高温后混凝土抗压强度及细观损伤机理实验研究  

Experimental study on compressive strength and meso-damage of concrete under high temperature

作　　者：花尉攀[1] 李凯峰[1] 谢晓杰 HUA Wei-pan;LI Kai-feng;XIE Xiao-jie(Anyang Vocational and Technical College,Henan Anyang 455000,China;School of Civil Engineering,Zhengzhou University,Henan Zhengzhou 450001,China)

机构地区：[1]安阳职业技术学院,河南安阳455000 [2]郑州大学土木工程学院,河南郑州450001

出　　处：《消防科学与技术》2021年第9期1317-1321,共5页Fire Science and Technology

摘　　要：为了研究高温条件下混凝土力学性能与细观结构的损伤规律,对不同温度影响下的混凝土开展单轴压缩、CT扫描及XRD衍射实验,分析了混凝土高温损伤的细观机理。结果表明:随温度从20℃增加至1000℃,混凝土的抗压强度fcu、弹性模量E呈先慢后快的衰减趋势,且加热时间越长,强度的衰减幅度越高;采用CT扫描探测了混凝土的细观结构损伤程度,随加热温度提高,混凝土内部裂纹的数量和尺寸逐渐增加;混凝土孔隙率随温度升高呈指数型上升趋势,弹性模量与孔隙率呈负相关的线性关系;矿物成分变化规律表明:高温条件下混凝土内部胶凝物质的脱水分解是导致其力学性能损伤的机理。In order to study the strength attenuation characteristics and damage effects of microstructure of concrete under high temperatures,the CT scanning,unconfined compression and XRD diffraction tests were carried out.Meanwhile,the mechanism of concrete damage at high temperatures was analyzed.The experimental results show that the unconfined compressive strength fcu and elastic modulus E of concrete gradually decrease with the increase of temperature from 20℃to 1000℃,and the attenuation rate is first slow and then fast.The attenuation amplitude of unconfined compressive strength and elastic modulus increases with the extension of heating time.The damage degree of concrete meso-structure accumulates gradually in the process of fire development.With the increase of fire temperature,the number and size of concrete cracks increase gradually.The porosity of concrete increases exponentially with the increase of temperature,and the unconfined compressive strength has an obvious negative linear correlation with the porosity.The gradual dehydration and decomposition process of gel materials is the essential mechanism of the high temperature damage effects of concrete.

关 键 词：混凝土 火灾高温 细观结构 弹性模量 

分 类 号：X932[环境科学与工程—安全科学] TU528.01[建筑科学—建筑技术科学]