盐冻环境下塔里木灌区水工玄武岩纤维混凝土抗腐蚀性能试验研究

Experimental study on corrosion resistance of hydraulic basalt fiber concrete under salt-freezing environment in Tarim irrigation area

为探究塔里木灌区盐渍土环境下水工玄武岩纤维混凝土的抗冻性能,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,在不同浓度复合盐溶液(NaCl+MgSO_(4)+Na_(2)SO_(4))侵蚀与冻融循环共同作用下的腐蚀劣化试验.结果表明:(1)玄武岩纤维的掺入提高了水工混凝土抵抗盐冻破坏的能力,随着复合盐溶液浓度的增大及冻融循环次数的增加,试件发生由表及里的损伤破坏,纤维掺量为0.3%试件的质量损失率最小,相对动弹性模量波动幅度最小,抗盐冻性能最好。(2)玄武岩纤维的掺入减缓了混凝土内部Ca(OH)_(2)的消耗速率,腐蚀产物的含量也相应减少,混凝土抵抗盐冻破坏的能力随之增强。(3)复合盐侵蚀与冻融循环作用下,试件的腐蚀产物主要为钙矾石(AFt)和石膏,冻胀与腐蚀产物对毛细孔隙和微裂缝的破坏是混凝土微观结构损伤的主要原因。研究成果可为玄武岩纤维混凝土在塔里木灌区的实际工程应用提供科学依据。

To explore the frost resistance of hydraulic basalt fiber concrete in saline soil environment of Tarim irrigation area,the corrosion degradation tests of basalt fiber concrete with different volume content(0,0.1%,0.2%,0.3%)were carried out under the linked reaction of the composite salt solution(NaCl+MgSO_(4)+Na_(2)SO_(4))with different concentration and freezing-thawing cycle.The results show that(1)the addition of basalt fiber improves the resistance of hydraulic concrete to salt and frost damage.With the increase of composite salt solution concentration and freeze-thaw cycle number,the specimen was damaged from the outside to the inside.The fluctuation range of the relative dynamic elastic modulus and the mass loss rate of the specimen with the fiber content of 0.2%are the lowest,so the salt-frost resistance is the best.(2)The addition of basalt fiber delayed the consumption rate of Ca(OH)2 in concrete,decreased the content of corrosion products correspondingly and the salt resistance of concrete is enhanced.(3)Under the linked reaction of composite salt erosion and freeze-thaw cycle,the corrosion products of specimens are mainly calcium alum stone(AFt)and gypsum.The destruction of capillary pores and micro-cracks by freeze-swell and corrosion products is the main reason for the concrete microstructure damage.The research results could provide scientific evidence for the practical engineering application of basalt fiber concrete in Tarim irrigation area.