A comprehensive comparative analysis of the impact of metakaolin and fly ash additions on the mechanical performance of fiber-reinforced concrete beams

ABSTRACT This study explores the effects of metakaolin (MK), fly ash (FA), superplasticizer, and banana and basalt fibers on concrete’s mechanical properties through a comprehensive experimental analysis. The materials employed include ordinary Portland cement (OPC) 53 grade, M-sand, coarse aggregates, 12.5% MK and FA, and superplasticizer (Sika at 0.5%), blended with banana and basalt fibers in varying proportions of 0%, 0.5%, 1%, and 1.5%. A total of 13 beam specimens, each measuring 1000 mm × 100 mm × 150 mm, were cast, including a control specimen. The primary focus of the study is to evaluate the mechanical behavior of the concrete beams under single-point load testing. Key parameters such as deflection, ductility, stiffness, energy absorption, and energy dissipation were examined. Among the various mixes, the combination with 1.5% basalt fiber and 12.5% MK (BSFM3) exhibited superior performance in terms of strength, stiffness, and overall mechanical properties. The study conducts a detailed microstructural analysis to understand the concrete mixes and performance. Comparative analysis with experimental results and existing literature underscored the enhanced performance of this mix and analyse the microstructural properties. These findings provide valuable insights for optimizing concrete mix designs, enabling engineers, architects, and construction professionals to create durable, sustainable structures.