粉煤灰与应力水平对混凝土渗透性的影响

通过氯离子加速渗透试验,测定阳极溶液中氯离子浓度,分析了粉煤灰掺量、应力水平和渗透时间的关系.结果表明:养护至28 d的未加载混凝土中,粉煤灰掺量越大,混凝土氯离子渗透性越高;较长养护龄期的粉煤灰混凝土的氯离子渗透性均比相应养护至28 d粉煤灰混凝土的氯离子渗透性有所降低;施加5次0.4fcy(轴心抗压强度)重复应力后,氯离子渗透的非稳定阶段显著缩短,粉煤灰混凝土的氯离子渗透性增大;施加5次0.8fcy重复应力后,粉煤灰混凝土的氯离子渗透性进一步增大.粉煤灰混凝土强度等级设计的龄期采用相对较长龄期为宜.

Influence of fly ash and stress level on permeability of concrete

In order to analyze the relationship between fly ash replacement,stress level and permeation time,the chloride ion concentration in anode chamber was measured during the accelerated chloride penetration test.The results showed that the fly ash concrete exhibits high rate of chloride ion penetration when the specimens are cured in water for 28 days;a long curing period can decrease the chloride ion penetration of fly ash concrete.The application of 5 times of 0.4 fcy(axial compressive strength) increases the chloride penetration of concrete obviously.The chloride ion penetration of concrete has a further increment when the stress level rises from 0.4 fcy to 0.8 fcy.The long curing period is better for the strength grade design of fly ash concrete.