摘要
为提高再生混凝土(RAC)的力学性能,以玄武岩纤维(BF)和纳米氧化硅(NS)为增强材料对再生混凝土进行改良.通过立方体抗压性能试验,研究了BF及NS掺量对再生混凝土7,28及90 d立方体抗压强度的影响;结合电镜扫描、X射线衍射及能谱分析等微观测试手段,分析了28 d再生混凝土内部微观结构.结果表明:各龄期抗压强度均随再生粗骨料取代率的增大而降低;添加适量纤维有利于再生混凝土早中期抗压强度的提高,但对90 d强度发展贡献较小;适量的NS有利于各龄期强度发展.不添加NS时,再生混凝土结构较为松散,钙硅比较大,纤维与基体的黏结性能较差;适量的添加NS,混凝土致密性有所提高,钙硅比有所降低,纤维与基体的黏结性能增强;当NS掺量过大时,钙硅比上升,混凝土致密性有所下降;就立方体抗压强度及微观结构而言,取代率不超过50%时,最佳NS掺量为6%;取代率为100%时,最佳NS掺量为8%.
In order to improve the mechanical properties of the recycled aggregate concrete,basalt fiber and nano-silica were used as the reinforcing materials.The influence of basalt fiber and nano-silica content on the cubic compressive strength at 7,28 and 90 days were studied by the cubic compressive strength test.Moreover,the microstructure of recycled aggregate concrete at 28 days was analyzed by the scanning electron microscopy,X-ray diffraction and energy spectrum analysis.The results show that the cubic compressive strength at each age decreases with the increase of the replacement ratio.The proper content of basalt fiber is beneficial to the improvement of the cubic compressive strength at 7 days and 28 days,but it has little contribution to the improvement of the cubic compressive strength at 90 days.The appropriate content of nano-silica is conducive to the improvement of the cubic compressive strength at each age.When the nano-silica is not added,the microstructure of recycled aggregate concrete is slightly loose,the calcium-silicon ratio is high,and the bonding performance between the basalt fibers and cement matrix is poor.The appropriate content of nano-silica is conducive to the improvement of the recycled aggregate concrete density and the performance of the interface transition zone,thereby increasing the bridge effect of the basalt fibers.When the nano-silica content is high,the calcium-silicon ratio increases,and the concrete density decreases.In terms of the cubic compressive strength and microstructures,when the recycled aggregate replacement ratio is no more than 50%,the optimum nano-silica content is 6%,and when the recycled aggregate replacement ratio is 100%,the optimum nano-silica content is 8%.
作者
王永贵
牛海成
范玉辉
WANG Yonggui;NIU Haicheng;FAN Yuhui(School of Civil Engineering,Henan Polytechnic University,Jiaozuo,Henan 454000,China;Henan Province Engineering Laboratory for Eco-architecture and the Built Environment,Henan Poliytechnic University,Jiaozuo,Henan 454000,China)
出处
《中国矿业大学学报》
EI
CAS
CSCD
北大核心
2019年第5期1012-1019,共8页
Journal of China University of Mining & Technology
基金
国家自然科学基金项目(51608179)
河南省自然科学基金项目(182300410134)
河南省科技攻关项目(182102310877)
河南省高校基本科研业务费专项资金项目(NSFRF180418)
关键词
再生混凝土
取代率
玄武岩纤维
纳米氧化硅
抗压强度
微观结构
recycled aggregate concrete
replacement ratio
basalt fiber
nano-silica
compressive strength
microstructure
