Experimental study and modeling on stress-strain curve of sulfate-corroded concrete

The stress-strain curve of concrete under a uniaxial compression can reflect much information about its mechanical properties. This paper performs an experimental study and modeling on the stress-strain curve of concrete subjected to external sulfate attack (ESA). To shorten the experimental period, cement mortar specimen (CMS) with a small size is selected as research objected, and is immersed into purified water, 2.5% and 5.0% Na2SO4 solution. First, an economic test equipment is designed by adding rigid elements to ordinary hydraulic testing machine. Second, the evolution of stress-strain curve and mechanical properties of sulfate-corroded CMS with immersion time is obtained. Based on least-square method, the expressions of two chemical damage parameters are determined to respectively characterize the time-varying elastic modulus and compression strength of CMS caused by ESA. Then, a coupling chemo-mechanical damage constitutive model for sulfatecorroded CMS is established by introducing the chemical damage parameters. Finally, the numerical solution of the model is presented, and is validated by the above experimental data of stress-strain curve of CMS.