Feasibility of using waste linear low-density polyethylene plastic as binder with quarry dust for paving blocks

Recycling waste plastic as a binding material and substitution of sand with quarry offers a promising alternative. This study investigates the potential of recycled waste linear low-density polyethylene (LLDPE) plastic as a sustainable alternative binder to cement in construction block production. An extrusion technique was adopted to melt the plastic and disperse and distribute quarry dust within the molten plastic to produce a composite. Waste LLDPE plastic-quarry dust composite samples were produced at varying mix ratios of 1:0, 1:1, 1:2, and 1:3. Similar ratios were used to produce cement-quarry dust composite samples. The density, morphology, compressive strength, split tensile strength, water absorption, flexural strength, ultrasonic pulse velocity, and skid resistance of the composites were evaluated. Comparative analysis was conducted, evaluating the performance of waste LLDPE plastic-quarry dust composites against cement-quarry dust composites at various mix ratios. Results revealed that the density of the waste LLDPE plastic-quarry dust composites were in the range of 1288-1571 kg/m³, and its compressive strength increased with increasing quarry dust content, reaching 18.22 MPa at a 1:3 ratio. Conversely, cement-quarry dust composites exhibited a decreasing compressive strength trend with increasing quarry dust, and the lowest strength of 17.57 MPa was obtained at a 1:3 ratio. A statistical analysis approach using post hoc analysis with Bonferroni adjustments validates the significant difference for the mix compressive strengths. Notably, the waste LLDPE plastic-quarry dust composites demonstrated promising performance characteristics, particularly at higher quarry dust ratios, suggesting a viable eco-friendly composite block.