Properties of concrete containing fly ash and bottom ash mixture as fine aggregate

About one-fifth of coal ash produced by the thermal power plants are the bottom ash, and the rest is fly ash. During the past few decades, studies are made to use either of them as the partial replacement of sand in concrete manufacturing. The present study examines the behaviour of concrete manufactured by the complete replacement of natural sand with an optimum mixture of these ashes. The effect of fly ash and bottom ash mixture is ascertained through workability, strength tests, and resistance to acid attacks. It is observed that the mixture containing 50% fly ash and 50% bottom ash mix as fine aggregate has nearly the same compressive strength, 10% more split tensile strength, and higher flexural strength than the control concrete, yet, has 12.15% less density than the control concrete. The water absorption value and volume of pore space was found to be more for concrete containing the fly ash and bottom ash mixture. However, such concrete performed better in resisting sulphuric acid and sulphate attacks. All these conclusions suggested that the mixture containing 50% fly ash and 50% bottom ash may be used as a suitable replacement for natural sand in concrete in moderate environments.