Investigating the feasibility of using laterite soil, recycled polyethylene terephthalate (pet), and cement for the production of interlocking brick

Abstract

The global plastic waste crisis, generating 430 million tons annually, coupled with Uganda’s daily production of 600 tons, of which 42% remains uncollected in Kampala, exacerbates environmental pollution and flooding. Concurrently, the abundant laterite soil in Uganda, characterized by its iron- and aluminum-rich composition, remains underutilized in sustainable construction. This study investigates the feasibility of producing interlocking bricks using laterite soil, recycled polyethylene terephthalate (PET), and cement to address plastic waste management and affordable housing demands. Laterite soil was characterized for physical and mechanical properties, including moisture content (7.2%), particle size distribution (SW-SC classification), maximum dry density (2.235 g/cm³), and plasticity index, ensuring suitability for construction. Mix proportions were optimized using Response Surface Methodology (RSM) in Minitab, identifying an optimal mix of 2400 g laterite, 200 g PET, and 400 g cement, which achieved a compressive strength of 3.7 MPa and flexural strength of 1.3157 MPa after 28 days of curing. These strengths meet Uganda’s National Building Review Board standards for non-load-bearing elements (2-5 N/mm²) but fall short for load-bearing applications (5-10 N/mm²). Compared to conventional bricks, the optimized bricks align with stabilized soil bricks but are less robust than clay or concrete bricks. This eco-friendly approach reduces plastic pollution, leverages local resources, and supports affordable housing, contributing to Sustainable Development Goals 11 (Sustainable Cities) and 12 (Responsible Consumption). Recommendations include water absorption tests and exploration of additional stabilizers to enhance strength for broader applications.