Deformation behaviour and failure criteria of plastic concretes under compression stresses

摘要

Plastic concrete is a ductile building material, made of aggregate, cement, water and bentonite clay mixed at a high water/cement ratio. To explore its deformation behaviour and failure criteria, we tested plastic concrete samples under uniaxial, biaxial, conventional triaxial and true triaxial compression. The characteristics of the stress-strain and axial strain-volumetric strain curves of plastic concrete samples were investigated. There were three types of stress- strain curve: softening, plasticising and hardening. A deformation parameter was introduced to quantitatively evaluate the curve type and the steepness of the descending post-peak portion. Under multiaxial compression, the volume of the specimens decreased, reaching a minimum, then expanded. Failure occurred in the weakest lateral confinement direction. The octahedral shear strain and peak strain showed a linear relation at failure, and the correlation coefficient decreased with increasing bentonite content. The failure rule between the octahedral shear stress and normal stress is presented.