Properties of fly-ash lightweight aggregate concretes

Lightweight concrete with sintered fly-ash aggregates was compared with that of normal weight concrete with granite aggregates for various water/binder ratios starting from 0·30 to 0·50. They both had the same mixture proportion by volume and the only difference between them was the coarse aggregate used. Test results indicated that when granite aggregates have been replaced completely with lightweight aggregates, a reduction of 20% in the density of concretes was observed. Lightweight concrete exhibited higher workabilities than the corresponding normal weight concrete mixtures. With the exception of the elastic modulus all the other properties such as compressive strength, splitting tensile strength and chloride permeability of the lightweight concrete mixtures were comparable with normal weight concrete mixtures at water/binder ratios of 0·45 and 0·50. The ratios of splitting tensile strength to compressive strength of lightweight concrete were found to be similar to that of normal weight concrete.