Effects of Erosion Forms and Admixture on Cement Deterioration Characteristics in Sulfate Environment

The effects of solution concentration, admixtures, erosion form, and age on the flexural and compressive strength of Portland cement subjected to a sulfate environment were investigated, and the corresponding relationship between the mechanical properties and influencing factors of the cement specimen was proposed. Furthermore, the phase components, crystal morphology, microstructure, and morphology of erosion products were also investigated. The research findings indicate that the flexural and compressive strengths of specimens subjected to a sulfate environment for 4 months decreased as the content of admixture increased. There exists a GaussMod function between the content of fly ash and flexural strength of a specimen subjected to a sulfate environment, and the Boltzmann function can be used to characterize the variation between the slag content and compressive strength of the specimen. After being attacked by a saturated sulfate solution, the strength of specimens with fly ash increased at first and then decreased as the content of fly ash increased. In the semi-immersion erosion form, the strength of the specimens containing admixture that were attacked by sulfate was lower than that of the control sample. Admixture can observably change the morphology and microstructure of the specimens. Rodlike and slab-like sulfate erosion products can be easily observed in the specimens containing admixture that were attacked in the semi-immersion form. This is significant for further research on the mechanism and evolution process of concrete sulfate erosion and for predicting durability and conducting an operational life assessment of concrete constructions subjected to a sulfate environment.