Production and Characterization of Eco-Friendly Bricks Using Recycled Plastic Waste

Abstract

The escalating accumulation of plastic waste, particularly polyethylene terephthalate (PET), high-density polyethylene (HDPE), and polypropylene (PP), poses serious environmental and public-health risks. In response, this study investigates the feasibility of converting these thermoplastics into eco-friendly composite bricks as a sustainable alternative to traditional fired clay masonry. Recycled PET, HDPE, and PP were processed individually and in combination with sand and fly ash through controlled thermomechanical blending and compression molding. The resulting bricks were characterized for density, compressive strength, thermal conductivity, and water absorption, and benchmarked against established masonry performance indicators. Results show that PET-based composites exhibited the highest density (1.43 g·cm⁻³ with mineral fillers) and superior compressive strength, reaching up to 18 MPa, attributable to reduced porosity and enhanced polymer–filler interlocking. All polymer-based bricks demonstrated low thermal conductivity (0.22–0.34 W·m⁻¹·K⁻¹), confirming their potential as effective insulating materials relative to conventional clay bricks. Water absorption remained below 2% across all compositions, reflecting the hydrophobic nature of the matrices and indicating strong durability under moisture exposure. Preliminary carbon-emission comparison further revealed that the manufacturing process, absent of high-temperature kiln firing, reduces energy consumption by approximately 30% compared to traditional brick production. Collectively, these findings affirm that recycled-plastic bricks combine structural reliability, thermal efficiency, and environmental advantages, aligning strongly with circular economy principles. The PET + sand + fly ash composite emerged as the optimum formulation, offering balanced performance for non-load-bearing and selected semi-structural applications. The study recommends further long-term durability assessments, fire-performance evaluation, and standardization efforts to facilitate industrial adoption and policy integration.