冻融-干湿耦合作用下粉煤灰混凝土碳化性能试验研究

Experimental Study on Carbonation Performance of Fly Ash Concrete under Freeze-thaw Dry Wet Coupling

为了考察复杂多变环境下粉煤灰混凝土的碳化性能,对粉煤灰掺量分别为0、10%、20%、30%的粉煤灰混凝土进行了基准碳化、冻融-碳化、干湿-碳化和冻融-干湿-碳化耦合损伤试验。试验结果表明:粉煤灰混凝土的动弹性模量随着循环次数增大而逐渐减小;动弹性模量在粉煤灰掺量20%时达到极大值;干湿循环对动弹性模量的影响大于冻融循环。碳化深度与粉煤灰掺量、碳化龄期成正比例增长;冻融循环对碳化深度的影响大于干湿循环。建立了粉煤灰混凝土碳化深度预测模型,该模型考虑了粉煤灰掺量、碳化时间及环境因素,拟合系数大于0. 95,该模型能够很好地模拟多因素耦合作用下的碳化深度,可为工程设计提供参考。

In order to investigate the carbonation performance of fly ash concrete under complex and changeable environment,the damage tests of reference carbonation,freeze-thaw-carbonation,dry wet carbonation and freeze-thaw dry wet carbonation coupling were carried out for the fly ash concrete with 0,10%,20%and 30%fly ash content respectively.The test results show that the dynamic elastic modulus of fly ash concrete decreases with the increase of cycle times;the dynamic elastic modulus reaches the maximum value when the content of fly ash is 20%;the effect of dry wet cycle on dynamic elastic modulus is greater than that of freeze-thaw cycle.The carbonation depth increases in proportion to the content of fly ash and carbonation age,and the influence of freeze-thaw cycle on carbonation depth is greater than that of dry wet cycle.The prediction model of carbonation depth of fly ash concrete was established.The model takes into account the amount of fly ash,carbonation time and environmental factors,and the fitting coefficient is greater than 0.95.The model can simulate the carbonation depth under the coupling effect of many factors,which can provide reference for engineering design.