Durability and Strength Properties of Concrete Containing Coal Bottom Ash

In Europe coal bottom ash production represents approximately one tenth of coal combustion by-products. About 44% of coal bottom ash is used in the construction sector, but its application as addition in concrete is very low. This study evaluates the influence of replacing cement by bottom ashes or fly ashes, from the same Portuguese coal power station, on the properties of fresh and hardened concrete, namely on workability, compressive strength, accelerated carbonation, chloride diffusion, absorption and capillary porosity. The results revealed that concrete incorporating coal bottom ash have a performance analogous to that of concrete with coal fly ash, although it is necessary to increase the dosage of admixture to control the loss of workability that is generally observed with bottom ash. Coal bottom ash can than be envisaged as a promising addition type II for concrete.