纳米二氧化硅强化再生骨料混凝土微观结构研究  

Study on the Microstructure of Nano-silica modified Recycled Aggregate Concrete

作　　者：李美寿 LI Meishou(Fujian Hancheng Construction Engineering Company Limited)

机构地区：[1]福建省涵城建设工程有限公司

出　　处：《广东建材》2024年第5期14-18,共5页Guangdong Building Materials

摘　　要：利用纳米二氧化硅增强的再生骨料(RAs)制备再生骨料混凝土(RAC)并研究其微观结构。试验中选取5种浓度(0%、1.0%、1.5%、2%、2.5%)的纳米二氧化硅溶液,分别在两种不同条件下(常压和1bar的真空加压)浸泡RAs。测试了纳米二氧化硅增强RAs和RAC的化学组分、孔隙率和孔隙结构并表征了其微观形貌。结果表明,单独使用真空加压条件时,2%为二氧化硅溶液的最佳浓度。该处理条件使CH含量降低了40%以上,总孔隙率下降,平均孔径缩小,以及少害孔(小于50nm)的体积分数降低。该结果经环境扫描电镜(ESEM)验证,归因于二次水化使水化产物增多和纳米颗粒的填充作用。微观层面的研究解释了纳米二氧化硅对再生骨料混凝土的强化作用,为建筑与拆除废弃物的高质利用奠定了理论基础。Recycled aggregate concrete(RAC)was prepared and its microstructure was investigated using recycled aggregates(RAs)reinforced with nano-silica.Five concentrations(0%,1.0%,1.5%,2%,2.5%)of nano-silica solutions were selected and immersed in RAs under two different conditions(atmospheric pressure and vacuum pressurization at 1 bar).The chemical composition,porosity and pore structure of the nano-silica reinforced RAs and RACs were tested and their micro-morphology was characterized.The results show that 2%is the optimum concentration of silica solution when vacuum pressurization conditions are used alone.This treatment condition reduced the CH content by more than 40%,the total porosity,the average pore size,as well as the volume fraction of less harmful pores(less than 50 nm).The results were verified by Environmental Scanning Electron Microscopy(ESEM)and attributed to the increase of hydration products due to secondary hydration and the filling effect of nanoparticles.The micro-level study explains the reinforcing effect of nano-silica on recycled aggregate concrete and lays the theoretical foundation for the high-quality utilization of construction and demolition waste.

关 键 词：建筑废弃物 混凝土 再生骨料 纳米二氧化硅 孔结构 

分 类 号：TU528[建筑科学—建筑技术科学]