Experimental and modeling study on the triaxial mechanical behavior of sulfate-deteriorated mortar

Abstract

Considering the significance of sulfate attack to structure durability and frequent existence of multiaxial loadings, it is relevant to study the triaxial mechanical behavior of sulfate-deteriorated cementitious materials. The triaxial compression tests with three confining pressures were conducted in previous study. To give a reliable constitutive model, this research investigated the triaxial mechanical behavior of sulfate-deteriorated mortar in experimental and modeling aspects. All stress–strain curves of the mortar samples immersed in 5% Na2SO4 solution up to 270 d were shown and analyzed. The ingress of sulfate decreased the axial strain at improvement stage, but slightly increased the strain at deterioration stage. The volume of mortar sample changed from contraction to dilation with loading, indicating a non-associated flow rule. A nearly linear relationship between the square root of triaxial failure stress and elastic modulus of mortar was observed, proved by other research results as well. The lateral confinement attenuated the negative effect of sulfate deterioration on the two mechanical indexes. On the basis of elastoplasticity theory and experimental results, an elastoplastic model considering sulfate deterioration was proposed. The effect of sulfate deterioration was implemented to the elastic modulus, failure criterion and hardening law through 2nd polynomial. Numerical simulations showed that the proposed model can well reproduce the compression behavior of sulfate-deteriorated mortar with different confining pressures.