涂层混凝土氯离子扩散的修正模型与数值模拟

Modified model and numerical simulation of chloride diffusion in coated concrete

氯离子侵蚀是影响混凝土耐久性能的主要原因之一,通过在混凝土表面刷涂层的方式可以有效阻止氯离子在混凝土中的扩散。通过MATLAB与COMSOL Multiphysics软件联合仿真,建立三维随机骨料混凝土模型,并在COMSOL Multiphysics中建立涂层模型模拟氯离子扩散的影响。而涂层与混凝土材料完全不同,其扩散系数的推导也不相同。通过建立改进的涂层模型,模拟涂层对氯离子侵蚀混凝土的影响。对比无涂层混凝土,试验周期90~150 d的聚氨酯涂层、聚脲涂层混凝土在0~15 mm厚度范围氯离子浓度下降分别可达97%、96%;而水泥基涂层混凝土氯离子浓度下降75%,证明涂层对阻止氯离子侵蚀混凝土效果显著。对比无涂层及不同涂层模型结果,其模拟值与试验值误差在10%左右,相关系数在0.98以上,扩散模型准确性较高,对后续研究具有一定指导意义。

Chloride ion erosion is one of the main reasons that affect the performance of concrete,and the diffusion of chloride ions in the concrete can be effectively prevented by brushing the coating on the surface of the concrete.Through the joint simulation of MATLAB and COMSOL Multiphysics software,a three-dimensional random aggregate concrete aggregate model is established,and a coating model is established in COMSOL Multiphysics to simulate the influence of chloride ion diffusion.The coating is completely different from the concrete material,and the derivation of its diffusion coefficient is also different.By establishing an improved coating model,the impact of the coating on the corrosion of concrete by chloride ions is simulated.Compared with uncoated concrete,the chloride ion concentration of polyurethane-coated and polyurea-coated concrete with a test period of 90~150 d days decreases by 97% and 96% in the thickness range of0~15 mm respectively.While the chloride ion concentration of cement-based coated concrete decreases by 75%.It proves that the coating has a significant effect on preventing the corrosion of concrete by chloride ions.Comparing the results of uncoated and different coating models,the error between the simulated value and the experimental value is about 10%,the correlation coefficient is above 0.98,and the accuracy of the diffusion model is high,which has certain guiding significance for subsequent research.