酸雨-冻融耦合侵蚀作用下混凝土性能劣化规律

Performance Degradation Law of Concrete under Coupling Effects of Acid Rain and Freeze-Thaw Cycles

为研究冻融循环对混凝土酸雨侵蚀的影响,对比了酸雨(4A)、先酸雨后冻融(3A-F)、先冻融后酸雨(F-3A)三种侵蚀作用下混凝土的酸性化深度变化规律及其质量、抗压强度、动弹性模量等性能的劣化规律,分析了冻融循环影响混凝土酸雨侵蚀的微观机理,量化了冻融循环对酸雨侵蚀下混凝土酸性化深度的影响。结果表明,在3A-F和F-3A侵蚀作用下混凝土的酸性化深度要远大于4A侵蚀,混凝土的质量、抗压强度与动弹性模量等性能的劣化也要比4A制度严重得多,说明冻融循环加速了酸雨对混凝土的侵蚀速率;冻融循环使混凝土内部出现连通裂纹,增大了H+的迁移速率,从而加速酸雨侵蚀;引入冻融循环对混凝土酸性化的影响系数,发现冻融循环次数越多,冻融循环对混凝土酸雨酸性化的影响越大,3A-F和F-3A两种耦合侵蚀制度下冻融循环对于混凝土酸性化深度的影响系数平均值分别为1.50和1.53。

To study the effect of freeze-thaw cycles on concrete acid rain corrosion,the change law of acidification depth of concrete and the degradation law of mass,compressive strength and dynamic elastic modulus of concrete under three kinds of corrosions(4A,3A-F,F-3A)were compared.Then the microscopic mechanism of freeze-thaw cycles affecting acid rain corrosion of concrete was analyzed,and the effect of freeze-thaw cycles on acidification depth of concrete under acid rain corrosion was quantified.The results show that under the erosion of 3A-F and F-3A,the acidification depth of concrete is much larger than that of 4A,and the deterioration of concrete mass,compressive strength and dynamic elastic modulus is much more serious than the 4A erosion.Explain that freeze-thaw cycles accelerates the erosion rate of concrete by acid rain,freeze-thaw cycles causes interconnected cracks inside the concrete,increasing the migration rate of hydrogen ions,thereby accelerating the corrosion rate of acid rain.By introducing the influence coefficientλ,it is found that the more freeze-thaw cycles,the greater the influence of freeze-thaw cycles on the acid rain corrosion of concrete and the average value ofλunder the 3A-F and F-3A corrosions is 1.50 and 1.53.