The Potential of Replacing Concrete with Sand and Recycled Polycarbonate Composites: Compressive Strength Testing

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.