Effects of Partial Replacement of Coarse Aggregates with Coconut Shell and Polyethylene Terephthalate on the Mechanical Properties of Concrete

Rising cost of building materials and environmental pollution as a result of non-biodegradable wastes like polyethylene has become a thing of concern in the world today. This has lead to various researches on how these biodegradable wastes can by utilized in the construction industry as supplementary building materials thereby reducing environmental pollution which will also reduce the cost of building materials. Therefore, this study investigated mechanical properties of concrete using Polyethylene Terephthalate (PET) and Crushed Coconut Shell (CCS) as substitutes for conventional coarse aggregates to solve the challenge of increasing cost and environmental pollution. CCS and PET were crushed to sizes and sieve analysis was done for appropriate aggregate distribution. Specific gravity was done for coarse aggregates and cement, while consistency, fineness, initial and final tests were conducted on cement. Ten concrete mixes (A to J) were produced, replacing conventional coarse aggregates with CCS and PET in varying proportions from 0% to 100%. Water absorption and slump tests were conducted on fresh concrete to assess workability, while compressive, flexural and split tensile tests were done for hardened concrete, after curing for 7, 14 and 28days. Results showed incorporating CCS and PET in concrete improved workability, reduced density, and maintained acceptable mechanical strength. Sample G (50% granite, 20% PET, 30% CCS) exhibited maximum strengths. Thus, concrete blends 50% gravel, 20% PET, 30% CCS (Sample G) are viable alternatives to conventional concrete.