不同纤维掺量的铁尾矿再生混凝土抗盐雾侵蚀性能试验研究

Experimental Study on Salt Spray Resistance of Recycled Concrete from Iron Tailings with Different Fiber Contents

为了改善铁尾矿再生混凝土的脆性性能,对不同废弃纤维掺量的铁尾矿再生混凝土的盐雾侵蚀性能进行了试验研究.通过对侵蚀深度,氯离子含量及孔隙率的研究结果表明:同一条件下,再生混凝土(RAC)的抗侵蚀能力低于普通混凝土(NAC),掺加30%铁尾矿使再生混凝土的抗侵蚀能力增强,少量纤维(≤0.9%)对其抗侵蚀能力影响不大,但当掺量较大时,其抗侵蚀能力有大幅降低;距侵蚀面不同深度处的总氯离子含量变化不大,自由氯离子含量随侵蚀周期的增加而增加,结合氯离子则呈相反趋势.当纤维掺量为0.6%时,各侵蚀工况下的氯离子浓度与NAC相近;当掺量为1.2%时,自由氯离子与总氯离子含量达到最高,与RAC的含量相近.通过核磁共振分析,随着纤维掺量的增加,孔隙数量先变小后变大,孔径则持续增加使其呈现出不同的侵蚀规律.经过研究,当废弃纤维的掺量为0.6%~0.9%时,铁尾矿再生混凝土的抗盐雾侵蚀能力最优,研究结果可为工程应用提供参考.

To improve the brittleness of recycled concrete with iron tailings,its corrosion resistance with different amounts of waste fiber in different salt spray erosion cycles was studied.The results showed that the anti-corrosion ability of recycled aggregate concrete(RAC)was lower than that of natural aggregate concrete(NAC),and the anti-corrosion ability of RAC was enhanced by adding 30%iron tailings into RAC.When the fiber content was small(≤0.9%),its anti-corrosion ability changed little,but while the fiber content was large,its anti-corrosion ability was greatly reduced.Finally,the total chloride ion content at different depths from the erosion surface did not change much.The free chloride ion content increased with the increase of erosion cycle,while the bound chloride ion content was on the contrary.When the fiber content was 0.6%,the chloride ion concentration under various erosion conditions was similar to NAC,and while the fiber content was 1.2%,the free chloride ion and total chloride ion content reached or even exceeded RAC.Through nuclear magnetic resonance analysis,with the fiber increase,the number of pores first decreased and then increased,and the pore size continued to increase,showing different erosion laws.When the content of waste fiber was 0.6%-0.9%,the salt spray resistance of recycled concrete with iron tailings reached the strongest.