Natural fiber-reinforced LDPE–sand–glass waste composites: Optimization and mechanical characterization for paver blocks

Abstract

Low-density polyethylene (LDPE) accumulates in landfills, due to its limited recyclability. Previously, LDPE has been mostly used in combination with more recyclable plastics such as HDPE or PET as a binder for plastic paver block. This study investigates the exclusive use of LDPE. Paver blocks were fabricated by compression Molding from molten shredded LDPE (20–40 wt.%), sand, crushed glass waste (0.425 and 4.75 mm) incorporated separately as a partial sand replacement at 15–45 wt.%, and alkali-treated luffa and coir fibers (up to 2 wt.%) as reinforcement. Compressive strength test (ASTM D695) and the Shore D hardness test (ASTM D2240) were used for testing mechanical properties. The optimal unreinforced matrix comprised of 30 wt.% LDPE. Replacing some of the sand with 30% of 4.75 mm crushed glass increased the compressive strength. Using luffa fibers in the composite made the paver block less brittle, gave a compressive strength of 36.1 MPa, and a Shore D hardness of 71 exceeding the standards (IS 15658:2006) for light-duty paving blocks. LDPE-sand – crushed glass waste paver blocks with natural fibers make high-performance paver blocks. This is a sustainable and eco-friendly way to upcycle plastic and crushed glass waste streams that are hard to recycle.