This contribution presents the self-healing performance of cracks in strain-hardening cement-based composites (SHCCs) containing different amounts of magnesia expansive agents (MEAs) with different reactivities. Specimens were preloaded under a four-point bending test to induce cracks and then exposed to water fog curing conditions. The changes in the crack width before and after curing were measured with a digital microscope, and a water absorption test was also performed to measure the sealing ability of the cracks. The test results show that three reactive MgO expansive agents can significantly improve the crack healing efficiency of SHCC under water fog curing conditions. However, the self-healing effect of the 10% dosage was not as good as that of the 5% dosage when the reactivity of the MEA was the same, and the MgO expansive agent with a reactivity value of 110 s shows the most promising effect on crack healing. Moreover, it should be noted that the 10% dosage was too high for the 110 s MgO expansive agent, resulting in poor volume stability.

此贡献显示了应变硬化水泥基复合材料（SHCC）中的裂缝的自我修复性能，该复合材料包含不同量的具有不同反应性的氧化镁膨胀剂（MEA）。样品在四点弯曲试验下预加载以引起裂纹，然后暴露于水雾固化条件下。用数字显微镜测量固化前后裂纹宽度的变化，并且还进行吸水测试以测量裂纹的密封能力。试验结果表明，三种活性MgO膨胀剂在水雾固化条件下可以显着提高SHCC的裂纹愈合效率。但是，当MEA的反应性相同时，10％剂量的自愈效果不如5％剂量的自愈效果，活性值为110 s的MgO膨胀剂对裂纹愈合表现出最有希望的效果。此外，应注意的是，对于110 s MgO膨胀剂，10％的剂量太高，导致体积稳定性差。