Concrete contributes 8% of all global carbon emissions, making the need to find substitutes critical for environmental sustainability. Research has indicated the potential for recycled plastics to be used as concrete substitutes. This study extends existing research by investigating the use of polycarbonate (PC) in plastic sand bricks as a mechanical equivalent to concrete. PC has high compressive strength, durability, impact strength, thermal resistivity, clarity, fatigue resistance, and UV resistance. This work provides a method and mold to produce a matrix of sand–plastic sample compositions with dimensions adhering to the ASTM D695 standard for compressive properties of rigid plastic. Compositions of 0% (control), 20%, 30%, 40%, and 50% sand by weight were tested. Samples were tested for compressive strength until yield and stress–strain behaviors were plotted. The results for 100% PC demonstrated an average and maximum compressive strength of 71 MPa and 72 MPa, respectively. The 50% PC and 50% sand composition yielded an average and maximum compressive strength of 71 MPa and 73 MPa, respectively, with an increase in compressive stiffness and transition to shear failure resembling concrete. With a composite density of 1.86 g/cm³ compared to concrete’s average of 2.4 g/cm³, and a compressive strength exceeding commercial concrete demands of 23.3 MPa to 30.2 MPa, this lightweight alternative meets the strength demands of concrete, reduces the need for new construction materials, and provides an additional recycling opportunity for nonbiodegradable waste plastic.

Recent work demonstrated that 50:50 sand-recycled polycarbonate (rPC) composites have an average compressive strength of 71 MPa, which dramatically exceeds the average offered by commercial concrete (23.3–30.2 MPa). Due to the promising technical viability of replacing carbon-intensive concrete with recycled sand plastic composites, this study analyzes the cradle-to-gate environmental impacts with a life cycle assessment (LCA). Sand-to-plastic composites (50:50) in different sample sizes were fabricated and the electricity consumption monitored. Cumulative energy demand and IPCC global warming potential 100a were evaluated to quantify energy consumption and greenhouse gas emission associated with sand–plastic brick and two types of concrete, spanning the life cycle from raw material extraction to use phase. The results showed that at small sizes using Ontario grid electricity, the composites were more carbon-intensive than concrete, but as samples increased to standard brick–scale rPC composite bricks, they demonstrated significantly lower environmental impact, emitting 96% less CO₂/cm³ than sand–virgin PC (vPC) composite, 45% less than ordinary concrete, and 54% less than frost-resistant concrete. Energy sourcing has a significant influence on emissions. Sand–rPC composite achieves a 67–98% lower carbon footprint compared to sand–vPC composite and a 3–98% reduction compared to both types of concrete. Recycling global polycarbonate production for use in sand–rPC composites, though small compared to the total market, could annually displace approximately 26 Mt of concrete, saving 4.5–5.4 Mt of CO₂ emissions. The results showed that the twin problems of carbon emissions from concrete and poor plastic recycling could be partially solved with sand–rPC building material composites to replace concrete.

Although there has been considerable progress in distributed manufacturing of open-source designs for mobility aids, there is a notable lack of affordable, open-source crutches. Crutches are a vital tool for many individuals with mobility impairments, yet the high costs limit accessibility. Even more, they are in short supply in regions undergoing conflict. The goal of this study is to address this need by leveraging the principles of free and open-source hardware and the capabilities of digital distributed manufacturing to create a low-cost, functional crutch that can be easily produced and customized locally using inexpensive desktop 3D printers. All the design files are open-source, and the design process incorporated load-bearing tests using a hydraulic actuator under static loading conditions to meet the ISO 11334-1:2007 standard for walking aids. The open-source forearm crutch developed in this study not only surpasses the requirements of the ISO method for load capacity (1,516.3 ± 169.9 N, which is 51.6% percent above needs), weighs a fraction of comparable commercial systems (0.612 kg or 27% of proprietary devices), and is customizable, but also offers a highly cost-effective solution; costing CAD $36 in material, which is less than all equivalent crutches on the open market. If recycled plastic is used, the material cost of the crutch could be further reduced to under CAD $13, making it much more accessible.

Alternative food sources are essential in both low-resource settings and during emergencies like abrupt sunlight reduction scenarios. Seaweed presents a promising option but requires investigation into the viability of unconventionally sourced ropes for harvesting. In this regard, a low-cost reliable method to test the tensile strength of rope is needed to validate alternative materials for use in harvesting seaweed. Commercial rope testing jigs alone range in price from several thousand to tens of thousands of dollars, so there is interest in developing a lower-cost alternative. Addressing these needs, this article reports on an open-source design for tensile strength rope testing hardware. The hardware design focuses on using readily available parts that can be both sourced from a hardware store and manufactured with simple tools to provide the greatest geographic accessibility. The jig design, which can be fabricated for CAD 20, is two to three orders of magnitude less expensive than commercially available solutions. The jig was built and tested using a case study example investigating denim materials (of 1 5/8”, 3 1/4”, 4 7/8”, 6 1/2”, and 8 1/8” widths) as a potential alternative rope material for seaweed farming. Denim demonstrated strengths of up to 1.65 kN for the widest sample, and the jig demonstrated sufficient strength and stiffness for operations at forces below 4 kN. The results are discussed and areas for future improvements are outlined to adapt the device to other circumstances and increase the strength of materials that can be tested.

Concrete contributes 8% of all global carbon emissions making the need to find substitute critical for environmental sustainability. Research has indicated the potential for recycled plastics to be used as concrete substitutes. This study extends existing research by investigating the use of polycarbonate (PC) in plastic sand bricks as a mechanical equivalent to concrete. PC has high compressive strength, durability, impact strength, thermal resistivity, clarity, fatigue resistance, and UV resistance. This work provides a method and mold to produce a matrix of sand-plastic sample compositions with dimensions adhering to ASTM D695 standard for compressive properties of rigid-plastic. Compositions of 0% (control), 20%, 30%, 40%, and 50% sand by weight were tested. Samples were tested for compressive strength until yield and stress-strain behaviors plotted. The results for 100% PC demonstrated an average and maximum compressive strength of 71 MPa and 72 MPa, respectively. The 50% PC and 50% sand composition yielded an average and maximum compressive strength of 71 MPa and 73 MPa respectively with an increase in compressive stiffness, and transition to shear failure resembling cement. With a composite density of 1.86 g/cm3 against concrete’s average 2.4 g/cm3, and a compressive strength exceeding commercial concrete demands of 23.3 MPa to 30.2 MPa, this lightweight alternative meets the strength demands of concrete, reduces the need for new construction materials, and provides an additional recycling opportunity for nonbiodegradable waste plastic.

Alternative food sources are essential in both low-resource settings or during emergencies like abrupt sunlight reduction scenarios. Seaweed presents a promising option but requires investigation into the viability of unconventionally sourced ropes for harvesting. As such, a low-cost reliable method to test the tensile strength of rope is needed to validate alternative materials for use in harvesting seaweed. Unfortunately, commercial rope testing jigs alone range in price from several thousand to tens of thousands of dollars. To fill this need, this article reports on an open-source design for tensile strength rope testing hardware. The hardware design focuses on using readily available parts that can be both sourced from a hardware store and manufactured with simple tools to provide for the greatest geographic accessibility. The jig design, which can be fabricated for CAD$20 is two to three orders of magnitude less expensive than commercially available solutions. The jig was built and tested using a case study example investigating denim materials (of 1 5/8”, 3 1/4", 4 7/8”, 6 1/2", and 8 1/8” widths) as a potential alternative rope material for seaweed farming. Denim demonstrated strength up to 1.65kN for the widest sample and the jig demonstrated sufficient strength and stiffness for operating at forces below 4kN. The results are discussed and areas for future improvements are outlined to adapt the device to other circumstances and increase the strength of materials that can be tested.