ENGINEERING AND THERMAL PERFORMANCE ASSESSMENT OF STRUCTURAL PLASTIC-SAND COMPOSITE BLOCKS WITH INTEGRATED PASSIVE COOLING FOR AFFORDABLE HOUSING

The escalating global housing deficit, particularly in developing nations such as Nigeria, necessitates innovative, cost-effective, and environmentally sustainable building material solutions. This study presents a comprehensive engineering and thermal performance assessment of structural plastic-sand composite (PSC) blocks incorporating integrated passive cooling features for application in affordable housing construction. Waste polyethylene terephthalate (PET) and high-density polyethylene (HDPE) plastics were combined with river sand at varied mix ratios (20:80, 30:70, 40:60, and 50:50 plastic-to-sand by weight) and subjected to compressive strength, flexural strength, water absorption, thermal conductivity, and embodied energy tests. The study was guided by four objectives: (1) assessment of structural and mechanical performance; (2) evaluation of thermal resistance and passive cooling integration; (3) environmental lifecycle analysis; and (4) cost-benefit analysis for affordable housing deployment. Results indicate that the 30:70 PSC mix achieved optimal compressive strength of 8.2 N/mm², a thermal conductivity of 0.19 W/mK, and a unit cost approximately 46% lower than conventional sandcrete blocks. The integrated passive cooling features — hollow core channels and micro-ventilation fins — reduced simulated indoor temperatures by 4.8°C on average. Environmental analysis confirmed a 63% reduction in CO₂ embodied emissions per unit compared to conventional fired bricks. These findings position PSC blocks as a viable, scalable, and environmentally responsible alternative building material for sub-Saharan Africa's affordable housing sector.