Reproportioning of aggregate mixes for optimal workability with pond ash as a fine aggregate in concrete

Thermal power plants in India, adopt the wet process of disposal of ash resulting in large quantities of pond ash. Pond ash differs from flyash nwinly in its physical characteristics. The paper examines the workability and compressive strength of concrete, in which pond ash has been incorporated as a part replacement of fine aggregate. The results of the investigation show that workability is optimal for a particular coarse aggregate (CA) to fine aggregate (FA) ratio of a given mix of constant paste volume for both reference and pond ash concretes. Workability of the pond ash concrete, reduces with the increase in percentage of fine aggregate replacement. However, on reproportioning the CA/FA ratio of the mixes, workability can be restored to a large extent. It is also shown that the reproportioned mixes of optimal workability also correspond very nearly to least voids mixtures and hence result in higher compressive strength.