高温后再生混凝土力学性能研究

发布时间：2018-04-18 20:40

本文选题：再生混凝土 + 高温作用后　；参考：《建筑结构学报》2017年12期

【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。
[Abstract]:168 standard prism specimens of recycled concrete were designed and manufactured with the following parameters: the highest temperature, the replacement rate of recycled coarse aggregate, the type of coarse aggregate and the strength of concrete. The physical and mechanical properties of 168 recycled concrete standard prism specimens were tested after high temperature.In the experiment, the apparent changes and failure modes of the specimens after high temperature were observed, and the stress-strain curves of the whole process of axial compression of recycled concrete were obtained, and the loss rate at high temperature and the stress-strain curves of each specimen under axial compression were obtained.Based on the analysis of the influence of various parameters on the physical and mechanical properties of recycled concrete after high temperature, a formula for evaluating the axial compressive strength of recycled concrete after high temperature is put forward according to the maximum fire temperature and mass loss rate.The results show that with the increase of temperature, the recycled concrete changes from greyish gray to brown gray after high temperature, and finally appears gray and white, the phenomenon of temperature crack and exfoliation appears, and the burning loss rate increases with the increase of temperature.The effect of temperature on the failure form and mechanical properties of recycled concrete after high temperature is the greatest. The higher the temperature, the wider the crack zone and the more serious the failure degree is.With the increase of temperature, the attenuation of elastic modulus is greater than that of peak stress, and the influence of high temperature on the mechanical properties of recycled aggregate concrete is more significant than that of recycled concrete with gravel aggregate.The strength of concrete and the replacement ratio of recycled coarse aggregate have no obvious influence on the mechanical properties of recycled concrete after high temperature.Based on the experimental results, the calculated results of the axial compressive strength of recycled concrete after high temperature are in good agreement with the measured results.
【作者单位】：广西大学土木建筑工程学院;广西大学工程防灾与结构安全教育部重点实验室;华南理工大学亚热带建筑科学国家重点实验室;
【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)
【分类号】：TU528

【相似文献】