Enhancing strength and durability of concrete: a comparative analysis of metakaolin and fly ash replacement

Abstract

The construction industry continually seeks sustainable practices to mitigate environmental impacts, on reducing the reliance on ordinary Portland cement (OPC). This study investigates the potential of metakaolin (MK) and fly ash (FA) as partial replacements for OPC in concrete formulations, aiming to enhance performance and sustainability. MK and FA were incorporated on a gravimetric basis at levels of 11%, 12%, 13%, 14%, and 15% for MK, and 21%, 22%, 23%, 24%, and 25% for FA. The fresh concrete mixes workability is evaluated using the slump cone test, ensuring practical applicability in real-world construction scenarios. To assess the mechanical properties of the cured concrete, a series of tests were conducted, including compressive strength (CS), split tensile strength (STS), flexural strength (FS), and modulus of elasticity (MoE). The results demonstrated that concrete with MK substitution exhibited enhanced mechanical properties, with significant improvements in CS (14.06%), STS (17.64%), and FS (14.82%) compared to the control mix. Although FA replacements also enhanced strength properties, the improvements were slightly lower, with increases of 8.72% in CS, 13.54% in STS, and 9.77% in FS. These findings suggest that MK is a more effective replacement material for achieving higher strength characteristics in concrete. The study provides valuable insights for researchers and engineers in optimizing concrete formulations, thereby enhancing sustainability and performance in construction projects.