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对不同组混凝土试件在多种情况下进行了耐久性试验,结合试验数据选取试件的相对质量评价参数和相对动弹性模量评价参数作为评价指标,探究了混凝土的表观损伤特征、相对质量及相对动弹性模量的变化规律,同时对不同组混凝土试件取样进行电镜扫描、EDS能谱分析及化学成分测定,以揭示混凝土的微观结构及损伤劣化机理.研究结果表明,相对质量评价参数和相对动弹性模量评价参数能直观地表征混凝土的劣化过程;西宁盐渍土地区混凝土的破坏形式为盐分的化学腐蚀和物理结晶,化学腐蚀对混凝土劣化具有加速效应,二者相互作用使混凝土发生了严重的破坏,主要的腐蚀产物有石膏、碳酸钙及硅灰石膏,特别地在西宁盐渍土地区混凝土发现了更为危害的硅灰石膏型硫酸盐侵蚀;西宁地区现场暴露混凝土已经受到盐渍土的侵蚀,其评价参数波动性变化,经过1 230d的试验还处于劣化初期.
Different groups of concrete specimens were tested for durability under various conditions. Based on the experimental data, the relative quality evaluation parameters and the relative dynamic elastic modulus parameters were selected as the evaluation indexes to explore the apparent damage characteristics of concrete. The relative Mass and relative dynamic elastic modulus of the concrete specimens were also studied.At the same time, the samples of different groups of concrete specimens were examined by SEM, EDS and chemical composition to reveal the microstructure and damage mechanism of the concrete.The results show that the relative quality evaluation Parameters and relative dynamic elastic modulus evaluation parameters can visually characterize the deterioration process of concrete; the destruction form of concrete in Xining saline soil area is the chemical corrosion and physical crystallization of salt; chemical corrosion accelerates the deterioration of concrete; the interaction between the two Concrete has been severely damaged, the main corrosion products are gypsum, calcium carbonate and wollastonite, especially found in Xining saline soil area of the more harmful wollastonite sulphate erosion; Xining area exposed concrete has been Affected by the erosion of saline soil, its evaluation parameters fluctuate after 1 230 d test is still in the early stages of deterioration.