Selecting Environment-Friendly Mineral Admixtures to Improve the Durability of Shotcrete under Sulfate Attack
Renhe Yang, Tingshu He, Yongdong Xu
Abstract
The main purpose of this study was to explore the deterioration of shotcrete with different liquid accelerators and mineral admixtures under sulfate attack. By measuring the mass loss, compressive strength, and relative dynamic elastic modulus of shotcrete with liquid accelerators and mineral admixtures, the regularity of sulfate resistance of shotcrete was obtained. In addition, visual observation of surface macro-morphology of shotcrete was conducted. Compared with shotcrete with 4.0% AR and 7.0% AS, it was found that the overall surface condition of shotcrete with mineral admixtures was better in the presence of 7.0% AF. Meanwhile, the result of MIP analysis showed that adding 7.0% AF or 10% silica fume was more conducive to shotcrete compactness. Furthermore, the crystal composition and micromorphology of hydration products were analyzed by XRD, TG, and SEM. It was found that the addition of mineral admixtures could improve the sulfate resistance of shotcrete to varying degrees in the presence of different liquid accelerators.