Rapid repair mortar (RRM) is widely used to repair infrastructures, which must achieve high early strength and long-term service. This study investigated the influence of hot/wet harsh environmental conditions on RRM prepared using solid-waste-based sulfoaluminate cement (WSAC). Orthogonal experiments were conducted to obtain the optimized WSAC-based RRM. Then, the impact of simulated harsh conditions (cross-combination of 20/60 °C and 10/40/90%RH humidity) on RRM and synthetic ettringite was studied. High temperature and low humidity restrained the volume deformation and promoted the growth of the later-age compressive strength of the RRM, but reduced the flexural strength. In this case, ettringite lost some water molecules in the Ca–H₂O groups and transformed into amorphous meta-ettringite, which retained its needle-rod morphology. A small amount of ettringite decomposed into gypsum, AH₃, and Ca(OH)₂ under high-humidity conditions, which caused a slight expansion and reduced the compressive strength of the RRM. Fortunately, most ettringite was well protected by the dense RRM matrix, and harsh temperature and humidity conditions could only slowly promote the transformation of ettringite in RRM over a long period. Therefore, short-term rain or hot weather has little effect on the mechanical properties of WSAC-based RRM. This study provides a theoretical basis and data support for the promotion of industrialization of WSAC-based RRM, which is in line with the concept of green and sustainable development.

中文翻译：

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硫铝酸盐水泥基快速修复砂浆在湿热恶劣条件下的实验研究：机械强度、水化产物和钙矾石演化机制


快速修复砂浆（RRM）广泛用于修复基础设施，必须实现高早期强度和长期使用。本研究研究了热/湿恶劣环境条件对使用固体废物基硫铝酸盐水泥（WSAC）制备的 RRM 的影响。进行正交实验以获得优化的基于 WSAC 的 RRM。然后，研究了模拟恶劣条件（20/60 °C 和 10/40/90%RH 湿度的交叉组合）对 RRM 和合成钙矾石的影响。高温低湿抑制了RRM的体积变形，促进了RRM后期抗压强度的增长，但降低了抗弯强度。在这种情况下，钙矾石失去了 Ca-H ₂ O 基团中的一些水分子，转化为无定形偏钙矾石，并保留了针杆形态。少量钙矾石在高湿条件下分解为石膏、AH ₃ 和Ca(OH) ₂ ，引起RRM的轻微膨胀，降低了RRM的抗压强度。幸运的是，大多数钙矾石都受到致密的RRM基质的良好保护，恶劣的温度和湿度条件只能在很长一段时间内缓慢地促进RRM中钙矾石的转变。因此，短期降雨或炎热天气对WSAC基RRM的力学性能影响不大。本研究为推动基于WSAC的RRM产业化提供了理论依据和数据支撑，符合绿色可持续发展理念。