Effect of Metakaolin and Crumb Rubber on the Properties of Roller-Compacted Concrete Containing PP Fibers

Abstract

This study investigates the combined effects of metakaolin (MK), crumb rubber (CR), and polypropylene (PP) fibers on the mechanical and durability-related properties of hardened Roller-compacted concrete (RCC). MK was used as a partial cement replacement at levels ranging from 0% to 20% by weight of cement, while PP fibers were incorporated at volume fractions of 0% to 0.2%, and CR was introduced at replacement ratios up to 1% by weight of aggregate. The performance of the mixtures was evaluated through compressive strength, splitting tensile strength, flexural strength, and water absorption tests. The results indicate that the incorporation of MK significantly enhances mechanical performance up to an optimal replacement level of 15%, beyond which strength gains diminish. PP fiber reinforcement notably improves tensile and flexural behavior, with the optimal fiber content identified as 0.1% by volume. Higher fiber dosages resulted in reduced compressive strength due to fiber agglomeration effects. The synergistic use of MK and PP fibers partially mitigates the adverse effects of CR, resulting in improved mechanical performance and acceptable durability characteristics for RCC applications.