混凝土氧气扩散性能的预测模型

Predicting Oxygen Diffusion in Concrete

钢筋保护层处混凝土的氧气扩散速率是影响混凝土内钢筋锈蚀速率的重要因素.为确定保护层处混凝土氧气扩散速率,从多孔材料气体扩散的基本原理出发,根据Fick扩散定律并结合影响混凝土中氧气扩散速率的具体因素,建立了混凝土氧气扩散性能的预测模型,并通过试验对模型进行了验证.试验表明预测模型的计算结果和试验测试结果基本一致;混凝土氧气扩散系数随混凝土孔隙率、环境温度和相对湿度的增高而增大,在温湿度条件不变的情况下,混凝土孔隙率由0.09增大到0.18时,混凝土氧气扩散系数约增大4倍.

Oxygen diffusion into the concrete covering is an important factor affecting the corrosion rate of concrete reinforcement.The oxygen diffusion rate was estimated from Fick＇s law of diffusion and the known performance of porous materials.Experimentation was done to check the model.The results show that the calculations give estimates similar to the observed test results and that the oxygen diffusion coefficient of concrete becomes higher as the porosity of the concrete,temperature and humidity increase.For unchanging temperature and humidity conditions the oxygen diffusion coefficient is estimated to increase about four times when the concrete porosity increases from 0.09 to 0.18.