摘要
为了研究再生混凝土内部损伤随应力变化的演变规律,基于声发射技术对龄期为14 d、28 d、60 d的不同再生粗骨料替代率和不同粉煤灰掺量的混凝土进行了动态检测,获得了表征掺粉煤灰再生混凝土损伤演化过程的典型能量-应力图、撞击累计数-应力曲线以及声发射损伤定位图,探究了再生粗骨料替代率、粉煤灰掺量和龄期对声发射参数的影响,揭示了各应力阶段与内部损伤情况的关系。结果表明:再生粗骨料替代率越高,压密阶段占整个应力上升阶段的时间越长,由1/5上升到1/2,且各阶段的划分不突出,应力破坏阶段相应提前;掺加适量的粉煤灰可以密实再生混凝土内部的初始缺陷,但是,当粉煤灰掺量为30%时,试块在塑性阶段的撞击累计数开始出现剧增现象,使得捕捉材料破坏的预兆信息提前;不同龄期对再生混凝土的内部初始缺陷有一定影响,尤其体现在压密阶段和破坏阶段的撞击累计数上。
In order to study the evolvement rule of the internal damage of recycled concrete with the change of stress caused by the initial defect,based on acoustic emission technology,dynamic monitoring was conducted for concrete with different recycled coarse aggregate replacement rate and different fly ash content with ages of 14 d,28 d and 60 d.The typical energy-strain impact cumulative stress curve and acoustic emission damage location diagram representing the damage evolution process of recycled concrete with fly ash were obtained.The influence of recycled coarse aggregate replacement rate,fly ash content and age on acoustic emission parameters was explored,and the relationship between each stress stage and internal damage was revealed.The results show that the higher the recycled coarse aggregate replacement rate,the longer the compaction stage takes up in the whole stress rising stage,from 1/5 to 1/2,and the division of each stage is not convex,and the stress failure stage is corresponding to the premise.Adding appropriate amount of fly ash can compact the internal defects of recycled concrete.However,when the fly ash content is 30%,the cumulative number of impacts of test block in the plastic phase begins to increase dramatically,which leads to the advance of capturing the foreshadowing information of material failure.Different ages have a certain influence on the internal initial defects of recycled concrete,especially in the cumulative impact of compaction stage and failure stage.
作者
张仕桦
刘京红
刘婷
周双双
刘子倩
ZHANG Shi-hua;LIU Jing-hong;LIU Ting;ZHOU Shuang-shuang;LIU Zi-qian(School of Civil Engineering,Tianjin Chengjian University,Tianjin 300384,China;Jianke EET Co.,Ltd.,Beijing 100013,China;Academy of Agricultural Planning and Engineering,MARA,Beijing 100125,China;College of Urban and Rural Construction,Agricultural University of Hebei,Baoding 071001,China;The 6th Subsidiary of Hebei 4th Building Company,Baoding 071000,China)
出处
《混凝土与水泥制品》
2021年第4期94-98,共5页
China Concrete and Cement Products
基金
河北省教育厅重点项目(ZD2019117)
河北农业大学理工基金项目(LG201803)。
关键词
粉煤灰
再生粗骨料
混凝土
声发射
Fly ash
Recycled coarse aggregate
Concrete
Acoustic emission
