碳化混凝土硫酸钠盐结晶破坏

Sodium Sulfate Salt Crystallization Distress on Carbonated Concrete

研究了不同水灰比、不同粉煤灰、矿渣掺量混凝土试件快速碳化10 d和20 d后,半浸泡在10%硫酸钠溶液中,在恒温恒湿环境下[(20±1)℃,相对湿度RH(60±5)%],混凝土试件水分蒸发区的破坏特征及其质量损失率随侵蚀时间的变化规律。结果表明:混凝土碳化深度越大,混凝土破坏越严重;用粉煤灰和矿渣取代水泥加剧混凝土碳化,导致混凝土破坏更严重;碳化混凝土中发生的硫酸钠结晶是混凝土发生破坏的原因。

Concrete specimens with different water-cement ratios and different dosages of fly ash and slag were carbonated for 10 d and 20 d and then partially exposed into 10% Na2SO4 solution under the condition of （20±1）℃, （60±5）% relative humidity. The mass loss rate of specimen was measured and the visual observation of damaged concrete was compared. The results show that the concrete carbonation accelerates its failure. The evaporation zone of concrete specimens with fly ash and slag was damaged more severely rather than the ordinary concrete due to the greater carbonation depth. Based on the results by X-ray diffraction, the sodium sulfate crystallization in the carbonated concrete causes the concrete failure.