PHYSIOCHEMICAL CHARACTERIZATION OF COFFEE HUSK ASH AND ITS EFFECT ON PROPERTIES OF CONCRETE WHEN USED AS A PARTIAL REPLACEMENT OF CEMENT IN CONCRETE

Abstract

Recent studies are focusing on ways of utilizing either industrial or agricultural wastes as a source of raw materials for the construction industry around the world. This is used to minimize the emission of CO2 during the manufacturing of cement. One of the agricultural waste products is coffee husk which is found in large amounts in Ethiopia. This thesis aims to characterize the physiochemical characterization of Coffee Husks Ash (CHA) by using X-ray diffraction (XRD), Scanning electron microscope (SEM), and Fourier Transforms Infrared Spectroscopy (FTIR) tests, and also the experiment were conducted to determine the compressive, split tensile and flexural strength of the material and durability tests were determined at replacement ratio of 0%, 5%, 10%, 15%, 20% and 25% by volume of cement. The result have shown that up 10% replacement, the XRD, FTIR and SEM showed that crystalline material decreases, the peaks are sharp and the dense microstructure respectively, whereas, the replacement percent increases above 10%, the crystalline material increases, the peak intensity disappeared, and also the micro pores or air void are increases, which may lead to decreasing the strength of concrete. In the case of compressive, flexural and split tensile strength of concrete, there has been increment in 7.2%, 4.5% and 8.08% respectively at 5% CHA replacement and also the compressive strength up to 10% replacement more than the expected target strength value at 28days, after10% CHA replacement the compressive strength value become decreases. Water absorption and sulfate attack at 5% of partially replaced concrete are shown an improvement in the durability of concrete.