HCSA补偿收缩混凝土收缩裂缝自愈合性研究

Investigation on Shrinkage Crack Self-healing of HCSA Shrinkage Compensating Concrete

对掺加高性能混凝土膨胀剂HCSA的水泥净浆水化产物进行X射线衍射、扫描电镜与差热分析,同时研究了由其制备的补偿收缩混凝土裂缝自愈性能。结果表明,与空白样相比,掺HCSA膨胀剂水泥净浆水化产物中具有更多的Ca(OH)_2。即使早期未进行水养护,遇水后掺HCSA膨胀剂的补偿混凝土也会产生较大的膨胀应力,从而具有比普通混凝土更强的裂缝自愈合能力。HCSA混凝土裂缝愈合的主要驱动力是膨胀应力,其次是结晶沉淀修复。掺HCSA膨胀剂的补偿收缩混凝土裂缝处析出物质主要是碳酸钙。此外,工程实践证明,地下工程采用掺加HCSA膨胀剂的补偿收缩混凝土具有良好的自愈合性。

The hydration products of cement paste with HCSA high performance agent were analyzed by X-ray diffraction, scanning electron microscope and differential thermal analysis. The self-healing of shrinkage compensating concrete(SCC) prepared by HCSA was also studied. The results show that there are more Ca(OH)_2 in the hydration products of cement paste with HCSA compared with reference sample. Shrinkage compensating concrete prepared by HCSA can produce major expansion stress when wet, even if without any water curing, thus generate a greater crack self-healing ability than ordinary concrete. The key drivers of HCSA shrinkage compensating concrete crack self-healing are expansion stress, followed by crystallization and settlement repair. The leaching materials from cracks of HCSA shrinkage compensating concrete are mainly calcium carbonate. In addition, it is proved by engineering practices that SCC with HCSA expansive agent has better self-healing ability.