Strength and deformation properties of structural lightweight concrete under true tri-axial compression

摘要

The lightweight aggregate (LWA) used today is mainly from natural sources (sintered clay ceramsite or shale ceramsite), or from manufactured materials (sintered and cold-bonded fly ash aggregates). Compared to normal-weight aggregates, the greatest distinctive feature of LWAs is their brittle, weak, and porous structure, so the brittleness of LWC is higher than NWC for the same mix proportion and compressive strength class [3]. Cui et al. [4] explained the mechanism difference between LWC and NWC from the point of three-phase micro-level structure. He found that the stiffness of normal-weight aggregate (i.e. limestone or granite) was larger than that of cement mortar, so the cracks generally initiated in the ITZ and travelled around the aggregates. While the stiffness of LWA was smaller than that of cement mortar in structural LWC, under uniaxial tension and compression stress state, cracks would travel through the LWA particles. It is the difference of internal stress transfer mechanism that leads to the difference of macroscopic mechanical properties between LWC and NWC [5].