偏高岭土对活性粉末混凝土力学性能及微观结构的影响  

Effect of Metakaolin on Mechanical Properties and Microstructure of Reactive Powder Concrete

作　　者：陈丽[1] 周长顺[2,3] 蒋晨辉 CHEN Li;ZHOU Changshun;JIANG Chenhui(College of Architecture and Design Art,Shaoxing Vocational and Technical University,Shaoxing 312000,China;Yuanpei College,Shaoxing University,Shaoxing 312000,China;School of Civil Engineering,Central South University,Changsha 430100,China;College of Civil Engineering,Shaoxing University,Shaoxing 312000,China)

机构地区：[1]绍兴职业技术学院建筑与设计艺术学院,绍兴312000 [2]绍兴文理学院元培学院,绍兴312000 [3]中南大学土木工程学院,长沙430100 [4]绍兴文理学院土木工程学院,绍兴312000

出　　处：《硅酸盐通报》2021年第4期1162-1169,共8页Bulletin of the Chinese Ceramic Society

基　　金：国家自然科学基金(41572305)。

摘　　要：活性粉末混凝土(RPC)具有优异的力学性能和耐久性能,应用前景广阔。为探讨偏高岭土(MK)对RPC的影响,通过MK火山灰活性指数测试,抗压强度、抗折强度和弹性模量试验,以及X射线衍射分析仪(XRD)、扫描电子显微镜(SEM)、压汞和纳米压痕分析,研究了0%、5%、10%、15%和20%的MK等质量取代胶凝材料对RPC力学性能和微观结构的影响。研究结果表明,MK在水泥水化早期就表现出较高的火山灰活性,其中MK掺量为10%时RPC的28 d抗压强度、抗折强度和弹性模量较基准组分别提高了20.1%、18.0%和11.4%,MK的最佳掺量为10%。微观结构分析显示,MK的掺入降低了RPC基体的孔隙率,并且通过“二次水化”反应生成更多额外的水化硅酸钙(C-S-H)凝胶填充基体的孔隙,改善了RPC的微观结构。纳米压痕试验研究表明,掺入质量分数为10%的MK增加了高密度C-S-H的含量,这可能归因于MK的火山灰活性和微集料填充效应。Reactive powder concrete(RPC)is a promising material which exhibits extrordinary mechanical properties and durability.To investigate the effect of metakaolin(MK)on RPC,the effects of 0%,5%,10%,15%and 20%mass ratio of cementitious materials replaced by MK on the mechanical properties and microstructure of RPC were studied,which included MK pozzolanic activity index test,and the compressive,flexural strength and elastic modulus tests,X-ray diffraction analyzer(XRD),as well as scanning electron microscope(SEM),MIP and nanoindentation measurements.The results show that MK exhibits high pozzolanic activity at the early stage of cement hydration,and the 28 d compressive strength,flexural strength and elastic modulus of RPC with 10%MK increase by 20.1%,18.0%and 11.4%,respectively,comparing with the reference group.The optimal dosage of MK is 10%.It shows that the incorporation of MK reduces the porosity of RPC matrix,and more additional C-S-H gel filling the pores of RPC matrix is generated by the“secondary hydration”reaction,which improves the microstructure of RPC after the microstructure analysis.Nanoindentation investigation shows that the mass fraction of 10%MK increases the content of high density C-S-H to increase the mechanical properties of RPC.This may be attributed to the pozzolanic activity and the micro-aggregate filling effect of MK.

关 键 词：偏高岭土 活性粉末混凝土 力学性能 微观结构 纳米压痕 

分 类 号：TU528[建筑科学—建筑技术科学]