盐雾干湿循环作用下基于Wiener过程的钢筋混凝土劣化行为研究

Degradation behavior of reinforced concrete based on Wiener process under wet and dry cycle of salt spray

针对西部盐渍土地区钢筋混凝土结构病害严重问题,通过盐雾与烘干相结合的方法模拟该地区大气环境,对钢筋混凝土进行室内加速腐蚀劣化试验。设置未掺矿物掺合料(P组)、单掺30%粉煤灰(PF组)、单掺30%矿粉(PS组)及15%粉煤灰与15%矿粉复掺(PFS组)4个配合比,采用混凝土相对动弹性模量(Er)和钢筋腐蚀电流密度(icorr)作为性能劣化指标,分别表征钢筋混凝土保护层及内部钢筋在盐雾干湿循环环境下的劣化规律及矿物掺合料掺量、种类对其劣化行为的影响作用。基于钢筋混凝土性能劣化规律研究结果,结合Wiener随机过程对其性能劣化全过程进行描述,并进行可靠性分析。研究结果表明:在盐雾干湿循环作用下,钢筋混凝土内部钢筋及外部混凝土保护层的耐腐蚀性呈现出先强化后劣化的变化趋势,活性矿物掺合料的掺入可以有效抑制其腐蚀劣化速度,其大小关系为:PS>PFS>PF>P;icorr增量与Er增量随时间的变化规律均服从正态分布,即Wiener随机过程可有效描述盐雾干湿循环作用下钢筋混凝土性能劣化全过程;P组可靠度在200 d左右接近于0,而PS组可靠度在400 d左右接近于0,与试验测试结果相吻合。研究结果可为西部盐渍土地区钢筋混凝土结构耐久性设计及低碳长效运维提供理论支撑。

In view of the serious diseases of reinforced concrete structures in the western saline soil area,this article simulated the atmospheric environment in this area by combining salt spray and drying,and conducted out indoor accelerated corrosion deterioration experiment of reinforced concrete.Four mixing proportions of no mineral admixture(Group P),single 30%fly ash(Group PF),single 30%slag(Group PS)and 15%fly ash and 15%slag(Group PFS)were set.The relative dynamic elastic modulus of concrete(Er)and the corrosion current density of reinforcement(icorr)were used as performance deterioration indicators to indicate the deterioration law of reinforced concrete protective layer and internal reinforcement under the salt spray dry and wet cycle environment and the influence of the content and type of mineral admixture on deterioration behavior.Based on the research results of the performance degradation law of reinforced concrete,combined with Wiener stochastic process,the whole process of performance degradation was described,and the reliability was analyzed.The results show that under the action of salt spray dry and wet cycle,the corrosion resistance of reinforced concrete protective layer and internal reinforcement show a trend of strengthening first and then deteriorating.The mixing of mineral admixture can inhibit the corrosion deterioration rate effectively,and the relationship is PS>PFS>PF>P.The change of icorr increment and Er increment obey the normal distribution,the Wiener stochastic process can describe the whole process of performance deterioration of reinforced concrete under the action of salt spray dry and wet cycle.The reliability of group P is close to 0 at about 200 d,while that of group PS is close to 0 at about 400 d,which is consistent with the test results.The research results can provide theoretical support for the durability design and low-carbon long-term operation and maintenance of reinforced concrete structures in western saline soil area.