Cementitious-based composite materials, processes for manufacturing, and methods of using the same

Abstract

A cementitious-based composite material includes an aggregate including a ground plastic material and a cement binder. The ground plastic material is mixed with the cement binder in a mortar cement mixture at a predetermined cement-to-aggregate ratio by volume and the ground plastic material includes up to 100% of the aggregate.

Description

CEMENTITIOUS-BASED COMPOSITE MATERIALS, PROCESSES FOR MANUFACTURING, AND METHODS OF USING THE SAMECROSS REFERENCE TO RELATED APPLICATIONSThis application claims priority from U.S. Provisional Application Ser. No. 63 / 605,101. titled “PLASTIC WASTE-BASED FINE AGGREGATE MATERIAL PROCESSING FOR CONCRETE USAGE." filed December 1, 2023, incorporated herein by reference.BACKGROUND OF THE INVENTIONThe rapid expansion of the industrial sector has led to a substantial increase in demand for two key industries: concrete and plastics. The modem era, marked by rapid urbanization and population grow th, has witnessed significant advancements in the cementbased products industry, with various cementitious mixtures offering a wide range of properties and applications. However, this growth has raised concerns about the finite natural resources required to sustain these industries.The drive for energy efficiency and environmental protection has led to increased demand for plastic materials that provide design flexibility. The production of plastic materials has surged annually, in step with the growing global economy and the demand for plastic products. However, this rapid growth in plastic production has caused a corresponding increase in the recycling challenge for end-of-life plastics, which stands in stark contrast to environmental goals. Thermoset polymeric materials, often found in landfills, cannot be remelted due to their covalent bonds, while thermoplastics, like ABS, can produce harmful fumes when heated at extreme temperatures exceeding 410 °F [210 °C], Therefore, finding environmentally and financially viable solutions for recycling or reuse is essential to a circular economy.Despite efforts to manage the plastic industry’s waste production, current methods struggle to keep pace with the growing volume of w aste generated. Industrial waste recycling is one of the most effective strategies for providing economic value to waste materials. The concrete industry offers opportunities for utilizing recycled waste plastics as aggregates, primarily due to its high-volume production. For this purpose, researchers have endeavored to design lightw eight and required structural quality concretestructures by adding mechanically recycled waste plastics into cementitious mixtures in recent years to reduce the loads on landfills.Numerous studies have explored the use of waste plastics as complete or partial substitutes for natural sand aggregates. Some studies address the effects of using recycled plastics at different replacement ratios on the mechanical performance of cementitious mixtures, but not the impact of graded particle size. These studies primarily focused on uniform particle sizes or different Wpes of plastics without a detailed investigation into the graded particle size ranges derived from recycling processes and quantifying their effect on the mechanical performance of concrete. As such, current research still lacks a comprehensive understanding of the effects of graded plastics with specific size ranges, which is an important factor to consider when particle sizes are obtained after the recycling process and are not uniform.SUMMARY OF THE INVENTIONOne aspect of the invention relates to a cementitious-based composite material, comprising an aggregate comprising a ground plastic material; and a cement binder, wherein the ground plastic material is mixed with the cement binder in a mortar cement mixture at a predetermined cement-to-aggregate ratio by volume and the ground plastic material comprises up to 100% of the aggregate.In embodiments, the aggregate further comprises sand, and wherein the ground plastic material is mixed with the cement binder and the sand in a mortar cement mixture having a cement-to-aggregate ratio of 50 / 50 wherein the sand comprises 10-40% by volume and the ground plastic material comprises 40-10% by volume.In embodiments, the ground plastic waste material is a product of a process comprising cooling an unground plastic material to a temperature below a brittle-ductile transition temperature of the plastic material, and grinding the cooled plastic waste material to obtain the ground plastic material.In embodiments, ground plastic waste material product process further comprises passing the ground plastic feedstock through one or more mechanical sieves with predetermined mesh parameters to obtain a graded ground plastic material.In embodiments, the graded ground plastic material comprises particles with sizes ranging from 4.75 mm to 0. 15 mm.In embodiments, the unground plastic material comprises a plastic waste material comprising a thermoset or thermoplastic polymer waste material.In embodiments, the ground plastic material comprises ground acrylonitrile butadiene styrene (GRABS).In embodiments, the predetermined cement-to-aggregate ratio is a 50 / 50 cement-to-aggregate ratio and the graded plastic feedstock comprises between 20% and 80% of the aggregate by volume and the sand comprises between 80% to 20% of the aggregate by volume.Another aspect of the invention relates to a method of making a cementitious-based composite material, the method comprising the steps of: a) cooling a plastic waste material to a temperature below a brittle-ductile transition temperature of the plastic waste material; b) grinding the cooled plastic waste material to obtain a ground plastic feedstock; c) passing the ground plastic feedstock through one or more mechanical sieves with predetermined mesh parameters to obtain a graded plastic feedstock; and d) mixing the graded plastic feedstock with a cement binder in a mortar cement mixture at a predetermined cement-to-aggregate ratio in which the aggregate comprises up to 100% graded plastic feedstock.In embodiments, the predetermined cement-to-aggregate ratio is 50 / 50 by volume and the aggregate comprises sand, further comprising mixing the graded plastic feedstock with the cement binder and sand in the mortar cement mixture at a replacement ratio of the graded plastic feedstock for sand of 20% to 80% by volume relative to an aggregate composition of 100% sand.In embodiments, the graded plastic feedstock comprises 20% to 50% of a volume of the aggregate and the sand comprises between 80% to 50% of the volume of the aggregate.In embodiments, the plastic w aste material comprises a thermoset or thermoplastic polymer waste material.In embodiments, the graded plastic feedstock comprises ground acrylonitrile butadiene styrene (GRABS).In embodiments, the graded plastic feedstock comprises particles with sizes ranging from 4.75 mm to 0.15 mm.In embodiments, the graded plastic feedstock comprises particles with sizes less than 0.6 mm.In embodiments, step c) comprises gradually reducing a particle size of the ground plastic feedstock from mesh-size No. 4 to mesh-size No. 50 by sequentially passing the ground plastic feedstock through a plurality of mechanical sieves to produce the graded plastic feedstock.In embodiments, the cementitious-based composite material exceeds a minimum compressive strength of 4060 psi [28 MPa].In embodiments, step a) comprises cooling the plastic waste to cryogenic temperatures.In embodiments, step a) comprises immersing the plastic waste in a cryogenic liquid.In embodiments, the cryogenic liquid comprises liquid nitrogen.In embodiments, the predetermined mesh parameters comprise sieve openings with diameters ranging between 150 pm and 4.75 mm.In embodiments, the predetermined mesh parameters comprise a mesh size between a No. 4 and a No. 50.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 A depicts a recycling process of recycled plastics as described herein.FIG. IB depicts morphological views of plastics before and after grinding during the recycling process of FIG. 1A.FIG. 2 depicts a sieve analysis of recycled plastic aggregates showing a particle size distribution and gradation of GRABS recycled plastics versus masonry sand.FIG. 3A depicts optical micrographs of ungraded GRABS particles, according to an aspect of the invention.FIGs. 3B-3G depict optical micrographs of graded GRABS particles from sieves no. 4, 8, 16, 30, 50, and 100, respectively, according to aspects of the invention.FIGs. 4A-4F depict cross-sectional microstructures of mortar structures including different gradations of recycled waste plastics (black) retained on sieves no. 4, 8, 16, 30, 50, and 100, respectively.FIG. 5A depicts experimental tests conducted to characterize mechanical properties via compressive tests.FIG. 5B depicts experimental tests conducted to characterize mechanical properties via tensile tests.FIG. 5C depicts experimental tests conducted to characterize mechanical properties via shear tests.FIG. 6A is a bar graph depicting a reduction in fresh density values as the GRABS percentage is increased.Fig. 6B is a bar graph depicting the effect of GRABS gradation compared to a control group (G-Mix) with ungraded particles.FIG. 7A is a bar graph depicting the spread-flow test results of fresh mixtures with various amounts of GRABS recycled plastic.FIG. 7B is a bar graph depicting the effect of GRABS gradation in spreadflow test results of fresh mixtures.FIG. 8A is a bar graph depicting the compressive strength values of specimens of ungraded GRABS vary ing with curing time and recycled plastic substitute ratio.FIG. 8B is a bar graph depicting the variation in compressive strength for gradation samples of graded GRABS with 50% cement, 25% sand, and 25% recycled plastic example with different sizes of sieved waste plastics.FIG. 9A is a bar graph illustrating the impact of different replacement ratios on the tensile properties of specimens containing ungraded plastics.FIG. 9B is a bar graph illustrating that sample groups containing graded recycled plastic exhibit improved tensile properties compared to the control group (G-Mix) containing 25% ungraded plastic.FIG. 10A is a bar graph illustrating shear strength values for ungraded GRABS-containing mortars.FIG. 1 OB is a bar graph illustrating shear strength values for graded GRABS- containing mortars.FIG. 11 A depicts voids observ ed on surfaces of the control group samples (without plastic) on 10C:0S:0P.FIG. 1 IB depicts voids observed on surfaces of the control group samples (without plastic) on 5C:5S:0P.FIG. 11C depicts voids observed on surfaces of the control group samples (with plastic) on 5C:4S:1P.FIG. 1 ID depicts voids observed on surfaces of the control group samples (with plastic) on 5C:3S:2P.FIG. 1 IE depicts voids observed on surfaces of the control group samples (with plastic) on 5C:2S:3P.FIG. 1 IF depicts voids observed on surfaces of the control group samples (with plastic) on 5C:0S:5P.FIG. 12A depicts a fracture pattern in a shear test sample based on replacement ratio 10C:0S:0P.FIG. 12B depicts a fracture pattern in a shear test sample based on replacement ratio 5C:5S:0P.FIG. 12C depicts a fracture pattern in a shear test sample based on replacement ratio 5C:4S: 1P.FIG. 12D depicts a fracture pattern in a shear test sample based on replacement ratio 5C:3S:2P.FIG. 12E depicts a fracture pattern in a shear test sample based on replacement ratio 5C:2S:3P.FIG. 12F depicts a fracture pattern in a shear test sample based on replacement ratio 5C:0S:5P.FIGs. 13A-13F depict fracture patterns in mortar with varying plastic particle sizes.FIG. 14 illustrates the interaction between a waste plastic and a crack that nucleates from a void.FIG. 15A depicts a fracture line image of a tensile test specimen on 10C:0S:0P.FIG. 15B depicts a fracture line image of a tensile test specimen on 5C:5S:0P.FIG. 15C depicts a fracture line image of a tensile test specimen on 5C:4S: 1P.FIG. 15D depicts a fracture line image of a tensile test specimen on5C:3S:2P.FIG. 15E depicts a fracture line image of a tensile test specimen on5C:2S:3P.FIG. 15F depicts a fracture line image of a tensile test specimen on 5C:0S:5P.FIG. 16A is a photographic image of mutual fracture surfaces of multi-scale recycled plastic containing shear test specimens.FIG. 16B is a microscopic image of a sample containing recycled plastic.FIG. 17A depicts the impact of shear deformation on a region near the free edges of a fracture surface of shear samples on 10C:0S:0P.FIG. 17B depicts the impact of shear deformation on a region near the free edges of a fracture surface of shear samples on 5C:0S:5P.DETAILED DESCRIPTION OF THE INVENTIONDisclosed herein are a method of making a cementitious-based composite material and a cementitious-based composite material including ground recycled acrylonitrile butadiene styrene (GRABS) plastic. As used herein, the term “recycled” means that the plastic feedstock used in the embodiments described herein comprises plastic waste, which may comprise post-consumer waste, industrial waste, or a combination thereof, and by using the plastic waste in the cementitious composite, the plastic is being “recycled” rather than being landfilled, burned, or disposed in some other manner. The GRABS recycled plastic is graded and mixed with sand and a cement binder in a mortar cement mixture at a replacement ratio of the graded GRABS recycled plastic for sand of between 20% and 50% by volume, in a mortar having an aggregate-to-cement (a / c) ratio of 50 / 50. As referred to herein, replacement of sand by volume is relative to an aggregate comprising 100% sand, meaning that for a 50 / 50 aggregate-to-cement ratio of 50 / 50 by volume, replacement of between 20-50% of the sand results in a mixture by volume in which the cement comprises 50%, the plastic is in a range of 10-25%, and the sand is in a range of 40- 25%. While concrete components are mixed volumetrically, they are typically weighed out for practicality. The density of ABS is significantly lower than that of sand, resulting in a concrete that is approximately 25% lighter when sand is fully replaced with ABS. This reduced weight could offer distinct advantages depending on the application. Embodiments of the invention feature graded GRABS recycled plastic including particles with sizes ranging from 4.75 mm to 0. 15 mm. Experimental testing was conducted to reveal to whatextent the cementitious composite properties were altered, thereby influencing their overall mechanical performance, when both ungraded and graded ground recycled acrylonitrile butadiene styrene (GRABS) plastics were used as a natural sand aggregate replacement in cementitious mortar.The present disclosure quantifies the effects of vary ing particle sizes and volume fractions of waste plastics acquired through mechanical recycling and their influences on the mechanical properties of mortars containing plastics as a composite material. Comparing the results from fresh and hardened material properties to conventional mortar properties demonstrates the impact of various GRABS particle sizes and volume fractions on the overall material strength. While replacing sand with recycled plastic generally reduces the mechanical properties, the resulting mixes still met the minimum compressive strength of 4060 psi [28 MPa], according to the ASTM Cl 50 standards for Portland cement. Notably, graded plastic particles with sizes less than 0.024 inches [0.6 mm] demonstrate an overall improvement in mechanical properties compared to ungraded particles. These results reveal that GRABS recycled plastics, when combined with sand at appropriate particle sizes and volume fractions, have the potential to create tailored mixes to meet minimum mix design standards for construction applications.The present disclosure examines the impact of particle size and replacement ratio on mechanical performance by adding GRABS plastics, which range in size and uniformity’, to concrete structures. The embodiments disclosed herein explore how particle size and volume fraction of recycled waste plastics affect mortar properties, with a focus on using waste materials to minimize environmental impact and reduce costs. Although compressive strength is usually considered in the design of mortar structures containing plastic for durability' and usability', the tensile and shear strengths, which are of significant importance, are often overlooked. Examining and characterizing tensile and shear properties is important because these properties provide a comprehensive understanding of the behavior of cementitious structures under complex loading conditions. Unlike compressive strength, which measures only axial load resistance, tensile and shear strengths can predict how mortar will perform under flexural stresses, such as those in beam structures where tensile, compressive, and shear forces are at play. This detailed understanding can inform the design of mixes that incorporate recyclable materials, enabling engineers to optimize particle-matrix interactions for enhanced structural integrity'. Additionally, incorporatingrecycled plastics into mortar alters its matrix, affecting crack propagation and interfacial bonding, making it vital to assess tensile and shear properties to avoid structural failures and ensure long-term durability and service life. Considering that mortar structures are not always subjected to pure compression loading during service, knowing their capacities to resist cracking or breaking under tensile or shear loads, namely, tensile and shear strengths, is important for designing safe structures. For this purpose, the present disclosure investigates the impacts of the use of ungraded and graded ground recycled acrylonitrile butadiene styrene (GRABS) plastics as replacements for natural sand in mortar on the structure’s compressive, tensile, and shear strength. To the best of the present inventors’ knowledge, this is the first attempt focusing on the effect of the waste plastic size and its impact as a composite material on mortar’s fresh and hardened performance.MaterialsExemplary cementitious-based composite material replacing natural sand wi th recycled plastics in the mortar was carried out with two different approaches, which used uniform and a range of recycled plastic particle sizes obtained through sieving, as shown in FIGS. 1A-1B. An exemplary process can use a Portland Type I cement (ty pe I), such as the one available from Keystone Cement Company. A masonry sand complying with ASTM C 144 can be used as a natural aggregate. The recycled waste plastic used was ABS. Samples were prepared with ungraded 10 to 50% GRABS and graded 25% GRABS with particle sizes ranging from 0.19 in [4.75 mm] to 0.006 in [0.15 mm]. Waste ABS plastics were mechanically converted into GRABS via an electric grain mill grinder with a 6-inch steel burr mill operated 5-hp electric, as depicted schematically in FIG. 1 A. Prior to mechanical recycling, waste plastics were washed to remove impurities.One way to break the ductile plastic down is to make its physical property more brittle. A preferred way to do this, without changing its typical properties, is to freeze it to cryogenic temperatures. Cryogenic temperatures are typically defined as the range of temperatures from -150 °C (-238 °F) to absolute zero (-273 °C or -460 °F). Liquid nitrogen with approximately -320 °F [-196 °C] is a suitable medium to reduce the temperature of the plastics to a point where they are brittle enough to grind into ground plastic. In the described embodiments, liquid nitrogen was used due to commercial availability, low cost, and lower safety concerns compared to other options, such as dry' ice or other liquified gasses, for example. While it is not strictly necessary' for ABS to reachcry ogenic temperatures, it is important that the temperature is low enough to maintain the plastic in the brittle zone of its brittle-ductile curve during the grinding process. The objective is to remain below the ductile-brittle transition temperature to ensure that the material behaves in a brittle manner during the grinding process. As the material becomes colder, it transitions more effectively into a sand-like state with dimensional properties matching concrete sand. Cooling to cryogenic temperatures (e.g., using a liquified gas) is a practical way to achieve this. The cryogenic temperature reduces the likelihood of exceeding the ductile-brittle transition temperature during the grinding process, ensuring improved brittleness, material handling, and quality control of particle size. As depicted in FIG. 1A, ABS waste plastics were placed in an insulated foam container before being processed through a grinder and filled with liquid nitrogen until completely covered. Recycled plastics obtained from the grinding processes can have different particle sizes, as seen in FIG. IB.To compensate for dimensional differences and evaluate the impact of particle size on mechanical performance, ground waste plastics can be classified by passing from RoTap RX-29-10 mechanical shaker’s sieves of mesh numbers 4 (0.18 in [4.75 mm]) up to 100 (0.006 in [150 pm]) according to ASTM C 1260. FIG. 2 illustrates the sieve analysis of recycled waste plastic aggregates. In particular, FIG. 2 depicts a sieve analysis of recycled plastic aggregates showing a particle size distribution and gradation of GRABS recycled plastics versus masonry sand.Morphological properties can significantly impact the mechanical properties by affecting the recycled waste plastics’ particle size distribution, particle-binder bonding, air content, and clustering effects. The GRABS’ structural morphology7is depicted in FIGs. 3A-3G. For example, recycled plastics have an angular and smoother surface texture and consist of different-sized particles from millimeter scale to micrometric scale. While the ability to obtain a homogeneous binder mixture with recycled waste plastics captured in ungraded or low mesh number screens is limited, plastic particles with more uniform size distribution are evident with the reduction of sieve opening sizes. In particular, FIG. 3 A depicts optical micrographs of ungraded GRABS particles, according to an aspect of the invention. FIGs. 3B-3G depict optical micrographs of graded GRABS particles from sieves no. 4, 8, 16, 30, 50, and 100, respectively, according to aspects of the invention.The process is not limited to ABS, and other plastics, such as a #2 plastic, for example, which has a much lower density, can work as well. However, this can result in a reduced strength in the final mix design. In general, it is a matter of balancing where the critical point is getting to the ductile-brittle transition zone. The denser and harder plastics, such as ABS, for example, tend to perform better, offering greater strength and improved properties in the resulting material. Selection of plastic material can consider the balance between density, hardness, and the specific performance requirements of the application. Regardless of plastic material used, a similar procedure or methodology is used for maintaining temperatures below the ductile-brittle transition of the selected plastic material when grinding.Mortar Mix DesignExemplary embodiments use an aggregate-to-cement (a / c) ratio of 50 / 50 for mortar cement mixtures described herein. Experiments were conducted with mortar of SOSO cement-aggregate mixture, where 20-50% of the sand was replaced in the aggregate, such that the final mixtures were 50% cement binder, 10-25% plastic, and 25-40% sand. In the case of different mesh-size recycled w aste plastic replacements, the particles w ere incorporated into mortar mixtures from 10% to 50% by volume as a substitute. The investigation of particle size effects in a cement matrix considers a replacement rate of 25% to ensure that the interaction between the sand and plastic particles was observable to determine the optimal size of plastic particles for use in the mortar mix design. This intermediate replacement rate facilitates a balanced assessment of how- different particle sizes interact with the cement matrix while maintaining a meaningful proportion of sand in the mix. This approach aids in determining the optimal plastic particle size for effective use in mortar mix design. Given that sand generally is added in the mortar mix, understanding the interactions among the different fine aggregates is important for interpreting the test results. The water-to-cement (w / c) ratio was 0.36 for control samples. Table 1 presents the mixing ratios of cementitious mortar structures. The "C", "S", and "P" represent cement, sand, and recycled plastic, respectively. The "X" in the mix ID code (5C:2.5S:2.5P / G-X) given for 'graded samples' denotes the sieve number, and the code will be abbreviated as G- X henceforth. Additionally, the abbreviated label "G-Mix" will be used for the control group of ungraded samples. Although Table 1 shows increments of 10% total plastic in the 50 / 50 cement / aggregate mix, as w ell as a 25 / 25 plastic / sand aggregate mix, it should beunderstood that embodiments may include any percentage of plastic up to 100% of the aggregate in any relative percentage of plastic / sand in mixes where both plastic and sand are present. Likewise, although grading the plastic is demonstrated for a 25 / 25 plastic / sand mix, it should be understood that the graded plastic may be used in any ratio of sand / plastic up to 100% plastic.Table 1. Mix proportions for cementitious mortar structures., Mass ot Mass , of Mass oi Plastic Mass oiMix ratios Mix ID C _ement A . Sand ggregate A . ggreg °ate WaterC S P(%) (%) (%) lb [g] lb [g] lb [g] lb [g]100 0 0 10C:0S:0 2.2

[1000] 0 [0] 0 [0] 0.79

[0357] 50 50 0 5C:5S:0Pf 2.2

[1000] 2.20

[1000] 0 [0] 0.79

[0357] 50 40 10 5C:4S:1P 2.2

[1000] 1.76

[0800] 0.16

[0714] 0.79

[0357] 50 30 20 5C:3S:2P 2.2

[1000] 1.32

[0600] 0.31 [142.8] 0.79

[0357] 50 20 30 5C:2S:3P 2.2

[1000] 0.88

[0400] 0.47 [214.2] 0.79

[0357] 50 10 40 5C:1 S:4P 2.2

[1000] 0.44

[0200] 0.63 [285.6] 0.79

[0357] 50 0 50 5C:0S:5P 2.2

[1000] 0 [0] 0.79

[0357] 0.79

[0357] 5C 2 5S'2 550 25 25 1.65

[0750] 1.65

[0750] 1.18

[0535] 0.59

[0267] P / G-X** X denotes various sieve numbers as shown in FIG. 2. t denotes the control group of ungraded mortar referenced throughout the present disclosure.In the mortar specimen preparation process, a precise mixing procedure was performed to achieve a consistent performance between the batches. The cement and aggregate mixes were initially dry-blended with, e.g., a Hobart CT-345 mechanical table mixer for nearly 3 minutes, for example. Then, the required amount of water was added to the mix and stirred for a further 10 minutes, for example, to ensure proper dispersion. Meanwhile, stainless-steel molds were well-cleaned, and a thin-layer DuoGuard formrelease agent was applied to easily remove hardened specimens from molds. The sample casting into the molds began immediately after the end of the mixed process, and molding was completed within 15 minutes. The casting process was conducted in two steps. Initially, the prepared mix was poured up to half of the mold and consolidated by the rodding method; then, the remaining volume was filled and again rodded. The molds’ exposed surfaces were then covered with steel plates to limit water evaporation. All poured moldswere stored for 24 hours at room temperature. After removal from the molds, samples were cured for up to 28 days at approximately 80 °F [26.7 °C] with 90% humidity in a fog room. Each sample was allowed to dry for one hour after removal from the moist cure room before tests. The microstructures of the mortar structures are shown in FIGs. 4A-4F. For example, FIGs. 4A-4F depict cross-sectional microstructures of the mortar structures including different gradations of recycled w aste plastics (black) retained on sieves numbers 4, 8, 16, 30, 50, and 100. respectively. It is apparent that the GRABSs are relatively well dispersed in the cement binder, even as the particle size becomes smaller.Fresh Mortar PropertiesBecause the mixtures described herein do not include coarse aggregates and the present disclosures focuses on the workability of cementitious mortars with fine aggregates rather than conventional mortar, the standard slump test was not applicable. Instead, the jumping table test, which is standardized under ASTM C 1437-20, can be used to provide reliable and comparable data on the flow properties of the fine aggregate mixtures described herein. The workability assessment of the fresh mortar mixtures was conducted by measuring the flow spreading diameter, following the procedures outlined in the standard. For example, a jumping table and a truncated cone die can be used in a workability assessment of fresh mortar mixtures, according to an aspect of the invention. A jumping table having a vibration drop distance of 0.4 in [10 mm] and a table diameter of 9.8 in [250 mm] was operated manually. Fresh mortar was poured into a truncated cone die with an upper diameter of 2.8 in [70 mm], a lower diameter of 3.4 in

[0100] mm, and a height of 2.4 in [60 mm], placed on the jumping table. After lifting the cone vertically, the table was immediately dropped 25 times within 15 seconds. Subsequently, two perpendicular diameters were measured, and the mean value was reported. The fresh properties of each mixture were characterized by conducting the tests as three repeats to ensure statistical reliability.Mechanical Testing ProcedureAs illustrated in FIGs. 5a-5C, the impact of using recycled waste plastics as sand-substitution on the mechanical performance of mortar structures can be characterized by compressive, tensile, and shear tests. The cubic compressive test specimens were prepared and tested according to ASTM Cl 09 standards. The compressive tests were performed using the Humboldt HCM-2500iHAC 250K testing machine at a rate of 300 Ibf / s[1335 N / s], To evaluate the tensile properties, briquet specimens were prepared according to ASTM C307. Tensile specimens were pulled centrally using clamps at a speed of 0.20 in / min [5.08 mm / min] via a servo-hydraulic Instron 1331 testing machine. The shear strengths of the specimens were measured with guillotine shear tests, conducted per ASTM D905 by Tinius Olsen Super-L 400 testing machine at a displacement rate of 0.015 in / min [0.381 mm / min]. All tests were conducted with a minimum of six repetitions. The resulting test data underwent statistical analysis at a significance level of 0.05, utilizing the p-value associated with a one-sample t-test. Subsequently, average strength values were calculated by averaging at least three confident samples. The reduction from 6 to 3 specimens was due to rigorous quality control measures. Specimens showing significant deviations in behavior — likely caused by minor imperfections in preparation or handling — were excluded. These deviations were isolated incidents and not indicative of systemic issues. By excluding specimens with visible defects, it was ensured that the data accurately represented the material’s true properties, using only high-quality and homogeneous specimens in the final analysis.Results1. Fresh Mortar Properties1. 1. Fresh Density ValuesFIGs. 6A and 6B are bar graphs depicting the fresh density values of mortar mixes. FIG. 6A illustrates a reduction in fresh density values as the plastic aggregate substitution rate (e.g., various amounts of GRABS percentage) is increased. This decline can be attributed to the lower density of recycled plastics compared to sand aggregate. Specifically, the fresh unit weight values of the 5C:0S:5P specimen decreased by 25.2% compared to those of the 5C:5S:0P variant. However, the fresh density values of the mixtures containing graded plastics (ranging from G-4 to G-100) closely resemble those of the control (G-Mix) samples with ungraded particles (FIG. 6B). The bar graphs of FIGs. 6A and 6B depict the average values, and the accompanying error bars represent the standard deviation.1.2 Workability!The spread-flow values of fresh mixtures with various amounts of recycled plastic are shown in FIGs. 7A and 7B. The average flow values of cement only (10C:0S:0P) and cement-sand only (5C:5S:0P) control specimens are 7.5 in [190.5 mm] and 7.2 in[182.9 mm], respectively (FIG. 7A). Due to the increasing plastic concentration, which decreases the plasticity and uniformity of the fresh mortar, the flowability decreases to 6.2 in [157.5 mm] as expected when the replacement ratio of recycled plastics reaches up to 20%. The reduction in the spread-flow diameter can be attributed to the uneven surface of the aggregates, resulting in increased friction and higher flow resistance. Notably, the spread diameters increase when the replacement ratio exceeds 20% in fresh mortar. This may be due to the limited amount of sand available to reduce water content in the mixture, as the plastics have limited water absorption capacity. The retained water, which does not interact with the cement, promotes mobility among the components, thereby enhancing the blend's workability. Additionally, this phenomenon can be attributed to the low density and lightweight nature of plastics compared to sand aggregates. In contrast, while reducing the particle size initially led to increased dispersion in graded samples, waste plastics smaller than sieve number 30 resulted in a decrease in dispersion (FIG. 7B). The agglomeration tendency observed in plastics smaller than this limit value may have been attributed to Van der Waals interactions, which is believed to cause the decline in flow-spread values.2. Mechanical Testing (Hardened Properties)2 1. Compressive StrengthFIG. 8A illustrates the compressive strength values of specimens varying with curing time and recycled plastic substitute ratio. In general, the specimens’ strengths increase with the curing duration, but decrease with increasing waste plastic replacement ratios. For example, for 5C:0S:5P specimens utilizing a maximum level of recycled waste plastics, the strength decrease was observed at 48.8, 54.9, 49.8, and 51.9% compared to the specimen containing cement only (10C:0S:0P) after 7-, 14-, 21-, and 28-days curing, respectively. When the 5C:0S:5P specimen was compared to the 5C:5S:0P control group for the same periods, the strength reductions were measured as 46.9, 52.5, 48.5, and 44.7%. Notably, compressive strength values exceeded the minimum ASTM Cl 50 requirements (4060 psi [28 MPa]) for all sample cases.FIG. 8B illustrates the variation in compressive strength for gradation samples for 50% cement, 25% sand, and 25% recycled plastic example with different sizes of sieved waste plastics. While embodiments are not limited to 50% cement, the samples should behave similarly to standard concrete mix designs, as lowering cement content generally affects the strength of the mortar. Raising the cement content may createshrinkage and cracking depending upon the cement used and possibly the plastic utilized. Adjustments can be made to achieve the desired strength and performance based on the specific application. The highest compressive strength was obtained when sand was substituted with sieve number 100 mesh-size plastics, and the increase in compressive loadbearing capacity was 9.8% compared to the control sample (G-Mix) having ungraded plastics. When lower mesh-sized plastic aggregates were used, the strength was reduced by 22.7% even though the plastics have a relatively uniform structure. These results suggest that as the mesh size increases, the reuse efficiency of the waste plastic increases, which can be explained by the enhancement of smaller plastics’ packing and dispersion ability.2.2. Tensile propertiesFIG. 9A illustrates the impact of different replacement ratios on the tensile properties of specimens containing ungraded plastics. Tensile test results indicate that replacing sand with recycled plastic at levels below 20% leads to a reduction in tensile strength, while replacement ratios exceeding 20% (2P and above) result in a significant improvement. Additionally, the specimen with 40% waste plastic demonstrates a loadcarrying performance close to the control specimen (5C:5S:0P). Considering the ongoing decreasing trend noted in compressive strength as the sand replacement rate with plastic rises, this variable trend in tensile properties suggests that damage development is controlled by distinct mechanisms under various loading conditions. The improved tensile strength may be explained by increasing plastic-crack interaction-dependent mechanisms such as crack pinning or more micro-crack formations; cracks require more energy to propagate when these mechanisms occur. It is also possible that the enhancement in tensile performance may be due to the recycled plastics restricting or slowing down the crack propagation.FIG. 9B demonstrates that all sample groups containing recycled plastic exhibit improved tensile properties compared to the control group (G-Mix) containing 25% ungraded plastic. Gradually reducing the plastic particle size from mesh-size 4 (4.75 mm) to 50 (0.3 mm) consistently enhances the tensile properties. As used in the present disclosure and claims, the term “gradually” refers to using incremental gradation sizes, similar to those used for sand gradations. Thus, for example, the method may include subjecting the ground plastic to a controlled progression through the gradation range of sieves sequentially through a No. 4, then a No. 8, then a No. 16, then a No.30, then a No. 50 sieve. In the caseof the mesh-size 50 plastics, the average tensile strength increases by 46.5% compared to G- Mix specimens. However, the mesh size 4 specimen group achieves a higher strength value by 8.6%. This is attributed to the effective plastic pull-out and crack bridging by larger particles, resulting in an increased deformation capacity.2.3. Shear StrengthThe impact of recycled plastic usage on shear loading performance is depicted in FIGs. 10A and 10B. For example, FIG. 10A is a bar graph illustrating shear strength values for ungraded GRABS-containing mortars. Substituting natural sand aggregates with recycled plastic up to a 20% ratio reduces shear strength capacity by 18.9%. However, substitution rates exceeding 30% lead to a significant reduction in shear strength, amounting to a 53.8% decrease (FIG. 10A). The control group, comprising only cement, exhibits the highest shear deformation capability, with a slight reduction in shear ductility for the control specimens (5C:5S:0P) containing 50% sand.FIG. 10B illustrates the influence of plastic aggregate size on the mortar’s shear properties. For example, FIG. 1 OB is a bar graph illustrating shear strength values for graded GRABS-containing mortars. When recycled plastics are made finer, it can be seen as an increase in their specific surface area, leading to enhanced plastic-cement interfacial interaction. The impact of larger plastics on toughness and strength is complex due to their random distribution. Targe plastics oriented perpendicular to shear loading can form bridges between the lower and upper shear boxes (the parts on either side of the shear plane on the test sample to which applied force and reaction force are applied) or slightly increase internal friction by enhancing grain interlocking. Conversely, plastics aligned parallel to shear loading create vulnerable areas that may serve as starting points for damage due to their limited interfacial connections. On the other hand, in the case of smaller plastic particles, it is estimated that many plastics at the interface between the lower and upper shear boxes exhibit roughness (plastic protrusion) along the shear line, making deformation more challenging (see FIGs. 13A-13F).The bar graphs in FIGs. 10A-10B display average values with error bars representing the standard deviation to highlight damage initiation along the failure plane of each sample group (see FIGs. 13A-13F). FIG. 10A reveals limited improvement in shear capacity with increased plastic volume due to surface roughness, while FIG. 10B shows enhanced shear strength with smaller particle sizes, indicating better interfacial interactionwi th cement. Morphological investigations reveal the impact of plastic size distribution and orientation on failure, underscoring the importance of material design in optimizing mechanical properties.3. Fracture Surface Analyses3. 1. Fracture morphologies of compressive test specimensThe fracture morphology of compressive specimens can change based on vary ing ratios of waste plastic replacement. A smooth fracture surface with macro-cracks, typically called a brittle fracture, is observed in the sample containing cement only, e.g., 10C:0S:0P. However, with the addition of sand (e.g., 5C:5S:0P), the crack path becomes more tortuous, and the fracture morphology becomes rougher because crack propagation tends to deviate at the interface between the sand grains and the cement binder. Nevertheless, the presence of debonded sand holes on the fracture surface diminishes in the waste plastic-substituted samples (e.g., 5C:3S:2P and 5C:2S:3P. respectively). This phenomenon can be attributed to two factors. First, the interface adhesion between cement pastes and plastic substitutes is generally^ weaker than that of natural aggregate material. Second, the waste plastic particles used are larger than sand grains, providing less contact surface area for bonding with cement compared to sand. As a result, plastic-substituted specimens exhibit poor interfacial interactions between particles and cement binders as the plastic content increases. Additionally, as cracks prefer to propagate along the plasticcement interface where adhesion is weaker, the visibility' of sand holes decreases.Conversely, as the proportion of plastic increases, plastics become more prominent on the fracture surface, and the presence of minimal cement debris on shiny black plastics indicates poor adhesion. The fracture morphology exhibits a smoother surface after plastic addition due to the reduction of smaller-sized sand grains. It is worth noting that sand inclusions in the cementitious material can provide kinematic constraints by inducing crack pinning and effectively impeding crack propagation. Therefore, the reduction in strength can be attributed to the decrease in toughness mechanisms induced by sand, such as crack path deflection and crack pinning mechanisms. In addition, when large plastic aggregates are used, the formation of air voids becomes a noteworthy factor, significantly affecting the reduction in mechanical performance. The almost non-absorption of water in plastic aggregates causes water to accumulate in the interfacial transition zone, making it more porous.The impact of waste plastics on mechanical performance can be demonstrated by plastic-cement debonding due to low interfacial bonding on 5C:3S:2P. 5C:2S:3P and 5C: 1S:4P from compressive test specimens, respectively. For example, crack nucleation can occur at the edge of the waste plastic particle, followed by crack propagation at the interface and within the cement matrix. Given that waste plastic aggregate possesses lower mechanical properties compared to natural sand aggregate, it becomes evident that plastics function as stress concentration zones, encouraging crack initiation and propagation within the structure. For example, crack initiation and propagation can start at the edge of the plastic on 5C:3S:2P, 5C:2S:3P and 5C: 1S:4P from compressive test specimens, respectively, ultimately causing debonding damage resulting from the low interfacial strength between the plastic aggregate and the cement binder.3.2. Fracture morphologies of tensile test specimensFIGs. 11 A-l IF illustrate the post-fracture surfaces of tensile test specimens containing ungraded plastics. In FIGs. 11 A-l IB, for example, voids are observed on the surfaces of the control group samples (without plastic), e.g., on 10C:0S:0P and 5C:5S:0P, respectively, albeit in small numbers. These void formations may be caused by the reduction in the volume of hydrate phases, which results from the loss of bound water mass released from the cement paste. As the plastic replacement ratio increases, more frequent and larger void formation is noticeable near the plastics, attributed to the presence of excess free water in the structure (FIGs. 1 IE-1 IF). Free water molecules surrounding the plastics weaken the interfacial interaction between particles and cement paste, leading to a less dense zone with significant void formation and poor adhesion. On the other hand, recycled plastics are more frequently located around the voids at high substitution levels. Here, it is essential to note the effect of plastics in restricting the crack propagation in the brittle cement matrix. When a void-induced microcrack develops, the plastics in the vicinity of the void can arrest these cracks or cause more energy absorption through crack path deflection mechanisms (see FIG. 14). One possible reason for the noticeable increase in tensile performance when the substitution ratio is more than 20% may be due to an increase in strength due to the different-sized particle toughness mechanisms of plastics offsetting the strength-reducing effects caused by voids. Mechanisms such as crack pinning, crack bridging, and crack branching are considered to be additional factors contributing to the increase in tensile strength (see FIGs. 15A-15F).After the tensile test, the broken parts were re-joined to observe the effect of plastics at the fracture line, and the rupture line was examined under a microscope (FIGs. 15A-15F). In the case of the control group (without plastic), specimens exhibit a smooth transverse fracture, resulting in a good fit between the joined parts (FIGs. 15A-15B). However, the joined parts do not align perfectly along the oblique and comminuted fracture line due to the roughness created by plastics on the fracture surface. Although plastics have relatively low interfacial interactions with the cement matrix due to their chemistry and morphology, they contribute to stress transfer through mechanisms, such as slip-friction at the interface and crack bridging (FIG. 15C). Another reason for the improvement in tensile properties can be attributed to shear yield and crack branching caused by waste plastics (FIGs. 15D-15E). Before the crack branching phenomenon occurs, various scenarios exist for the behavior of a crack when it encounters plastic. If the plastic particles are too rigid to be cut by the crack, the crack may either arrest (crack pinning) or change direction (crackpath deflection) with increasing loading (FIG. 15D and FIG. 15F). These mechanisms lead to greater fracture energy absorption by the specimen, resulting in improved mechanical properties under tensile loading for samples with a high replacement ratio compared to those with a low plastic ratio.3.3. Fracture morphologies of shear test specimensFIGs. 12A-12F illustrate the failure patterns on the specimen surfaces under shear loading. In the control specimens, ultimate damage manifests as splitting into two parts with multiple cracks forming around the shear plane. In the low replacement ratio samples (e.g., 10% and 20%), since the propagation of the crack in the shear plane is restricted by the plastics, the damage progresses at an angle to the shear loading direction by significant deflection within the specimen, and the sample splits into three pieces. It is plausible that this results in increased absorbed damage energy because the crack follows a longer path, forming new fracture surfaces and resulting in more fracture energy. Although plastics may lead to some reduction in strength, they appear to influence the fracture pattern through crack-plastic interactions. At high substitution rates (e.g., 30-50%), cracks can easily propagate within the shear plane under shear forces due to the weak interfacial interactions in the shear load transfer plane. In addition, the significant weakening of pure shear strength in mortar with an increase in the replacement ratio can be attributed to plainmortar having higher cohesive stress and internal frictions. The influence of plastic aggregates on shear strength is also illustrated in FIGs. 16A-16B and FIGs. 17A-17B. focusing on the role of the interfacial transition zone (ITZ) and plastic agglomeration.FIGs. 16A and 1 B illustrate the fracture surfaces of the multi-scale recycled plastic containing shear test specimens. The fracture surface of the plastic-containing samples is notably rougher (FIG. 16 A). Roughness and extent of shearing in the aggregate play an important role in differentiating the failure surfaces of the specimens. Samples in which damage primarily occurred around aggregates within the interfacial transition zone (ITZ) exhibits a relatively rough damage surface, but has lower strength. Conversely, samples with smoother fracture surfaces exhibit higher strength values due to the shearing off of aggregates. When examining the fracture surface of the sample containing plastic aggregates, it becomes evident that the plastics are separated rather than cut (FIG. 16B). The progression of damage along the ITZ during shear loading suggests that the ITZ has become more critical than the plastic aggregates. In this context, the ITZ is believed to offer a weaker path compared to an alternative path where the crack propagates by cutting through the aggregate, resulting in a slightly rougher surface in mortar containing recycled plastic. Hence, plastics may not exhibit any strengthening mechanism under shear loading.Additionally, plastic agglomeration, where few plastics within the structure come together and create weak ITZ, is another contributing factor to poor shear strength. The arrows in FIG. 16B represent the weak areas where two plastics overlaps. Cracks tend to propagate through these weak interfaces where cementitious binder penetration is limited due to the clustering of plastic particles, which can negatively impact shear performance.FIGs. 17A-17B illustrate the impact of shear deformation on a region near the free edges. It is observed that the cement matrix crumbles and flakes off, resembling powder on the surface of the plastic-containing sample. Forcing the plastics to displace under shear deformation disrupts the integrity of the cement matrix. Consequently, in tensile loading, a crack starting from a weak edge may interact with the plastics to exhibit relatively high performance. However, plastics typically create a favorable environment for damage initiation or propagation during shear action due to the weak ITZ, and as a result, they may not enhance performance under shear loading.The embodiments described herein focus on evaluating the mechanical performance of mortar mixes containing ungraded and graded waste plastics, which need tobe quantified for designing mixes with composite materials. Potential applications of these mortar composite materials include construction materials for eco-friendly cementitiousbased pathways, paver blocks, and rigid pavement, for example. Exemplary samples were prepared with ungraded 10 to 50% ABS waste plastic and graded 25% waste plastic with particle sizes ranging from 0.19 in [4.75 mm] to 0.006 in [0.15 mm]. The exemplary specimens were tested for fresh mortar properties and hardened properties via compressive, tensile, and shear strength capacities that were compared with control samples. Results showed that:Fresh densities decreased with an increase in the plastic aggregate replacement ratio, attributed to the lower density of recycled plastics compared to sand aggregates.Flowability decreased as the amount of plastic particles increased up to a 20% replacement ratio of recycled plastics. Subsequently, spread diameters increased when the replacement ratio exceeded 20%.Reduction in mesh-sized particle distribution initially increased slump dispersion in graded samples: however, plastics with particle sizes smaller than 0.024 in [0.6 mm] (sieve no. 30) resulted in decreased dispersion.The compressive strength of the 5C:0S:5P specimen decreased by 48.8% and 46.9% when compared to the cement-only (10C:0S:0P) and cement-sand-only (5C:5S:0P) control specimens, respectively. However, the compressive strength values of all samples still exceeded the minimum ASTM C150 requirements (4060 psi [28 MPa]) for Portland cement, showing viability of these composite materials for minimum standard specifications. When employing differently sized sieved plastics, the highest compressive strength is attained when particle sizes 0.024 in [0.6 mm] and less are utilized, leading to a 9.8% increase compared to the control sample mix with ungraded plastics.The tensile strength of the 5C:3S:2P specimen decreased by 44.2%, while the 5C: 1S:4P specimen surprisingly exhibited a load-carrying performance close to the control specimen (10C:0S:0P) thanks to increased plastic-crack interactions at high replacement rates. In samples with graded 25% waste plastic (mix), there is a consistent improvement in tensile properties as the plastic particle size decreases. Notably, the mesh-size 50 plastics (0.012 in [0.3 mm] and smaller sizes passing sieve no. 50) increased the average tensile strength by 46.5% due to the improved packing and dispersion ability of smaller plastics.The shear load-cartying capacity decreased by 18.9% for the specimen with 20% plastic substitution, while it dropped more significantly by 53.8% for substitution rates exceeding 30%. This significant drop is attributed to the weak interfacial transition zones formed by plastic agglomerations, which hinder the exhibition of plastics toughness mechanisms. Graded plastic particles of 0.024 in [0.6 mm] and lesser size in the specimen had a minimal impact on shear load-carrying capacity' compared to the ungraded plastic.Fracture surface morphological investigations suggest that plastics can cause more energy absorption under tensile loading through microscale toughness mechanisms, such as crack pinning or crack path deflection. The decrease in shear strength can be associated with a weak interfacial transition zone and plastic agglomerations.Overall, the examples disclosed herein demonstrate the advantages and tradeoffs when fine aggregates are replaced using GRABS at various replacement ratios and particle sizes. The mechanical performance is influenced in different ways that can be controlled in a mix design, and the test results contribute towards quantifying these effects that have not been previously determined to date. Ultimately, the present disclosure provides better understanding the effects of particle size and volume fraction of waste plastic that can be used in mortar as a composite material for construction applications instead of landfills.Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.

Claims

WHAT IS CLAIMED IS:

1. A cementitious-based composite material, comprising: an aggregate comprising a ground plastic material; and a cement binder, wherein the ground plastic material is mixed with the cement binder in a mortar cement mixture at a predetermined cement-to-aggregate ratio by volume and the ground plastic material comprises up to 100% of the aggregate.

2. The cementitious-based composite material of claim 1, wherein the aggregate further comprises sand, and wherein the ground plastic material is mixed with the cement binder and the sand in a mortar cement mixture having a cement-to-aggregate ratio of 50 / 50 wherein the sand comprises 10-40% by volume and the ground plastic material comprises 40-10% by volume.

3. The cementitious-based composite material of claim 1, wherein the ground plastic waste material is a product of a process comprising cooling an unground plastic material to a temperature below a brittle-ductile transition temperature of the plastic material, and grinding the cooled plastic waste material to obtain the ground plastic material.

4. The cementitious-based composite material of claim 3, wherein ground plastic waste material product process further comprises passing the ground plastic feedstock through one or more mechanical sieves with predetermined mesh parameters to obtain a graded ground plastic material.

5. The cementitious-based composite material of claim 4. wherein the graded ground plastic material comprises particles with sizes ranging from 4.75 mm to 0.15 mm.

6. The cementitious-based composite material of claim 4, wherein the unground plastic material comprises a plastic waste material comprising a thermoset or thermoplastic polymer waste material.

7. The cementitious-based composite material of claim 6, wherein the ground plastic material comprises ground acrylonitrile butadiene styrene (GRABS).

8. The cementitious-based composite material of claim 4, wherein the predetermined cement-to-aggregate ratio is a 50 / 50 cement-to-aggregate ratio and the graded plastic feedstock comprises between 20% and 80% of the aggregate by volume and the sand comprises between 80% to 20% of the aggregate by volume.

9. A method of making a cementitious-based composite material, the method comprising the steps of: a) cooling a plastic waste material to a temperature below a brittle- ductile transition temperature of the plastic waste material; b) grinding the cooled plastic waste material to obtain a ground plastic feedstock; c) passing the ground plastic feedstock through one or more mechanical sieves with predetermined mesh parameters to obtain a graded plastic feedstock; and d) mixing the graded plastic feedstock with a cement binder in a mortar cement mixture at a predetermined cement-to-aggregate ratio in which the aggregate comprises up to 100% graded plastic feedstock.

10. The method of claim 9, wherein the predetermined cement-to- aggregate ratio is 50 / 50 by volume and the aggregate comprises sand, further comprising mixing the graded plastic feedstock with the cement binder and sand in the mortar cement mixture at a replacement ratio of the graded plastic feedstock for sand of 20% to 80% by volume relative to an aggregate composition of 100% sand.

11. The method of claim 10. wherein the graded plastic feedstock comprises 20% to 50% of a volume of the aggregate and the sand comprises between 80% to 50% of the volume of the aggregate.

12. The method of claim 9, wherein the plastic waste material comprises a thermoset or thermoplastic polymer waste material.

13. The method of claim 9, wherein the graded plastic feedstock comprises ground acrylonitrile butadiene styrene (GRABS).

14. The method of claim 9, wherein the graded plastic feedstock comprises particles with sizes ranging from 4.75 mm to 0. 15 mm.

15. The method of claim 9, wherein the graded plastic feedstock comprises particles with sizes less than 0.6 mm.

16. The method of claim 9, wherein step c) comprises gradually reducing a particle size of the ground plastic feedstock from mesh-size No. 4 to mesh-size No. 50 by sequentially passing the ground plastic feedstock through a plurality of mechanical sieves to produce the graded plastic feedstock.

17. The method of claim 9, wherein the cementitious-based composite material exceeds a minimum compressive strength of 4060 psi [28 MPa].

18. The method of claim 9, wherein step a) comprises cooling the plastic waste to cryogenic temperatures.

19. The method of claim 18, wherein step a) comprises immersing the plastic waste in a cryogenic liquid.

20. The method of claim 19. wherein the cryogenic liquid comprises liquid nitrogen.

21. The method of claim 9, wherein the predetermined mesh parameters comprise sieve openings with diameters ranging between 150 pm and 4.75 mm.

22. The method of claim 9, wherein the predetermined mesh parameters comprise a mesh size between a No. 4 and a No. 50.

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