硫酸盐环境下混凝土裂缝矿物自愈合性能研究

研究了30%粉煤灰混凝土在4种预加载损伤程度下,于清水和5.0%硫酸盐环境中的裂缝矿物自愈合性能,并对其自愈合产物进行了微观测试。采用相对动弹模量和抗压强度的相对变化来表征裂缝自愈合程度,探讨了5.0%硫酸盐溶液、30%粉煤灰、4种预加载程度和4个自愈合养护龄期对混凝土裂缝矿物自愈合的影响。试验结果表明,5.0%硫酸盐在设计的自愈合养护龄期内可以促进预加载损伤混凝土相对动弹模量和抗压强度的恢复;无论清水还是硫酸盐养护溶液,只有预加载程度较大时,30%粉煤灰对混凝土相对动弹模量和相对抗压强度的恢复才有显著的促进作用;5.0%硫酸盐溶液养护环境中,混凝土自愈合后的相对动弹模量和相对抗压强度的恢复能力都随着预加载程度的增大而逐渐降低,在28d自愈合养护龄期结束后,其混凝土相对动弹模量趋于稳定;微观测试分析结果表明,5.0%硫酸盐环境中的混凝土裂缝矿物自愈合产物成分主要是碳酸钙和少量钙矾石。

Research on Self-healing of Concrete Crack in Sulfate Environment

The damage test of concrete mixed with 30% fly ash was carried out under four grades of preloa-ding. Then the perfor-mance of mineral self-healing of the concrete in sulfate environment was researched and the self-healing products were analyzed by micro-test. The degree of self-healing was represented with relative dynamic modulus and compressive strength. The effect of 5% sodium sulfate solution, 30% fly ash, four kinds of preloading degree and self-healing curing age on the performance of mineral self-healing of concrete was discussed. The results showed that 5% sulfate could accelerate the recovery of relative dynamic modulus and compressive strength of concrete during the designed curing age. Both in water and sulfate solution, only when the preload damage degree was relatively high, could 30% fly ash improve the recovery range of relative dynamic modulus and relative compressive strength. With the increase of preload damage degree, in 5% sulfate solution environment, the recovery capability of relative dynamic modulus and relative compressive strength would decrease after the mineral self-healing. After self-healing curing age of 28 days, the relative dynamic modulus would stabilize. The self-healing products of concrete in 5% sulfate environment was mainly calcium carbonate and some ettringite.