冻融与氯盐耦合作用下超细粉煤灰混凝土抗碳化性能研究

Study on Carburization Resistance of Superfine Fly Ash Concrete Coupled With Freeze-thaw and Chlorine Salt

为了研究氯盐与冻融耦合作用下超细粉煤灰混凝土的碳化性能,对不同掺量超细粉煤灰混凝土进行了抗压强度试验、基准碳化试验、冻融-碳化试验和盐冻-碳化耦合试验。结果表明:在标准养护条件下,混凝土试件中掺入少量超细粉煤灰会降低试件本身的抗压强度,但降低幅度不大,而掺入大量的超细粉煤灰其抗压强度下降比较明显。干燥养护下,掺入超细粉煤灰对试件的抗压强度影响较小,其抗压强度随掺量没有出现骤降。掺入适量的超细粉煤灰能提高混凝土的抗碳化性能,随着超细粉煤灰掺量增加,抗碳化性降低,当超细粉煤灰掺量超过25%时对混凝土抗碳化性能影响不大。当超细粉煤灰参量一定时,盐冻-碳化循环试验对混凝土碳化深度最不利,且超细粉煤灰混凝土的碳化深度与循环次数呈现二次函数关系。

In order to study the carbonation performance of ultrafine fly ash concrete under the coupling action of chlorine salt and freeze-thaw,the compressive strength test,benchmark carbonation test,freeze-thaw-carbonization test and salt freeze-carbonization coupling test of ultrafine fly ash concrete with different fly ash content were carried out.The results showed that under the standard curing condition,a small amount of ultrafine fly ash in the concrete specimen reduced the compressive strength of the specimen itself,but the decrease was not large,but the compressive strength of the concrete specimen with a large amount of ultrafine fly ash was obviously decreased.Under dry curing,the influence of ultrafine fly ash on the compressive strength of the specimen was small,and the compressive strength did not drop sharply with the content.Adding proper amount of ultrafine fly ash could improve the carbonation resistance of concrete.With the increase of the content of ultrafine fly ash,the carbonation resistance decreased,and when the content of ultrafine fly ash exceeded 25%,the carbonation resistance of concrete was not affected.When the parameters of ultrafine fly ash were certain values,the salt freeze-carbonization cycle test was the most unfavorable to the carbonation depth of concrete,and the carbonation depth of ultrafine fly ash concrete showed a quadratic function relationship with the cycle times.