硫酸盐环境对活性粉末混凝土抗拉强度的影响

发布时间：2018-06-07 00:24

本文选题：活性粉末混凝土 + 硫酸盐浓度　；参考：《铁道学报》2017年11期

【摘要】：通过硫酸盐冻融-干湿循环耦合作用试验,研究Na_2SO_4溶液浓度对预加载活性粉末混凝土劈裂抗拉强度的影响规律,并结合SEM、XRD微观分析方法研究其破坏机理。结果表明:0%、5%、10%浓度Na_2SO_4浓度溶液冻融-干湿循环耦合作用下,劈裂抗拉强度的变化经历初期劣化、强化和后期劣化共三个阶段。Na_2SO_4溶液浓度对劈裂抗拉强度的影响较大,其中,5%浓度的影响最大,其次为10%浓度,最后为0%浓度。冻融循环、干湿循环过程中的温度交变作用是初期劈裂抗拉强度下降的主要原因;侵蚀过程中产生的Na_2SO_4晶体和石膏晶体对裂缝和孔隙起到填充作用,未水化水泥和硅灰二次水化产生的修复作用,共同作用使得劈裂抗拉强度经历了强化段;后期劣化阶段结晶更好的石膏晶体与钙矾石晶体等侵蚀性产物的有害膨胀应力与Na_2SO_4结晶应力共同作用造成基体损伤。5%浓度Na_2SO_4溶液耦合循环6次后,活性粉末混凝土、C60高性能混凝土的劈裂抗拉强度损失率分别为6.09%、48.89%,活性粉末混凝土在耦合作用下的耐久性远优于C60高性能混凝土。
[Abstract]:The effect of concentration of Na_2SO_4 solution on splitting tensile strength of pre-loaded reactive powder concrete was studied by coupling test of sulfate freeze-thawing and dry-wet cycle, and its failure mechanism was studied by means of SEM / XRD microanalysis. The results show that under the coupling of freeze-thaw and dry-wet cycle with 10% Na_2SO_4 concentration, the change of splitting tensile strength goes through the initial deterioration, and the concentration of Na2SO4 solution has a great influence on the splitting tensile strength. The effect of 5% concentration was the biggest, followed by 10% concentration and 0% concentration. The temperature alternation in freeze-thaw cycle and dry-wet cycle is the main reason for the decrease of tensile strength in the initial fracturing, and the Na_2SO_4 crystals and gypsum crystals produced during the erosion process play a role in filling the cracks and pores. The repair effect of unhydrated cement and silica fume by secondary hydration makes the splitting tensile strength go through the strengthening section. At the later stage of deterioration, the harmful expansion stress of the corrosive products such as gypsum crystal and ettringite crystal and the Na_2SO_4 crystal stress caused the matrix damage. 5% Na_2SO_4 solution coupling cycle for 6 times. The loss rate of split tensile strength of reactive powder concrete is 6.09 and 48.89 respectively. The durability of reactive powder concrete under coupling is much better than that of C60 high performance concrete.
【作者单位】：北京交通大学土木建筑工程学院;碧桂园股份有限公司;
【基金】：国家自然科学基金(51578049,51278039) 中央高校基本科研业务费专项资金(2016JBM045)
【分类号】：TU528

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