INVESTIGATING MIX PROPORTIONING EFFECTS ON COMPRESSIVE STRENGTH OF CONCRETE CONTAINING PELLETIZED PLASTIC AGGREGATES FOR ENVIRONMENTAL BENEFIT

The increasing volume of non-recyclable plastic waste necessitates its sustainable incorporation into construction materials. This research assesses the effects of incorporating varying percentages of pelletized waste plastic (0% to 20% mass replacement of fine aggregate) on the fresh and hardened properties of concrete across three distinct mix ratios: 1:1:2, 1:1.5:3, and 1:2:4. Test such as Slump and Compacting Factor tests were conducted on the fresh concrete while test such as compressive strength, flexural strength, density, and water absorption rate were conducted on the hardened concrete.​The results shows that both compressive and flexural strengths exhibited a substantial decrease as the plastic content increases, thus attributed to the weak inherent mechanical properties of the plastic and a compromised interfacial transition zone (ITZ). The maximum 28-day compressive strength reduction exceeded 45% in the leaner mixes. Concurrently, slump, compacting factor and density decreases with plastic inclusion while the water absorption rate increases. In conclusion, while pelletized plastic offers a viable route for waste valorization and density reduction, its detrimental effect on structural strength and workability requires strict limitations on substitution levels and the implementation of compensatory mix design strategies to achieve performance parity with conventional structural concrete.