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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。
By simulating the coexistence environment between electric field and sulfate, the macroscopic properties such as appearance, compressive strength and other properties of concrete with different proportions were tested. By means of energy spectrum analysis, scanning electron microscopy and X-ray diffraction And other methods to explore the deterioration mechanism of concrete. The results showed that the Ca2 + concentration in the concrete pore solution was decreased by the electric field, which led to the decrease of Ca2 + concentration. Ca (OH) 2 decomposed and dissolved Ca2 + to maintain its equilibrium. In addition, Ca2 + / Si ratio decreased, indicating that CSH gel also decomposes Ca2 +, which has an adverse effect on the strength. In the meantime, a large amount of SO42- enters the concrete interior from the cathode solution due to the electric field and reacts with cement hydration products to generate more ettringite and gypsum crystals, resulting in a further decrease in strength. The corrosion resistance of low water cement ratio or fly ash concrete is improved, but the deterioration is still obvious. Therefore, when the concrete is affected by electric field and sulfate attack together, we should put forward more reasonable concrete durability design and preventive measures.