大掺量矿物掺合料再生自密实混凝土的力学性能  

Mechanical properties of recycled self-compacting concrete with large volume mineral admixtures

作　　者：董春汝 宗震宇 唐刘洋 郭樟根[1] 陈晨 DONG Chunru;ZONG Zhenyu;TANG Liuyang;GUO Zhanggen;CHEN Chen(College of Civil Engineering,Nanjing Tech University,Nanjing 211800,China;Jiangsu Hongji Energy Saving New Technology Co.Ltd.,Nanjing 210032,China)

机构地区：[1]南京工业大学土木工程学院,江苏南京211800 [2]江苏鸿基节能新技术股份有限公司,江苏南京210032

出　　处：《南京工业大学学报（自然科学版）》2023年第4期434-443,共10页Journal of Nanjing Tech University(Natural Science Edition)

基　　金：国家自然科学基金(52178144);同济大学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);江苏省研究生科研与实践创新计划(SJCX19_0229)。

摘　　要：采用再生混凝土骨料替代天然骨料,工业废料替代水泥,制备了生态型再生自密实混凝土(RA-SCC)。对3种水胶比(0.35、0.39和0.45),2种再生粗骨料取代率(50%、100%)和2种矿物掺和料取代率(50%、75%)共23个RA-SCC试件的力学性能进行试验研究。采用坍落扩展度和J环扩展度试验分析新拌混凝土的填充性能、通过性能、黏性,通过筛析法分析混凝土的抗离析性能。基于Matlab非线性数值计算,分析硬化混凝土的抗压强度和弹性模量;此外,利用扫描电镜成像技术,对RA-SCC的微观结构进行分析;同时,研究了不同再生骨料处理方法对力学性能的影响。结果表明:大掺量矿物掺合料RA-SCC具有良好的工作性能;再生混凝土骨料降低了混凝土的抗压强度和弹性模量;复掺不同粒径粉煤灰、矿渣、硅灰可以弥补再生粗骨料的不利影响,有效提高了RA-SCC的抗压强度和弹性模量;复掺矿物掺合料提高了RA-SCC的水泥石基体和界面过渡区的密实性,从而提高了RA-SCC的力学性能。通过对试验结果的回归分析,提出了RA-SCC的抗压强度和弹性模量计算公式。研究成果既有助于降低对水泥和砂石等不可再生自然资源的消耗,又可降低建筑及工业垃圾的处理难度,具有明显的经济和社会效益。A ecological recycled aggregate self-compacting concrete(RA-SCC)were prepared by recycled coarse aggregate replacing nature coarse aggregate and supplementary cementitious material replacing ordinary Portland cement.The mechanical properties of a total of 23 RA-SCC specimens prepared with three water to binder ratios(0.35,0.39 and 0.45)and two recycled coarse aggregate replacement ratios(50% and 100%)as well as two mineral admixture replacement ratios(50% and 75%)were studied.Slump expansion test and J ring expansion test were used to analyze the filling ability,passing performance and viscosity of fresh concrete.The segregation resistance of concrete was analyzed by sieving method.Based on the nonlinear analysis program of Matlab,the compressive strength and elastic modulus of hardened concrete were analyzed.In addition,the microstructure of RA-SCC was analyzed by scanning electron microscopy imaging technology.At the same time,the effects of different recycled aggregate treatment methods on mechanical properties were studied.Results indicated that RA-SCC with large volume mineral admixtures exhibited superior workability.Recycled concrete aggregate reduced the compressive strength and elastic modulus of concrete.The combination of fly ash,slag and silica fume with different particle sizes compensated for the detrimental effect of recycled coarse aggregates and effectively improved the compressive strength and elastic modulus of RA-SCC.Composite addition of mineral admixtures improved the compactness of cement matrix and interface transition zone of RA-SCC,thus improving the mechanical properties of RA-SCC.Based on the regression analysis of test results,the calculation formula for the compressive strength and elastic modulus of RA-SCC were proposed.The research results not only help to reduce the consumption of non-renewable natural resources such as cement and sand,but also reduce the difficulty of building and industrial waste treatment,which has obvious economic and social benefits.

关 键 词：自密实混凝土(SCC) 再生粗骨料(RCA) 辅助胶凝材料(SCM) 再生混凝土 微观结构 

分 类 号：TV431.2[水利工程—水工结构工程]