A study on improving the performance of cement-based mortar with silica fume, metakaolin, and coconut fibers

Cement mortar is the primary choice for construction due to its widespread usage. However, certain applications demand high-performance cement mortar. In this pioneering study, we explore using agriculture waste products, industrial by-products, and naturally occurring kaolinite clay as potential additives in composite cement. Our research aims to assess these materials' physical and mechanical attributes to ascertain their efficacy in elevating cement performance. To achieve this, we replaced 20% of the cement in the composite with silica-fume and metakaolin, following a precise mix design fraction of 1:1 (binding materials: sand) for the mortar composites. We successfully identified the optimum combination of metakaolin and silica fume through systematic experimentation that maximizes compression strength. Subsequently, we introduced various proportions of coir fibers (ranging from 3% to 15% by weight) into the cement composite to enhance its structural support capabilities. We carefully calibrated the ratio of the water-to-binding material (ranging from 0.35 to 0.6) to maintain the workability of the cement mixtures. Next, we subjected the cement composites to meticulous curing in water for 7 days, 14 days, and 28 days, respectively, to observe their performance over time. Our comprehensive study encompassed the investigation of critical parameters, including moisture content, density, and water absorption, as well as essential mechanical properties such as compressive strength and modulus of rupture. A total of 270 specimens underwent rigorous testing, yielding compelling results. The composite featuring a combination of 10% silica fume, 10% metakaolin, and 6% coconut fibers showcased superior mechanical and physical properties. SEM and EDX studies also showed dense and packed microstructure of mortar samples. These findings showcase the remarkable potential of this specific composite composition as an environmentally conscious and sustainable alternative to enhance cement performance in construction applications. This research advances eco-friendly construction practices by harnessing the strength of waste-derived materials and naturally occurring resources, supporting a more sustainable and resilient approach to infrastructure development.