多盐耦合腐蚀环境下混凝土性能劣化规律

Performance Degradation Law of Concretes in the Multi-salt Coupling Corrosion Environment

为了探究实际工业化学腐蚀环境对混凝土物理力学性能的影响规律,在氯盐、硫酸盐及镁盐环境下,进行了半浸泡与全浸泡的现场暴露试验,并在室内进行了相应的腐蚀模拟试验,研究不同水胶比、腐蚀质量分数及干湿周期对混凝土质量、抗压强度、动弹性模量及损伤层厚度的影响.结果表明:半浸泡混凝土与室内模拟试验混凝土相对质量、相对动弹性模量、抗压强度均随时间先上升后下降,损伤层厚度随时间持续上升.全浸泡方式对混凝土的劣化损伤远低于半浸泡方式,全浸泡方式延长了半浸泡方式各转折点所需时间.水胶比增大、质量分数提升及干湿周期缩短均促进Friedel盐、钙矾石及氢氧化镁等生成,加速混凝土劣化.腐蚀性离子渗入混凝土的先后顺序为:氯离子、硫酸根离子、镁离子.

In order to explore the effect of the actual industrial chemical corrosion environment on the physical and mechanical properties of concretes,the site exposure tests of half immersion and full immersion were adopted in the chlorine,sulfate and magnesium salt environments,and therewith the corresponding corrosion simulation tests were carried out in the laboratory.The effects of different water-binder ratios,different corrosion concentrations and different dry-wet periods on concretes’quality,compressive strength,dynamic elastic modulus and thickness of the damaged layer were studied.The results showed that the relative mass,relative dynamic elastic modulus and compressive strength of half-immersed concretes and laboratory simulated concretes all increase first and then decrease with time and the thickness of the damaged layer continues to increase with time.The degradation damage of full-immersed concretes is much lower than those by half immersion,and the time required for each turning point by full immersion is prolonged.With the increase of the water-binder ratio,concentration,and shortening of the dry-wet period,it is easier to produce Friedel’s salt,ettringite,and magnesium hydroxide in concretes,and accelerate the deterioration of concretes.The order of corrosive ions infiltrating into concretes is:chloride ions,sulfate ions and magnesium ions.