PRODUCTION OF CONCRETE FOR STRUCTURAL APPLICATION BY USING AGRICULTURAL BY-PRODUCTS AS SUPPLEMENTARY CEMENTITIOUS MATERIALS (COFFEE HUSK ASH AND BAMBOO LEAFASH

Abstract

Concrete is a mixture of aggregate, cement, and water, of these materials the most expensive and polluting element is cement. The production process of cement affects the environment by means of release of CO2 gas into the atmosphere and affects ecology due to the exploitation of virgin materials. Therefore, searching for other inexpensive cementing materials is of great attention to deal with such circumstances. The primary aim of this research is to obtain the capability of using coffee husk ash and bamboo leaf ash as a ternary blended material in concrete production. The coffee husk and bamboo leaves that have been used for this research investigation were obtained from the Gamo zone, which were calcined at a controlled temperature of 550°C and 600°C for two and three hours respectively. To understand the effect of these materials on the fresh properties such as workability, mechanical property experiments such as tensile, compressive, and flexural have been conducted and, for a durability property test acid attack and water absorption tests have been conducted and for a micro-structural characterization XRD and SEM have been conducted concerning the designed dosage replacement content of 0%, 7.5%, 15% and 20% by weight of cement. The result observed from the experimental studies demonstrated that the workability of mixtures showed a decreasing trend with an increase in the proportion of the CHA and BLA content, in which the measured slump values ranged between 42 and 25 mm. On the other hand, the setting time of concrete mixtures showed an increasing trend with an increase in CHA and BLA content. The initial and final setting times of the concrete mixtures were within the range of 81-198 minutes and 298-538 minutes, respectively, which meets the criteria set by the standards. The compressive strength of the concrete mixtures C7.5B7.5 and C7.5B10 exhibited an increase of (+0.83%) and (+0.56%) respectively, compared to the control mix (C0B0), which has a mean strength of 37.04 MPa on the 28th day of testing. On the 56th day of testing, the replacements of C7.5B7.5 and C7.5B10 further increased the concrete strength by 2.31% and 1.49% respectively. The water absorption and sulfate attack resistance of the CHA and BLA-blended concrete showed significant improvements in the C7.5B7.5 and C7.5B10 dosage contents. Based on these findings, it can be concluded that the blended mixes of CHA and BLA have the potential to replace cement up to 17.5% without compromising the quality of the concrete.