干燥环境下混凝土内部损伤的量化

Quantification of Damage in Concrete Under Drying Condition

采用数字图像相关法(DIC)测试了C50混凝土在73%,55%和40%相对湿度环境下干燥1d至60d的非均匀变形。结合混凝土材料细观损伤模型,计算了混凝土内部的等效拉应变(e),用于获得混凝土内部损伤的分布特征,发现包裹粗骨料的砂浆拉应变较大,容易造成损伤,产生微裂缝。根据e的大小和分布计算了混凝土内部损伤因子(D_(e)),用于量化混凝土内部损伤,发现混凝土在55%和40%相对湿度环境下干燥60 d的D_(e)分别增加至101μm/m和135μm/m,相对较高,说明55%及以下相对湿度环境容易对混凝土内部造成损伤,产生微裂缝。

The non-uniform deformations of C50 concrete under drying at different relative humidities(i.e.,73%,55%and 40%)from 1 d to 60 d were determined by a digital image correlation(DIC)technique.The equivalent tensile strains ein concrete were calculated based on the meso-scale damage model of concrete,which were used to identify the damage distribution in concrete.The results show that the mortar phase surrounding the coarse aggregates has great tensile strains,thus readily occurring damage and micro-cracks.The damage index(D_(e))calculated from the value and distribution of ewas used to quantify the drying-induced damage in concrete.The D_(e)of the concretes under drying at 55%and 40%relative humidities increases to 101μm/m and 135μm/m,respectively,indicating that the drying conditions with≤55%relative humidity could cause damage and micro-cracks.