电场与硫酸盐侵蚀共同作用下混凝土的劣化及其机理

发布时间：2018-11-08 20:25

【摘要】：通过试验模拟电场与硫酸盐的共存环境,测试了不同配比的混凝土在这两种因素共同作用后的外观、抗压强度等宏观性能变化,并借助能谱分析、扫描电子显微镜和X射线衍射等方法,探讨了混凝土的劣化机理。结果表明:在电场作用下,混凝土孔溶液中的Ca2+发生定向迁移从而导致Ca2+浓度降低;Ca(OH)2分解溶出Ca2+来维持其平衡;此外,水化硅酸钙(C-S-H)凝胶的Ca/Si比下降,表明C-S-H凝胶也分解析出Ca2+,这对强度产生不利影响。同时,大量SO42 因电场作用从阴极溶液进入混凝土内部,并与水泥水化产物反应生成更多钙矾石和石膏晶体,导致强度进一步降低。低水胶比或掺粉煤灰混凝土的耐蚀性有所提高,但其劣化仍较为明显。因此,当混凝土受到电场和硫酸盐侵蚀共同作用时,应针对性地提出更为合理的混凝土耐久性设计及防范措施。
[Abstract]:By simulating the coexistence environment of electric field and sulfate, the appearance, compressive strength and other macroscopic properties of concrete with different proportions were tested after the interaction of these two factors, and the results were analyzed by energy spectrum. The deterioration mechanism of concrete is discussed by means of scanning electron microscope and X-ray diffraction. The results show that under the action of electric field, the Ca2 in the solution of concrete pore occurs directional migration, which results in the decrease of Ca2 concentration and the decomposition and dissolution of Ca2 from; Ca (OH) _ 2 to maintain its equilibrium. In addition, the Ca/Si ratio of the hydrated calcium silicate (C-S-H) gel decreased, indicating that the C-S-H gel also decomposes and precipitates Ca2, which has a negative effect on the strength. At the same time, a large number of SO42 ions enter the concrete from cathode solution to concrete due to electric field, and react with cement hydration products to produce more ettringite and gypsum crystals, resulting in further decrease of strength. The corrosion resistance of low water-binder ratio or fly ash concrete is improved, but its deterioration is still obvious. Therefore, when concrete is affected by electric field and sulfate erosion, more reasonable concrete durability design and preventive measures should be put forward.
【作者单位】：重庆大学材料科学与工程学院;
【基金】：国家自然科学基金面上项目(51572038) 重庆市科委自然科学基金资助项目(cstcjcyja30004)
【分类号】：TU528

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