养护湿度对补偿收缩混凝土碳化速率的影响

Effect of curing humility on carbonation rate of shrinkage-compensating concrete

在混凝土中掺入一定量膨胀剂可以减小混凝土收缩趋势、补偿收缩,而养护湿度对膨胀剂的补偿收缩效果具有决定性的影响。研究了养护湿度对补偿收缩混凝土抗碳化能力的影响规律,并运用显微硬度分析和TG-DSC耦合分析等方法对其影响机理进行了探讨,研究四种不同的养护制度(自然养护RH=60%、标准养护RH=90%、浸水养护3 d后自然养护和浸水养护7 d后自然养护)对混凝土的强度和加速碳化深度的影响。结果表明:养护条件对补偿收缩混凝土的碳化速率影响较为明显;自然养护条件下补偿收缩混凝土的碳化速率较快,早期浸水养护3 d对混凝土的抗碳化能力无显著改善作用;浸水养护7 d后自然养护可较大程度提高混凝土抗碳化能力,碳化速率与全龄期标准养护条件下补偿收缩混凝土的碳化速率接近。

Expansive admixture can compensate the stuinkage of concrete, while the relative humidity of curing environment has significant effect on the shrinkage-compensating performance.This paper discusses the influence of environmental humidity on carbonation rate of shrinkage-compensating concrete.Micro-hardness analysis and TG-DSC analysis were used to study the mechanism.Four different curing conditions were set up, namely the natural environment （RH=60%）, standard environment （RH=90%）, early age water curing environment for 3 days and 7 days.The results show that natural condition lead to a relatively worse carbonation degree, curing in water for 3 days is harmful to the carbonation resistance, while curing in water for 7 days lead to an equivalent carbonation degree with standard condition, which show the most improvement to carbonation resistance ability.