1.南京水利科学研究院 水文水资源与水利工程科学国家重点实验室，江苏 南京 210029;2.水安全与水科学协同创新中心，江苏 南京 210024
范向前（1982—），男，河南登封人，南京水利科学研究院正高级工程师，博士. E-mail：xqfan@nhri.cn
范向前（1982—），男，河南登封人，南京水利科学研究院正高级工程师，博士. E-mail：xqfan@nhri.cn
TU528.01
国家自然科学基金资助项目（52171270，51879168）；国家自然科学基金委-区域创新发展联合基金重点资助项目（U23A20672）；黄河水科学研究联合基金资助项目（U2243223）
1.State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering， Nanjing Hydraulic Research Institute， Nanjing 210029， China;2.Cooperative Innovation Center for Water Safety & Hydro Science，Nanjing 210024， China
为探究早龄期混凝土的断裂性能，针对5种养护龄期（3、7、14、21、28 d）的混凝土试件，开展20根含预制裂缝的三点弯曲梁断裂试验，得到其荷载-裂缝口张开位移（P-CMOD）曲线.基于该曲线，计算得到早龄期混凝土的断裂韧度（起裂韧度和失稳韧度）和断裂能.采用声发射（AE）技术，通过振铃计数和累计振铃计数与时间的关系曲线，探讨养护龄期对早龄期混凝土试件损伤断裂过程的影响；通过计算上升角（RA）和平均频率（AF），分析了早龄期混凝土的破坏模式.结果表明：早龄期混凝土的断裂韧度和断裂能均随着养护龄期的增加而增大，抗开裂能力提高，延性变差.当养护龄期由3 d增至14 d时，混凝土的断裂韧度和断裂能增速较快；当养护龄期由14 d增至28 d时，混凝土的断裂韧度和断裂能增速变缓.振铃计数和累计振铃计数均能较好地反映早龄期混凝土的损伤破坏过程，其中累计振铃计数的增速随着养护龄期的增加而减小.混凝土的剪切裂缝占总裂缝的比例随着养护龄期的增加而增加.
In order to explore the fracture performance of early-age concrete， 20 three-point bending beam fracture tests with precast cracks were carried out for concrete specimens of 5 different curing ages （3 ， 7， 14， 21， 28 d） to obtain their load-crack mouth opening displacement （P-CMOD） curves. Based on these curves， the fracture toughness （crack initiation toughness and unstable toughness） and fracture energy of early-age concrete were calculated. The effect of the curing age on the damage fracture process of early-age concrete specimens was investigated by using the acoustic emission （AE） technique through the curves of ringing counts and cumulative ringing counts versus time. The failure mode of early-age concrete was analyzed by calculating the rise angle （RA） and average frequency （AF）. The results show that the fracture toughness and fracture energy of early-age concrete increase with the increases of curing age， the cracking resistance improves and the ductility deteriorates. The growth rate of concrete fracture toughness and fracture energy are faster from 3 d to 14 d， while the growth rate of concrete fracture toughness and fracture energy are slower from 14 d to 28 d. Both ringing counts and cumulative ringing counts can reflect the damage and failure process of concrete in early age. The growth rate of cumulative ringing counts decreases with the increases of curing age. The proportion of shear cracks to total cracks increases with the increases of curing age.
范向前,葛菲.基于声发射技术的早龄期混凝土断裂性能[J].建筑材料学报,2024,27(2):153-160
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