冻融循环作用下粉煤灰混凝土碳化规律研究

研究不同粉煤灰掺量(0%、20%、40%、60%)下高性能混凝土经快速冻融试验后的碳化现象;定义冻融循环作用下混凝土碳化判定新准则;采用图像处理技术定量分析不同粉煤灰掺量、不同冻融破坏程度对碳化的影响规律。试验表明:经冻融破坏后混凝土碳化现象和传统碳化现象有所不同,碳化深度测试法已不能表征其新特征,而碳化面积法能较好阐述混凝土冻融破坏后的碳化规律;冻融破坏后的碳化面积与粉煤灰掺量呈二次抛物线关系;碳化面积与冻融破坏程度服呈线性相关;混凝土冻融循环作用下的碳化研究对冻融地区混凝土结构耐久性和寿命预测具有现实意义。

STUDY ON CARBONATION OF FLY ASH CONCRETE WITH FREEZE-THAW CYCLE

Carbonation of high performance concrete under freeze-thaw cycles was studied with different fly ash proportion(0%,20%,40%,60%);the new rules to estimate carbonation of concrete under freeze-thaw cycles were defined.The influence of different fly ash proportion and different freeze-thaw damage on carbonation was analyzed quantitatively by image processing techniques.Experiment results showed that the carbonation of concrete after freeze-thaw cycles was different from the traditional carbonation of concrete.The traditional testing method using carbonation depth could not express new feature of carbonation after freeze-thaw damage.And the new testing method using carbonation area could better express the carbonation law.The carbonation area and fly ash proportion subject quadratic equation δ=45.12-1.35FA+0.035FA2;and the carbonation area and freeze-thaw damage degree linear equation δ=35+0.306x.The research on the carbonation of concrete under freeze-thaw cycles possesses the real meaning to the structure durability and life prediction of concrete in the freeze-thaw area.