Yuan Lianwang, Chen Shuaishuai, Wang Shoude, Huang Yongbo, Yang Qingkuan, Liu Shuai, Wang Jinbang, Du Peng, Cheng Xin, Zhou Zonghui
Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, Jinan 250022, Shandong, China.
School of Materials Science and Engineering, University of Jinan, Jinan 250022, Shandong, China.
Materials (Basel). 2019 Sep 2;12(17):2818. doi: 10.3390/ma12172818.
Overgrinding of Portland cement brings excessive shrinkage and poor self-healing ability to concrete. In this paper, through the ultrasonic test and optical micrograph observation, the self-healing properties of concrete prepared by cement with different particle size distributions were studied. Besides, the effect of carbonation and continued hydration on self-healing of concrete was analyzed. Results show that, for the Portland cement containing more particles with the size 30~60 μm, the concrete could achieve a better self-healing ability of concrete at 28 days. For the two methods to characterize the self-healing properties of concrete, the ultrasonic test is more accurate in characterizing the self-healing of internal crack than optical micrograph observation. The autogenous self-healing of concrete is jointly affected by the continued hydration and carbonation. At 7 days and 30 days, the autogenous self-healing of concrete is mainly controlled by the continued hydration and carbonation, respectively. The cement particle size could affect the continued hydration by affecting un-hydrated cement content and the carbonation by affecting the Ca(OH) content. Therefore, a proper distribution of cement particle size, which brings a suitable amount of Ca(OH) and un-hydrated cement, could improve the self-healing ability of concrete.
硅酸盐水泥过度粉磨会给混凝土带来过大的收缩和较差的自愈能力。本文通过超声测试和光学显微镜观察，研究了由不同粒径分布的水泥制备的混凝土的自愈性能。此外，还分析了碳化和持续水化对混凝土自愈的影响。结果表明，对于含有较多30~60μm粒径颗粒的硅酸盐水泥，混凝土在28天时可实现较好的自愈能力。对于表征混凝土自愈性能的两种方法，超声测试在表征内部裂缝自愈方面比光学显微镜观察更准确。混凝土的自愈合受到持续水化和碳化的共同影响。在7天和30天时，混凝土的自愈合分别主要受持续水化和碳化控制。水泥粒径可通过影响未水化水泥含量来影响持续水化，并通过影响Ca(OH)含量来影响碳化。因此，适当的水泥粒径分布，带来适量的Ca(OH)和未水化水泥，可提高混凝土的自愈能力。
