氯盐对再生混凝土硫酸盐侵蚀的抑制作用研究

将再生骨料取代率为50%的混凝土试块自然浸泡在单一Na₂SO₄溶液、MgSO₄溶液和NaCl-Na₂SO₄复合溶液、NaCl-MgSO₄复合溶液中,其中复合溶液中的氯盐质量分数分别为0%,2%,5%和10%。在整个试验周期内,每隔30 d测量不同溶液中再生混凝土试块的表观形貌、超声声速和质量变化率,得出了氯盐对Na₂SO₄溶液和MgSO₄溶液侵蚀再生混凝土的抑制规律。最后结合试验结果,详细分析了氯盐抑制不同硫酸盐溶液侵蚀再生骨料混凝土相关性能差异的机理。研究结果表明:氯盐对再生混凝土的硫酸钠侵蚀有明显抑制作用,氯盐质量分数为5%时抑制效果最明显,但是氯盐质量分数继续增大,抑制效果没有明显的提高; 氯盐对硫酸镁溶液侵蚀再生混凝土的抑制效果较弱,甚至在氯化钠质量分数为2%时,再生混凝土试块表观侵蚀程度比未掺加氯化钠的还严重; 氯离子对硫酸根离子侵蚀有抑制作用,但是对镁离子的侵蚀无明显抑制作用; 所得结论为再生骨料混凝土在实际工程中的耐久性应用提供了借鉴。

Study on Inhibitory Effect of Chlorine Salt on Sulfate Corrosion of Recycled Concrete

The concrete test block with a recycled aggregate replacement ratio of 50% was naturally immersed in pure Na₂SO₄ solution, pure MgSO₄ solution, NaCl-Na₂SO₄ composite solution and NaCl-MgSO₄ composite solution, Wherein the chlorine salt concentration in the composite solution was 0%, 2%, 5% and 10% respectively. During the test cycle, the inhibition rules of chloride salt on Na₂SO₄ solution and MgSO₄ solution eroded recycled concrete were obtained by the apparent morphology, ultrasonic sound velocity and mass change rate of recycled concrete test blocks, which were measured every 30 d. Finally, combined with the test results, the mechanism of chlorine salt inhibiting the erosion of recycled aggregate concrete by different sulfate solutions was analyzed detailed. The research results show that chloride salt has significant inhibitory effect on sodium sulfate corrosion of recycled concrete, and the inhibitory effect is the most obvious when the concentration of chloride salt is 5%. But the concentration of chloride salt continues to increase, the inhibitory effect is not significantly improved. The inhibitory effect of solution erosion on recycled concrete is relatively weak, even when the sodium chloride concentration is 2%, the apparent corrosion degree of the recycled concrete test block is more serious than that without sodium chloride. It is found that the main reason is that chloride ions have inhibitory effect on sulfate ion erosion, but there is no obvious magnesium ions effect. It provides a reference for the durability application of recycled aggregate concrete in practical engineering.