Tensile strength of structural expanded clay lightweight concrete subjected to different curing conditions

Abstract

In this paper the tensile strength of Lightweight Aggregate Concrete (LWAC) produced with different types of expanded clay aggregates is characterized. A comprehensive experimental study was carried out on different concrete compositions with mean compressive strengths from 30 to 70 MPa and density classes from D1.6 to D2.0. The influence on the splitting tensile strength and modulus of rupture of the curing conditions and initial wetting of lightweight aggregate is studied. For concretes of equivalent compressive strength, the tensile strength is almost independent of the type of lightweight aggregate. The tensile strength of LWAC was about 0.8–0.85 of that of Normal Weight Concrete (NWC) of equal strength, decreasing to about 0.7 in LWAC with lightweight sand. Contrary to compressive strength, the LWAC with less porous aggregates has lower tensile structural efficiency than NWC. But the tensile structural efficiency of moist-cured concrete is little affected by the volume and wetting conditions of aggregate. There is a reduction in the splitting strength of air-cured concrete that is not predicted in the normalization and it is greater for NWC than for LWAC. However, the modulus of rupture of air-cured LWAC can only be about 0.5–0.8 of that of NWC of equal strength.