Effects of nanomaterials on early-age properties and microstructure of calcium sulfoaluminate-Portland cement-based repair mortar under −10 °C curing

作者：Yihan Chen, Xiaohui Zeng, Yuting Zhang, Xinyu Liu, Yi Min Xie, Hong Guo, Yu Wang · 发表于：Case Studies in Construction Materials · 年份：2025 · DOI：10.1016/j.cscm.2025.e05536 · 被引用次数：2 · 研究领域：Concrete and Cement Materials Research、Concrete Properties and Behavior、Innovative concrete reinforcement materials

To meet the repair needs of concrete structures in high-latitude and high-altitude areas during winter, improving the early-age properties of repair mortar under negative temperatures has significant engineering significance. Due to the dramatically retarded hydration rate of cement in such environment, nanoadditives are employed to accelerate cement hydration. This study investigates the effects of two types of nanomaterials, 0–3 % nano-SiO 2 (NS) and C-S-H seeds (CSHs), on the setting time, mechanical properties, hydration temperature rise, and microstructure evolution of the calcium sulfoaluminate cement (CSA) - Portland cement (PC) binary system (with a CSA: PC mass ratio of 8:2) at −10 °C. The pore structure changes, phase evolution, and microstructure development of hydration products are analyzed using nitrogen adsorption and desorption (NAD), X-ray diffraction (XRD), thermogravimetric analysis (TG-DTG), and scanning electron microscopy (SEM), respectively. The results demonstrate that incorporating nanomaterials accelerates the setting time and enhances the early hydration heat release in the binary cement system, leading to a substantial improvement in early-age compressive strength, yet may adversely affect flexural strength, indicating a potential trade-off between strength types. Specifically, the addition of 3 % NS and CSHs increases the compressive strength by 27.8 % and 15.4 % at 6 h, and by 41.5 % and 20.8 % at 1 day, respectively. Microstructural analyses rev...