A start-and stop-dynamic mixer end-effector for additive manufacturing (three-dimensional printing) with printable cementitious and slurry-based materials

Abstract

Methods of additive manufacturing a printable cementitious or slurry-based composition in a first operational mode pass the composition through a printhead of a robotic additive manufacturing device comprising an extrusion nozzle to deposit the material on a target. The composition may be diverted within the printhead to a storage area in a second operational mode where the composition does not pass through the extrusion nozzle. The first operational mode may then be repeated afterwards, providing a start-stop extrusion process that eliminates time delays and prevents under / over extrusion. A printhead of a robotic additive manufacturing device includes a split pipe connection in fluid communication with a mixing barrel and a storage area, wherein the split pipe connection is configured to divert material into the storage area in a diversion operational mode and a pinch valve configured to be closed in the diversion operational mode and open in a printing operational mode.

Description

Attorney Docket No. 2115-008423-WO-POAA START- AND STOP- DYNAMIC MIXER END-EFFECTOR FOR ADDITIVE MANUFACTURING (THREE-DIMENSIONAL PRINTING) WITH PRINTABEE CEMENTITIOUS AND SLURRY-BASED MATERIALSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 687,999, filed on August 28, 2024. The entire disclosure of the above application is incorporated herein by reference.FIELD

[0002] The present disclosure relates methods of additive manufacturing that include a first operational mode where a printable cementitious or slurry-based composition is deposited on a target and a second operational mode where the composition is diverted from a printhead into a storage area. Printheads for a robotic additively manufacturing device are also provided.BACKGROUND

[0003] This section provides background information related to the present disclosure which is not necessarily prior art.

[0004] Additive manufacturing (AM) also commonly referred to as three-dimensional (3D) printing, can be used to print cementitious materials, like concrete or other slurry-based materials. Additive manufacturing (AM) / three-dimensional (3D) printing is a process by which flowable and extrudable material is applied in an additive, layer-by-layer formation technique. Additive manufacturing can form structures having complex geometries and freeform shapes and is of particular interest in the construction industry. 3D printing of cementitious materials, like concrete can be referred to as concrete additive manufacturing or concrete three-dimensional printing - 3DP (3DCP).

[0005] Additive manufacturing can comprise depositing a printable (e.g., cementitious or slurry-based) composition on a toolpath by passing the printable composition through a printhead of a robotic additive manufacturing device to deposit the cementitious composition onto a target. The printhead is often part of an end effector of a robotic arm. The printing head / printhead typically comprises at least one aperture, for example, an aperture of a nozzle of a 3D printhead, where the printable cementitious composition passes and is deposited onto a target. Notably, the printhead / aperture may define different extruded shapes, such as round, rectangular, or irregular shapes. In the fresh state, the cementitious composition is flowable and extrudable. Thus, theAttorney Docket No. 2115-008423-WO-POA cementitious or other printable composition may be deposited in a flowing continuous stream that is formed by a deposited ribbon or filament of the cementitious material. The deposited composition also transforms into a hardened state.

[0006] The ability to start and stop material deposition at the end effector in 3D cementitious printing, as well as for other slurry-based materials, is essential for producing complex parts with separate island print paths. For example, having this capability enables creating materially optimized parts with branching structures and intricate geometries. It allows for precise control over the deposition process, ensuring precise printing without excessive material, even when intricate details and structural complexities are involved.

[0007] Existing 3DCP technologies are mainly one component (IK), two component (2K), and more than two component (2K+) systems. In all these systems, a concrete or other slurry mix is pumped to the end effector having a printhead, depositing the material layer by layer. A significant difference lies in the 2K and 2K+ 3DCP systems, where an admixture such as concrete accelerators, aggregates, or fibers are pumped to the end effector and mixed with the slurry just before the deposition to enhance or control specific properties for the primary 3D printed slurry.

[0008] Multiple challenges exist for starting and stopping material extrusion in 2K and 2K+ systems. For example, a) there is a time delay between the pump start / stop and the extrusion start / stop, which can result in over / under extrusion and other geometrical defects in the final 3D printed part. Further, b) stopping the pumps might result in air gaps in the hose, leading to air gaps in the extruded filament and thus in the final 3D printed part. Further, c) when stopping material, the previously pumped material can clog the end effector, pumping hose, and the pumps.

[0009] It would be desirable to overcome these challenges to provide a mechanism that enables the starting and stopping of the extrusion process at the nozzle without necessarily needing to stop the mixing process.SUMMARY

[0010] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0011] In certain variations, the present disclosure contemplates a method of additive manufacturing of a printable cementitious or slurry-based composition includes depositing a printable composition in a first operational mode by passing the printable composition through a printhead of a robotic additive manufacturing device comprising an extrusion nozzle to deposit the printable composition onto a target. The method further includes diverting the printable composition within the printhead to a storage area in a second operational mode where theAttorney Docket No. 2115-008423-WO-POA printable composition does not pass through the extrusion nozzle. The method further includes repeating the depositing the printable composition in the first operational mode so that the printable composition passes through the extrusion nozzle onto the target, after the diverting in the second operational mode.

[0012] In one aspect, the printhead further includes a main inlet, at least one ancillary inlet, a mixing barrel in fluid communication with the main inlet and the at least one ancillary inlet, a split pipe connection in fluid communication with the mixing barrel and the storage area, and a pinch valve. The split pipe connection and the pinch valve are disposed upstream of the extrusion nozzle.

[0013] In one further aspect, the diverting minimizes or prevents pressure build-up in the mixing barrel to prevent interruptions during the repeating the depositing in the first operational mode.

[0014] In one further aspect, the mixing barrel includes a mixing blade. The mixing blade runs in both the first operational mode and the second operational mode.

[0015] In one further aspect, the mixing barrel includes a mixing blade. The mixing blade runs only in the first operational mode.

[0016] In one further aspect, the method prevents overextrusion or underextrusion of the printable composition on the target and minimizes or eliminates geometrical defects in a three- dimensional part formed by the printable composition.

[0017] In one further aspect, the method forms a three-dimensional part including one or more islands by the depositing the printable composition on the target.

[0018] In one further aspect, the depositing the printable composition generates a filament as the printable composition passes through the extrusion nozzle. The method minimizes or prevents air gaps from being formed in the filament after passing through the extrusion nozzle onto the target.

[0019] In one further aspect, a pump feeding the printable composition runs in both the first operational mode and the second operational mode.

[0020] In one further aspect, the printable composition includes a cementitious composite material.

[0021] In one further aspect, the printable composition includes an additive selected from the group consisting of: an accelerator, a retardant, a binder, a fiber, a reinforcing particle, a reinforcing aggregate, a mineral, a water reducer, a viscosity modifying admixture, a chemical admixture, and combinations thereof.Attorney Docket No. 2115-008423-WO-POA

[0022] In certain further variations, the present disclosure contemplates a method of additive manufacturing of a cementitious or slurry-based composition includes depositing a printable composition in a first operational mode by passing the printable composition through a printhead of a robotic additive manufacturing device to deposit the printable composition onto a target. The robotic additive manufacturing device includes a mixing barrel, a split pipe connection in fluid communication with the mixing barrel and a storage area, and a pinch valve. The split pipe connection and the pinch valve are disposed upstream of an extrusion nozzle through which the printable composition passes onto the target. The method further includes diverting the printable composition within the printhead to the storage area in a second operational mode where the printable composition does not pass through the extrusion nozzle. The method further includes repeating the depositing the printable composition in the first operational mode so that the printable composition passes through the mixing barrel, pinch valve, and the extrusion nozzle onto the target, after the diverting in the second operational mode. A pump feeding the printable composition runs in both the first operational mode and the second operational mode.

[0023] In one aspect, the mixing barrel includes a mixing blade. The mixing blade either runs in both the first operational mode and the second operational mode or the mixing blade only runs in the first operational mode.

[0024] In one further aspect, the method prevents overextrusion or underextrusion of the printable composition on the target and minimizes or eliminates geometrical defects in a three- dimensional part formed by the printable composition.

[0025] In one further aspect, the depositing the printable composition generates a filament as the printable composition passes through the extrusion nozzle. The method minimizes or prevents air gaps from being formed in the filament after passing through the extrusion nozzle onto the target.

[0026] In certain other variations, the present disclosure contemplates a printhead of a robotic additive manufacturing device for additively manufacturing a cementitious or slurry -based material includes: a main inlet, at least one ancillary inlet, a mixing barrel, a split pipe connection, a pinch valve, and an extrusion nozzle. The mixing barrel is in fluid communication with the main inlet and the at least one ancillary inlet to form a printable composition. The mixing barrel has an outlet. The split pipe connection is in fluid communication with the outlet of the mixing barrel. The split pipe connection is further in fluid communication with a storage area. The split pipe connection is configured to divert the printable composition into the storage area in a diversion operational mode. The pinch valve is configured to be closed in the diversion operational mode and open in a printing operational mode. The extrusion nozzle is disposed downstream of the splitAttorney Docket No. 2115-008423-WO-POA pipe connection and the pinch valve. The printable composition passes through the extrusion nozzle in the printing operational mode.

[0027] In one aspect, the printable composition includes a cementitious composite material.

[0028] In one further aspect, the printable composition includes an additive selected from the group consisting of: an accelerator, a retardant, a binder, a fiber, a reinforcing particle, a reinforcing aggregate, a mineral, a water reducer, a viscosity modifying admixture, a chemical admixture, and combinations thereof.

[0029] In one further aspect, the mixing barrel includes a mixing blade.

[0030] In one further aspect, an automated additive manufacturing system includes the printhead disposed on at least one robotic device or a computer numerical control (CNC) gantry.

[0031] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.DRAWINGS

[0032] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0033] FIG. 1 shows an additive manufacturing system for additively manufacturing a cementitious or slurry-based material according to certain variations of the present disclosure;

[0034] FIG. 2 shows a printhead of a robotic additive manufacturing device for additively manufacturing a cementitious or slurry-based material according to certain variations of the present disclosure;

[0035] FIG. 3 shows another printhead of a robotic additive manufacturing device for additively manufacturing a cementitious or slurry-based material according to certain variations of the present disclosure; and

[0036] FIG. 4 shows a flowchart of a method of additive manufacturing according to certain variations of the present disclosure.

[0037] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.Attorney Docket No. 2115-008423-WO-POADETAILED DESCRIPTION

[0038] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific compositions, components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0039] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, elements, compositions, steps, integers, operations, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Although the open-ended term “comprising,” is to be understood as a non-restrictive term used to describe and claim various embodiments set forth herein, in certain aspects, the term may alternatively be understood to instead be a more limiting and restrictive term, such as “consisting of’ or “consisting essentially of.” Thus, for any given embodiment reciting compositions, materials, components, elements, features, integers, operations, and / or process steps, the present disclosure also specifically includes embodiments consisting of, or consisting essentially of, such recited compositions, materials, components, elements, features, integers, operations, and / or process steps. In the case of “consisting of,” the alternative embodiment excludes any additional compositions, materials, components, elements, features, integers, operations, and / or process steps, while in the case of “consisting essentially of,” any additional compositions, materials, components, elements, features, integers, operations, and / or process steps that materially affect the basic and novel characteristics are excluded from such an embodiment, but any compositions, materials, components, elements, features, integers, operations, and / or process steps that do not materially affect the basic and novel characteristics can be included in the embodiment.

[0040] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed, unless otherwise indicated.Attorney Docket No. 2115-008423-WO-POA

[0041] When a component, element, or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other component, element, or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0042] Although the terms first, second, third, etc. may be used herein to describe various steps, elements, components, regions, layers and / or sections, these steps, elements, components, regions, layers and / or sections should not be limited by these terms, unless otherwise indicated. These terms may be only used to distinguish one step, element, component, region, layer or section from another step, element, component, region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first step, element, component, region, layer or section discussed below could be termed a second step, element, component, region, layer or section without departing from the teachings of the example embodiments.

[0043] Spatially or temporally relative terms, such as “before,” “after,” “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially or temporally relative terms may be intended to encompass different orientations of the device or system in use or operation in addition to the orientation depicted in the figures.

[0044] Throughout this disclosure, the numerical values represent approximate measures or limits to ranges to encompass minor deviations from the given values and embodiments having about the value mentioned as well as those having exactly the value mentioned. Other than in the working examples provided at the end of the detailed description, all numerical values of parameters (e.g., of quantities or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at leastAttorney Docket No. 2115-008423-WO-POA variations that may arise from ordinary methods of measuring and using such parameters. For example, “about” may comprise a variation of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in certain aspects, optionally less than or equal to 0.1%.

[0045] In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range, including endpoints and sub-ranges given for the ranges.

[0046] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0047] In various aspects, the present disclosure provides an enhanced extrusion-based three-dimensional printing (3DP) process, specifically addressing the starting and stopping of material extrusion. The extrusion-based 3DP process may be used in the additive manufacturing (AM) of a cementitious or slurry -based (e.g., concrete, clay, and wood-based slurries) composition for a cementitious composite material. In certain variations, the cementitious composite material may comprise a cementitious binder material and at least one reinforcement particle or fiber. In certain variations, the cementitious composite material is an engineered cementitious composite (ECC) structure.

[0048] ECC, a strain-hardening fiber-reinforced cementitious material, features high tensile strength and ductility. The broad family of cementitious materials is compatible with typical concrete processing methods (e.g., pouring into molds or forms / formwork, spraying, and the like) and can exhibit strain-hardening behavior by way of inclusion of a volume fraction amount of distributed polymer fibers or other reinforcing materials. Printable compositions have been developed for the purpose of improving durability and resiliency of critical structural and infrastructural components, while being compatible with additive manufacturing processes.

[0049] The inventive technology is particularly relevant for the manufacture of complex parts with separate islands, where precise control over the extrusion and 3DP process and contributes to an ability to avoid defects and ensure high-quality prints. In this manner, the methods and devices described herein can enable the starting and stopping of the extrusion process at a nozzle without necessarily needing to stop the material mixing process. In certain aspects, the material may be diverted when stopping and starting the 3DP process.

[0050] In certain aspects, the present disclosure contemplates an automated additive manufacturing system. The present disclosure contemplates an automated additive manufacturing process that can be done with robotics and other computer numerical control (CNC) driven machinery, such as a robotic device or a computer numerical control (CNC) gantry. The at leastAttorney Docket No. 2115-008423-WO-POA one robotic device or CNC gantry may have a printhead on an end effector, as described herein, that provides an ability manufacture complex three-dimensional printed structures with high resolution and minimal defects.

[0051] FIG. 1 shows a non-limiting and representative example of one variation of a suitable additive manufacturing system 10 that includes a feeding system 20 and an extruding system 22. The feeding system 20 includes a hopper 26 that receives material 28, which may be a cementitious material in a fresh state that flows and is pumpable. In various aspects, the material 28 comprises a cementitious or slurry-based composition. The material 28 may be mixed upstream (in a mixer not shown) in batches, or by a continuous, controllable process, whereby a machine(s) measures the constituent ingredients, mixes and mixes and pushes this material into the feeding system 20. The material 28 in the hopper 26 is then processed by one or more pumps 32 (e.g., a peristaltic pump, rotary screw, rotary lobe pump, auger-type (Archimedean screw) pumps, etc.). In other embodiments, the pump 32 may instead be a progressive cavity design. The one or more pumps 32 are in fluid communication with a conduit, such as a supply line, like a concrete hose 34, through which pressurized materials 28 is pumped. As will be appreciated by those of skill in the art, the feeding system may have other conventional components, including valves, actuators, flow rate, temperature, pressure, and / or flow rate monitors, pulsation dampers, and the like.

[0052] The extruding system 22 is connected to the feeding system 20 via the concrete hose 34. A pressure transducer 36 is connected to the concrete hose 34. After the pressure transducer 36, the concrete hose 34 is connected to a main inlet or main feed conduit 38 (e.g., main input) of an additive manufacturing device 40. As described above, the additive manufacturing device 40 may be a CNC or robotic controlled deposition head (e.g., extrusion tool and / or printhead), which synchronously deposits a printable composition 42 (FIG. 2) in subsequent layers to form a three-dimensional part or structure 43 (e.g., a monolithic solid structure) (FIG. 1). In certain variations, the structure 43 comprises discrete structures 44, such as separate islands (e.g., the printable composition 42 is deposited into discrete structures 44) (the discrete structures 44 are also referred to as “the islands 44”). The extruding system 22 is generally designed for rapid disassembly and easy cleaning.

[0053] As best shown in FIGS. 2-3, the material 28 is introduced to the robotic additive manufacturing device 40 via the main feed conduit 38. The main feed conduit 38 is connected to one or more feed pumps (not shown) (FIG. 1). The pressure transducer 36 (FIG. 1) at the inlet of the feed pump (e.g., PC pump) provides feedback to the one or more pumps to maintain a constant inlet pressure, even as the one or more feed pumps starts / stops or varies flow. The extrudingAttorney Docket No. 2115-008423-WO-POA system 22 may thus be fed by one or more demand-based feed pumps which may be controlled by a central Programmable Logic Control (PLC) system 45.

[0054] The printable composition 42 for additive manufacturing may have a fresh state, where the composition may be in a semi-liquid phase that flows and may be extruded for the additive manufacturing spraying process. The printable composition 42 may be a cementitious composition. After hydraulic setting and reaction proceeds; the cementitious composition is in a hardened state. The cementitious composition may comprises a cementitious material, which may include a cement or pozzolan. In certain variations, such a cementitious composition comprises ordinary Portland cement. The printable composition 42 may include a slurry or paste that includes clay, earth-based materials, starch, and the like.

[0055] The printable cementitious composition may comprise a variety of additives, such as an aggregate, like a fine aggregate, water, and other typical ingredients known to those of skill in the art, such as fly ash, plasticizers, water reducers, accelerators, and the like. In certain aspects, the printable composition comprises an additive selected from the group consisting of: an accelerator, a retardant, a binder, a fiber, a reinforcing particle, a reinforcing aggregate, a mineral, a water reducer, a viscosity modifying admixture, a chemical admixture, and combinations thereof, by way of non-limiting example.

[0056] A Portland cement typically comprises inorganic compounds, such as dicalcium silicate (C2S or 2CaO-SiO2), tricalcium silicate (C3S or 3CaO-SiO2), tricalcium aluminate (C3A or 3CaO-A12O3), and tetracalcium aluminoferrite (C4AF or 4CaO-A12O3-Fe2O3), which may be hydrated. Commercially available Portland cement often includes additives, such as gypsum (calcium sulfate) that serves as a set retardant, and pozzolans, like fly ash and ground granulated blast furnace slags (GGBFS), that can react with calcium hydroxide and water to form calcium silicate hydrates or calcium aluminate hydrates. When pozzolans are added to Portland cement, they are considered blended cements. ASTM, International Test C 150 called the “Standard Specification for Portland Cement” provides eight types of ordinary Portland cement for different applications, namely: Types I, IA, II, IIA, III, IIIA, IV, and V. In certain non-limiting aspects, the Portland cement used in the cementitious composition is Type I. The Portland cement may be present in the cementitious composition at greater than or equal to about 50 mass / weight % to less than or equal to about 98 mass % of the total mass of cementitious binder components, optionally at greater than or equal to about 60 mass / weight % to less than or equal to about 90 mass % of the total mass of cementitious binder components, and in certain variations, optionally at about 72% by mass of the total mass of the cementitious binder components.Attorney Docket No. 2115-008423-WO-POA

[0057] In certain variations, the printable cementitious composition may further comprise a fly ash that can be added to the cementitious composition and serves as a pozzolan / cementitious material. Fly ash is an industrial byproduct, for example, collected from effluent of a coal burning boiler unit. It can be used as a substitute for a portion of the Portland cement to reduce energy consumption required to form the overall product and increase the environmental friendliness of the cementitious composition, while contributing to the cementitious properties of the matrix / binder system of the concrete composite. In one variation, the fly ash may be a Class F fly ash as designated by ASTM C618, which is formed from combustion of anthracite and / or bituminous coals. ASTM C618 requires that Class F fly ash contain at least 70% pozzolanic compounds (silica oxide, alumina oxide, and iron oxide). The fly ash may be present in the cementitious composition at 0 mass / weight % to less than or equal to about 45 mass % of the total mass of cementitious binder components, optionally at 0 mass % to less than or equal to about 35 mass % of the total mass of cementitious binder components, and in certain aspects, optionally at about 23 mass % of the total mass of cementitious binder components. In other aspects, the fly ash may be present in the cementitious composition at 0 mass % to less than or equal to about 25 mass % of the total cementitious composition.

[0058] The printable cementitious composition may also include a fine aggregate, such as an inert sand or inert finely crushed stone. Fine aggregates may have a particle size distribution having approximately 95% passing on a 9.5 mm sieve (3 / 8 inch sieve). In certain variations, the fine aggregate is sand. The solid aggregate is distributed within the cementitious matrix to form a composite. In certain variations, the aggregate may be substantially homogeneously distributed within the cementitious composite (e.g., concrete) that is formed. The fine aggregate may comprise sand that has an average particle size of less than or equal to about 2 mm. In one nonlimiting variation, the aggregate may be an F-75 silica or quartz sand commercially available from U.S. Silica. The fine aggregate may be present in the cementitious composition at greater than or equal to about 20 mass / weight % to less than or equal to about 65 mass % of the total mass of cementitious binder components, optionally at greater than or equal to about 30 mass / weight % to less than or equal to about 60 mass % of the total mass of cementitious binder components, and in certain variations, optionally at about 45 mass % of the total mass of cementitious binder components.

[0059] The cementitious composition may also include a high range water reducing agent (HRWRA), also known as a plasticizer / superplasticizer. Inclusion of the HRWRA can serve to reduce water content needed in the cementitious composition by about 10% to about 30%. The HRWRA can create high fluidity with good flowability properties for the printable cementitiousAttorney Docket No. 2115-008423-WO-POA composition, contributing to making the cementitious composition suitable for extrusion via additive manufacturing by helping to eliminate the need for any vibration or compaction after deposition. An example of a suitable HRWRA is a low viscosity polycarboxylate based high- range water-reducing admixture commercially available from W.R. Grace as ADVA® 190. The HRWRA may be present in the cementitious composition at greater than or equal to about 0.3 mass / weight % to less than or equal to about 1.5 mass % of the total mass of cementitious binder components.

[0060] Water is also included in the printable cementitious composition. A mass ratio of water to cementitious binder components (e.g., Portland cement, and any other pozzolanic materials, like fly ash) may be greater than or equal to about 0.2 to less than or equal to about 0.55. Water temperature can be used intentionally to manipulate the fresh state properties of a particular cementitious material composition. Water temperature affects fresh state rheological properties due to the accelerated activation of pozzolanic reactions of the cementitious materials. Water may be present in the cementitious composition at greater than or equal to about 5 mass % to less than or equal to about 35 mass % of the total cementitious composition.

[0061] Further, the cementitious structural component may be a fiber-reinforced cementitious composite structure that comprises at least one type of fiber (e.g., discrete or chopped fibers) distributed or dispersed within the cementitious matrix to form a composite (in combination with the aggregate solid material). In certain variations, the plurality of fibers may be substantially homogeneously distributed within the printed cementitious composite (e.g., concrete) that is formed. In certain aspects, the fibers may have a single composition or may include a mixture of different compositions or other combinations of select properties, such as different lengths or diameters. The fibers may include a variety of distinct materials, such as carbon fibers, glass (e.g., fiberglass, quartz, silica, borosilicates, etc.), polymer fibers (e.g., polyvinyl alcohol (PVA) or polyalkylene fibers, such as polyethylene (PE) or polypropylene (PP), including high tenacity polypropylene (HTPP) fibers), aramid fibers (such as KEVLAR™ paraaramid synthetic fibers and TWARON™ para-aramid synthetic fibers)), basalt fibers, boron fibers, ceramic fibers, natural fibers, including plant-based fibers (derived from plants) and animal-based fibers (derived from animals), such as sisal, jute, hemp, bamboo, curaua fibers, cellulose-based fibers, goat hair, and the like, artificial fibers, and any combination thereof.

[0062] By way of non-limiting example, an aspect ratio or ratio between a length of the fiber (L) and a diameter (D) of the fiber (AR=L / D) may be greater than or equal to about 150. In certain variations, the AR may be greater than or equal to about 150 to less than or equal to about 900.Attorney Docket No. 2115-008423-WO-POA

[0063] In certain variations, a suitable fiber may have a length of greater than or equal to about 4 mm to less than or equal to about 20 mm, optionally greater than or equal to about 6 mm to less than or equal to about 15 mm, optionally greater than or equal to about 8 mm to less than or equal to about 12 mm, and in certain variations, optionally greater than or equal to about 8 mm to less than or equal to about 10 mm. In certain variations, a fiber in the fiber-reinforced cementitious composite structure has a diameter of greater than or equal to about 10 micrometers (pm) to less than or equal to about 200 pm. In one variation, the fiber is a glass fiber. In another variation, the fiber is a carbon fiber. The fiber may be present in the fiber-reinforced cementitious composite structure at greater than or equal to about 1 vol. % to less than or equal to about 4.5 vol. % of the total volume of the fiber-reinforced cementitious composite structure, optionally at greater than or equal to about 1.8 vol. % to less than or equal to about 4 vol. %, and in certain variations, optionally at about 2 vol. %.

[0064] Thus, in certain variations, one or more additives (e.g., accelerators, retardants, binders, fibers, reinforcing particles and / or aggregates, mineral additives, water reducers, viscosity modifying admixtures, other chemical admixtures, and the like) are introduced to the robotic additive manufacturing device 40 via one or more ancillary or additive inlets or ancillary or additive feed conduits 39 (e.g., the ancillary or additive inputs). The main feed conduit 38 and the one or more ancillary or additive feed conduits 39 are in fluid communication with a mixing barrel 46, where the material from the conduits 38, 39 are mixed together (e.g., the slurry or cementitious material and the one or more additives). The mixing barrel 46 may be one component of an inline dynamic mixer of the additive manufacturing device 40. In other words, the material 28 and the one or more additives are mixed through the mixing barrel 46 and combined to form the printable composition 42.

[0065] In certain variations, such as when the extruding system 22 is free of one or more additives, the printable composition 42 comprises only the material 28. In certain variations, the printable composition 42 further comprises the one or more additives mixed with the material 28. As can be appreciated by a person skilled in the art, when the printable composition 42 comprises one or more additives, the feeding system 20 may include an additional hopper or storage unit containing the one or more additive materials that is in fluid communication with the ancillary feed conduit 39.

[0066] With renewed reference to FIGS. 1-3, the additive manufacturing device 40 comprises a deposition head or printhead 50. The printhead 50 is in fluid communication with the mixing barrel 46, the main feed conduit 38, and / or one or more ancillary feed conduits. The printhead 50 defines a cavity 51 having a progressive cavity design, which minimizes flowAttorney Docket No. 2115-008423-WO-POA restrictions and dead-zones even with highly viscous, semi-solid materials, such as the printable composition 42. The printhead 50 may be equipped with a CNC controlled shaping system or nozzle steering system 52, which is steer with respect to the motion of the printhead 50. The printhead 50 further includes an extrusion nozzle 54. In certain variations, the extrusion nozzle 54 has a length or height 55 of greater than or equal to about 6 inches to less than or equal to about 15 inches.

[0067] After passing through the printhead 50, the printable composition 42 passes or is extruded through an opening 56 (FIG. 2) of the extrusion nozzle 54. The shape, size, and configuration of the extrusion nozzle 54 and opening 56 can be tailored or changed to suit varying needs and cross-sections of the deposited bead of printable composition. In a non-limiting example, the opening 56 of the extrusion nozzle 54 may have a maximum dimension of about 100 mm. By way of non-limiting example, the opening 56 may have a dimension 57 of greater than or equal to about 10 mm to less than or equal to about 100 mm, optionally greater than or equal to about 25 mm to less than or equal to about 50 mm. The opening 56 may be circular, rectangular, or any other suitable shape to form a desired filament shape of printed material.

[0068] The steering of the nozzle by the nozzle steering system 52 allows the deposited printable composition bead to closely approximate the desired cross-section and surface of the structure or components 43 (FIG. 1) to be formed on the target, thus provided for substantially better surface finishes and precise material control. The extrusion nozzle 54 is also designed with a specific flow profile, which controls thixotropic behavior and “buffers” changes in material flow rate (which are small, but inevitable when pumping viscous materials like to allow a consistently deposited bead that holds its shape). The design of the extrusion nozzle 54 also includes restrictions (not shown), which influence and promote the alignment of the reinforcing fibers, which enhances material properties of the structure 43, 44 formed after the printable composition 42 hardens.

[0069] In various aspects, the mechanism enables successful starting and stopping of the extrusion process at the extrusion nozzle 54 of the extruding system 22. In certain aspects, this may be achieved by incorporating two separate components in the additive manufacturing device 40 as shown in FIGS. 2 and 3 located between the mixing barrel 46 and the extrusion nozzle 54. In accordance with certain aspects of the present disclosure, the additive manufacturing device 40 includes a pinch valve 58 downstream of the mixing barrel 46. The pinch valve 58 can stop the mixed printable composition 42 from being extruded from the downstream extrusion nozzle 54. The additive manufacturing device 40 also comprises a split pipe connection 60, or wye pipe, disposed between the mixing barrel 46 and the pinch valve 58. This split connection componentAttorney Docket No. 2115-008423-WO-POA60 redirects the pumped printable composition 42 to a secondary hose or container 62 (FIG. 1) that provides excess volume for material storage, thus preventing the build-up of pressure in the mixing barrel 46.

[0070] In one variation, when the pinch valve 58 is positioned or turned in a direction so as to cease or stop material deposition from the extrusion nozzle 54, the one or more pumps 32 (FIG. 1) can remain running so that the printable composition 42 from the mixing barrel 46 is redirected via the split pipe 60 to the secondary hose or storage area 62. In one alternative variation, when the pinch valve 58 is turned so as to cease or stop material deposition, the one or more pumps 32 may be turned off simultaneously. In another variation, a mixing blade 64 (FIG. 2) in the additive manufacturing device 40 is not turned off and may remain running while deposition is ceased, while in other aspects, the mixing blade 64 may be turned off as well.

[0071] In another variation, a pattern of the printhead 50 technology is 2K or 2K+, such as component 3D concrete printing. In another variation, a pattern the printhead 50 deposits is contemplated to be IK. Further, in certain aspects, no accelerator is added in the printhead 50 for accelerating material setting time, in other words, accelerator is omitted.

[0072] In this manner, the printhead 50 design for additive manufacturing of cementitious or other slurry-based materials enables successful starting and stopping of the extrusion process at the extrusion nozzle 54. Thus, in certain aspects, as shown in FIG. 4, the present disclosure contemplates a method 100 for starting and stopping an additive manufacturing extrusion process directly at the extrusion nozzle 54 (FIGS. 1-3), independent of the mixing process, to eliminate time delays and prevent over / under extrusion. The method 100 includes depositing the printable composition 42 in a first operational mode at 102. The depositing the printable composition 42 includes passing the printable composition through the printhead 50 of a robotic additive manufacturing device 40 including an extrusion nozzle 54 to deposit the printable composition 42 onto a target. Next, at 104, the method 100 includes diverting the printable composition 42 within the printhead 50 to the secondary hose or storage area 62 in a second operational mode. At step 104, the printable composition 42 does not pass through the extrusion nozzle 54. Next, at step 106, the method 100 includes repeating the depositing the printable composition 42 in the first operational mode so that the printable composition 42 passes through the extrusion nozzle 54 onto the target, after diverting in the second operational mode (step 104). A pump feeding the printable composition may run in both the first operational mode and the second operational mode. In this way, the method 100 forms a three-dimensional part or structure 43 including one or more islands 44 by depositing the printable composition 42 on the target.Attorney Docket No. 2115-008423-WO-POA

[0073] In other aspects, the present disclosure contemplates the printhead 50 design that includes the pinch valve 58 and a split pipe connection 60 (or a wye pipe connection). A mechanism comprises the pinch valve 58 and the split pipe connection 60 between the mixing barrel 46 and an extrusion nozzle 54 (e.g., cold extrusion nozzle). For example, the pinch valve 58 and split pipe connection 60 are downstream of the mixing barrel 46 is upstream of The pinch valve 58 stops the mixed printable composition 42 from being extruded, while the split pipe 60 redirects the pumped printable composition 42 to the secondary storage area 62, preventing pressure build-up in the mixing barrel 46 and ensuring precise control over the extrusion process.

[0074] In yet another aspects, the present disclosure addresses time delays, air gaps, and pressure build-up during additive manufacturing of cementitious materials, like concrete, or other slurry-based materials. The system is designed to address a time delay between pump start / stop and extrusion start / stop, preventing over / under extrusion and geometrical defects in the final 3D printed structure 43, 44. It incorporates a mechanism to prevent air gaps in the hose and extruded filament, ensuring consistent material flow and high-quality prints. Additionally, the design prevents pressure build-up in the mixing barrel 46, maintaining optimal operational conditions and preventing interruptions in the extrusion process.

[0075] In certain aspects, the methods contemplated by certain aspects of the present disclosure can prevent pressure build-up in the mixing barrel to maintain optimal operational conditions and prevent interruptions in an extrusion process during the depositing in the first operational mode. Thus, method that includes diverting the printable material into the storage area minimizes or prevents pressure build-up in the mixing barrel to prevent interruptions when the depositing occurs or is repeated in the first operational mode. In certain further aspects, depositing the printable composition through such a printhead generates a filament of the printable composition that passes through the extrusion nozzle. The methods thus minimize or prevent air gaps from being formed in the filament after passing through the extrusion nozzle onto the target.

[0076] The present disclosure further contemplates a system that supports the manufacture of complex parts with separate islands 44 (FIG. 1) by enabling precise control over the extrusion process.

[0077] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in manyAttorney Docket No. 2115-008423-WO-POA ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

Attorney Docket No. 2115-008423-WO-POACLAIMSWhat is claimed is:

1. A method of additive manufacturing of a cementitious or slurry-based composition, the method comprising: depositing a printable composition in a first operational mode by passing the printable composition through a printhead of a robotic additive manufacturing device comprising an extrusion nozzle to deposit the printable composition onto a target; diverting the printable composition within the printhead to a storage area in a second operational mode where the printable composition does not pass through the extrusion nozzle; and repeating the depositing the printable composition in the first operational mode so that the printable composition passes through the extrusion nozzle onto the target, after the diverting in the second operational mode.

2. The method of claim 1, wherein the printhead further comprises: a main inlet; at least one ancillary inlet; a mixing barrel in fluid communication with the main inlet and the at least one ancillary inlet; a split pipe connection in fluid communication with the mixing barrel and the storage area; and a pinch valve, wherein the split pipe connection and the pinch valve are disposed upstream of the extrusion nozzle.

3. The method of claim 2, wherein the diverting minimizes or prevents pressure buildup in the mixing barrel to prevent interruptions during the repeating the depositing in the first operational mode.

4. The method of claim 2, wherein the mixing barrel comprises a mixing blade, and wherein the mixing blade runs in both the first operational mode and the second operational mode.

5. The method of claim 2, wherein the mixing barrel comprises a mixing blade, and wherein the mixing blade runs only in the first operational mode.Attorney Docket No. 2115-008423-WO-POA6. The method of claim 1, wherein the method prevents overextrusion or underextrusion of the printable composition on the target and minimizes or eliminates geometrical defects in a three-dimensional part formed by the printable composition.

7. The method of claim 1, wherein the method forms a three-dimensional part comprising one or more islands by the depositing the printable composition on the target.

8. The method of claim 1, wherein the depositing the printable composition generates a filament as the printable composition passes through the extrusion nozzle and the method minimizes or prevents air gaps from being formed in the filament after passing through the extrusion nozzle onto the target.

9. The method of claim 1, wherein a pump feeding the printable composition runs in both the first operational mode and the second operational mode.

10. The method of claim 1, wherein the printable composition comprises a cementitious composite material.

11. The method of claim 10, wherein the printable composition comprises an additive selected from the group consisting of: an accelerator, a retardant, a binder, a fiber, a reinforcing particle, a reinforcing aggregate, a mineral, a water reducer, a viscosity modifying admixture, a chemical admixture, and combinations thereof.

12. A method of additive manufacturing of a cementitious or slurry-based composition, the method comprising: depositing a printable composition on a target in a first operational mode by passing the printable composition through a printhead of a robotic additive manufacturing device comprising a mixing barrel, a split pipe connection in fluid communication with the mixing barrel and a storage area, a pinch valve, wherein the split pipe connection and the pinch valve are disposed upstream of an extrusion nozzle through which the printable composition passes onto the target; diverting the printable composition within the printhead to the storage area in a second operational mode, where the printable composition does not pass through the extrusion nozzle; andAttorney Docket No. 2115-008423-WO-POA repeating the depositing the printable composition in the first operational mode so that the printable composition passes through the mixing barrel, pinch valve and the extrusion nozzle onto the target, after the diverting in the second operational mode, wherein a pump feeding the printable composition runs in both the first operational mode and the second operational mode.

13. The method of claim 12, wherein the mixing barrel comprises a mixing blade, and wherein the mixing blade either runs in both the first operational mode and the second operational mode or the mixing blade only runs in the first operational mode.

14. The method of claim 12, wherein the method prevents overextrusion or underextrusion of the printable composition on the target and minimizes or eliminates geometrical defects in a three-dimensional part formed by the printable composition.

15. The method of claim 12, wherein the depositing the printable composition generates a filament as the printable composition passes through the extrusion nozzle and the method minimizes or prevents air gaps from being formed in the filament after passing through the extrusion nozzle onto the target.

16. A printhead of a robotic additive manufacturing device for additively manufacturing a cementitious or slurry-based material, the printhead comprising: a main inlet; at least one ancillary inlet; a mixing barrel in fluid communication with the main inlet and the at least one ancillary inlet to form a printable composition, the mixing barrel having an outlet; a split pipe connection in fluid communication with the outlet of the mixing barrel and further in fluid communication with a storage area, wherein the split pipe connection is configured to divert the printable composition into the storage area in a diversion operational mode; a pinch valve configured to be closed in the diversion operational mode and open in a printing operational mode; and an extrusion nozzle disposed downstream of the split pipe connection and the pinch valve, wherein the printable composition passes through the extrusion nozzle in the printing operational mode.Attorney Docket No. 2115-OQ8423-WO-POA17. The printhead of claim 16, wherein the printable composition comprises a cementitious composite material.

18. The printhead of claim 17, wherein the printable composition comprises an additive selected from the group consisting of: an accelerator, a retardant, a binder, a fiber, a reinforcing particle, a reinforcing aggregate, a mineral, a water reducer, a viscosity modifying admixture, a chemical admixture, and combinations thereof.

19. The printhead of claim 16, wherein the mixing barrel comprises a mixing blade.

20. An automated additive manufacturing system comprising the printhead of claim 16 disposed on at least one robotic device or a computer numerical control (CNC) gantry.

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