 20. FIG. 16C shows Geometry C with a separated toolpath configuration having a 14 mm gap between adjacent triangular extending elements 20. In each configuration, peripheral wall 10 may have dimensions of approximately 105 mm in width and 260 mm in height.

[0124] With continued reference to FIGS. 16A-16C, triangular extending elements 20 may be arranged in a zigzag pattern within the interior of peripheral wall 10. The zigzag arrangement creates internal cavities and air gaps that affect the thermal and structural properties of building block 100. In Geometry A, the overlapping configuration provides greater structural continuity due to the close proximity of adjacent triangular extending elements 20. In Geometry C, the separated configuration provides increased air entrapment for thermal insulation purposes due to the larger gaps between adjacent triangular extending elements 20. Geometry B represents an intermediate configuration where triangular extending elements 20 are positioned in near contact.

[0125] In some embodiments, building block 100 may be characterized by a thermal conductivity between about 0.1 and 0.2 W / mK. Building block 100 may be characterized by a compressive strength between about 0.6 to about 5 MPa. In some embodiments, building block 100 may be characterized by a density between about 0.4 and about 0.6 g / cm3. The overlapping toolpath configuration of Geometry A may achieve higher compressive strength values, while the separated toolpath configuration of Geometry C may achieve lower thermal conductivity values due to increased air entrapment within the internal cavities.

[0126] As shown in FIGS. 16A-16C, building block 100 may comprise a double-walled structure with an outer shell for improved structural integrity during printing. The doublewalled structure may provide enhanced layer stacking and greater structural integrity for taller prints compared to single-walled configurations. In some embodiments, the double-walled structure reduces uncontrolled offsets and improves stability under the weight of upper and peripheral structures during the fabrication process.

[0127] Reference is now made to FIGS. 18A-18K, which illustrate top views of various building block configurations according to some embodiments. FIG. 18A shows a first building block 400 comprising a rectangular peripheral wall 10 and rectangular extending elements 21 arranged in an alternating pattern extending inward from opposite sides of peripheral wall 10. Rectangular extending elements 21 may be oriented perpendicular to peripheral wall 10 and may be spaced apart to create gaps between adjacent elements. The alternating arrangement of rectangular extending elements 21 may create a tortuous path for heat transfer, thereby enhancing thermal insulation properties of first building block 400.

[0128] FIG. 18B depicts a second building block 405 comprising rectangular peripheral wall 10 and rectangular extending elements 22 arranged in an interleaved configuration. Tapered extending elements 22 may extend from both the top and bottom sides of peripheral wall 10 toward the center of second building block 405, forming a gap between the free adages of rectangular extending elements 22 from opposite sides if block 405. In some embodiments, rectangular extending elements 22 may be tapered elements and may have wider bases at peripheral wall 10 and narrower free ends directed toward the interior of second building block 405. The interleaved configuration of tapered extending elements 22 may optimize air entrapment within the internal cavities formed between adjacent tapered extending elements 22.

[0129] FIG. 18C illustrates a third building block 410 comprising peripheral wall 10 and parallel extending elements 23 extending uniformly from one side of peripheral wall 10 toward the opposite side. Parallel extending elements 23 may be evenly spaced and orientedperpendicular to peripheral wall 10. The uniform arrangement of parallel extending elements 23 may create consistent air channels that function as thermal breaks within third building block 410. In some embodiments, a gap may be maintained between the free edge of parallel extending elements 23 and the opposite side of peripheral wall 10.

[0130] FIG. 18D shows a fourth building block 415 comprising peripheral wall 10 and triangular extending elements 24 extending upward from the bottom portion of peripheral wall 10. Triangular extending elements 24 may have pointed apexes directed toward the top of fourth building block 415.

[0131] FIG. 18E depicts a fifth building block 425 comprising peripheral wall 10 and triangular extending elements 24 arranged in an opposing configuration, with elements extending from both the top and bottom portions of peripheral wall 10 toward the center. The opposing arrangement of triangular extending elements 24 may create staggered infill patterns designed to create long heat-bridging paths for enhanced thermal insulation properties and allow extension of triangular extending elements 24.

[0132] FIG. 18F illustrates a sixth building block 430 comprising peripheral wall 10, angled extending elements 26, and tapered extending elements 22. Angled extending elements 26 may be oriented diagonally within peripheral wall 10. The diagonal orientation of angled extending elements 26 may increase the complexity of heat transfer paths within sixth building block 430, thereby reducing thermal conductivity. The combination of angled extending elements 26 and tapered extending elements 22 may provide both structural support and thermal break formation.

[0133] In some embodiments, the peripheral wall may circumflex the entire perimeter, as shown Figs 18A to 18F, with respect to wall 10, or may partially circumflex the perimeter, as shown in Figs 18G and 18H, with respect to a wall 11.

[0134] 18G shows a seventh building block 440 comprising a peripheral wall 11 and rectangular extending elements 21 extending from one side of peripheral wall 11, has a U shape and is open at one side. In some embodiments, rectangular extending elements 21 are arranged in a comb-like arrangement.

[0135] FIG. 18H depicts an eighth building block 445 comprising peripheral wall 11 having an open U shape, and tapered extending elements 22 extending from one side of peripheral wall 11 in a uniform pattern. The comb-like and uniform arrangements may create air pockets that disrupt conductive heat paths within seventh building block 440 and eighth building block 445.

[0136] FIG. 181 illustrates a building block comprising peripheral wall 10 and a combination of triangular extending elements 24 and rectangular extending elements 22 arranged in an interleaved pattern extending from both the top and bottom portions of peripheral wall 10. The interleaved pattern of triangular extending elements 24 may create internal cavities with varying dimensions that affect both structural integrity and thermal performance.

[0137] In some embodiments, the peripheral wall of the building block may have various shapes including but not limited to rectangular, square, hexagonal, triangular, or other polygonal configurations. In some embodiments, at least a portion of the prefrail wall may be curved. As illustrated by hexagonal peripheral wall 12 and triangular peripheral wall 13 in FIGS. 18J and 18K, the peripheral wall geometry may be selected based on desired structural, thermal, or aesthetic requirements for a particular application. In some embodiments, the peripheral wall does not need to be fully closed. The peripheral wall may be partially open or may comprise discontinuous wall segments while still providing structural support for the extending elements. The internal arrangement of extending elements, such as tapered extending elements 22, triangular extending elements 20, rectangular extending elements 21, parallel extending elements 23, triangular extending elements 24, or angled extending elements 26, may be maintained regardless of the peripheral wall geometry or whether the peripheral wall is fully closed or partially open.

[0138] It should be understood that the building block is not limited to polygonal configurations or shapes and may adopt any configuration, such as curved configuration. Further, it should be appreciated that the term “building block” in some embodiments thereof may refer to a modular structural unit that is designed to interconnect, associate, or assemble with one or more complementary units to form a larger structure, system, assembly, or functional article. Additionally, the building block may encompass an article for use in construction. Thus, this term may include any structural or functional unit — whether discrete or integral — that participates in the formation, stabilization, connection, modification, or operation of the overall assembly, including components that may not, individually, constitute a standalone building block in the conventional sense. A building block may be discrete, repeatable, and configurable, and may possess mechanical, chemical, geometrical, or functional features enabling its integration with other units.

[0139] Alternatively, or additionally, the term “building block” may refer to any 3-dimensional object. The 3D object may be used as a construction unit or a construction article.

[0140] Exemplary building blocks include but are not limited to bricks, masonry units, structural blocks, interlocking construction pieces, modular building components, etc.Manufacturing process

[0141] Reference is now made to FIG. 19, which illustrates a flowchart for a method 500 for manufacturing a building block according to some embodiments. Method 500 comprises a step 510, a step 520, and a step 530 that transform raw materials into a finished building block with desired structural and thermal properties.

[0142] In some embodiments, step 510 comprises providing a shapeable composition comprising the wood powder, water, and the binder. The shapeable composition may have a weightratiobetweenthe wood powder and the binder that is between about 10:1 and 1.5:1 or between 15:1 and 1.5:1. The shapeable composition may have a water content of at least 50%. In some embodiments, the shapeable composition has a w / w concentration of the wood powder between about 15 to about 25%, the binder between about 5 and 15%, and water between about 60 and 75%. The binder may be characterized by a viscosity of between about 300 and 600 cP measured as a 2% water solution using Brookfield at 20°C. In some embodiments, the binder is characterized by a degree of substitution of 0.7-0.8.

[0143] With continued reference to FIG. 19, step 520 comprises shaping the shapeable composition by liquid modelling to obtain a wet article. In some embodiments, step 520 comprises applying extrusion force of at least 4 bar, at least 6 bar, or between 4.5 and 8 bar. Step 520 may be performed at a temperature ranging between 1 and 200°C. The liquid modelling process forms the shapeable composition into the desired building block configuration including peripheral wall 10 and extending elements such as triangular extending elements 20, rectangular extending elements 21, tapered extending elements 22, parallel extending elements 23, triangular extending elements 24, or angled extending elements 26.

[0144] As further shown in FIG. 19, step 530 comprises drying the wet article, thereby obtaining the article with water content below 10% by weight. In some embodiments, step 530 is performed using a two-phase protocol comprising air drying at room conditions followed by hot air drying at elevated temperature. Step 530 may comprise air drying at a temperature of 21±3°C and relative humidity of 60±5% followed by hot air drying at 50-60°C. The drying process reduces the water content of the article and transforms the wet article into building block 100 with the desired structural and thermal properties.

[0145] In another aspect, there is provided a method of manufacturing the article of the invention (i.e. the 3D printed article), the method comprises providing a shapeable composition comprisingthe wood powder, water and the binder, wherein the shapeable composition has a weight ratio between the wood powder and the binder between 10:1 and 1.5:1 and a water content of at least 40% or at least 50%; shaping the shapeable composition by liquid modelling (e.g. printing) to obtain a wet article; and drying the wet article.

[0146] In some embodiments, a w / w ratio between the wood powder and the binder in the shapeable composition is between 10:1 and 1.5:1, between 8:1 and 1.5:1, between 8:1 and 2:1, between 8:1 and 3:1, between 7:1 and 2:1, between 7:1 and 3:1, between 6:1 and 2:1, between 5:1 and 1.5:1, between 5:1 and 2:1, between 3:1 and 1.5:1, between 2:1 and 1.5:1, between 3:1 and 2:1, between 4: 1 and 2:1, including any range between. In some embodiments, a w / w ratio between the wood powder and the binder in the shapeable composition is as disclosed herein, wherein the wood powder is derived form a soft wood and is characterized by mesh particle size between about 400 and about 1200 micron and / or by mesh particle size distribution ranging between 400 and 1200 micron, as disclosed above. In some embodiments, the binder is CMC.

[0147] In some embodiments, the water content of the shapeable composition is between about 60 and 80%, between about 60 and 75%, between about 70 and 80%, between about 70 and about 75%, including any range between. In some embodiments, a weight ratio between the wood powder and water in the shapeable composition is about 2:7.

[0148] In some embodiments, the method comprises shaping the shapeable composition by liquid modelling. In some embodiments, liquid modelling is or comprises 3D printing comprises. In some embodiments, liquid modelling is performed by applying extrusion force on the shapeable composition to dispense the shapeable composition through the printing head.

[0149] In some embodiments, the extrusion force is at least 4 bar, or at least 6 bar. In some embodiments, extrusion force is between 4.5 and 10 bar, between 4.5 and 9 bar, between 6 and 10 bar, between 6 and 8 bar including any range between.

[0150] In some embodiments, shaping is performed at a temperature (i.e. ambient temperature) ranging between 1 and 200°C, between 3 and 200°C, between 5 and 200°C, between 10 and 200°C, between 10 and 180°C, between 10 and 160°C, between 10 and 130°C, between 20 and 200°C, between 20 and 160°C, between 1 and 150°C, between 1 and 250°C, including any range between.

[0151] In some embodiments, drying is performed by any one of: convective air drying, hot-air drying, vacuum drying, desiccant drying, infrared drying, microwave drying, or any combination thereof. In some embodiments, drying is performed at a temperature between about 1 and 100°C, between about 15 and 60°C, between about 30 and 60°C, between about 40 and 60°C, between about 60 and 100°C, including any range between.

[0152] In another aspect, there is provided a method of manufacturing the cast article of the invention, the method comprises providing a shapeable composition comprising the wood powder, water and the binder, wherein the shapeable composition has a weight ratio between the wood powder and the binder between about 10 : 1 and 1.5:1 and a water content of at least 25%; shaping the shapeable composition by casting to obtain a wet article; and drying the wet article.

[0153] In some embodiments, a w / w ratio between the wood powder and the binder in the shapeable composition is between about 10:1 and 1.5:1, between about 10:1 and 5:1, between 8:1 and 5:1, between 8:1 and 2:1, between 8:1 and 3:1, between 7:1 and 5:1, between 7:1 and 3:1, between 6:1 and 2:1, between 5:1 and 1.5:1, between 5:1 and 2:1, between 3:1 and 1.5:1, between2:l and 1.5:1, between 3:1 and 2:1, between 4:1 and 2:1, including any range between. In some embodiments, a w / w ratio between the wood powder and the binder in the shapeable composition is as disclosed herein, wherein the wood powder is derived form a soft wood and is characterized by mesh particle size below 1500, below 1400, below 1300 or up to 1200 micron.

[0154] In some embodiments, the wood powder is characterized by mesh particle size between about 400 and about 1200 micron and / or by mesh particle size distribution ranging between 400 and 1200 micron, as disclosed above. In some embodiments, the wood powder is characterized by mesh particle size between about 400 and about 1200 micron and / or by mesh particle size distribution ranging between 400 and 1200 micron; and wherein a w / w ratio between the wood powder and the binder in the shapeable composition is between about 8:1 and 1.5:1, is between about7:l and 1.5:1, is between about 8:1 and 5:1, is between about 8:1 and 7:1, is between about 8:1 and 6:1, is between about 6:1 and 1.5:1, is between about 5:1 and 1.5:1, including any range between.

[0155] In some embodiments, the wood powder is characterized by mesh particle size below 400 micron, or between about 10 and about 400 micron and / or by mesh particle size distribution ranging between 10 and 400 micron; and wherein a w / w ratio between the wood powder and the binder in the shapeable composition is between about 10:1 and 1.5:1, is between about 10:1 and 8:1, between 15:1 and 8:1, between about 10:1 and 7:1, between about 8:1 and 7:1, is between about 8:1 and 6:1, including any range between.

[0156] In some embodiments, the water content of the shapeable composition is between about 25 and 60%, between about 25 and 55%, between about 25 and 40%, between about 30 and about 55%, between about 30 and about 40%, between about 30 and about 45%, between about 30 and about 50%, including any range between. In some embodiments, the water content of the shapeable composition is between about 25 and 55% and a w / w ratio between the woodpowder and the binder in the shapeable composition is between about 10:1 and 8:1 or between about 10:1 and 7:1.

[0157] In some embodiments, a w / w concentration of (i) the wood powder in the shapeable composition is between about 35 to about 65%, between about 35 to about 60%, between about 40 to about 65%, between about 35 to about 50%, between about 35 to about 40%, between about 40 to about 50%, between about 50 to about 65%; (ii) the binder in the shapeable composition is between about 5 and 15%, between about 5 and 10%, between about 10 and 15%, and (iii) water is and between about 30 and 55%, between about 30 and about 40%, between about 30 and about 45%, between about 30 and about 50%, including any range between.

[0158] In some embodiments, shaping is performed by casting, wherein casting is selected from or comprises any one of: compression casting, injection molding and vacuum molding, including any combination thereof. In some embodiments, compression casting comprises applying pressure suitable for compression of the shapeable composition and a mold temperature ranging between 10 and 250°C, between 30 and 250°C, between 10 and 50°C, between 50 and 250°C, between 50 and 100°C, between 100 and 250°C, including any range between. In some embodiments, pressure suitable for compression is between 5-50MPa, between 5-10MPa, between 10-20MPa, between 20-30MPa, between 30-50MPa, including any range between.

[0159] In some embodiments, drying of the wet cast article is as described above for the 3D printed article.

[0160] In some embodiments, at least 80%, at least 85%, at least 90%, at least 95%, at least 97% or at least 99% or between 90 and 100%, between 95 and 100%, between 95 and 99% by weight of the shapeable composition consists of the wood powder, water and the binder.

[0161] In some embodiments, the method of manufacturing the cast article further comprising a preliminary step performed before the providing step, wherein the preliminary step comprises providing wood particles having a mesh particle size between 0.3 and 15 mm (or more) and subjecting the wood particles to wet grinding to obtain the wood powder having a mesh particle size as disclosed hereinabove (i.e. below 400 micron or up to 1200 micron, such as between 400 and 1200 micron).General

[0162] As used herein the term “about” refers to ± 10 %.

[0163] The terms "comprises", "comprising", "includes", "including", “having” and their conjugates mean "including but not limited to".

[0164] The term "consisting essentially of' means that the composition, method, or structure may include additional ingredients, steps and / or parts, but only if the additional ingredients, steps and / or parts do not materially alter the basic and novel characteristics of the claimed composition, method, or structure. Thus, the term "consisting essentially of' means that in addition to the disclosed constituents, the composition or article may further include additive(s) such as colorant, stabilizer, preservative, etc. In some embodiments, the terms “substantially” and the term “consisting essentially of’ are used herein interchangeably.

[0165] The term “consisting of means “including and limited to”.

[0166] The word “exemplary” is used herein to mean “serving as an example, instance or illustration”. Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features from other embodiments.

[0167] The word “optionally” is used herein to mean “is provided in some embodiments and not provided in other embodiments”. Any particular embodiment of the invention may include a plurality of “optional” features unless such features conflict.

[0168] The term “enhancing” or “reducing” is by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 80%, at least 100%, at least 150%, at least 200%, at least 250%, at least 300%, including any range or value therebetween, compared to a control.

[0169] As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

[0170] Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0171] Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases “ranging / ranges between” a first indicate number and a second indicate number and “ranging / ranges from” afirst indicate number “to” a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween.

[0172] As used herein the term "substantially" refers at least 60 %, at least 70 %, at least 80 %, at least 85 %, at least 90 %, at least 95 %, at least 97 %, at least 99 %, at least 99.9 %, including any rage or value therebetween. In some embodiments, the terms “substantially” and the term “consisting essentially of’ are used herein interchangeably.

[0173] As used herein the term "method" refers to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the chemical, pharmacological, biological, biochemical, and medical arts.

[0174] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments unless the embodiment is inoperative without those elements.

[0175] Various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below find experimental support in the following examples. Reference is now made to the following examples, which together with the above descriptions illustrate some embodiments of the invention in a non-limiting fashion.EXAMPLESEXAMPLE 1

[0176] Composites tested in the research were fabricated using two types of wood powders: Beech and Oak. The wood, procured in the form of shavings, were selected based on their availability in local industries, Beech (Fagus sylvatica) known for density and machining for furniture and flooring industry and Oak (Quercus Robur) for sturdy, mechanical strength.

[0177] Wood powder was further classified into three particle size ranges to develop 6 formulations for the study as shown in Table 1. Beech and Oak wood shavings was procured in dry state and stored at ambient room conditions. Each wood sawdust shavings were groundinto wood powder using a Ninja® Nutri -Blender Pro with Auto-iQ®, model BN40 in the small batches of 2 / 3rdthe container capacity in 60 seconds auto mode. The ground wood was manually sifted for 5 minutes using a sifting column with three sections having 1200-micron, 800- micron and 400-micron mesh. In total six wood powder ranges were prepared, three for each wood type, classified into <400 microns, 400-800 microns and 800-1200 microns (Fig.1). Additionally, wood powder with a mesh particle size up to 3000 microns was successfully implemented by the inventors in the shapeable compositions disclosed herein for 3D-printing of articles.

[0178] ASEL TY 300 (Aciselsan, Turkey), a technical -grade sodium carboxymethyl cellulose (Na-CMC), was used as a binder and interface. It appeared as a white to creamcolored powder or granule with a CMC content of 60 ± 2% (dry basis), DS of 0.7-0.8, pH of 8-11 (1% sol.), viscosity of 300-600 cP (2% sol., Brookfield, 20°C), and max. moisture content of 15%. Na-CMC is known for its stable composition for storage, for not forming lumps too easily, and for its ease of dissolving in water at room temperature. Tap water at room temperature was used as the base for the formulations.Table 1. Properties of the wood composite materials tested.

[0179] Initial explorations were done in smaller batches to optimize the Wood / CMC ratio to increase wood content across all the particle size ranges. Wood / CMC ratios of 4:1, 3:1 and 2:1 by weight were tested for developing a homogeneous paste. Water requirement was different across particle sizes and wood types ranging between 7 to 7.75. The highest value of optimized water amount was chosen to achieve homogeneous paste with standard ratios throughout the formulations. For the specimen fabrication, all the formulations mixes were prepared using the same wood to binder to water ratios as 2: 1 :7.75. This ensured wood type and particle sizes are particularly investigated.

[0180] Material preparation was carried out in two phases. In the first phase, the wood powder and CMC powder, in 2:1 weight ratio, were dry mixed in a pan for 1 minute to achieve ahomogeneous, lump-free mixture. The mixture was then transferred to a planetary mixer for further processing. In the second phase, water was added in batches of 1 / 3 of the total weight, in 3 cycles, until a clay-like homogeneous paste was formed. This ensured uniform consistency of the mix. In total the six materials were prepared with the same wood to CMC ratios by weight. The formulation was named 01, 02, 03 and Bl, B2, B3 for fine, medium and coarse size particles, and for Oak and Beech respectively (Table 1). Owing to CMC’s gelling time, the material was given a resting time of 15-20 minutes before it was kneaded again to be loaded into the 3D printer extrusion tank.Material properties of Wet Mixture

[0181] The rheological properties of the clay like mixture for 3D printing were evaluated manually through observation and tactile manipulation. The wood CMC wet mix shows a viscoelastic behavior due to CMC’s properties. The mixture was assessed for its resistance to cracking and adhesion to evaluate homogeneity and optimal water content. Every lump was manually kneaded for the water and CMC to homogeneously spread into the viscoelastic solid mixture (Fig. 2).Fabrication of 3D Printed Specimens

[0182] To develop specimen for each formulation, a single tool path describing a free wall geometry of 150 mm length and 80mm height were fabricated using the printing parameters shown in Table 2. The tool path was designed in Rhinoceros 8 using the Grasshopper plugin, using the generative tool path facilitated by the Droid v2.0.8 plugin (“Droid - 3d Print Slicer and Path Plotter,” 2018 A delta type AM setup was used to print the specimen. The setup involved the Delta wasp 40100 LDM 3D printer assembled with an Extruder XL 3.0 and a 3 Liter tank. A custom extrusion nozzle was designed with a 16 mm output diameter and 3D printed using PLA (Fig 4, Image 1). The pressure at the source was 9 to 11 bar which was regulated by the pressure valve maintained at a constant 4.5-5 bar pressure to extrude the material for uniform layer thickness.Table 2. Printing parameters for specimen fabrication

[0183] A sturdy mesh base was used to print, serving as a transport tray and enabling ventilation for the base of the print during the drying process.

[0184] Each print was dried using a two-phase protocol, air drying in room conditions and hot air drying. Air drying was done for 4 days at the temperature of 21±3°C and relative humidity of 60±5%. A setup was created with two mini table fans placed at the top and the bottom of the specimen to keep constant airflow on all the surfaces promoting even drying. In the second phase, the hardened specimens were hot air dried with a dehydrator for 10 hours at the temperature of 50°C. Post drying, the dried specimens were extracted from the fully dried 3D printed wall (Fig. 3, Image b, i) as per the compressive (Fig. 3, Image b, iii) and thermal conductivity (Fig. 3, Image b, ii) test standards, and further sanded to achieve smooth parallel surfaces.Mechanical and Thermal Performance of Dried 3D Printed Specimens

[0185] The compression test was conducted on four specimens measuring 18 * 27 * 18 mm (Fig. 4, a & b), following ISO 13061-5:2020, chosen for its suitability in evaluating small wood specimens. The test was performed using an Instron ElectroPuls® El 0000 Linear-Torsion press, capable of exerting up to 10 kN (Fig. 4).

[0186] Thermal conductivity was assessed using an extracted pair of square prisms (50 x 50 x 15 mm) for each formulation in accordance with the Transient Plane Source (TPS) method as per ISO 22007-2:2022 using TPS 2500S® model of Hotdisk®. The sensor used for the test was Kapton insulated sensor number 8563 with a radius of 9.9mm (Fig. 5). The TPS method was selected due to its availability, accuracy, and reliability in measuring the thermal properties of wood composites. Each test went through five cycles of test and standard deviation was assessed.

[0187] Each extracted sample of square prisms was weighed to measure their apparent density. All specimens were conditioned and tested at approximately 60% relative humidity under ambient temperature conditions.Design and Fabrication of Block Component

[0188] To assess the buildability and customization potential of the proposed wood composite formulation for large-scale 3D printing in architectural and construction applications, two test blocks were designed and fabricated as potential wall segments. The block dimensions were kept 200 mm in height, 350 mm in width, and 220 mm in depth. These dimensions were chosen to fit within the constraints of the Wasp Delta 40100 3D printer, which has a 400 mm diameter print bed.

[0189] The first block design incorporated a combination of single-walled and double-walled structures. One of the walls incorporated a negative cantilever and a staggered infill pattern (Figs. 6A), which was employed to imitate long heat-bridging paths aiming to enhance thethermal insulation properties. The single wall paths varied in length from 35 to 70 mm to evaluate how the formulation performed in buildability. The tool path geometry was designed using Rhinoceros 3D software, with the custom slicing performed through the Grasshopper plugin to develop a continuous tool path per layer. The nozzle diameter for extrusion was 6 mm, and a layer height of 3.2 mm was used for both blocks and extrusion pressure 4.5-5 bar.

[0190] Based on the examination of the printing outcomes of the first block (6 A), a second block (6B) was designed and fabricated using fine-tuned material ratios to improve buildability. The cantilever design was removed, the toolpath overlap was increased, a double outer wall was added, keeping the overall build dimensions of (200 mm x 350 mm x 220 mm consistent to the first block. The same printing parameters were maintained and the material was extruded at 6.5 bar pressure.

[0191] Both blocks were measured immediately after printing and again after a 14-day drying period. These measurements provided insights into the structural integrity and dimensional stability of the printed components as the moisture content decreased during drying. The shrinkage, and any deformations observed during the drying process were recorded for further analysis.Results and Discussion

[0192] The experimental results from the three research phases revealed significant findings regarding the influence of wood type, particle size, and formulation ratios on the thermal and mechanical properties of wood-CMC composites developed for LDM printing. These findings, in correlation to the 3D printing buildability challenges of large-scale block components from the developed composites, will be discussed in the following sections.Mixture Development and Printability

[0193] The first phase of material development focused on maximizing wood content and optimizing CMC and water ratios to develop an extrudable mix across different particle sizes of beech and oak wood. CMC / wood ratios 1:4, 1:3,1 :2 was explored. The water ratio required to ensure a homogeneous, clay-like paste ranged between 7 and 7.5. The second phase focused on material preparation of the formulation mix of wood / CMC / Water at ratio 2: 1 :7.75 and checking printability. This ratio was achieved for coarse particle size which was standardized for all the mixes for further printing of specimens, ensuring only wood type and particle size are the parameters for further evaluation.

[0194] In the first phase, CMC / wood ratio 1 :4 rendered a non-homogeneous crumbly mix for all the particles leading to wood particle separation from the CMC gel on material manipulation. While medium and fine particles achieved optimal homogeneity at around 1:3ratio. 1 :2 ratio was optimal for all the particle sizes. Smaller particles required less CMC and water to form an extrudable paste, while coarser particles experienced binder separation under high-pressure extrusion when excessive CMC was added. Water demand remained similar for both beech and oak, with beech requiring slightly less (~1% difference). It was revealed that both wood and CMC absorb significant amounts of water and may also be particle size dependent but extrudability is primarily governed by the viscosity of the Water-CMC gel interface, the ability of wood particles to move within the interface and the extrusion pressure. Water availability for paste formation depends on the residual water after absorption by wood particles. Water absorption and extrusion characteristics of Wood-CMC composites are influenced by particle size, surface area, and water distribution. Larger particles required more water for extrudability due to their granular structure, which may have hindered uniform paste formation.

[0195] In the second phase, while all the particle sizes were found easily extrudable, the workability of the mix was found to be sensitive to time. For example, Beech formulations benefited from a 15-20-minute resting period to achieve optimal workability. This may be attributed to the swelling time for wood particles which is species dependent and CMC. The order of mixing the wood and CMC to water may also contribute towards change of water and CMC ratios in the mixture. Higher viscosity grades of CMC tend to retain more water due to their increased molecular weight and higher degree of substitution, affecting the rheological properties and extrudability of the paste.Influence of Wood Particle Size on Thermal Conductivity and Compressive Strength

[0196] For all tested formulations, a decrease in particle size corresponded to an increase in thermal conductivity. The highest thermal conductivity values were observed in Bl (0.218 W / m K) and 01 (0.188 W / m K), while the lowest were recorded for B3 (0.175 W / m K) and 03 (0.14 W / m K) for Beech and Oak, respectively. A similar trend was noted in compressive strength measurements. Among the tested specimens, B 1 exhibited the highest compressive strength at 4.1 MPa, whereas 03 had the lowest at 0.6 MPa. Furthermore, the measured thermal conductivity values were lower than the bulk thermal conductivity reported for Beech (0.2365 W / m K) and Oak (0.2582 W / m K). The formulations containing fine particle sizes exhibited the highest standard deviation, followed by coarse particles, with the lowest observed in medium-sized particles. This variability may be attributed to the formation of minor internal cracks in the fine particle formulations and the non-uniform particle rearrangement in the coarse particle formulations. Compressive testing of all specimensdemonstrated only vertical deformation, indicating high material porosity and horizontal fiber directionality influenced by the printing process.Table 3: Specimen density, thermal conductivity and compressive strength of formulations.

[0197] Compared to Air Crete, which exhibits a thermal conductivity range of approximately 0.1-0.15 W / m K and a compressive strength typically ranging from 0.5 to 3 MPa, the wood composite materials show comparable thermal insulation potential while offering enhanced mechanical performance in formulations such as B2.

[0198] This suggests that wood composite materials can serve as alternative for non-structural building components where moderate insulation and compressive strength are required such as for making wall panels, insulation blocks, and partition systems. Given that the required thermal conductivity for insulation materials typically falls below 0.2 W / m K, and non-structural load-bearing materials often require a compressive strength above 0.5 MPa, these composites are promising for functional integration into sustainable construction practices.Influence of Wood Type on Thermal Conductivity and Compressive Strength

[0199] Beech-based formulations overall exhibited higher compressive strength and thermal conductivity than Oak-based formulations. Highest being 4.1 MPa and 0.218 W / m.K in Beech, and 1.6 MPa and 0.150 W / m.K in Oak. This can be correlated with slightly higher bulk density of Beech 0.68 g / cm3than Oak 0.64 g / cm3. The R-value (correlation coefficient) for the regression analysis between thermal conductivity and compressive strength is approximately 0.898. This indicates a strong positive correlation between the two variables in the bio-composite specimens (Fig. 7). This shows that the composites carry forward the physical properties of the wood used in it. Denser materials tend to transfer heat more efficiently because they have fewer air gaps and more solid contact. While this is beneficialfor structural applications, it may be a drawback for insulation, where lower thermal conductivity is preferred.Influence of Particle Distribution and Orientation on Thermal Conductivity and Compressive Strength

[0200] Using optical microscopy, visual analysis of morphology and the microstructure at the cross section of samples was done. Particle distribution, voids and inter particle bonding were observed, which are the main characteristics that influence thermal and physical properties of the material. The microscopy images presented in Fig. 8 illustrate the presence of voids that increase as the particle size grows, which can be correlated with the thermal conductivity and compressive strength decrease. The particle distribution shows homogeneous layer bonding in all the particle sizes which explains material homogeneity during the print. Particles also exhibit an orientation in the direction of print, more evident in large particle size, which explains only vertical deformation in compression tests samples, may also contribute to anisotropic behavior in strengths. In the microscopic images in Fig. 9, fine and medium particle size samples show a microstructure composed of closed pores within wood particles and inter-particle voids that form open pores. The larger voids in coarse particles likely increased moisture permeability during drying, influencing drying deformations and overall dimensional stability.Thermal Conductivity of CMC

[0201] This study faces uncertainty regarding the thermal conductivity of CMC within the dried composite. As the binder, CMC’s thermal properties could impact the composite’s overall conductivity, but precise data on its behavior in this form is lacking. To control this, the CMC content was kept constant across all formulations, allowing variations in performance to be mainly attributed to wood particle size and type.Buildability Results of Block Component

[0202] In order to assess the buildability of the proposed wood composite formulation for large-scale 3D printing, two blocks were designed and fabricated as potential wall segment. Based on the results, the B2 formulation was selected for its balanced thermal conductivity, compressive strength, and low standard deviation to further assess its buildability for large-scale block components. The block dimensions were kept 200 mm in height, 350 mm in width, and 220 mm in depth. 6mm nozzle diameter, 3.2mm layer height were used as printing parameters to print both the blocks. The first block incorporated cantilever geometry on one of its sides and printed using original B2 formulation. The first block collapsed (Fig. 10, bl and cl) likely due to bulking, which can be attributed to high water content in the mix andcantilever design. The material also showed pulling effect towards the center of the volume which may be due to central material bulking. The stability of the wet material may also be with regards to the reduced material overlap, and single wall reducing support for buildup.

[0203] Using these observations block two was designed without cantilever geometry, double wall shell was incorporated along with higher overlapped tool paths. An improved formulation of B2 with reduced water with new ratios of wood / CMC / water as 2: 1:7.1 was used which rendered a successful printed block (Fig. 10, a2). Higher extrusion pressure, up to 6.5bar, was required to extrude the material. Post-printing, the structure exhibited significantly improved stability with negligible layer buckling. The observed deformations were primarily attributed to the material’s viscoelasticity, water content, and top-layer loading.

[0204] When analyzed overall, single-path walls exhibited weak layer adhesion, leading to uncontrolled offsets and reduced stability under the weight of upper and peripheral structures. Additionally, infill lines provided insufficient support beyond critical length. In contrast, double-walled geometry demonstrated improved layer stacking, offering greater structural integrity for taller prints. The second block was self-standing when transported post-printing.

[0205] The wet material weighed 11.1 kg post printing. After 14 days of air drying, it hardened completely, the final weight was 5.2 kg, reflecting a 53% reduction from the wet weight and a 76% water loss, yielding a lightweight component (Fig. 12). An average shrinkage was of -16.5% vertically and -6-8% horizontally (Fig. 11). The horizontal shrinkage was higher on the top compared to bottom. This may be due to the higher weight on the lower particles due to rearrangement during printing and drying. Incomplete loss of water can be due to moisture retention properties of wood and CMC, and the water locked in inside the wood particles due to slow drying. Methods like oven drying above degrees may trigger further water loss.

[0206] The potential for introducing new architectural building components (e.g., blocks, paneling systems, partitions, and modular walls) using rigid wood-CMC printed composites, exhibits a significant degree of consistency. This development holds promise for advancing sustainable construction practices by incorporating wood waste streams through 3D printing LDM technology, facilitating the scalability of customized, thermo-mechanically efficient structures, also exhibiting potential new expression for wood tectonics in architecture.EXAMPLE 2

[0207] The inventors successfully manufactured cast articles (boards). Compression stress resistance of pine wood chipboards produced by different grinding methods was tested. Experiment Description:

[0208] The experiment compared two grinding methods and their effect on the compression resistance of molded wood chipboards: (a) Grinding using an industrial meat grinder to prepare the EPPS mixture - Extruded Pine Planing Shavings; (b) Grinding using a centrifugal hammer to prepare the HPPS mixture - Extruded Pine Planing Shavings.Raw Material Grinding:

[0209] Material 1 EPPS:a. Boiling 1 kg of pine wood shavings. b. Grinding the shavings immediately after boiling using a meat grinder. c. Drying the material at 50°C for 30 hours.

[0210] Material 2: HPPS1 kg of pine wood shavings from the same source was ground using a centrifugal hammer.

[0211] Material 3: E&HPPS375 g of EPPS was further ground with the centrifugal hammer, creating a new material named E&HPPS.

[0212] Four Casting Mixtures Were Prepared According to the Following Formulas: a. 375 g (EPPS) + 500 g JLO + 125 g (CMC) = Sample No. 01. b. 375 g (HPPS) + 500 g H2O + 125 g (CMC) = Sample No. 02. c. 187.5 g (HPPS) + 187.5 g (EPSD) + 500 g H2O + 125 g (CMC) = Sample No. 03. d. 375 g (E&HPPS) + 500 g H2O + 125 g (CMC) = Sample No. 04.Preparation Method for the Mixture:

[0213] a. The dry wood materials were weighed according to the formulas above in a bowl on a calibrated scale.

[0214] b. Water was added.

[0215] c. The mixture was stirred with a wooden spoon to break up the wood shavings and achieve uniform consistency.

[0216] d. CMC was added in three portions, distributing it over the surface and gently folding it in to ensure uniform distribution and optimal surface contact between the CMC particles and the wood shavings.

[0217] e. The mixture was passed through the meat grinder to ensure water and CMC penetration and compression into the wood fibers.Casting Process:

[0218] 500 g of the prepared mixture was placed into a dedicated mold with dimensions of 184x184 mm. The mold was compressed with a force of 4 tons and kept under pressure for approximately 12 hours, during which the force dropped to around 2 tons.Demolding and Drying:

[0219] The cast element was removed from the mold and placed in a drying oven. A drying cycle was conducted according to the following sequence:a. 10 hours at 40°C.b. 10 hours at 50°C.c. 10 hours at 60°C.d. 10 hours at 70°C.

[0220] The final sequence continued until moisture content dropped to below 5%.Sample Testing:

[0221] Two samples, each approximately 90x90 mm, were cut from each board. Using a strength testing machine, force (KN) was applied to the center of each sample with a round tool of 2.5 cm diameter, covering an area of 4.9 cm2. The machine applied steadily increasing force until the sample cracked. The device recorded the material's compression relative to the applied force, generating a stress-strain graph.Calculating the Material’s Elastic Modulus:

[0222] The elastic modulus (E) is a measure of a material's resistance to applied stress — its strength. E represents the slope of the graph in its linear region. In the compression test, a unique graph structure emerged with two linear segments, indicating that the material undergoes a phase change due to compression, and from a certain point onward, the elastic modulus changes.Critical Stress (Fracture):

[0223] The evaluation of each sample concluded at the moment of critical stress, when the measured stress dropped to zero, and a crack appeared in the sample. A crack is a mechanical event where bonds in the material separate along its weakest path. Thus, the fracture event may potentially serve as a metric for tensile resistance.

[0224] The Strongest Sample in Terms of Elastic Moduli (El and E2): E&HPPS It can be assumed that the low specific weight of the sawdust provides a very large surfacearea and finely divided, open fibers. This enhances the interaction between the water and the CMC particles, resulting in a higher number and density of hydrogen bonds per unit volume. Another interesting observation supporting this hypothesis is the relatively high final weight of the board after the drying cycle, which may indicate a larger amount of water that was broken down to form hydrogen bonds and remained within the material's structure.

[0225] HPPS and 50%HPPS+50%EPPS Samples Show Very Similar Behavior It almost seems like they are the same material. However, two effects of the longer fibers present in the 50%HPPS+50%EPPS mixture can be observed: during the First Phase (El)-the longer fibers weaken the material and increase the strain per unit stress. During the E2 Phase- the presence of longer fibers improves the sample’s ductility, enhances E2, and even extends its duration. This suggests that the E2 phase represents a transition where compressive forces are converted into tensile forces.

[0226] To this end, the inventors successfully prepared cast boards using inert alia a 2-step grinding of the wood shavings. The mixture for the casting process is prepared by boiling the wood particles, then grinding the wet mixture. Then excess water is extracted, and the flakes are dried in the oven. The dry flakes are mixed with water and CNC and ground again. The prepared mixture can be used immediately or dried for future use.

[0227] Casting can be performed using one of the two following processes:- Compression casting into a flat mold with a ratio between 1 :2.5 to 1 :5 of volumetric change. This process is suitable for simple, extruded shapes, 8-30 mm in final thickness.- Injection molding into shaped molds. This process is suitable for more complex 3D shapes with many surface details.- Vacuum molding using a one sided mold. This process is suitable for preparing laminates of wood flour with other natural fibers.

[0228] Various wood types can be implemented as the source of wood particles (soft wood, such as pine; Hardwood, such as beach; wood bark, etc.). The molds can be heated up to 130 deg Celsius to reduce initial water content, improve binding and quicken the drying process.

[0229] The inventors further observed that the cast boards showed significant water resistance: over one hour until water absorption. Water absorption has been tested using a test similar to the ASTM F3191-23 : Standard Practice for Field Determination of Substrate Water Absorption (Porosity) for Substrates to Receive Resilient Flooring. In brief, a single water droplet was placed on a surface of a cast article. The time required for the droplet to be fully absorbed by the cast article (until the droplet is no longer visible in its round form) is estimated. When the droplet was applied on the cast article of the invention having the woodpowder derived from pine bark, it remained round and clearly visible on the surface, and only disappeared after several hours, indicating high water resistance of the cast articles disclosed herein.EXAMPLE 3Materials and methods

[0230] The feedstock for the composite was pine shavings derived from local furniture industry residues, selected for their favorable thermal characteristics ( = 0.09 W / m.K) and carbon-sequestering potential. The biomass was processed using a hammer mill (model YF3-1) at 2600-2800 rpm with a 16-mesh screen, yielding a maximum particle size of 1200pm. The CMC featured a degree of substitution of 0.7-0.8 and a viscosity of 300-600 cP in a 2% solution. Preparation began by air-drying the biomass at ~ 60% ambient relative humidity. A hammer mill (model YF3-1), operating at 2600-2800 rpm with a mesh size of 16 (approximately 1200 microns). Sieve analysis subsequently segregated the output into four distinct particle size distributions: fine (<400 pm), medium (400-800 pm), coarse (800-1200 um), and mixed (<1200 um).

[0231] To test the effects of particle morphology and binder content on composite rheology and performance, the study developed five distinct formulations. The first series, comprising Pine 1, Pine 2, Pine 3, and Pine Mixed 2, utilized specific particle size ranges of <400 pm, 400-800 pm, 800-1200 pm, and <1200 pm, respectively. These mixtures maintained a constant wood / binder / water weight ratio of 2:1:7 (see Table 4). This compositional standardization isolated the variable of particle coarseness to quantify its specific impact on thermal conductivity and compressive strength.

[0232] In contrast, the Pine Mixed 1 formulation (<1200 pm) addressed the influence of binder content. This mix employed a modified 4:1:14 ratio (wood / binder / water) to maximize biomass volume while maintaining printability at extrusion pressures of 6-6.5 bar. Comparative analysis between this formulation and Pine Mixed 2 elucidated the interplay between binder ratios and mixed particle sizes regarding buildability, thermal conductivity, and compressive strength.Table 4: Formulation matrix of pine wood waste-CMC pastes tested for material characterization

[0233] To develop the mixtures, first the wood and CMC powders were dry mixed ensuring no lumps are formed, followed by transfer to a planetary mixer where water was added incrementally until a homogeneous paste was formed. After preparation, the material was rested for 15-20 minutes, kneaded to into small balls.Fabrication and Drying Setup

[0234] Toolpaths were parametrically modelled and converted to G-code using the Rhinoceros 8 and Grasshopper computational design environment (Robert McNeel & Associates). The fabrication setup consisted of a Delta WASP 40100 LDM 3D printer equipped with an Extruder XL 3.0. Material was supplied via a 3 L tank for specimen-scale fabrication and a 5 L tank for large-scale fabrication. Source pressure was maintained at 9 bar, with downstream regulation tuned via a pressure valve to accommodate specific mixture requirements. A 3D-printed porous mesh (35% infill) served as the substrate, ensuring ventilation and providing a rigid base for the transfer and drying processes.

[0235] For initial material characterization, free-standing walls (30-32 mm thickness) were fabricated using a 16 mm internal diameter nozzle. This configuration employed an 8 mm layer height and a deposition velocity of 8.5 mm / s to ensure adequate material density and layer adhesion.

[0236] Subsequently, an 8 mm internal diameter nozzle was utilized for geometric investigations. Based on printability testing, optimal vertical stability was achieved using a 4 mm layer height, a printing speed of 25 mm / s, and an extrusion rate of 1.05, resulting in an extrusion width of 10-11 mm.

[0237] The drying and conditioning of the printed specimens were carried out under controlled environmental conditions. Initial drying was conducted in the print room, maintained at 23-25 °C and 60-70% relative humidity. The specimens were then transferred to a drying chamber set at 60°C to accelerate moisture removal and stabilize the material. The drying process was considered complete once the mass change was less than 1% over a 24-hour period, with the total drying time recorded for each sample. Following drying, the specimens were stored in an airtight container to prevent reabsorption of ambient moisture prior to testing.Specimen Development and Material Characterization

[0238] The study fabricated specimens for each formulation by printing single-toolpath wall geometries (150 x 30 x 80 mm) using a 16 mm nozzle, represented in Figure 2. To ensure uniform layer thickness despite source pressure fluctuations (9-11 bar), a pressure valve maintained a constant extrusion pressure of 4.5-5 bar. Following a thorough drying process, the study extracted and sanded test specimens from these walls to achieve the smooth, parallel finishes required for accurate measurement. These dimensions ensured that the final specimens adhered to the specific size requirements dictated by ISO standards, with exact printing parameters detailed in Table .Table 5: Printing parameters for specimen fabrication

[0239] For mechanical characterization, the study performed compression testing on four specimens , measuring approximately 20 x 20 x 25 mm (Figure 13) using an Instron ElectroPuls® E10000 Linear-Torsion press equipped with a 10 kN load cell. This procedure followed ISO 13061-5:2020, a standard selected for its suitability in evaluating small-scale wood specimens.

[0240] Simultaneously, the study assessed thermal conductivity using a pair of square prisms (50 x 50 mm, for each formulation. This analysis employed the Transient Plane Source (TPS) method via a HotDisk® TPS 2500 S system, utilizing a Kapton-insulated sensor (radius 9.9 mm) across five test cycles per sample.Material Characterization and Selection

[0241] To test the effects of particle morphology and binder content on composite performance, the study evaluated five formulations across two investigative streams. The first series (Pine 1, 2, 3, and Mixed 2) maintained a constant 2:1:7 wood-to-binder-to-water ratio to isolate particle coarseness (<400 to <1200 pm) as the primary variable. Conversely, the study utilized the Pine Mixed 1 formulation with a 4: 1 : 14 ratio to maximize biomass volume and assess binder influence. Table presents the comprehensive physical, thermal, and mechanical data obtained from these investigations.Table 6: Material characterization results for pine-based composites and Aircrete benchmark.

[0242] Thermal conductivity (X) values across the tested formulations ranged from 0.117 to 0.147 W / m K, with the lowest conductivity observed in the Pine 2 composition. This trend highlights the impact of particle morphology and binder content, as reduced binder fractions and specific particle coarseness likely increased air entrapment and disrupted conductive networks. In contrast, Pine Mixed 2 (50% binder) exhibited the highest thermal conductivity at 0.147 W / m K, suggesting that the continuous matrix formed by a higher binder-to-wood ratio facilitates heat transfer. Regarding thermal storage, Pine Mixed 2 achieved the highest specific heat capacity (0.5689 MJ / m3K), while both Pine Mixed 1 and 2 demonstrated the lowest thermal diffusivity (0.26 mm2 / s), signifying slower heat propagation and superior insulation stability compared to the coarser single -fraction mixes.

[0243] The compressive strength results revealed a direct correlation between binder content and mechanical integrity. Pine Mixed 2 achieved the highest compressive strength at 3.58 ± 0.40 MPa, significantly outperforming the other formulations and exceeding the Aircrete benchmark (2.5 ± 0.2 MPa). While Pine Mixed 1 (25% binder) offered a lower compressive strength of 1.81 ± 0.10 MPa, it maintained a better balance of thermal insulation and density. The single-fraction formulations, Pine 2 and Pine 3, yielded the lowest strengths at 1.70 ± 0.18 MPa and 1.57 ± 0.32 MPa, respectively. These findings indicate that while higher binder concentrations enhance structural load-bearing capacity, a reduction in binder, as seen in PineMixed 1, is necessary to optimize the composite for thermal insulation while retaining sufficient stability for fabrication.

[0244] To this end, a broader particle size range was found to enhance packing density and material homogeneity while minimizing drying deformation compared to uniform particle sizes. During these trials, the influence of binder ratios was particularly evident in the mixed-particle formulations (Pine Mixed 1 and Pine Mixed 2). Specifically, the low-binder variant, Pine Mixed 1, consistently reached superior build heights across all trials, peaking at 125 mm. This performance demonstrates significantly enhanced structural stability during deposition compared to the high-binder variant. Due to its optimized balance of insulation, strength, and buildability, this 25% binder composite (i.e. a composite having a weight ratio between the wood powder and binder of 3:1) was selected as the reference formulation for subsequent material-geometry optimization.EXAMPLE 4Self-Supporting 3D-Printed articles

[0245] We designed toolpath geometries to optimize thermal resistance and structural integrity. Surprisingly, we identified material overlap as a critical printing parameter. Figure 14 illustrates the six corrugated-infill specimens (60 x 60x 250 mm) fabricated using toolpaths designed to maximize air entrapment and create discrete heat-flow breaks. By systematically varying the printed spacings from 0 to 14 mm, we evaluated how filament separation affects the dual objectives of vertical buildability and air retention within the cavities.

[0246] Before measuring shrinkage and dimensional changes, we dried all specimens to a constant mass. This spacing series revealed three distinct regimes:1. Overlapping (0-4 mm): Produced solid, robust structures with minimal air gaps. 2. Touching (8-10 mm): Positioned filaments in near-contact to form narrow, stable vertical voids that trap air.3. Separated (12-14 mm): Created continuous hollow cores with higher porosity but lower structural stability.

[0247] To evaluate the large-scale feasibility of these regimes, we redesigned three specific configurations, 4 mm (overlapping), 10 mm (touching), and 14 mm (separated), to incorporate a supporting wall, as illustrated by the toolpaths in Figure 15. We printed these toolpaths as tall block units with a 250 x 100 mm base footprint, extending the height to the printer’s 500 mm limit. We recorded the maximum print height achieved until the onset of structural or buildability issues.Hot Box Evaluation of Thermal Blocks

[0248] To evaluate thermal behavior at a geometrical scale, three buildability -validated configurations, overlapping, touching, and separated, were selected for block fabrication Figure 16. Toolpath dimensions were adjusted to compensate for the shrinkage of the Pine Mixed <1200 microns (Wood / CMC, 4:1, PM1) formulation, Specifically, the toolpaths accounted for approximately 10% vertical and 5% lateral shrinkage observed during the drying process. The gaps were kept the same. The fabricated blocks are shown in Figure 17.

[0249] Thermal behavior was evaluated using a Simple Hot-Box (SHB) method. While conventional guarded or climatic hot boxes offer higher precision, previous studies have demonstrated that SHBs provide stable and reliable measurements under controlled laboratory conditions. A custom SHB was designed and built for this study. Figure 20 shows the schematics of SHB. The test opening measured 250 x 250 mm, accommodating both composite and reference blocks.

[0250] To characterize the thermal response of the printed components, two complementary protocols were conducted using a simple hot-box setup instrumented only with thermocouples to track temperature evolution across the specimen.

[0251] The steady-state protocol follows the fundamental principles of calibrated hot-box testing for stabilized temperature gradients as outlined in established standards (ISO 8990, 1994.). The transient protocol is adapted from dynamic hot-box and heat-pulse studies commonly used to examine thermal storage, time lag, and delayed heat transfer in low-density or heterogeneous material.• Steady-state test - hot-side chamber maintained at 50 °C for 10 h, with temperature gradients monitored to assess equilibrium response.• Transient test - hot-side heated to 80 °C for 10 min, then switched off. Cooling and dissipation were tracked for 10 h to evaluate storage and delayed transfer.

[0252] Performance analysis was based on temperature gradients and time-dependent propagation, enabling comparative assessment with Aircrete.Compression Testing of Multi-Regime Corrugated Specimens

[0253] To assess structural adequacy in larger scale, compressive tests were also carried out on printed 100 x 100 x 100 mm cubic specimens representing three toolpath configurations: A (4 mm overlap), B (10 mm touching), and C (14 mm gap). Each configuration was tested using three trimmed samples on a 250 kN universal testing machine, and the stress-strain response was recorded up to 50-60% strain to determine compressive strength, stiffness, and deformation characteristics. Tests were performed using a 250 kN universal testing machine.Effect of Toolpath Spacing on Shrinkage and Air Retention

[0254] To evaluate the printing performance of the wood-CMC composite, we fabricated six corrugated specimens with varying toolpath spacings (0-14 mm) using an 8 mm nozzle to analyze air retention and shrinkage (Figure 21). Following this, we scaled three specific regimes: overlapping (4 mm), touching (10 mm), and separated (14 mm), into large-scale blocks with a 250 x 100 mm base, to test vertical build limits toward 500 mm.

[0255] The touching toolpath configurations (8-10 mm spacing) exhibited a distinct shrinkage-driven morphological transformation after drying. As illustrated in Figure 22, filaments that were initially printed in near contact underwent controlled dimensional reduction, resulting in the formation of narrow, continuous vertical micro-gaps between adjacent extruded paths. Quantitative measurements indicated an average lateral shrinkage of approximately 5% per filament, cumulatively generating vertical air channels, while vertical shrinkage across the printed height reached approximately 10%. Despite this dimensional change, the touching specimens maintained structural continuity and did not exhibit interlayer separation or collapse, confirming adequate material support during printing and drying. The resulting micro-gaps were uniformly distributed along the height of the specimens, producing a repeatable internal air network without the large voids observed in the separated (12-14 mm) regime. Compared to overlapping toolpaths (0-4 mm), which densified during drying and eliminated most internal voids, the touching geometry preserved air entrapment while retaining geometric stability.Large-scale buildability tests

[0256] To evaluate the vertical build limits of the wood-CMC composite, the study scaled the toolpath configurations into large-scale blocks using three specific spacing regimes: overlapping (4 mm), touching (10 mm), and separated (14 mm).

[0257] All three configurations significantly exceeded the literature benchmark. The overlapping geometry (4 mm) achieved the maximum height of 445 mm, maintaining continuous material support throughout the build, though minor buckling was observed beyond the 350 mm mark. The touching configuration (10 mm) reached a height of 390 mm; while cross-sectional analysis revealed a widening of the supporting voids, the structure remained stable without critical buckling. The separated geometry (14 mm) achieved 300 mm, remaining self-supporting despite a higher susceptibility to layer disconnection. These results demonstrate that wood-CMC composites can yield tall, stable prints far exceeding previously reported limits when toolpath spacing is carefully controlled. Consequently, thestudy identified the overlapping and touching configurations (4-10 mm) as the most reliable strategies for large-scale fabrication.Hot Box Evaluation Results

[0258] To comprehensively evaluate the thermal behavior of the scaled-up composite blocks, the study employed a dual-testing methodology comprising both steady-state and transient hot-box evaluations. While steady-state analysis serves as the established standard for quantifying long-term heat transfer and thermal resistance under equilibrium conditions(“EN 12667,” n.d.) it does not fully account for thermal inertia — the material's dynamic capacity to absorb, store, and delay heat release.

[0259] Consequently, transient hot-box testing was conducted following established protocols to characterize the time-dependent thermal response of the printed geometries. The experimental setup compared three Pine Mixed 1 configurations against a commercial Aircrete benchmark ( = 0.104 W / m K). These printed specimens included a solid 4 mm overlap geometry (Block 1), a 10 mm touching toolpath (Block 2), and a 14 mm separated toolpath (Block 3), representing a gradient from continuous to discontinuous internal structures.

[0260] The steady-state performance results, summarized in Table 7, indicate that internal discontinuity significantly enhances thermal resistance. Efficiency in this phase was defined by the internal equilibrium temperature and the temperature gradient (AT) maintained between the hot and cold surfaces. The 14 mm gap block (Block 3) achieved a temperature difference of 20.9 °C, which is nearly identical to the Aircrete benchmark of 21.5 °C. Furthermore, the time required to reach steady-state equilibrium increased proportionally with porosity; the 14 mm configuration required 4.06 hours to stabilize, compared to only 1.46 hours for the densified 4 mm overlap block. These gradients reflect different levels of resistance to heat transfer, as larger air pockets increased the distance and time for heat to travel through the material.

[0261] Table 7: Steady-state thermal results for scaled-up printed blocks and Aircrete benchmark.

[0262] Time to steady state: The 4 mm overlap block reached equilibrium fastest, stabilizing within about 1.5 hours. In contrast, the 10 mm touching and 14 mm gap blocks required longer to stabilize, approximately 2.9 hours and 4.1 hours, respectively. The Aircrete block reached steady state in roughly 3.5 hours, between the touching and gap cases. The gradual increase in time corresponds to the growing amount of entrapped air, which slowed the transfer of heat through the material. Internal temperature: At equilibrium, the 4 mm overlap block recorded the highest internal temperature (-41.8 °C), while the 10 mm touching and 14 mm gap blocks reached lower steady-state temperatures (-38.4 °C and -38.1 °C, respectively). The Aircrete showed a similar temperature (-38.6 °C). The lower internal temperatures in the touching and gap blocks indicate that less heat passed through the section under steady-state conditions.

[0263] Temperature difference (AT): The largest temperature gradients between the hot and cold sides were observed in the 14 mm gap block (-20.9 °C) and Aircrete(~21.5 °C), while the 4 mm overlap showed the smallest gradient (-19.6 °C). The 10 mm touching geometry maintained an intermediate AT (-18.9 °C). These gradients reflect the different levels of resistance to heat transfer, larger voids and air pockets increased the distance and time for heat to travel through the block. Together, these results show how geometry directly shapes the thermal response of the printed composite. The more open configurations slowed down heat flow, reaching equilibrium more slowly but sustaining higher temperature differences, a behavior comparable to commercial Aircrete.

[0264] These results demonstrate that geometrical porosity directly modulates insulation performance: narrower toolpaths act more like solid blocks, transmitting heat faster, while designed gaps enhance resistance by promoting air entrapment. Aircrete aligned most closely with the 14 mm gap configuration, suggesting that Pine Mixed 1 composites can achieve comparable insulation.

[0265] The transient hot-box analysis (80 °C hot-side heating for 10 minutes followed by 10 hours of cooling) revealed distinct differences in how each geometry absorbed, stored, and released heat (Table 8). Internal peak temperature: The 4 mm overlap block reached thehighest internal peak temperature of 38.95 °C, occurring after 7.84 hours, indicating a fast rise and delayed equilibrium. The 10 mm touching geometry peaked slightly lower at 38.75 °C but much earlier, after only 2.49 hours, showing rapid equilibration and quicker heat diffusion through the structure. The 14 mm gap block reached a comparable peak of 37.95 °C but at a later time (5.12 hours), while the Aircrete benchmark showed a nearly identical peak (37.95 °C) and delay (7.78 hours). The similar timing and magnitude between the 14 mm gap and Aircrete confirm that the designed internal porosity in the wood-CMC composite reproduces the transient heat-storage behavior of lightweight commercial materials. Thermal inertia: Half-cooling times, the time required for each specimen to lose half its stored heat, remained similar across all samples (~ 0.17 hours), but the overall decay profiles differed. The 14 mm gap and Aircrete maintained higher post-peak temperatures for longer durations, illustrating greater capacity to retain and gradually release stored heat compared with the denser 4 mm overlap block.

[0266] Together, these results show how the degree of internal voiding governs not only steady-state resistance but also the transient heat-storage and release behavior of the printed composites.Table 8: Transient thermal performance of scaled-up printed blocks and Aircrete benchmarkCompressive Test Results

[0267] The uniaxial compression tests revealed a clear mechanical hierarchy among the three toolpath geometries as illustrated in Figure 23. The data confirms that load-bearing capacity was directly dictated by the degree of filament contact in the order of A > B > C. Geometry A, characterized by a 4 mm overlap (represented by the blue curve in the graph), exhibited the most robust performance with a peak compressive strength of 3.82 MPa. This configuration significantly exceeded the Aircrete benchmark of ~2.5 MPa, largely due to itscontinuous filament contact which produced a dense, cohesive internal structure. The resulting stress-strain response featured a steep initial slope and gradual post-peak softening, characteristic of a strain-tolerant composite. Even at 10% strain, this geometry maintained a high stress level of ~3.5 MPa, confirming its superior structural stiffness and stability compared to the other configurations.

[0268] In contrast, the 10 mm touching geometry (Geometry B), shown as the green curve, demonstrated intermediate strength, averaging 2.54 MPa. While this value aligns closely with the Aircrete benchmark, the specimens exhibited greater variability; some approached the high performance of the overlapped geometry, while others plateaued earlier. This fluctuation suggests that shrinkage-related micro-discontinuities at the filament interfaces may have created localized weaknesses. Despite this, Geometry B maintained a balanced combination of stiffness and ductility, validating its suitability for component-scale architectural applications where moderate load-bearing capacity is required.

[0269] The 14 mm gap geometry (Geometry C), depicted by the orange curve, proved to be the weakest configuration, with an average peak strength of only 1.39 MPa. Its high porosity significantly hindered vertical load transfer, leading to early stress plateaus and pronounced deformation, as evidenced by the lower peak on the strain graph. Unlike the denser configurations, Geometry C failed through progressive crushing and localized wall buckling rather than abrupt structural failure. While its load-bearing capacity was limited — sustaining only ~1.4 MPa at 10% strain — the gradual post-peak behavior suggests a capacity for energy absorption typical of discontinuous porous structures.

[0270] Overall, these results demonstrate that the mechanical behavior of bio-based, waste-derived composites can be tailored up to the material limitations through toolpath design. The transition from overlapping to separated filaments, clearly visible in the diverging trajectories of the load-strain curves, illustrates a direct trade-off between material continuity and porosity.

[0271] To this end, the inventors observed that while hardwood benchmarks (Beech / Oak) required higher binder-to-wood ratios and exhibited significant deformation, the Pine-based formulations (soft wood) achieved lower binder concentrations combined with larger particle sizes resulted in superior dimensional stability. The optimized Pine formulations achieved a vertical shrinkage of less than 8%. This represents a >50% reduction in deformation compared to the -16.5% vertical shrinkage recorded for Beech-based benchmarks. The discovery that increasing particle size to 1200 microns while maintaining a relatively lowbinder content further stabilizes the matrix, contradicts standard material behavior where less binder typically increases shrinkage and cracking.

[0272] Furthermore, the inventors developed an Ultra-High Loading Formulation (<400pm): A wood-to-binder ratio of 10:1 by weight (with 30-35% water in the shapeable composition) was successfully realized using Pine particles under 400 microns. The shapeable composition further underwent casting to obtain a cast article with a dry biomass content of -90.9%.

[0273] Unless explicitly stated, the method embodiments described herein are not constrained to a particular order or sequence. Furthermore, all formulas described herein are intended as examples only and other or different formulas may be used. Additionally, some of the described method embodiments or elements thereof may occur or be performed at the same point in time.

[0274] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents may occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

[0275] Various embodiments have been presented. Each of these embodiments may of course include features from other embodiments presented, and embodiments not specifically described may include various features described herein.

Claims

CLAIMS1. An article comprising a wood powder and a binder, wherein:a ratio between the wood powder and the binder is between about 10:1 and 1.5:1;a water content of said article is below 10%w / w;the wood powder is characterized by mesh particle size between 10 and 10.000 micron; and wherein the binder comprises any one of: carboxymethyl cellulose (CMC), starch, methyl cellulose, hydroxypropyl methylcellulose (HPMC), including any salt and any mixture thereof.

2. The article of claim 1, wherein the wood powder is characterized by mesh particle size below about 1200 micron.

3. The article of claim 1 or 2, characterized by wood powder content of at least about 60% by dry weight of the article.

4. The article of any one of claims 1 to 3, wherein a ratio between the wood powder and the binder is between about 5:1 and about 1.5:1 or between about 3:1 and about 2:1; wherein the wood powder is derived from a soft wood; and wherein the wood powder is characterized by mesh particle size between about 400 and about 1200 micron.

5. The article of any one of claims 1 to 3, wherein a ratio between the wood powder and the binder is between about 10:1 and about 5:1; wherein the wood powder is characterized by mesh particle size between 10 and 400 micron or below 400micron; and wherein the wood powder is derived from a soft wood.

6. The article of claim 4, wherein the wood powder content is between about 60% and about 80% by dry weight of the article.

7. The article of claim 5, wherein the wood powder content is between about 80% and about 95% or between about 85% and about 90% by dry weight of the article.

8. The article of any one of claims 1 to 7, wherein the binder is CMC.

9. The article of any one of claims 1 to 4, 6 and 8, wherein at least 90% of the total weight of particles in the wood powder have a mesh particle size distribution ranging between 400 and 1200 micron; and wherein said article is a 3D printed article.

10. The article of claim 9, wherein the 3D printed article has a vertical buildability of up to about 60cm.

11. The article of claim 9 or 10, characterized by density between about 0.4 and about 0.6 g / cm3 and further characterized by at least one of: compressive strength between about 0.6 to about 5 MPa; thermal conductivity between about 0.1 and 0.2 W / mK; and by vertical shrinkage below 8%.

12. The article of any one of claims 5, 7 and 8, wherein at least 90% of the total weight of particles in the wood powder have a mesh particle size distribution ranging between 10 and 400 micron; and wherein said article is a cast article.

13. The article of claim 12, characterized by density between 0.65 and 1.1 g / cm3 and further characterized by compressive strength up to 100 MPa.

14. A building block, comprising a peripheral wall and one or more extending elements, extending inwards from an inner side of the peripheral wall; wherein:a material of the peripheral wall and of the one or more extending elements comprises a wood powder and a binder,a ratio between the wood powder and the binder within said material is between 10:1 and 1.5:1;a water content of said article is below 10%w / w; andthe wood powder is characterized by mesh particle size below 1200 micron.

15. The building block of claim 14, wherein the binder is or comprises any one of:carboxymethyl cellulose (CMC), starch, methyl cellulose, hydroxypropyl methylcellulose (HPMC), including any salt and any mixture thereof.

16. The building block of claim 14 or 15, wherein the wood powder is derived from a soft wood; wherein the building block is characterized by wood powder content of at least 60% by dry weight of the article; and wherein the ratio between the wood powder and the binder is between about 5 : 1 and about 1.5:1.

17. The building block of any one of claims 14 to 16, wherein the wood powder is characterized by mesh particle size between about 400 and about 1200 micron.

18. The building block of any one of claims 14 to 17, wherein the ratio between the wood powder and the binder between about 3 : 1 and about 2:1.

19. The building block of any one of claims 14 to 18, wherein the wood powder is characterized by mesh particle size between 10 and 400 micron; and wherein the wood powder is derived from a soft wood.

20. The building block of any one of claims 14 to 19, wherein at least one of: (i) the binder is CMC; and (ii) at least 90% of the total number of particles have a mesh particle size distribution ranging between about 400 and about 1200 micron, or both (i) and (ii).

21. The building block of any one of claims 14 to 20, wherein an as-fabricated building block further comprises a gap between a free end of a first extending element, extending from a first side, and a free end of a second extending element extending from a second side opposite the first side.

22. The building block of claim 21, wherein the gap is (i) at least 1mm and / or (ii) at least 10% of a width of the first extending element or of the second extending element.

23. The building block of any one of claims 14 to 22, wherein an as-fabricated building block further comprises a gap between a free end of one or more extending elements and an opposite side to the side from which the one or more extending elements extends.

24. The building block of claim 23, wherein the gap is at least 10% of a width of the one or more extending elements.

25. The building block of any one of claims 14 to 24, wherein the elements comprise one or more element pairs, each pair comprises two opposing extending elements; and wherein an as-fabricated building block further comprises a gap between free ends of the two opposing extending elements.

26. The building block of any one of claims 23 to 25, wherein the gap is between 1 and 4mm.

27. The building block of claim 26, wherein the gap is between 1.5 and 3mm.

28. A method for manufacturing the building block of any one of claims 14 to 27, comprising:providing a shapeable composition comprising the wood powder, water and the binder, wherein a weight ratio between the wood powder and the binder is between 10:1 and 1.5:1; and a water content of at least 50%;shaping the shapeable composition by liquid modelling to obtain a wet article; and drying said wet article, thereby obtaining the article.

29. The method of claim 28, wherein the water content is between about 60 and 80%, or between about 60 and 75%.

30. The method of claim 28 or 29, wherein said liquid modelling is or comprises printing.

31. The method of any one of claims 28 to 30, wherein the wood powder has a mesh particle size between about 400 and about 1200 micron.

32. The method of any one of claims 28 to 31, wherein the water content is between about 70 and about 75%.

33. The method of any one of claims 28 to 32, wherein said drying is performed at a temperature between about 15 and 60°C.

34. The method of any one of claims 28 to 33, wherein a weight ratio between the wood powder and the binder in the shapeable composition is between 5:1 and 1.5:1; and wherein the binder is CMC.

35. The method of any one of claims 28 to 34, wherein the wood powder has a mesh particle size between about 400 and about 1200 micron and at least 90% of the total number of particles have a mesh particle size distribution ranging between 400 and 1200 micron.

36. The method of any one of claims 28 to 35, wherein a ratio between the wood powder and water in the shapeable composition is about 2:7.

37. The article of claim 12 or 13, characterized by wood powder content of between about 80% and about 90% by dry weight of the article.

38. The article of any one of claims 12, 13 and 37, having a thickness of at most 10cm.

39. The article of any one of claims 12 - 13 and 37-38, manufactured by:mixing the wood powder, water and the binder to obtain a shapeable composition, having a ratio between the wood powder and the binder between about 10:1 and 2:1; and a water content of at least 25%w / w;shaping the shapeable composition by casting to obtain a wet article; anddrying said wet article.

40. The article of claim 39, wherein a w / w concentration of (i) the wood powder, (ii) the binder and (iii) water in the shapeable composition is between about 35 to about 65%, between about 5 and 15% and between about 30 and 55%, respectively.

41. The article of claim 39 or 40, wherein said casting comprises any one of: compression casting, injection molding and vacuum molding.

42. The article of claim 41, wherein said compression casting comprises applying pressure suitable for compression of the shapeable composition and a mold temperature ranging between 10 and 250°C; and wherein said pressure is between 5-50MPa; and wherein said drying is performed at a temperature between about 30 and 100°C.

43. The article of any one of claims 39 to 42, wherein the ratio between the wood powder and the binder in the shapeable composition is between about 10:1 and 5:1.

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