Meso-scale analysis of failure characteristics and mechanical properties of lightweight aggregate concrete (LWAC) with different aggregate volume fractions and shapes under axial tension

Abstract

LWAC is a concrete prepared by the natural or artificial lightweight aggregates (LWAs). It has been receiving much interest in construction engineering field due to its outstanding properties including lightweight, heat preservation and shock absorption. A cohesive crack model of LWAC with random aggregates was established in this paper, and failure characteristics and mechanical properties of the concrete with different aggregate shapes and with volume fractions between 0.3 and 0.8 were analyzed by numerical simulation under axial tension. Results show that the LWAC crack starts from the inside of LWA, penetrates through interfacial transition zones (ITZs) and mortar to other LWAs to form the main crack.An increase in aggregate volume fraction decreases the slope of the ascending section of the stress–strain curve and tensile strength of LWAC. The crack initiation time of LWAC with polygonal LWAs is earlier, and the strength is slightly lower than them of circular aggregate LWAC. However, its time and strain of penetrating crack are larger, and it is more suitable for structural engineering with seismic requirements. The finite element model can effectively describe the two-dimensional failure process of LWAC.