梯度结构混凝土的传输性能与寿命预测

摘要

采用无细观界面过渡区水泥基复合材料制备出梯度结构混凝土的高抗渗保护层,且高抗渗保护层的最佳厚度为10～20mm,可以有效降低GSC的传输性能,大幅降低GSC的Cl~-渗透性能,延长其使用寿命.与单层结构的高性能混凝土相比,不同厚度比例组合的GSC的Cl~-扩散系数DNEL均有不同幅度的下降,且随着MIF在GSC中厚度比例的增加,GSC的DNEL是降低的.当MIF在GSC中的厚度超过10mm时,GSC的DNEL会突降;当MIF在GSC中的厚度增加到25mm时,与HPC的DNEL相比,GSC的DNEL几乎下降了2个数量级,其Cl~-渗透性能"极低".根据考虑多种因素作用下的Cl-散理论模型,当GSC的Cl~-扩散系数为(2.0～3.0)×10~(-13)m~2/s时,其理论预测使用寿命在1700年以上,可以说是一种超高耐久混凝土--千年混凝土.%When Meso-interfacial transition zone-free cement-based materials is used for preparing high impermeability cover of gradient structural concrete and the optimal thickness of high impermeability cover is 10~20mm, the ability of chloride ion penetration of GSC is obviously decreased, but its service life of prediction is clearly increased. In comparison with the monolayer structural concrete named HPC, the chloride diffusion coefficient of the different thickness ration GSC is apparently decreased. To increase the thickness ration of MIF in GSC is decrease the chloride diffusion coefficient of GSC. When the thickness of MIF in GSC is more than 10mm, the chloride diffusion coefficient of GSC is markedly decreased. When the thickness of MIF in GSC approached to 25mm, the chloride diffusion coefficient of GSC is decreased by two orders of magnitude compared with that of HPC, and the ability of chloride ion penetration of GSC is extremely low. According to the multi-component diffusion equation, a service life of 1700 years for GSC is predicted when the chloride diffusion coefficient of GSC is 2. 0× 10~(-13)m~2/s to 3.0×10~(-13)m~2/s. Namely, the GSC is a kind of superhigh durability concretes.