硫酸盐作用下粉煤灰轻骨料混凝土力学性能及微观结构

发布时间：2018-07-15 22:15

【摘要】：以圆球型页岩陶粒为主要粗骨料,并用一级粉煤灰(FA(I))等体积取代30%普通砂,制备粉煤灰轻骨料混凝土.以超细粉煤灰(UFA)、硅灰(SF)分别等质量取代粉煤灰轻骨料混凝土10%~40%和5%~15%水泥,然后进行抗压强度试验、干湿循环试验、工业CT试验、压汞试验、动弹性模量试验,从混凝土抗蚀系数、孔隙率、动弹性模量等方面研究硫酸盐作用下粉煤灰轻骨料混凝土力学性能演变规律及微观结构变化情况.结果表明:在Na2SO4溶液浓度(质量分数)为0%~10%时干湿循环20次,混凝土抗压强度达到最高值,随后下降较快;在10%Na2SO4溶液中干湿循环50次,当UFA,SF取代率分别为20%,10%时,粉煤灰轻骨料混凝土抗蚀系数均达到最高值;掺UFA,SF粉煤灰轻骨料混凝土50~100nm孔所占体积分数明显增多,掺20%UFA和掺10%SF粉煤灰轻骨料混凝土100nm孔体积分数分别为普通混凝土的1.39,1.46倍;适量掺加UFA或SF能优化轻骨料-砂浆界面过渡区微观结构,增强轻骨料-砂浆界面黏结性能,延缓硫酸盐对粉煤灰轻骨料混凝土结构基体的进一步侵蚀.
[Abstract]:The fly ash lightweight aggregate concrete was prepared by using spherical shale ceramsite as the main coarse aggregate and replacing 30% ordinary sand with first-grade fly ash (FA (I). Superfine fly ash (UFA) and silica fume (SF) were used to replace 10% and 5% cement of fly ash lightweight aggregate concrete respectively, and then compressive strength test, dry and wet cycle test, industrial CT test, mercury injection test and dynamic elastic modulus test were carried out. The evolution of mechanical properties and microstructure of fly ash lightweight aggregate concrete under sulfate action were studied from the aspects of corrosion resistance, porosity and dynamic elastic modulus of concrete. The results show that when the concentration (mass fraction) of Na _ 2SO _ 4 solution is 0 ~ 10, the compressive strength of concrete reaches its maximum value 20 times and then decreases rapidly, and 50 times dry and wet cycles in 10Na _ 2SO _ 4 solution, when the replacement rate of UFA-SF is 20 and 10, respectively, The corrosion resistance coefficient of fly ash lightweight aggregate concrete reached the highest value, and the volume fraction of 50~100nm pore of fly ash lightweight aggregate concrete with UFA-SF increased obviously. The volume fraction of 100nm pore of fly ash lightweight aggregate concrete mixed with 20UFA and 10SF fly ash was 1.39 ~ 1.46 times that of ordinary concrete respectively. Proper addition of UFA or SF can optimize the microstructure of the transition zone between lightweight aggregate and mortar, enhance the interfacial adhesion between lightweight aggregate and mortar, and delay the further erosion of fly ash lightweight aggregate concrete matrix by sulfate.
【作者单位】：长沙理工大学交通运输工程学院;
【基金】：国家自然科学基金资助项目(11072041) 高等学校博士学科点专项科研基金资助项目(20104316120001) 湖南省教育厅资助科研项目(11A005)
【分类号】：TU528.2

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