Ding Hao, Shen Xuepeng, Chen Aili, Gu Rulin, Fang Ying, Li Dongxu
College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, China.
Nanjing Kunchang New Material Co., Ltd., Nanjing 210000, China.
Materials (Basel). 2023 Aug 16;16(16):5648. doi: 10.3390/ma16165648.
Despite having a high early mechanical strength and using sulfoaluminate cement as the primary cementitious material, self-compacting repair mortar (SCRM) suffers from rapid hydration rates leading to construction time constraints. This study examined how several forms of calcium sulfate, including hemihydrate gypsum, anhydrite, and dihydrate gypsum, affected SCRM's workability, hydration process, and microstructure. The outcomes demonstrated that adding hemihydrate gypsum sped up SCRM's early hydration rate and boosted its expansion rate. For a cement with 8% hemihydrate gypsum, 6 h after adding the water, the flexural strength and compressive strength increased by 39.02% and 34.08%, respectively. The hydration rate of SCRM can be efficiently delayed by dihydrate gypsum, although the result is subpar. The material exhibited the lowest fluidity loss in 20 min, the setting time was extended, and the 28-day flexural and compressive strengths were raised by 26.56% and 28.08%, respectively, after adding 8 percent anhydrite.
尽管自密实修复砂浆（SCRM）具有较高的早期机械强度，并使用硫铝酸盐水泥作为主要胶凝材料，但其水化速度过快，导致施工时间受限。本研究考察了几种硫酸钙形式，包括半水石膏、硬石膏和二水石膏，对SCRM工作性、水化过程和微观结构的影响。结果表明，添加半水石膏加快了SCRM的早期水化速度并提高了其膨胀率。对于含有8%半水石膏的水泥，加水6小时后，抗折强度和抗压强度分别提高了39.02%和34.08%。二水石膏可有效延缓SCRM的水化速度，不过效果欠佳。添加8%硬石膏后，该材料在20分钟内的流动性损失最低，凝结时间延长，28天抗折强度和抗压强度分别提高了26.56%和28.08%。
