Coal ash is the waste that is left after coal is combusted (burned). It includes fly ash (fine powderyrnparticles that are carried up the smokestack and captured by pollution control devices) as well asrncoarser materials that fall to the bottom of the furnace. Coal ash used as Portland cement constitutesrnor as ingredient of concrete will help in more sustainable cement production by lowering energyrnand raw material consumption. rnThis study aims to investigate the suitability of coal ashes produced in different factories ofrnEthiopia (AYKA Addis Textile factory and Dongfang Spinning and printing) as supplementaryrncementitious material in Cement Concrete production. The physical and chemical characteristicsrnof coal ash and concrete raw materials were investigated to check their compliance with thernrequirements of standards and specifications. rnCoal ashes taken from the factories were pulverized and sieved with 300Âµm sieve and finenessrndetermined by air-permeability test, results 3385.57 cmrn/g for FA-1 and FA-2rnrespectively. X-ray examination has shown that the fly ashes are mainly amorphous but there arernalso present crystal phases like feldspar, melilite, hematite, very little anhydrite, and quartz. rn2rn/g and 3788.9 cmrn2rnThe substitution portions of fly ashes were made 10%, 15%, 20% and 25% by volume of cementrnfor FA1 and 5%, 10%, 15% and 20% by volume of cement for FA2. Furthermore, two classes ofrnconcrete with a water-binder ratio of 0.4 and 0.6 were made to investigate the effect of coal ashesrnon the strength of concrete. rnThe performance of the concrete was evaluated by conducting compressive strength, flexuralrnstrength and water penetration tests. The results showed that both coal ashes possess sufficientrnpozzolanic characteristics to be used in the production of cement concrete, and the optimumrncement replacement level by these ashes can range between 5-15% by volume.