高温后再生混凝土力学性能研究  

Research on mechanical behavior of recycled aggregate concrete after high temperatures

作　　者：陈宗平[1,2] 周春恒[1] 李伊[1] 陈建佳 吴波[3] 

机构地区：[1]广西大学土木建筑工程学院,广西南宁530004 [2]广西大学工程防灾与结构安全教育部重点实验室,广西南宁530004 [3]华南理工大学亚热带建筑科学国家重点实验室,广东广州510640

出　　处：《建筑结构学报》2017年第12期105-113,共9页Journal of Building Structures

基　　金：国家自然科学基金项目(51578163);广西自然科学基金重点项目(2016GXNSFDA380032);广西高等学校高水平创新团队及卓越学者计划项目(桂教人[2017]38号)

摘　　要：以历经最高温度、再生粗骨料取代率、粗骨料类型、混凝土强度为变化参数,设计和制作了168个再生混凝土标准棱柱体试件,对其进行高温后的物理及力学性能试验。试验中观察了高温后试件的表观变化及其受力破坏形态,获取了再生混凝土的高温烧失率以及各试件的轴心受压全过程应力-应变曲线,通过分析各变化参数对历经高温后再生混凝土的物理及力学性能的影响规律,根据最高受火温度和质量烧失率分别提出高温后再生混凝土轴心抗压强度评估公式。结果表明:随着温度的提高,高温后再生混凝土由青灰色变为棕灰色,最后呈灰白色,出现温度裂缝及剥落现象;烧失率随着温度的提高、取代率的增大和强度的降低而显著增大;温度对高温后再生混凝土破坏形态及力学性能的影响最大,温度越高,其轴心受压破坏时的裂缝带越宽,破坏程度越严重;随着温度的升高,其弹性模量的衰减程度要比峰值应力的大;相比卵石骨料再生混凝土,高温对碎石骨料再生混凝土力学性能的影响更为显著;混凝土强度和再生粗骨料取代率变化对高温后再生混凝土的力学性能无明显影响。基于试验结果提出的高温后再生混凝土轴心抗压强度的评估计算结果与实测结果吻合较好。Based on the parameters which were temperature,recycled coarse aggregate replacement percentage,coarse aggregate type and concrete strength,168 standard prism specimens of recycled aggregate concrete were exposed to different high temperatures,and then subjected to axial compression test. The surface variation and compression failure mode of specimens after exposure to high temperature were observed in the experiment. The mass loss ratio,elasticmodel,axial compressive strength and stress-strain curve were obtained and analyzed through the effect of each parameter variation. Two methods of residual strength assessment,which is based on the mass loss ratio and the highest exposure temperature,for recycled aggregate concrete after elevated temperature were proposed. The test results show that with the increase of temperature,the color of specimens change from steel gray to brown gray,finally to gray. Crack and spalling due to elevated temperature appear on its surface. The mass loss ratio is increased with the increase of temperature,enhancement of replacement percentage and reduction of compressive strength. The influence of temperature for failure mode and mechanical behavior of recycled aggregate concrete after high temperature is most significant. The higher the temperature,the wider the crack band,and the higher of the damage level. With the increase of temperature,the decrease of elasticity modulus is greater than that of peak stress. The influence of high temperature on mechanical behavior of recycled gravel aggregate concrete is more significant than that of recycled pebble aggregate concrete. The change of concrete strength and recycled coarse aggregate replacement percentage has no obvious effect on mechanical behavior of recycled aggregate concrete after high temperature. The method of residual strength assessment is accurate. The calculated axial compressive strength of recycled aggregate concrete after high temperature based on the test agrees well with the measured results.

关 键 词：再生混凝土 高温作用后 静力试验 力学性能 强度评估 

分 类 号：TU528[建筑科学—建筑技术科学] TU317.1