Abstract
It is the aim of this paper to present the results of fundamental investigation of the mechanical properties of lightweight aggregate concrete for structural use. Four domestic lightweight aggregates and one normal weight sand-and-gravel aggregate have been prepared for the investigation. The data have been reported on the properties of stress-strain diagram under uniaxial loading, the static and dynamic moduli of elasticity, Poisson's ratio, the relationship between compressive and splitting strengthes, and the failure criterion for concrete under combined stresses produced by axial and torsional loading of cylindrical specimen.
Consequently, the following main results have been obtained by comparing various concretes on the bases of equal compressive strength.
(1) The test values of moduli of elasticity (Initial tangent modulus; Ei, Secant modulus at the stress of 0.3 times of compressive strength; E0.3F, and Dynamic modulus of elasticity; Ed) of lightweight concrete are somewhat lower than the normal weight concrete, and the rate of decrease of these values generally depend on the unit weight of concrete.
(2) The values of Poisson's ratio under the usual range of structural stresses are about 1/5-1/6 regardless of kind of concrete.
(3) The ratio of the compressive strength to the splitting strength of lightweight concrete is slightly larger than in normal weight concrete.
(4) The failure criterion for lightweight concrete analized according to Mohr's theory of failure differs from that in normal weight concrete. However, the failure criterion by octahedral stress analysis is somewhat independent of the kind of concrete.
