CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority benefit of U.S. Provisional Patent Application No. 63/343,507, filed May 18, 2022, and U.S. Provisional Patent Application No.

63/467,362, filed May 18, 2023, the entirety of each of the disclosures of which are explicitly incorporated by reference herein.

BACKGROUND

[0001] Earth architecture has been gaining renewed interest due its environmental benefits. In comparison to typical concrete building techniques, which is currently responsible for consuming 10% of global carbon emissions, earth construction makes use of locally available and minimally processed materials, reducing embodied energy demand by 38-83%, and embodied climate change potential by 60-82%.

[0002] In terms of applicability for 3D printing fabrication, earth materials offer responses to challenges posed for 3D printed concrete. The integration of vertical reinforcement in 3D printed concrete requires complex applications, and dispersed short steel, glass, and polymer fibers require further investigation. From an environmental standpoint, 3D printed concrete results in even higher carbon intensities than conventional concrete because it typically contains higher cement content to pass through the small pipe and nozzles at the print-head. Printed earth is vernacularly practiced with micro-scale vegetable fibers that provide increased ductility while also maximizing carbon storage of the mix design.

[0003] However, 3D printed earth mixture design research has been limited to mix designs that include low fiber content, such as cob mixtures. With high thermal capacity and low thermal resistivity, cob is limited by building codes to thick walls and is thus mostly suited warm-hot climates or as an assembly that is placed within the thermal envelope of a building. Light straw clay, a more promising carbon-storing building material, currently lacks advanced manufacturing techniques. As opposed to conventionally constructed earth materials, 3D printed earth includes mixtures with higher water content to reduce viscosity and facilitate the material extrusion, with 23-25% water. Previous research has shown challenges in increasing fiber content over 2% fiber in weight due to extrusion difficulties and increased viscosity that results in printing malfunction and clogging. [0002] What is needed, therefore, is an improved 3D printed earth mixture that addresses at least the problems described above.

SUMMARY

[0003] Accordingly, some embodiments of the disclosed subject matter are directed to extrudable earth-fiber mixtures with bio-based additives to provide enhanced thermal and structural properties over traditional 3D printed cob. Some embodiments of the disclosed subject matter are directed to carbon-storing clay-fiber wall assembly from 3D printed earth (mass) and/or 3D printed vegetable fiber (insulation) with increased thermal and environmental performance compared to the incumbent assembly (a concrete masonry unit (CMU) wall). By using less processed materials for 3D printing, earth- and fiber-based building materials substantially reduce transportation, chemical treatments, excess manufacturing, warehouse storage, and intermediary storages that are inextricably intertwined with conventional highly processed materials.

[0004] According to an embodiment of the disclosed subject matter, a 3D printed structure is provided. The structure includes a composition that is formed from a mixture. The mixture includes an earth component, a fiber component, a water component, and at least one additive. The structure includes an insulation portion and an exterior support portion surrounding the insulation portion. The exterior support portion includes an earth:fiber:water weight ratio of about 65:4:32. The insulation portion includes an earth:fiber:water weight ratio of about 65:244: 1480.

[0005] In some embodiments, the structure includes an interior support portion that is positioned at least partially between the exterior support portion and the insulation portion. The interior support portion includes an earth: fib er: water weight ratio of about 65: 12:67.5.

[0006] In some embodiments, the exterior support portion includes a first exterior wall at a first side of the structure and a second exterior wall at a second side of the structure opposite the first side. The interior support portion has a substantially double-helical shape and is positioned between the first exterior wall and the second exterior wall thereby forming a plurality of pockets within the structure. The insulation portion is positioned in the plurality of pockets.

[0007] In some embodiments, the earth component includes a naturally occurring soil, a synthetic soil, a subsoil, or combinations thereof. [0008] In some embodiments, the fiber component includes a wheat straw, a hemp, or combinations thereof.

[0009] In some embodiments, the fiber component includes a plurality of fibers having an average length between about 0.5 mm and 4 mm. In some embodiments, the plurality of fibers have an average length between about 1 mm and 3 mm. In some embodiments, the plurality of fibers are no greater than 3 mm.

[0010] In some embodiments, the at least one additive includes a cellulose, a polypeptide, a natural polysaccharide, or combinations thereof, with and without lime.

[0011] In some embodiments, the at least one additive includes a cellulose and an alginate. The exterior support portion includes a cellulose:alginate weight ratio of about 1 : 1, and the insulation portion includes a cellulose:alginate weight ratio of about 36.7:46.3. In some embodiments, the interior support portion includes a cellulose:alginate weight ratio of about 0.99: 1.35.

[0012] In some embodiments, the mixture includes a sand component.

[0013] According to another embodiment of the disclosed subject matter, a 3D printed building structure is provided. The structure includes a panel having a frame. The frame has a composition that is formed from a mixture. The mixture includes an earth component, a fiber component, a water component, and at least one additive. The frame includes an earth: fib er: water weight percent ratio of about 3: 13:79.

[0014] In some embodiments, the at least one additive includes a cellulose and an alginate. The frame further includes a cellulose:alginate weight percent ratio of about 2:3.

[0015] In some embodiments, the frame is 3D printed to form a tessellating geometry.

[0016] In some embodiments, the frame includes a plurality of apertures passing therethrough.

[0017] According to another embodiment of the disclosed subject matter, a method of making the structure of any of the disclosed embodiments is provided. The method includes 3D printing the structure with the mixture.

[0018] In some embodiments, the method includes 3D printing the structure by extruding the mixture from a nozzle of a 3D printer in a predetermined pattern. The predetermined pattern includes at least one continuous and non-intersecting path. [0019] Further objects, aspects, features, and embodiments of the present technology will be apparent from the drawing Figures and below description.

BRIEF DESCRIPTION OF DRAWINGS

[0020] Some embodiments of the present technology are illustrated as an example and are not limited by the figures of the accompanying drawings, in which like references may indicate similar elements.

[0021] FIG. l is a perspective view of a 3D printed structure according to some embodiments of the disclosed subject matter.

[0022] FIG. 2 is a top plan view of a 3D printed structure according to some embodiments of the disclosed subject matter.

[0023] FIG. 3 A is a top plan view of a first path for 3D printing the structure of FIG. 2 according to some embodiments of the disclosed subject matter.

[0024] FIG. 3B is a top plan view of a second path for 3D printing the structure of FIG. 2 according to some embodiments of the disclosed subject matter.

[0025] FIG. 3C is a top plan view of the first path of FIG. 3 A and the second path of FIG. 3B overlayed on one another.

[0026] FIGS. 4A-4B are perspective views showing the assembly of a 3D printed structure according to some embodiments of the disclosed subject matter.

[0027] FIG. 5A is a perspective view of a form for molding the shape of a 3D printed structure according to some embodiments of the disclosed subject matter.

[0028] FIG. 5B is a perspective view of a 3D printed structure positioned on the form of FIG. 5 A according to some embodiments of the disclosed subject matter.

[0029] FIG. 6 is a perspective view of a process of 3D printing a structure according to some embodiments of the disclosed subject matter. DETAILED DESCRIPTION

[0030] Accordingly, some embodiments of the disclosed subject matter are directed to extrudable earth-fiber mixtures with bio-based additives to provide enhanced thermal and structural properties over traditional 3D printed cob. Some embodiments of the disclosed subject matter are directed to carbon-storing clay-fiber wall assembly from 3D printed earth (mass) and/or 3D printed vegetable fiber (insulation) with increased thermal and environmental performance compared to the incumbent assembly (a concrete masonry unit (CMU) wall). Earth materials combined with vegetable fibers offer a high performance, carbon-storing alternative to CMUs and synthetic insulation due to their carbon storage potential, affordability, safety, and wide range of hygrothermal capabilities. By using less processed materials for 3D printing, earth- and fiber-based building materials substantially reduce transportation, chemical treatments, excess manufacturing, warehouse storage, and intermediary storages that are inextricably intertwined with conventional highly processed materials. In some embodiments, the mixtures use biopolymer binding agents to develop mix designs for 3D printed earth while increasing fiber content, and thus, carbon storage and thermal resistivity. These embodiments link applied building technology research with digital fabrication (3D printing) and multi-scale thermal (and structural) investigations to reduce embodied emissions, increase the atmospheric carbon included in the finished product, and bolster commercialization potential of 3D printed residential construction. Additionally, embodiments of the disclosed subject matter support building policy and standardization by producing environmental and social life cycle assessments (ELCA and SLCA) that can be expanded into environmental and health product declarations (EPD and HPD).

[0031] As shown in FIG. 1, a 3D printed structure according to some embodiments of the disclosed subject matter is generally designated by the numeral 100. The structure 100 includes a composition that is formed from a mixture. In some embodiments, the mixture includes an earth component, a fiber component, a water component, and at least one additive. In some embodiments, the mixture also includes a sand component. In some embodiments, the earth component includes a naturally occurring soil, a synthetic soil, or combinations thereof. In some embodiments, the earth component includes a subsoil. In some embodiments, the fiber component includes wheat straw, hemp, or combinations thereof. In some embodiments, the fiber component includes a plurality of fibers having an average length between about 0.5 mm and about 4 mm. In some embodiments, the plurality of fibers have an average length between about 1 mm and about 3 mm. In some embodiments, the plurality of fibers have an average length of about 3mm. In some embodiments, the plurality of fibers have a length no greater than 3 mm. In some embodiments, the at least one additive includes a cellulose, a polypeptide (e.g., gelatin), a natural polysaccharide (e.g., alginate, xanthan gum, guar gum), or combinations thereof, with and without lime. In some embodiments, the mixture further includes a sand component. In some embodiments, the mixture further includes a clay component.

[0032] In some embodiments, the structure 100 includes an exterior support portion 110 and an insulation portion 130, as shown in FIG. 1. The exterior support portion 110 includes a first exterior wall 112 at a first side of the structure 100 and a second exterior wall 114 at a second side of the structure 100. The insulation portion 130 is positioned between the first exterior wall 112 and the second exterior wall 114 such that the exterior support portion 110 surrounds the insulation portion 130. In some embodiments, the structure 100 includes an interior support portion 120 that is positioned between the first exterior wall 112 and the second exterior wall 114 and partially surrounds the insulation portion 130. In some embodiments, the interior support portion 120 has a substantially double-helical shape and is positioned between the first exterior wall 112 and the second exterior wall 114 thereby forming a plurality of pockets 140 within the structure 110, as shown in FIG. 1. In such embodiments, the insulation portion 130 is positioned in each of the plurality of pockets 140. In some embodiments, the structure 100 is 3D printed as a plurality of layers 150 stacked on top of one another. In some embodiments, the plurality of layers 150 have a height between about 3 mm and about 5 mm. In some embodiments, the plurality of layers 150 have a height of about 4 mm. In some embodiments, the structure 100 is formed as a building structure component, such as a foundation block, wall panel, floor tile, etc.

[0033] In some embodiments, the exterior support portion 110 has an earth: fib er: water weight ratio of about 65:4:32. In some embodiments, the insulation portion 130 has an earth: fib er: water weight ratio of about 65:244: 1480. In some embodiments, the interior support portion 120 has an earth:fiber:water weight ratio of about 65: 12:67.5. In some embodiments, the at least one additive includes a cellulose and an alginate, the exterior support portion 110 has a cellulose:alginate weight ratio of about 1 : 1, the insulation portion 130 has a cellulose:alginate weight ratio of about 36.7:46.3, and the interior support portion 120 has a cellulose:alginate weight ratio of about 0.99: 1.35. By way of example, in some embodiments, the exterior support portion 110 is formed of a cob mixture, the interior support portion 120 is formed of a light cob mixture, and the insulation portion 130 is formed of a light straw clay mixture having the components and weight ratios shown in Table 1 below.

Table 1: Example mixtures

[0034] As shown in FIG. 2, a 3D printed structure according to some embodiments of the disclosed subject matter is generally designated by the numeral 200. The structure 200 includes a panel 210 having a frame 220. The frame 220 includes a composition that is formed from a mixture. In some embodiments, the mixture includes an earth component, a fiber component, a water component, and at least one additive. In some embodiments, the mixture also includes a sand component. In some embodiments, the earth component includes a naturally occurring soil, a synthetic soil, or combinations thereof. In some embodiments, the earth component includes a subsoil. In some embodiments, the fiber component includes wheat straw, hemp, or combinations thereof. In some embodiments, the fiber component includes a plurality of fibers having an average length between about 0.5 mm and about 4 mm. In some embodiments, the plurality of fibers have an average length between about 1 mm and about 3 mm. In some embodiments, the plurality of fibers have an average length of about 3mm. In some embodiments, the plurality of fibers have a length no greater than 3 mm. In some embodiments, the at least one additive includes a cellulose, a polypeptide (e.g., gelatin), a natural polysaccharide (e.g., alginate, xanthan gum, guar gum), or combinations thereof, with and without lime. In some embodiments, the mixture further includes a sand component. In some embodiments, the mixture further includes a clay component.

[0035] In some embodiments, the frame 220 has an earth: fib er: water weight percent ratio of about 3 : 13 :79. In some embodiments, the at least one additive includes a cellulose and an alginate, and the frame 220 has a cellulose:alginate weight percent ratio of about 2:3. In some embodiments, the cellulose is a food-grade methyl cellulose. In some embodiments, the alginate is sodium alginate. In some embodiments, the mixture includes about 0.1 weight percent of clay, such as a natural red clay to adjust the pigmentation of the mixture. By way of example, in some embodiments, the frame 220 is formed of a light straw clay mixture having the components and weight ratios shown in Table 2 below.

Table 2: Example light straw clay mixture

[0036] As shown in FIG. 2, in some embodiments, the frame 220 has a first end 222 and a second end 224 opposite the first end 222. The first end 222 and the second end 224 have corresponding contours such that the first end 222 of a first frame 220 can be aligned in an interlocking arrangement with the second end 224 of a second frame 220. In some embodiments, the frame 220 has a third end 226 and a fourth end 228 opposite the third end 226. The third end 226 and the fourth end 228 have corresponding contours such that the third end 226 of a first frame 220 can be aligned in an interlocking arrangement with the fourth end 228 of a second frame 220. In some embodiments, the frame 220 includes a plurality of apertures 230 passing therethrough. In some embodiments, the plurality of apertures 230 are arranged and shaped such that the frame 220 has a tessellating geometry. In some embodiments, the frame 220 has a substantially mashrabiya pattern. In some embodiments, the structure 200 is formed as a building structure component, such as a foundation block, wall panel, floor tile, etc.

[0037] In some embodiments, the frame 220 is 3D printed in at least one continuous and non-intersecting path such that the mixture is substantially uniformly extruded to form the frame 220. FIGS. 3A-3C show example paths for 3D printing the frame 220 according to some embodiments of the disclosed subject matter. FIG. 3 A shows a first path 240 and FIG. 3B shows a second path 250. FIG. 3C shows the first path 240 and the second path 250 overlayed to form the frame 220. In some embodiments, the first path 240 is printed first and the second path 250 is printed second. In some embodiments, the second path 250 is printed first and the first path 240 is printed second. Although the figures show the frame 220 having a substantially mashrabiya pattern, the disclosed subject matter is not limited thereto and contemplates the frame 220 having other tessellating geometries, such as labyrinthine patterns, Hilbert curves, etc. In some embodiments, the structure 200 is 3D printed as a plurality of layers stacked on top of one another, as discussed herein regarding structure 100. In some embodiments, the plurality of layers have a height between about 3 mm and about 5 mm. In some embodiments, the plurality of layers have a height of about 4 mm. In some embodiments, the structure 200 includes one to five layers. In some embodiments, the structure 200 includes three layers.

[0038] In some embodiments, the structure 200 includes a plurality of connected panels 210. As shown in FIG. 4A, in some embodiments, the structure 200 includes a first panel 210 is positioned a distance from a second panel 210’ forming a gap G. In some embodiments, the gap G is about 25% of a length L of the first panel 210. In some embodiments, the gap G is between about 5% and about 50% of the length L. A third panel 210” is positioned over the first panel 210 and the second panel 210’ substantially centrally aligned with the gap G. While the first panel 210, the second panel 210’, and the third panel 210” are in a wet condition following the 3D printing process, the third panel 210” is placed on top of the first panel 210 and the second panel 210’ such that the panels bond together while drying, as shown in FIG. 4B. In some embodiments, the first panel 210, the second panel 210’, and the third panel 210” are all of equal dimensions. In some embodiments, the third panel 210” is larger than the gap G, but smaller than the first panel 210 and the second panel 210”. For example, in some embodiments, the third panel 210” has a length that is between about 5% and about 30% larger than the gap G. In some embodiments, the first panel 210 and the second panel 210’ are connected after drying by securing their respective corresponding ends 222, 224, 226, 228 together. For example, in some embodiments, the first panel 210 and the second panel 210’ are tied together with a twine.

[0039] In some embodiments, the structure 200 can be molded to a predetermined shape by positioning the structure 200, while in a wet condition following the 3D printing process, on a mold form 260, as shown in FIGS. 5A-5B. After a predetermined drying time, the structure 200 can be removed from the mold form 260 such that the structure 200 has a shape corresponding to the mold form 260. Although the figures show a mold form 260 have a generally sinusoidal shape, the disclosed subject matter is not limited thereto and contemplates embodiments in which the mold form 260 has a different shape. In some embodiments, the predetermined drying time is about 36 hours. In some embodiments, the predetermined drying time is between about 24 hours and about 48 hours.

[0040] FIG. 6 shows the 3D printing process of making the structures 100, 200 via a 3D printer 300 according to some embodiments of the disclosed subject matter. The 3D printer 300 includes a feed tube 310 having a 3D printing filament 320 housed therein. The 3D printing filament 320 includes the mixture discussed herein regarding structures 100, 200. A nozzle 330 is connected to the feed tube 310, and the 3D printing filament 320 is extruded out through the nozzle 330 onto a print bed 340 to form the structures 100, 200. In some embodiments, the nozzle 330 has an 8 mm wide opening for extrusion. However, in some embodiments, the nozzle 330 has a different sized opening, such as 4 mm, 5 mm, or 6 mm. In some embodiments, the print bed 340 can be lowered as each layer is 3D printed and the print bed 340 can be translated and/or rotated such that the 3D printing can follow the paths 240, 250 discussed herein. In some embodiments, the print bed 340 remains stationary and the feed tube 310 and nozzle 330 can be raised as each layer is 3D printed and feed tube 310 and nozzle 330 can be translated and/or rotated such that the 3D printing can follow the paths 240, 250 discussed herein.

[0041] As will be apparent to those skilled in the art, various modifications, adaptations, and variations of the foregoing specific disclosure can be made without departing from the scope of the technology claimed herein. The various features and elements of the technology described herein may be combined in a manner different than the specific examples described or claimed herein without departing from the scope of the technology. In other words, any element or feature may be combined with any other element or feature in different embodiments, unless there is an obvious or inherent incompatibility between the two, or it is specifically excluded. The term "and/or" means any one of the items, any combination of the items, or all of the items with which this term is associated. The phrase "one or more" is readily understood by one of skill in the art, particularly when read in context of its usage. Each numerical or measured value in this specification is modified by the term “about.” The term "about" can refer to a variation of ± 5%, ± 10%, ± 20%, or ± 25% of the value specified. For example, "about 50" percent can in some embodiments carry a variation from 45 to 55 percent. For integer ranges, the term "about" can include one or two integers greater than and/or less than a recited integer at each end of the range. Unless indicated otherwise herein, the term "about" is intended to include values and ranges proximate to the recited range that are equivalent in terms of the functionality of the composition, or the embodiment.