Mechanical and durability properties of concrete with recycled polypropylene waste plastic as a partial replacement of coarse aggregate

Reusing non-biodegradable plastic waste materials can be a viable solution for minimizing the consumption of natural resources for construction purposes and reducing environmental hazards. Thus, this study inspects the potentialities of polypropylene (PP) plastic waste as coarse aggregate in concrete. This study aims to evaluate the mechanical and durability properties of PP concrete. It focuses mainly on workability, hardened density, compressive strength , modulus of elasticity (MoE), splitting tensile strength (STS), flexural strength, bond strength, temperature effect on compressive strength, shrinkage properties, and chloride ion penetration . The experimental work includes a varying percentage of PP aggregate as 10% and 20% of the volume of coarse aggregate and the water-cement ratios as 0.35, 0.40, 0.45, and 0.50. The experimental results revealed that the workability of concrete increased with the addition of PP aggregate into the mixture. Almost 5% and 10% reduction in concrete density can be possible while using 10% and 20% PP content, respectively. In terms of compressive strength, MoE, STS, and flexural strength, all the properties were decreased after incorporating PP aggregate into the concrete. At elevated temperatures, compressive strength decreased up to 10.8% and 34% at 100 °C and 200 °C, respectively. Besides, the shrinkage percentage increased with increasing the percentage of PP aggregate. However, the chloride ion penetrability of all PP concrete fell in the moderate category. The 10% PP concrete exhibited better bond strength and a higher slip bearing capacity than the other percentages. Moreover, the PP concrete cylinders exhibited comparatively ductile failure than the brittle failure of the reference concrete. Finally, to produce efficient and eco-friendly concrete, it is suggested to use PP aggregate up to 10% in structural concrete. • Increment in PP aggregate decreased the compressive strength up to 26.9%, with varying PP percentages and w/c ratios. • At 100°C and 200°C temperatures, the compressive strength was reduced by 10.8% and 34% for various PP percentages. • The concrete containing 10% PP aggregate exhibited better bond strength and a higher slip bearing capacity. • The chloride ion penetrability for all PP concrete fell in the moderate category. • The shrinkage percentage for PP concrete increased up to 0.061% with changing PP percentages and the w/c ratios.