A mixing component for a printhead with mixing rotor and multiple inlets for mixing fibers, coarse aggregates, liquid additives, and slurry for an additive manufacturing (three-dimensional printing) device

Abstract

A mixing component for a printhead of an additive manufacturing device receives a plurality of distinct material streams (e.g., including aggregates or fibers) to form a printable material. The mixing component comprises a mixing barrel component defining an internal chamber. A rotary mixer component defines a central shaft having a first region comprising a feeding screw and a second region. The rotary mixer component is at least partially disposed in the internal chamber of the mixing barrel component. A motor is in driving engagement with the rotary mixer component to rotate the rotary mixer component. The plurality of distinct material streams are configured to be fed into the internal chamber of the mixing barrel component and mixed to form the printable material. The mixing component further comprises a terminal extrusion nozzle connected to an outlet of the mixing barrel component through which the printable material passes.

Description

Attorney Docket No. 2115-008425-WO-POAA MIXING COMPONENT FOR A PRINTHEAD WITH MIXING ROTOR AND MULTIPLE INLETS FOR MIXING FIBERS, COARSE AGGREGATES, LIQUID ADDITIVES, AND SLURRY FOR AN ADDITIVE MANUFACTURING (THREE-DIMENSIONAL PRINTING) DEVICECROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 688,069, filed on August 28, 2024. The entire disclosure of the above application is incorporated herein by reference.FIELD

[0002] The present disclosure relates to a mixing component for a printhead of an additive manufacturing device receiving a plurality of distinct material streams, for example, including a slurry, an aggregate and / or fiber, and / or liquid additives, to form a printable material that is deposited via additive manufacturing / three-dimensional printing.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, through which the printable cementitious composition passes and is deposited onto a target. Notably, the printhead / aperture may define different extruded shapes, such as round, rectangular,Attorney Docket No. 2115-008425-WO-POA or irregular shapes. In the fresh state, the cementitious composition is flowable and extrudable. Thus, the 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] Existing 3DCP technologies are mainly one component (IK), two component (2K), and more than two component (2K+) systems. In all these systems, a cementitious / 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 multiple streams are combined to form an admixture, such as concrete accelerators, aggregates, or fibers, which are all pumped to the end effector and mixed with the slurry before the deposition to enhance or control specific properties for the primary 3D printed slurry.

[0007] For conventional 3DCP technologies, which are mainly IK (one component stream printhead) and 2K (two component stream printhead) systems, a concrete slurry is pumped to the print-head, depositing the material layer-by-layer. One difference in the 2K system, relative to a IK system, is its rapid stiffening of a concrete mix at the printhead by introducing chemical accelerators in a second stream. An accelerator is pumped separately and mixed with the concrete slurry in the printhead, for example, just before deposition, allowing precise control over the material’s open and setting times. Open time is the period during which the concrete mix remains flowable for successful extrusion, while setting time is the duration required for the printed layers to gain enough strength to support subsequent layers without deforming.

[0008] One of the main drawbacks of 3D printing with cementitious / concrete and other slurry materials is the inability to introduce coarse aggregates and short fibers to the material mixture. Often aggregates or short fibers may be added to the pump in 3D printing slurries (e.g., fresh cementitious mortar), which presents several challenges. For example, short fibers can cause blockages in the pump and piping system. Further, achieving a consistent mix of fibers throughout the concrete is difficult. Eastly, the addition of fibers can alter the concrete’s rheological properties, such as flowability and viscosity. Thus, short fibers and coarse aggregates are often avoided. This limitation reduces the compressive and tensile strength of the final mixed slurry and acts as a bottleneck for the widespread adoption of 3D printing with slurry materials outside research laboratories. It would be desirable to avoid the drawbacks of the current extrusion systems for 3D printing with slurry materials, so that coarse aggregates and short fibers can be successfully mixed with the main slurry material and used without processing complications.Attorney Docket No. 2115-008425-WO-POASUMMARY

[0009] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0010] In certain variations, the present disclosure contemplates a mixing component for a printhead of an additive manufacturing device receiving a plurality of distinct material streams to form a printable material. The mixing component includes a mixing barrel component, a rotary mixer component, a motor, and a terminal extrusion nozzle. The mixing barrel component defines an internal chamber. The rotary mixer component defines a central shaft having a first region including a feeding screw and a second region distinct from the first region. The rotary mixer component is at least partially disposed in the internal chamber of the mixing barrel component. The motor is in driving engagement with the rotary mixer component to rotate the rotary mixer component. The plurality of distinct material streams are fed into the internal chamber of the mixing barrel component and mixed to form the printable material. The terminal extrusion nozzle is connected to an outlet of the mixing barrel component through which the printable material passes.

[0011] In one aspect, the mixing barrel component further includes at least two distinct inlets to receive the plurality of distinct material streams.

[0012] In one further aspect, at least one of the two distinct inlets receives the slurry or cementitious material.

[0013] In one further aspect, at least one of the at least two distinct inlets receives a material comprising an aggregate or a fiber.

[0014] In one further aspect, the mixing barrel component includes three distinct inlets. Each of the three distinct inlets receives a different material.

[0015] In one further aspect, the second region of the rotary mixer component includes a plurality of stationary pins extending radially outward from the central shaft.

[0016] In one further aspect, the rotary mixer component is configured to provide a medium shear mixing level.

[0017] In one further aspect, the second region of the central shaft of the rotary mixer component includes a plurality of paddle-shaped fins extending radially outward from the central shaft.

[0018] In one further aspect, the rotary mixer component is configured to provide a low shear mixing level.

[0019] In one further aspect, a robotic additive manufacturing device for additively manufacturing a cementitious or slurry-based material includes an end effector having theAttorney Docket No. 2115-008425-WO-POA printhead including the mixing component. The printable material includes the cementitious or slurry-based material.

[0020] In certain variations, the present disclosure contemplates a mixing component for a printhead of an additive manufacturing device receiving a plurality of distinct material streams to form a printable material. The mixing component includes a mixing barrel component, at least two distinct inlets to receive the plurality of distinct material streams; a rotary mixer component, a motor, and a terminal extrusion nozzle. The mixing barrel component defines an internal chamber. The rotary mixer component defines a central shaft having a first region including a feeding screw and a second region distinct from the first region. The rotary mixer component is at least partially disposed in the internal chamber of the mixing barrel component. The feeding screw is configured to move material received from the at least two distinct inlets to the second region. The second region of the rotary mixer component includes a plurality of stationary pins extending radially outward from the central shaft. The motor is in driving engagement with the rotary mixer component to rotate the rotary mixer component. The plurality of distinct material streams are fed into the internal chamber of the mixing barrel component at the first region and mixed at the second region to form the printable material. The terminal extrusion nozzle is connected to an outlet of the mixing barrel component through which the printable material passes.

[0021] In one aspect, the mixing barrel component includes at least three distinct inlets to receive the plurality of distinct material streams.

[0022] In one aspect, at least one of the two distinct inlets receives the slurry or cementitious material.

[0023] In one further aspect, at least one of the at least two distinct inlets receives a material comprising an aggregate or a fiber.

[0024] In one further aspect, a robotic additive manufacturing device for additively manufacturing a cementitious or slurry-based material includes an end effector having the printhead including the mixing component. The printable material includes the cementitious or slurry-based material.

[0025] In certain variations, the present disclosure contemplates a mixing component for a printhead of an additive manufacturing device receiving a plurality of distinct material streams to form a printable material. The mixing component includes a mixing barrel component, at least two distinct inlets to receive the plurality of distinct material streams; a rotary mixer component, a motor, and a terminal extrusion nozzle. The mixing barrel component defines an internal chamber. The rotary mixer component defines a central shaft having a first region including a feeding screw and a second region distinct from the first region. The rotary mixer component isAttorney Docket No. 2115-008425-WO-POA at least partially disposed in the internal chamber of the mixing barrel component. The feeding screw is configured to move material received from the at least two distinct inlets to the second region. The second region of the rotary mixer component includes a plurality of paddle-shaped fins extending radially outward from the central shaft. The motor is in driving engagement with the rotary mixer component to rotate the rotary mixer component. The plurality of distinct material streams are fed into the internal chamber of the mixing barrel component at the first region and mixed at the second region to form the printable material. The terminal extrusion nozzle is connected to an outlet of the mixing barrel component through which the printable material passes.

[0026] In one aspect, the mixing barrel component includes at least three distinct inlets to receive the plurality of distinct material streams.

[0027] In one further aspect, at least one of the two distinct inlets receives the slurry or cementitious material.

[0028] In one further aspect, at least one of the at least two distinct inlets receives a material comprising an aggregate or a fiber.

[0029] In one further aspect, a robotic additive manufacturing device for additively manufacturing a cementitious or slurry-based material includes an end effector having the printhead including the mixing component. The printable material includes the cementitious or slurry-based material.

[0030] 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

[0031] 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.

[0032] FIG. 1 shows a schematic of a process for making printable materials in a one component (IK) additive manufacturing / three-dimensional printing system and also in at least two component (2K+) additive manufacturing / three-dimensional printing system;

[0033] FIG. 2 shows an additive manufacturing system for additively manufacturing a cementitious or slurry-based material according to certain variations of the present disclosure;

[0034] FIG. 3 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;Attorney Docket No. 2115-008425-WO-POA

[0035] FIG. 4 shows an assembly for a mixer that may be used with an end effector for a robotic additive manufacturing device for printing slurry based materials that include aggregates and / or fibers, including a rotating rotor blade and a mixing chamber stator having multiple inlets, where the rotor blade provides medium shear mixing according to certain aspects of the present disclosure; and

[0036] FIG. 5 shows an assembly for a mixer that may be used with an end effector for a robotic additive manufacturing device for printing slurry based materials that include aggregates and / or fibers, including a rotating rotor blade and a mixing chamber stator having multiple inlets, where the rotor blade provides low shear mixing according to certain aspects of the present disclosure.

[0037] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.DETAILED 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 alsoAttorney Docket No. 2115-008425-WO-POA 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.

[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) asAttorney Docket No. 2115-008425-WO-POA 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 least 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 new designs for a printhead of a robotic additive manufacturing device for additively manufacturing a cementitious or other slurry-based materials (e.g., concrete, clay, hemp, and wood-based slurries) where at least two components are added and mixed together (2K and 2K+ 3DCP systems). More specifically, the printhead includes new rotor blade designs to enhance mixing of aggregates and / or fibers.

[0048] As background, FIG. 1 shows a process 2 for 3DCP technologies with either IK and 2K systems. In both systems, a concrete slurry 10 is pumped to a printhead 12, depositing the material 14 layer-by-layer to fabricate a structure 16. As noted above, the nomenclature of IK, 2K, and 2K+ refers to printhead technologies and the number of component inlets, either one component inlet (IK), two component inlets (2K), or more than two component inlets (2K+), with subsequent evolutions of the technology. Generally, dry material, water, and optional additives are introduced together. They may be mixed and pumped as a slurry through an extrusion systemAttorney Docket No. 2115-008425-WO-POA including the printhead 12, where the 3DCP printer device forms the construct or three- dimensional printed structure 16 from the printed material. One main difference in the 2K system, relative to a IK system, is its rapid stiffening of a concrete mix at the printhead by introducing chemical accelerators via one of the inlets / material streams. An accelerator is pumped separately and mixed with the concrete slurry in the printhead just before deposition, allowing precise control over the material’s open and setting times. In certain aspects, 2K+ technology includes introduction of multiple additives (e.g., accelerators, thickeners, and superplasticizers) added at the printhead, thus providing greater control over the slurry’s properties than possible with basic 2K systems.

[0049] In various aspects, the present disclosure pertains to advanced extrusion systems for 3D printing with slurry materials, specifically focusing on enhancing the mixture quality of concrete and other slurry-based materials by developing capabilities and enables incorporating coarse aggregates, short fibers, and various admixtures. In this manner, the present disclosure provides an ability to improve the mechanical properties of 3D printed structures, such as compressive and tensile strength, thus facilitating the broader adoption of 3D printing technologies in industrial applications. Further, the present technology improves the 3D printing process, providing greater control over setting time and open time (e.g., workability window), by enabling integration of multiple additives at the end effector or printhead.

[0050] More specifically, the present disclosure contemplates a mixer for an additive manufacturing device receiving a plurality of distinct material streams to form a printable material. In certain aspects, at least one of the plurality of distinct material streams comprises an aggregate or fiber reinforcement phase material.

[0051] The additive manufacturing device 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. ECC, a strain-hardening fiber-reinforced cementitious material, features high tensile strength and ductility.

[0052] The broad family of cementitious and slurry-based 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 cementitious and slurry-based compositions have been developed for the purpose of improving durability andAttorney Docket No. 2115-008425-WO-POA resiliency of critical structural and infrastructural components, while being compatible with additive manufacturing processes.

[0053] In certain aspects, the present disclosure contemplates an automated additive manufacturing system. The present disclosure contemplates an automated additive manufacturing device that can utilize robotics and other computer numerical control (CNC) driven machinery, such as a robotic device or a computer numerical control (CNC) gantry. The at least 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.

[0054] FIG. 2 shows a non-limiting and representative example of one variation of a suitable additive manufacturing system 100 that includes a feeding system 120 and extruding system 122. The feeding system 120 includes a hopper 126 that receives material 128, which may be a cementitious material in a fresh state that flows and is pumpable. In various aspects, the material 128 comprises a cementitious or slurry-based (e.g., concrete, clay, and wood-based slurries) composition. The material 128 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 120. The material 128 in the hopper 126 is then processed by one or more pumps 132 (e.g., a peristaltic pump, rotary screw, rotary lobe pump, auger-type (Archimedean screw) pumps, etc.). In other embodiments, the pump 132 may instead be a progressive cavity design. The one or more pumps 132 are in fluid communication with a conduit, such as a supply line, like a concrete hose 134, through which pressurized materials 128 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, and / or flow rate monitors, pulsation dampers, and the like.

[0055] The extruding system 122 is connected to the feeding system 120 via the concrete hose 134. A pressure transducer 136 is connected to the concrete hose 134. After the pressure transducer 136, the concrete hose 134 is connected to a main inlet or main feed conduit 138 (e.g., main input) of an additive manufacturing device 141. As described above, the additive manufacturing device 141 may include a CNC or robotic controlled deposition head 150 (e.g., extrusion tool and / or printhead 150), which synchronously deposits a printable composition 142 in subsequent layers to form a three-dimensional component or structure 143 (FIG. 2).

[0056] With reference to FIGS. 3-5, the material 128 is introduced to the printhead 150 of the additive manufacturing device 141 via the main feed conduit 138. The main feed conduit 138 is connected to one or more feed pumps (not shown) (FIG. 2). The pressure transducer 136Attorney Docket No. 2115-008425-WO-POA(FIG. 2) 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 extruding system 122 may thus be fed by one or more demand-based feed pumps which may be controlled by a central Programmable Logic Control (PLC) system 145.

[0057] 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 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.

[0058] 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.

[0059] A Portland cement typically comprises inorganic compounds, such as dicalcium silicate (C2S or 2CaO-SiO2), tricalcium silicate (C3S or SCaOSiCh), tricalcium aluminate (C3A or SCaOAhCF), 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 theAttorney Docket No. 2115-008425-WO-POA 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.

[0060] 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.

[0061] 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.

[0062] 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 toAttorney Docket No. 2115-008425-WO-POA 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 cementitious 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.

[0063] 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.

[0064] 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.

[0065] 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. InAttorney Docket No. 2115-008425-WO-POA certain variations, the AR may be greater than or equal to about 150 to less than or equal to about 900.

[0066] 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. %.

[0067] 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 (e.g., thickeners), superplasticizers, other chemical admixtures, and the like) are introduced to the printhead 150 via one or more ancillary or additive inlets or feed conduits (e.g., ancillary or additive inlets or inputs). In the example embodiment of FIGS. 3- 5, the printhead 150 includes a first ancillary feed conduit 139 and a second ancillary feed conduit 140. As can be appreciated by a person skilled in the art, the feeding system 120 may include an additional hopper or storage unit containing the one or more additive materials that is in fluid communication with the ancillary feed conduits 139, 140.

[0068] In various aspects, the main feed conduit 138 and the one or more ancillary or additive feed conduits 139, 140 are in fluid communication with a mixer 144. The mixer 144 may be an inline mixer that comprises a rotary mixer component and a motor (not shown) in driving engagement with the rotary mixer component. The motor may include a servo motor-gearbox assembly. In certain variations, the mixer 144 includes a mixing barrel 146 that may be a stator or stationary component defining an internal region or internal chamber 210 in which the rotary mixer component is at least partially disposed and rotates. The mixing barrel 146 is configured to process the printable material 142. For example, the material from the conduits 138, 139, 140 are mixed together (e.g., the slurry or cementitious material and the one or more additives) in the mixing barrel 146 to form the printable material 142. In other words, the material 128 and the oneAttorney Docket No. 2115-008425-WO-POA or more additive materials are mixed through the mixing barrel 146 and combined to form the printable material 142.

[0069] The main feed conduit 138 and the one or more ancillary or additive feed conduits 139, 140 are in fluid communication with a mixing barrel 146, where the material from the conduits 138, 139, 140 are mixed together (e.g., the material 128 and the one or more additives). In other words, the material 128 and the one or more additives are mixed through the mixing barrel 146 and combined to form the printable composition 142. As can be appreciated by a person skilled in the art, when the printable composition 142 comprises one or more additives, the feeding system 120 may include one or more additional hoppers or storage units containing the one or more additive materials that is in fluid communication with the ancillary feed conduits 139, 140.

[0070] In certain variations, like that shown in FIG. 2-3, the printhead 150 further includes a terminal extrusion nozzle 176 connected to an outlet 126 (FIGS. 4-5) of the mixing barrel 146. The extrusion nozzle 176 may be a cold extrusion nozzle. In certain variations, the extrusion nozzle 176 has a length or height of greater than or equal to about 6 inches to less than or equal to about 15 inches. After passing through the printhead 150, the printable composition 142 is extruded through the extrusion nozzle 176. Specifically, the printable material 142 passes through the outlet 126 into and through the terminal extrusion nozzle 176 to be deposited on a target and ultimately form a structure (see, e.g., structure 143 of FIG. 1). The shape, size, and configuration of the extrusion nozzle 176 can be tailored or changed to suit varying needs and cross-sections of the deposited bead of printable composition 142. In a non-limiting example, an opening of the extrusion nozzle 176 may have a dimension 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 of the extrusion nozzle 176 may be circular, rectangular, or any other suitable shape to form a desired filament shape of printed material.

[0071] With reference to FIG. 4, in various aspects, the mixer 144 includes a mixing rotor 222. The mixing rotor 222 comprises a shaft 230 extending through the mixing barrel 146. The shaft 230 is divided into an upper or first region 224, and a lower or second region 226. In one example, the first region 224 is a material-feeding screw at the top comprising a blade 232 extending radially outward from the shaft 230.

[0072] In various aspects, the lower region 226 comprises mixing features (e.g., pins, blades, paddles, and the like) could be cylindrical pins (see, e.g., pins 234 of FIG. 4) or paddleshaped (see, e.g., fins 334 of FIG. 5) to facilitate aggregate mixing, and the mixing blade 232 can have different geometries for low, medium, and high shear mixing. Further, the lower region 226 could incorporate existing concrete mixing impellers and propellers.Attorney Docket No. 2115-008425-WO-POA

[0073] As shown in FIG. 4, in certain variations, the printhead 150 features a medium shear rotary mixer component design. The lower region 226 includes a series of mixing pins 234 or other mixing features that extend radially outward from the shaft 230. The pins 234 extend radially outward at regular intervals spaced apart from one another and staggered along a length of the central shaft 330 to facilitate combining the streams of material from feed conduits 138, 139, and 140 in the mixing chamber 210 of the mixing barrel 146. This provides a medium shear mixing in the printhead 150 for combining the various streams of material in the internal chamber 210 of the mixing barrel 146.

[0074] The mixer 144 includes the feed conduits 138, 139, 140 at the top that separately introduce materials — such as slurry, additives, aggregates, and fibers — into the first region 224. These feed conduits 138, 139, 140 may be positioned between the screw blades 232. The first region 224 including the material-feeding screw of the central shaft 230 of the mixing rotor 222 receives, directs, and pushes the material forward, while the pins 234 (second region 226) of the central shaft 230 mix the material. Both the blade 232 and the pins 234 can be designed in various configurations to optimize performance and suit the input materials.

[0075] With reference to FIG. 5, in certain variations, the printhead 150 features a low shear rotary mixer. The mixer 144 includes a mixing rotor 322 that comprises a shaft 330 extending through the mixing barrel 146. The shaft 330 is divided into an upper or first region 324 and a lower or second region 326. The first region 324 is a material-feeding screw comprising a blade 332 extending radially outward from the shaft 330. Like the first region screw of FIG. 4, the first region 324 screw of FIG. 5 receives, directs, and pushes material forward through the mixing barrel 146 towards the lower region 326. The lower region 326 includes a series of paddle-shaped fins 334 or other mixing features that extend radially outward from the shaft 330. The fins 334 extend radially outward at regular intervals spaced apart from one another and staggered along a length of the central shaft 330. This provides a low shear mixing in the printhead for combining the various streams of material in the internal chamber 210 of the mixing barrel 146.

[0076] As noted above, the rotary mixer component can be selected based on the desired use for either liquid-liquid mixing or solid-liquid mixing and depending on the inlet streams, can be designed for different shear levels. A solid-liquid mixing rotor blade refers to a blade that can mix solid, liquid, slurry, and other states in between, for example, slurry material, liquid additives, fibers and coarse aggregates. For example, in a solid- liquid mixing embodiment, the rotary mixer component may have a central shaft divided into two regions. An upper region of the shaft has a first mixing feature in the form of a material-feeding screw that receives, directs and pushes solids and liquids to a lower region of the rotating central shaft. The lower region of the central shaftAttorney Docket No. 2115-OQ8425-WO-POA may have a distinct design from the upper region to achieve necessary mixing. In FIG. 4, the lower region 226 comprises a plurality of cylindrical pins 234 extending radially outward and disposed at regular intervals on a surface of the central shaft 230 to provide mixing within the internal chamber 210 of the mixing barrel 146. In FIG. 5, the lower region 326 comprises a plurality of paddle-shaped fins 334 extending radially outward and disposed at regular intervals on a surface of the central shaft 330 to provide mixing within the internal chamber 210 of the mixing barrel 146.

[0077] In this manner, the mixer 144 for end effectors of additive manufacturing devices provide mixing rotor designs that serve to uniformly incorporate coarse aggregates and short fibers into a slurry, downstream of a pump, resulting in improved processing and concurrently providing greater compressive and tensile strength in a final printed product.

[0078] 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 many 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. 2115-008425-WO-POACLAIMSWhat is claimed is:

1. A mixing component for a printhead of an additive manufacturing device receiving a plurality of distinct material streams to form a printable material, the mixing component comprising: a mixing barrel component defining an internal chamber; a rotary mixer component defining a central shaft having a first region comprising a feeding screw and a second region distinct from the first region, the rotary mixer component at least partially disposed in the internal chamber of the mixing barrel component; a motor in driving engagement with the rotary mixer component to rotate the rotary mixer component, wherein the plurality of distinct material streams are fed into the internal chamber of the mixing barrel component and mixed to form the printable material; and a terminal extrusion nozzle connected to an outlet of the mixing barrel component through which the printable material passes.

2. The mixing component of claim 1, wherein the mixing barrel component further comprises at least two distinct inlets to receive the plurality of distinct material streams.

3. The mixing component of claim 2, wherein at least one of the two distinct inlets receives the slurry or cementitious material.

4. The mixing component of claim 2, wherein at least one of the at least two distinct inlets receives a material comprising an aggregate or a fiber.

5. The mixing component of claim 2, wherein the mixing barrel component comprises three distinct inlets, and wherein each of the three distinct inlets receives a different material.

6. The mixing component of claim 1, wherein the second region of the rotary mixer component comprises a plurality of stationary pins extending radially outward from the central shaft.

7. The mixing component of claim 6, wherein the rotary mixer component is configured to provide a medium shear mixing level.

8. The mixing component of claim 1, wherein the second region of the central shaft of the rotary mixer component comprises a plurality of paddle- shaped fins extending radially outward from the central shaft.

9. The mixing component of claim 8, wherein the rotary mixer component is configured to provide a low shear mixing level.

10. A robotic additive manufacturing device for additively manufacturing a cementitious or slurry-based material, the robotic additive manufacturing device comprising anAttorney Docket No. 2115-008425-WO-POA end effector having the printhead comprising the mixing component of claim 1, wherein the printable material comprises the cementitious or slurry-based material.

11. A mixing component for a printhead of an additive manufacturing device receiving a plurality of distinct material streams to form a printable material, the mixing component comprising: a mixing barrel component defining an internal chamber; at least two distinct inlets to receive the plurality of distinct material stream; a rotary mixer component defining a central shaft having a first region comprising a feeding screw and a second region, the rotary mixer component at least partially disposed in the internal chamber of the mixing barrel component, wherein: the feeding screw is configured to move material received from the at least two distinct inlets to the second region, and the second region of the rotary mixer component comprises a plurality of stationary pins extending radially outward from the central shaft; a motor in driving engagement with the rotary mixer component to rotate the rotary mixer component, wherein the plurality of distinct material streams are fed into the internal chamber of the mixing barrel component at the first region and mixed at the second region to form the printable material; and a terminal extrusion nozzle connected to an outlet of the mixing barrel component through which the printable material passes.

12. The mixing component of claim 11, wherein the mixing barrel component comprises at least three distinct inlets to receive the plurality of distinct material streams.

13. The mixing component of claim 12, wherein at least one of the two distinct inlets receives the slurry or cementitious material.

14. The mixing component of claim 12, wherein at least one of the at least two distinct inlets receives a material comprising an aggregate or a fiber.

15. A robotic additive manufacturing device for additively manufacturing a cementitious or slurry-based material, the robotic additive manufacturing device comprising an end effector having the printhead comprising the mixing component of claim 11, wherein the printable material comprises the cementitious or slurry-based material.

16. A mixing component for a printhead of an additive manufacturing device receiving a plurality of distinct material streams to form a printable material, the mixing component comprising: a mixing barrel component defining an internal chamber;Attorney Docket No. 2115-008425-WO-POA at least two distinct inlets to receive the plurality of distinct material stream; a rotary mixer component defining a central shaft having a first region comprising a feeding screw and a second region, the rotary mixer component at least partially disposed in the internal chamber of the mixing barrel component, wherein: the feeding screw is configured to move material received from the at least two distinct inlets to the second region, and the second region of the central shaft of the rotary mixer component comprises a plurality of paddle- shaped fins extending radially outward from the central shaft; a motor in driving engagement with the rotary mixer component to rotate the rotary mixer component, wherein the plurality of distinct material streams are fed into the internal chamber of the mixing barrel component at the first region and mixed at the second region to form the printable material; and a terminal extrusion nozzle connected to an outlet of the mixing barrel component through which the printable material passes.

17. The mixing component of claim 16, wherein the mixing barrel component comprises at least three distinct inlets to receive the plurality of distinct material streams.

18. The mixing component of claim 17, wherein at least one of the two distinct inlets receives the slurry or cementitious material.

19. The mixing component of claim 17, wherein at least one of the at least two distinct inlets receives a material comprising an aggregate or a fiber.

20. A robotic additive manufacturing device for additively manufacturing a cementitious or slurry-based material, the robotic additive manufacturing device comprising an end effector having the printhead comprising the mixing component of claim 16, wherein the printable material comprises the cementitious or slurry-based material.

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