冻融循环条件下粉煤灰对混凝土渗透性的影响

Influence of fly ash on concrete permeability under freezing-thawing cycle condition

为了分析冻融循环条件下粉煤灰对混凝土渗透性的影响,试验采用粉煤灰等量替代水泥掺量的10%、20%和30%,水胶比为0.42和0.35,对不同掺量粉煤灰混凝土进行了冻融循环试验和交流电渗透性试验,并与普通混凝土进行了对比.试验结果表明,当水胶比为0.42时,随着粉煤灰含量的增加,混凝土的抗渗透性能提高,而抗冻性能降低;当水胶比为0.35时,随着粉煤灰含量的增加,混凝土的抗渗透性能提高,而抗冻性能先提高后降低,存在一个最佳值.冻融循环后,混凝土的渗透性明显增大,可以用冻融循环后混凝土渗阻损失率来表征混凝土的抗冻破坏程度.

In order to analyze the influnce of fly ash on the concret permeability under freezing-thawing cycle condition, the fly ash was used to replace the cement equivalently with mixing contents of 10%, 20% and 30%, and the water-binder ratios of 0. 42 and 0. 35 were adopted in the experiment. The freezeing-thawing cycle and alternating current permeability tests were carded out for the concrete with different mixing contents of fly ash, and the results were compared with those of ordinary concrete. The experimental results show that when the water-binder ratio is 0. 42, the permeation resistance of the concrete gets enhanced while the freezing resistance of the concrete decreases with increasing the content of fly ash. When the water-binder ratio is 0. 35, the permeation resistance of the concrete is improved while the freezing resistance of the concrete firstly increases and then reduces with increasing the content of fly ash. After freezing-thawing cycle, the concrete permeability increases obviously. And the freezing damage resistance of the concrete can be characterized by the permeation resistance loss of the concrete after freezing-thawing cycle.