This work evaluates the influence of the accelerator type, the cement type and age of exposure on the degradation mechanism and the durability of sprayed mortars subjected to external sulphate attack (ESA). Cores and prisms were extracted from panels sprayed with 8 mortar compositions (with 2 sulphate-resisting cement types and 4 setting accelerators) and then exposed to a sulphate solution at the ages of 7 or 28 days for 400 days. The evolution of the ESA was assessed through XRD, SEM, compressive strength, dimensional variation and ultrasonic pulse velocity. Results show that alkaline accelerators increase drastically the vulnerability of the matrix to the ESA. The degradation is enhanced by the higher solubility of aluminate phases and the increased formation of expansive phases. Results reveal that the use of sulphate-resisting cement might not suffice to mitigate severe material degradation.

这项工作评估了促进剂类型，水泥类型和暴露时间对遭受外部硫酸盐侵蚀（ESA）的喷砂浆的降解机理和耐久性的影响。从喷涂了8种砂浆组合物（具有2种抗硫酸盐的水泥类型和4种凝结促进剂）的板上提取岩心和棱柱，然后在7天或28天的年龄下暴露于硫酸盐溶液中400天。通过XRD，SEM，抗压强度，尺寸变化和超声脉冲速度评估ESA的演变。结果表明，碱性促进剂大大增加了基质对ESA的脆弱性。铝酸盐相的较高溶解度和膨胀相的增加形成促进了降解。