复合盐侵蚀-干湿耦合作用下玄武岩纤维混凝土腐蚀劣化试验

Experimental study on corrosion degradation of basalt fiber concrete under combined salt erosion and drying-wetting coupling action

为探究玄武岩纤维混凝土在复合盐溶液与干湿循环耦合作用下的腐蚀劣化规律,开展了不同体积掺量(0%、0.1%、0.2%、0.3%)的玄武岩纤维混凝土试件,在不同浓度(清水、基准浓度、5倍基准浓度、10倍基准浓度)的复合盐溶液(NaCl+MgSO4+Na2SO4)与干湿循环共同作用下的宏-微观腐蚀劣化试验。研究结果表明:(1)玄武岩纤维的掺入提高了混凝土抗复合盐侵蚀的能力,纤维掺量为0.3%时,试件的相对动弹性模量波动最小,表现最稳定;(2)复合盐溶液侵蚀作用下,混凝土腐蚀产物主要为钙矾石(AFt)和石膏,随着干湿循环次数的增加,腐蚀产物不断增多,试件最终在物理腐蚀和化学腐蚀的共同作用下发生破坏;(3)由不同腐蚀龄期的腐蚀产物分析发现,玄武岩纤维的掺入降低了混凝土内部Ca(OH)2的消耗速率,腐蚀产物的含量也相应减少,混凝土抵抗复合盐侵蚀的能力得以增强。研究成果可为玄武岩纤维混凝土在新疆南疆盐渍土地区的工程应用提供科学依据。

In order to explore the corrosion and deterioration law of basalt fiber concrete under the coupling effect of compound salt solution and dry-wet cycle, the macro-microscopic corrosion degradation tests of basalt fiber concrete specimens with different volume contents(0%, 0.1%, 0.2%, 0.3%) were carried out, under the combined action of composite salt solution(NaCl+MgSO4+Na2SO4) with different concentrations(clean water, reference concentration, 5 times reference concentration, 10 times reference concentration) and dry-wet cycles. The results show that the addition of basalt fiber improves the salt corrosion resistance of concrete, and when the content of basalt fiber is 0.3%, the relative dynamic elastic modulus of the specimen has the smallest fluctuation and the most stable performance. Concrete corrosion products are mainly ettringite(AFt) and gypsum under the action of combined salt solution corrosion. The corrosion products increase continuously with the increase of the number of drying and wetting cycles, and the specimen is finally destroyed by the combined action of physical and chemical corrosion. According to the microstructure and composition analysis of corrosion products in different corrosion ages, it is found that adding basalt fiber reduces the consumption rate of Ca(OH)2in concrete, and the content of corrosion products decreases correspondingly, and the ability of concrete to resist compound salt erosion is enhanced. The results can provide scientific basis for the engineering application of basalt fiber concrete in the saline soil area of Southern Xinjiang.