Recycled Plastic Waste in Production of Paving Blocks for Construction of Non-motorized Transport Facilities

Abstract

This thesis examines the use of recycled plastic waste in production of paving blocks for construction of non-motorized transport facilities. The study mainly focuses on determining the optimum design mix for production of Recycled Plastic Waste Paving Blocks (RPPB) for construction of Non-Motorized Transport (NMT) facilities. The study specifically focuses on determining the physical and mechanical properties of the produced RPPB, the percentage of plastic waste in the partial replacement of fine aggregates in the production of RPPB and the percentage of plastic waste in the partial replacement of coarse aggregates in the production of RPPB. In the Production of Recycled Plastic Waste Paving Blocks (RPPB), the plastic waste was obtained from suppliers in the form of shredded plastic waste and pulverized plastic waste. The plastic waste, quarry dust, and ballast were graded through a sieve analysis to determine the gradation curves. The study began with an initial mix ratio of 1:1.7:3.75 as cement: fine aggregate: coarse aggregates. This was used as the initial mix in the partial replacement of the weight of fine aggregate (crushed stone dust) and coarse aggregate (ballast) with plastic waste. The initial partial replacement by percentages was: (i) 20:80, (ii) 40:60, (iii) 60:40, and (iv) 80:20 for fine aggregates and coarse aggregates, respectively. The paving blocks produced using shredded plastic waste as a partial replacement of quarry dust and ballast did not meet the compressive strength specifications of 35MPa as per the KEBS standard KS 827:2003. On the other hand, paving blocks produced using pulverized plastic waste as a partial replacement of quarry dust and ballast met the compressive strength specifications of 35MPa as per the KEBS standard KS 827:2003. The tested samples were produced using the determined optimum design mix of [𝐶:𝐶𝑆𝐷:𝐵:𝑃]=[1:0.971:1.051:0.228] for Cement, Crushed stone dust, ballast and plastic. The samples were cured and tested at 28 days to determine their physical and mechanical properties. A 28-day cured paving block produced using shredded plastic waste and pulverized plastic waste as a partial replacement of fine and coarse aggregates gave compressive strength of 33MPa and 50MPa, respectively. The water absorption for the produced paving block was attained at 6%, which is within the recommendation by BS EN-1338:2003. An economic analysis revealed that the produced paving block has a lower production cost and better strength than similar paving blocks made from traditional concrete materials in the Kenyan market. The study recommends the produced paving blocks as suitable for construction of walkways and cycle paths for Non-Motorized Transport facilities. Future studies need to consider using plastic waste as a binder to eradicate the use of cement and other natural products