Sulfate Corrosion Mechanism of Cement Mortar Under Multi-sources and Multi-ion Coupling Effect
Multi-source and multi-ion coupling corrosion is widespread in cast-in-situ structures in sulphate saline soil area.By premixing Mg2+,Cl-and SO42-into mortar and placing it in different corrosive environments,the pore distribution,mass,size and sulfate concentration at different depths,as well as the evolution law of flexural and compressive strength of specimens were measured during corrosion period.The microstructure and mineral composition of specimens were observed by scanning electron microscope-energy dispersive spectroscopy analysis(SEM-EDS),X-ray diffraction(XRD)and thermogravimetric analysis(TG-DTG).Results show that internal corrosion increased the content of harmful pores and accelerated the corrosion process.Internal corrosion has a significant adverse effect on the development of flexural strength,the strength of the specimens are reduced by 50%~67%compared with that of the specimens without internal corrosion.Internal Mg2+negatively affects the development of the flexural strength of the specimens in the sulfate environment,the flexural strength of the specimens are only 4.4%of that of the non-corrosive specimens.Mg2+in the periphery of specimens alleviates the increasing trend of harmful pore content and has a certain protective effect on the internal structure.
cast-in-situ structuresulfate attackmulti ion corrosioninternal corrosiondeterioration mechanism