混凝土在碳化和干湿循环作用下的抗硫酸盐腐蚀性能

采用自然浸泡和干湿循环的试验方法, 研究了碳化后的粉煤灰混凝土(FAC)、 大掺量矿物掺合料混凝土(HVMAC)及高性能混杂纤维增强膨胀混凝土(HPHFREC)在5%硫酸镁溶液中的损伤过程。结果表明: 碳化一定程度上密实了混凝土表层, 但改变了混凝土表层的化学组成, 降低混凝土的抗硫酸镁腐蚀性能。干湿循环加速硫酸镁的扩散作用, 扩展混凝土内部原有的微裂缝。在碳化+硫酸镁双重破坏因素作用下, HVMAC具有优异的抗腐蚀性能, 适合应用于硫酸镁腐蚀的严酷环境; 在碳化+干湿循环+硫酸镁多重破坏因素作用下, HPHFREC2的三元纤维混杂起到明显的增强增韧效果, 抗腐蚀性能较好。

Resistance of concrete to magnesium sulfate attack under combined action of carbonation and dry-wet cycles

Deterioration of carbonized fly ash concrete(FAC),concrete with high volume mineral admixture(HVMAC),and high performance hybrid fibers reinforced expansive concrete(HPHFREC) exposed to 5% magnesium sulfate solution was investigated.Two corrosion regimes were employed: natural immersion and dry-wet cycle.Experiment results show that carbonation changes the chemical component of concrete surface and reduces the resistance of concrete to magnesium sulfate attack,though carbonation compacts the concrete surface to some extent.The dry-wet cycles accelerate the diffusion of magnesium sulfate and develop the micro-crack of concrete.Under combined action of carbonation and magnesium sulfate,HVMAC gets the best resistance to sulfate attack and is applicable to the atrocious environment,but FAC which has been broken up is not applicable to the concrete engineering in such environment.Under combined action of carbonation,dry-wet cycle,and magnesium sulfate,HPHFREC2,of which the reinforced effect of the fibers is obviously well,shows the better resistance of concrete to sulfate attack.