Experimental Investigation on Physio – Mechanical and Microstructural Behavior of Bamboo Fibered Concrete with Partial Replacement of Cement by Metakaolin

Abstract

Concrete has low tensile strength. To improve this, natural fibers like Bamboo are added to enhance its properties. Cement production is a major source of carbon dioxide emissions. Incorporating pozzolanic materials like metakaolin can lower cement consumption and enhance strength. The aim of this study is to optimize the mechanical properties and durability performance of bamboo fiber and Metakaolin-modified concrete. Factors examined include workability, compressive strength, flexural strength, water absorption, sulfate attack resistance, and microstructure. The American Concrete Institute's mix design method was used to develop a C-25 grade concrete mix. The mixes produced included a control mix, as well as variations incorporating different percentages of metakaolin (10%, 15%, and 20% by weight of cement) and bamboo fiber (0.5%, 1%, and 1.5% by volume of concrete). The results show that workability decreases as the bamboo fiber and metakaolin content increases. Compressive and flexural strength reach a peak at the mix with 1% bamboo fiber and 15% metakaolin, and then slightly decline. However, all mixes exhibit improved performance compared to the control. The mix with 1% bamboo fiber and 15% metakaolin demonstrates the best overall results, indicating the optimum combination. The concrete matrix's pore structure is filled due to the formation of calcium silicate hydrate (C-S-H) gel, leading to lower water absorption for this mix. Furthermore, the incorporation of bamboo fiber and metakaolin enhances the concrete's resistance to sulfate attack. The XRD pattern reveals sharp peaks for Albite and lower intensity peaks for calcium hydroxide (CH) and calcium silicate hydrate (C-S-H). Albite reacts with calcium hydroxide from cement hydration to form more C-S-H gel, enhancing concrete's strength and durability. SEM analysis reveals that at optimal fiber content, bamboo fibers are evenly distributed in the concrete matrix, improving overall performance. However, at 1.5% fiber content, excess fibers can adversely affect their orientation. This improvement enables the concrete to last longer, which leads to fewer maintenance needs over time and reduces the environmental impact associated with the demolition of structures.