酸性腐蚀下混凝土试件物理力学性能演化规律

The evolution of physical and mechanical properties of concrete specimens under acid corrosion

为分析硫酸腐蚀对深埋排水调蓄隧道(简称“深隧”)衬砌结构力学性能的影响,通过对钢纤维体积率为0%和1%的混凝土标准试件开展初始pH=1的硫酸腐蚀试验,考虑单面浸泡和全周浸泡两种腐蚀工况,对不同腐蚀时间下混凝土试件表面pH值、质量变化率、单轴抗压强度和反应产物进行系统分析。结果表明:混凝土强度随腐蚀时间呈非线性变化;由于钢纤维的掺加抵抗了硫酸溶液的扩散,使得腐蚀前期反应进程减慢、反应产物减少,酸腐蚀浸泡下钢纤维混凝土强度和质量的增加速率不及同等条件下的素混凝土;全周浸泡下混凝土试件的质量增加速率大于同等条件下单面浸泡的试件,结合XRD分析可知,反应后生成了石膏,而全周腐蚀与硫酸的接触面更大,因而反应产物生成更快,初期强度和质量也增加更快。

In order to analyze the influence of sulfuric acid corrosion on the mechanical properties of the deep water storage and sewage tunnel lining structure(short for“deep tunnel”),this research carried out sulfuric acid corrosion tests with initial pH=1 on the standard concrete specimens with a steel fiber volume ratio of 0%and 1%,and considered two corrosion conditions of single-face and all-face immersion.The surface pH value,mass change rate,uniaxial compressive strength and reaction products of concrete specimens under different corrosion time were systematically analyzed.The results showed that the concrete′s strength changed nonlinearly with corrosion time.Because the addition of steel fiber resists the diffusion of sulfuric acid,the reaction process in the early stage of corrosion was slowed down and the reaction products were reduced.Therefore,the strength and quality of steel fiber concrete under acid corrosion immersion did not change as rapidly as that of plain concrete under the same condition.The mass increase rate of concrete specimens under all-face immersion was greater than that of specimens soaked on one side under the same conditions.Combined with XRD analysis,it could be seen that gypsum was formed after reaction.The contact area between all-face corrosion and sulfuric acid was larger,so the reaction products were generated faster,and the corresponding strength and mass increase were also faster.