单轴压荷载下掺合料对混凝土渗透性的影响

Influence of Mineral Admixtures on Permeability of Concrete under Sustained Uniaxial Compressive Load

利用自行设计的加载装置研究了单掺矿物掺合料(矿渣、粉煤灰、硅灰)的素混凝土在单轴持续压荷载作用下的氯离子渗透性,并提出了相应的数学模型.结果表明:单轴持续压荷载显著影响混凝土的渗透性,氯离子扩散系数与应力比近似满足抛物线的数学模型.掺入矿物掺合料可以改善混凝土抗氯离子渗透性,改善效果硅灰最佳,矿渣次之,粉煤灰最差.掺入矿物掺合料的混凝土,其氯离子扩散系数随矿物掺合料掺量的增大而近似呈负指数函数减小.对于掺矿物掺合料的混凝土,其渗透性与抗压强度不具相关性.

By using a self-designed loading device, the chloride ion permeability of plain concrete with dif- ferent mineral admixtures（slag, fly ash, silica fume） under sustained uniaxial compressive load were stud- ied, and the corresponding mathematical models were proposed as well. The results show that the sus- tained uniaxial compressive load has a significant impact on the permeability of concrete and the relation- ship between chloride ion diffusion coefficient and stress rate approximately agrees with the mathematic model of parabola. Separate addition of different mineral admixtures into concrete can improve its resist- ance to chloride ion permeation, and the effectivness of silica fume is the best, followed by slag, fly ash is the worst. The chloride ion diffusion coefficient decreases with increasing mineral admixture content by the negative exponential function. For concrete mixed with mineral admixtures, the permeability and the com- pressive strength does not have a good correlation.