The effect of aggregate shape upon the strength of structural lightweight-aggregate concrete

The influence of the shape of a lightweight aggregate (a sintered fly-ash) upon the compressive strength of lightweight-aggregate concrete is described. The effective strength of the lightweight aggregate was calculated by extrapolation from the Bache-Christensen model. It is shown that: (a) the compressive strength of lightweight-aggregate concrete depends upon the shape of the aggregate particles—the concrete tested with rounded aggregate (n = 0·40) had a compressive strength about 6 to 8 N/mm² greater than those with elongated form (length/thickness ratio 4·0); (b) the effective strength of lightweight aggregate depends upon the shape of the aggregate particles—the rounded aggregate particles used had a strength of approximately 25·0 N/mm² and the elongated had strengths of approximately 17·5 N/mm² and 20·0 N/mm² for length/thickness ratios of 4 and 2 respectively.