A New Generation of Structural Lightweight Concrete

Abstract

Two types of lightweight concrete were investigated. The first was made with polystyrene beads and blast furnace slag aggregate. The second type of concrete investigated was made from sintered fly ash aggregate as a total replacement of both coarse and fine aggregate. This concrete yielded a dry density of about 1790 kg/cubic meter and a compressive strength above 70 MPa, and values for the moduli of rupture and elasticity of 5.5 MPa and 21 GPa respectively. The stress-strain relationship of this concrete is a straight line until very near to failure thus underlining its brittle nature. The shrinkage values for this concrete are lower than normal weight concrete and this is attributed mainly to the excellent bond capability and to the high absorptive capacity of the aggregate. Addition of fly ash as a partial replacement of fines was beneficial in eliminating segregaton and increasing workability and cohesion of the fresh concrete.