大掺量矿物掺合料再生自密实混凝土力学性能及微观结构研究  

Mechanical properties and microstructure of self-compacting concrete with high volume of recycled coarse aggregate and supplementary cementitious material

作　　者：秦大强 郭樟根[1] 宗震宇 唐刘洋 QIN Daqiang;GUO Zhanggen;ZONG Zhenyu;TANG Liuyang(College of Civil Engineering,Nanjing Tech University,Nanjing 211800,China)

机构地区：[1]南京工业大学土木工程学院,江苏南京211800

出　　处：《混凝土》2024年第3期42-48,共7页Concrete

基　　金：国家自然科学基金(52178144);工程结构性能演化与控制教育部重点实验室开放课题(2019KF-2);江苏省研究生科研创新计划(KYCX21_1152)。

摘　　要：采用再生粗骨料代替天然粗骨料、矿物掺合料代替水泥制备了9组再生自密实混凝土(RA-SCC)。研究了再生粗骨料和矿物掺合料对RA-SCC立方体抗压强度、轴心抗压强度和弹性模量的影响。通过对大量试验结果的回归分析,提出RA-SCC的龄期强度计算式和弹性模量计算式。此外,采用扫描电镜和X射线衍射对RA-SCC的微观结构进行研究。研究结果表明通过掺加20%粉煤灰、20%粒化高炉矿渣粉和10%硅灰可以有效弥补再生粗骨料对RA-SCC力学性能的不利影响。龄期-强度计算式和弹性模量计算式的预测值与实测值吻合较好。微观结构分析证实了RA-SCC力学性能改善的原因,主要归因于粉煤灰、粒化高炉矿渣粉和硅灰组合的火山灰反应显著提高了再生粗骨料-水泥石界面过渡区的质量以及水泥石基体的密实性。A total of 9 recycled aggregate self-compacting concrete(RA-SCC)mixes were produced by substituting natural aggregates and cement with supplementary cementitious material(SCM)and recycled coarse aggregate(RCA),respectively.The influences of RCA and SCM on the mechanical properties of RA-SCC were assessed,including cube compressive strength,axial compressive strength and elastic modulus.Based on the regression analysis of a large number of test results,the age compressive strength formulas and elastic modulus formulas were proposed.Furthermore,scanning electron microscope and X-ray diffraction were implemented to study the microstructure of RA-SCC.The results show that incorporating SCMs with a combination of 20%FA,20%ground granulated blast furnace slag(GGBFS)and 10%silica fume(SF)compensated for the detrimental effect of RCA on mechanical properties.The calculated values of the two formulas were in good agreement with the measured values.Microstructure analysis confirmed the reasons of improvement,which is mainly attributed to the pozzolanic reaction of SCMs by replacing cement with a combination of fly ash(FA),GGBFS and SF,resulting in a stronger interfacial transition zone and more compact cement matrix.

关 键 词：再生自密实混凝土 矿物掺合料 力学性能 龄期-强度式 弹性模量式 微观结构 

分 类 号：TU528.53[建筑科学—建筑技术科学]