Development and Analysis of Eco-Friendly Composite Materials for Low-Load Structural Applications Using Plastic Waste and PET Bottles

Rapid urbanization in Kenya triggers explosive demand for precast concrete products. Conventional production relies heavily on natural river sand. Over-exploitation causes scarcity and environmental destruction. Simultaneously, uncontrolled plastic waste accumulation worsens environmental health. This study investigates developing eco-friendly composite materials to produce interlocking paving blocks, partition blocks, and landscaping tiles. We replace natural fine aggregates with postconsumer recycled Polyethylene Terephthalate (PET) waste. We replace river sand with shredded PET bottles at volumetric mass equivalent levels of 0, 5, 10, 15, and 20 percent in standard cementitious mixes. We evaluated physical and mechanical properties including workability, density, water absorption, and compressive strength per standard BS EN and ASTM protocols. Results indicate systematic reduction in density and workability with increasing PET content. Compressive strength decreases progressively due to stiffness incompatibility and hydrophobic nature of the interfacial transition zone. The 5 percent PET replacement mix achieved a 28-day compressive strength of 14.49 MPa. This formulation satisfies requirements for pedestrian walkways, cycle paths, and non-load-bearing applications. This research demonstrates the technical viability of diverting municipal plastic waste into sustainable urban infrastructure.

Polyethylene Terephthalate (PET), Composite Materials, Eco-Friendly Concrete, Interlocking Paving Blocks, Circular Economy, Compressive Strength

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