Sustainable Alternatives in Construction: Repurposed Waste LLDPE Plastic and Kaolin Clay Composites as Cementless Binders

Cement is a prominent binder material in the construction industry. Its production releases harmful gases and is a major contributor to CO 2 emissions. The rising global waste plastic generation has negative ecological and environmental impacts. Repurposing waste plastic and exploring its binding properties for construction products would reduce reliance on cement, promote the circular economy, and reduce waste. This study explores an innovative approach to utilize repurposed linear low‐density polyethylene (LLDPE) waste plastics as a binding material for manufacturing novel composite blocks, promoting sustainable construction practices in alignment with circular economy principles. Through extrusion techniques, repurposed LLDPE waste plastic was combined with kaolin clay in varying mix proportions of 1:1, 1:2, and 1:3. Comparative blocks were also produced using similar cement and kaolin clay mix proportions. The research systematically examined the impact of different mix proportions on density, compressive strength, flexural strength, tensile strength, water absorption characteristics, and microstructure analysis of the resultant composites. Extensive comparisons were drawn between the properties of repurposed LLDPE waste plastic and kaolin clay composites against those of cement and kaolin clay composites. The result revealed that the repurposed LLDPE waste plastic composite exhibited optimal compressive strength when mixed in a ratio of 1:2, which was superior to the cement composite’s performance and demonstrated superior tensile splitting and flexural strength compared to the cement binder composite. The strength values of repurposed LLDPE waste plastic composites significantly met the stringent requirements for load‐bearing blocks according to both BS EN 771‐3:2011 and ASTM C90 standards. Furthermore, the water absorption properties were distinctly favorable for the repurposed LLDPE waste plastic composites, consistently registering less than 1%, while the cement composites exhibited values exceeding 2%. These results demonstrate the potential of using waste plastic as a binder in building materials and aid in creating creative and sustainable building materials.