Replacement of Lightweight Aggregate Fines with Natural Sand in Structural Concrete.

Reports results of an Investigation of the effect of replacing the fines of four particular structural lightweight aggregates with equal volumes of natural sand. Cement contents were varied to obtain compressive strengths over the range of 3000 to 6000 psi. A comparison of the reported physical properties for lightweight concrete was provided by tests of normal weight concrete of corresponding compressive strength. The test results are presented for each of the lightweight aggregates showing the mix and physical properties, as functions of the partial or complete fine aggregate replacement, for concretes at compressive strength levels of 3000, 4000, 5000, and 6000 psi. in general, the structural properties were improved as the amount of natural sand was increased, but this improvement was achieved only with considerable increase in the unit weight. Decrease of total water and cement contents required for a given slump and compressive strength were greater for the harsher crushed aggregates. [ABSTRACT FROM AUTHOR]