摘要
为了解决再生骨料生态混凝土过高的碱性制约其推广应用的问题,本文以工程渣土再生骨料为研究对象,通过L16(44)正交表设计生态混凝土配合比,研究了设计孔隙率、水胶比、粉煤灰掺量和硅灰掺量对生态混凝土的酸碱度、有效孔隙率、抗压强度、抗折强度和劈裂抗拉强度这5个测试指标的影响规律,结合Z值综合评价法筛选得到最优配合比,研究了喷涂硅烷浸渍剂和质量分数为2％的过磷酸钙溶液、掺入过磷酸钙或氯化铝对生态混凝土的降碱效果.结果表明:①再生骨料生态混凝土的最优配合比:设计孔隙率为24％,水胶比为0.34,粉煤灰掺量为30％,硅灰掺量为6％.②设计孔隙率对生态混凝土的酸碱度、有效孔隙率、抗压强度、抗折强度和劈裂抗拉强度的影响程度大于水胶比、粉煤灰掺量和硅灰掺量分别对这5个测试指标的影响程度,是这5个测试指标的主要影响因素.③喷涂1次硅烷浸渍剂可将生态混凝土的pH降至8.55,其降碱效果最好;其次是掺入6％氯化铝和6％过磷酸钙,生态混凝土 pH降至9.54和9.65;喷涂3次质量分数为2％的过磷酸钙溶液仅能将生态混凝土 pH降至10.26,其降碱效果较差.
Abstract
To address the issue that the excessive alkalinity of recycled aggregate eco-concrete restricts its popularization and application,in this research,the recycled aggregate from construction spoil is taken as the research object,different eco-concrete mix ratios are designed by an L16(44)orthogonal table to explore the influence that design porosity,water-to-binder ratio,fly ash content,and silica fume content exert on test indexes of eco-concrete,including pH,effective porosity,compressive strength,flexural tensile strength,and splitting tensile strength.The optimal eco-concrete mix ratio is selected using the Z-score method to further study alkali reduction effects.Four methods are used for reducing alkalinity:spraying a silane impregnation,spraying a 2％mass fraction of calcium superphosphate solution,mixing calcium superphosphate,and mixing aluminum chloride.The results indicate that:①The recycled aggregate eco-concrete at the optimal mix ratio is made with a water-to-binder ratio of 0.34 which contains 30％fly ash and 6％silica fume.Meanwhile,the designed porosity of the eco-concrete is 24％.②The effect of design porosity on the pH,effective porosity,compressive strength,flexural tensile strength,and splitting tensile strength of eco-concrete is significantly greater than that of water-to-binder ratio,fly ash content,and silica fume content on the five test indexes.This makes design porosity the main factor affecting these five test indexes.③The most effective method for reducing alkalinity is by spraying silane impregnation once,and the pH can be reduced to 8.55.This is followed by adding 6％aluminum chloride and 6％calcium superphosphate,which reduce the pH of eco-concrete to 9.54 and 9.65,respectively.However,spraying a 2％mass fraction of calcium superphosphate solution three times can only reduce the pH of eco-concrete to 10.26,which is the worst method for reducing alkalinity.
维普
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