Effect of coal bottom ash as partial replacement of sand on properties of concrete

Coal bottom ash (CBA) is formed in coal furnaces. It is made from agglomerated ash particles that are too large to be carried in the flue gases and fall through open grates to an ash hopper at the bottom of the furnace. Bottom ash is mainly comprised of fused coarser ash particles. These particles are quite porous and look like volcanic lava. Bottom ash forms up to 25% of the total ash while the fly ash forms the remaining 75%. One of the most common uses for bottom ash is as structural fill. Published literature shown that there is a strongly possibility of coal bottom ash being used as substitute/replacement of fine aggregate (sand). Its use in concrete becomes more significant and important in view of the fact that sources of natural sand as fine aggregates are getting depleted gradually, and it is of prime importance that substitute of sand be explored. This paper presents an overview of the published literature on the use of coal bottom ash in concrete. Effect of coal bottom ash on the properties of concrete such as workability, bleeding, setting times, compressive strength, split tensile strength, flexural strength, shrinkage, and durability are presented. (C) 2012 Elsevier B.V. All rights reserved.