三点弯曲下再生砂浆断裂性能与裂纹扩展过程  

Fracture properties and crack propagation process of recycled mortar under three-point bending

作　　者：唐宇翔 肖建庄[1,3] 夏冰 TANG Yuxiang;XIAO Jianzhuang;XIA Bing(College of Civil Engineering,Tongji University,Shanghai 200092,China;School of Transportation,Changsha University of Science&Technology,Changsha 410114,Hunan,China;Institute of Science and Technology for Carbon Peak&Neutrality,Guangxi University,Nanning 530004,Guangxi,China)

机构地区：[1]同济大学土木工程学院,上海200092 [2]长沙理工大学交通学院,湖南长沙410114 [3]广西大学双碳科学与技术研究院,广西南宁530004

出　　处：《建筑科学与工程学报》2025年第2期114-121,共8页Journal of Architecture and Civil Engineering

基　　金：国家重点研发计划项目(2022YFC3803400,2022YFE0198300);国家自然科学基金项目(52078358);上海市科委“科技创新行动计划”科技支撑项目(22dz1207300)。

摘　　要：为研究再生细骨料(RFA)取代率对砂浆断裂性能与裂纹扩展特性的影响,开展了4种RFA取代率(0%、25%、50%和100%)下的砂浆断裂行为试验研究。基于三点弯曲切口梁试验,获得再生砂浆断裂响应,包括完整的荷载-裂纹口张开位移曲线、临界裂纹扩展、起裂韧度、失稳韧度与断裂能。利用非接触式数字图像相关技术,测得试件表面变形,获取再生砂浆裂纹发展全过程。结果表明:RFA的使用降低了再生砂浆荷载-位移曲线的初始线性段斜率与峰值荷载,主要影响再生砂浆临界裂纹宽度方向的张开而不是裂纹长度方向的扩展;再生砂浆的起裂韧度、失稳韧度和断裂能随着RFA取代率的增加而逐渐减小,当RFA取代率为100%时,砂浆的起裂韧度、失稳韧度和断裂能分别减小了31.1%、29.5%和37.8%;不同RFA取代率下再生砂浆的断裂过程区长度l FPZ发展表现出相似的特征,即先缓慢发展至峰值荷载(l FPZ为0.24倍~0.32倍的韧带长度),接着迅速增加至完全发展(l FPZ为0.83倍~0.91倍的韧带长度),之后l FPZ随裂纹的扩展而减小。To investigate the effect of the replacement ratios of recycled fine aggregate(RFA)on the fracture properties and crack propagation characteristics of mortar,experimental studies were conducted on the fracture behavior of mortar with four types of RFA replacement ratios(0%,25%,50%,and 100%).Based on the three-point bending notched beam tests,the fracture responses of recycled mortar were obtained,including the complete load-crack mouth opening displacement curves,critical crack propagation,initial cracking toughness,unstable toughness,and fracture energy.By using non-contact digital image correlation technology,the surface deformation of the specimen was measured to obtain the entire process of crack propagation in recycled mortar.The results show that the use of RFA reduces the initial linear slope and peak load of the load-displacement curves of recycled mortar,mainly affecting the critical crack propagation in the opening direction rather than the extension direction.The initial cracking toughness,unstable toughness,and fracture energy of recycled mortar gradually decrease with the increase of RFA replacement ratio.When the RFA replacement ratio is 100%,the initial cracking toughness,unstable toughness,and fracture energy of mortar decrease by 31.1%,29.5%,and 37.8%,respectively.The development of the fracture process zone length of recycled mortar l FPZ with different RFA replacement ratio exhibits similar characteristics,which slowly develops to the peak load(0.24 times to 0.32 times the ligament length),then rapidly increases to fully development(0.83 times to 0.91 times the ligament length),and then l FPZ decreases with crack propagation.

关 键 词：再生砂浆 再生细骨料取代率 三点弯曲断裂试验 双K断裂韧度 断裂能 裂纹扩展特性 

分 类 号：TU528[建筑科学—建筑技术科学]