火灾高温对混凝土残余强度和微观结构的影响  

Effect of High Temperature on Residual Strength and Microstructure of Concrete

作　　者：宋宝峰[1] 李和玉[2] 张淑芬[1] 王保权[1] SONG Baofeng;LI Heyu;ZHANG Shufen;WANG Baoquan(College of Urban Construction,Eastern Liaoning University,Dandong 118003,China;College of Urban Construction,Heilongjiang Forestry Vocation-Technical College,Mudanjiang 157011,China)

机构地区：[1]辽东学院城市建设学院,丹东118003 [2]黑龙江林业职业技术学院城市建设学院,牡丹江157011

出　　处：《硅酸盐通报》2020年第11期3522-3527,共6页Bulletin of the Chinese Ceramic Society

基　　金：辽宁省高校自然科技基金(2302017FRF-TP-17-027A1)。

摘　　要：为了研究混凝土力学性能和微结构的耐火性特征,对混凝土试件进行不同高温的加热作用,然后开展相应的三轴压缩试验和CT扫描试验。结果表明,随着加热温度增加,混凝土试样的三轴试验峰值强度逐渐减小;在相同温度下,试件的残余峰值强度随固结围压增大呈线性上升趋势;根据CT扫描试验获得的混凝土二维/三维图像发现混凝土的孔隙度和平均孔隙半径随着温度增大而逐渐上升;混凝土的残余强度随温度升高存在明显劣化效应,其原因是作用于混凝土试件的温度越高,混凝土内部高温裂解效应越明显,导致孔隙体积增加,从而使得热裂解后的残余强度相对降低。本试验研究结果为深入认识粉煤灰混凝土耐火性的特征提供了参考。In order to study the concrete mechanical properties and the fire resistance characteristics of the microstructure,the concrete specimens were heated at different high temperatures,and then the corresponding triaxial compression tests and CT scan tests were carried out.The results show that as the heating temperature increases,the peak strength of the concrete specimen in the triaxial test gradually decreases.At the same temperature,the residual peak strength of the specimen increases linearly with the increase of the consolidated confining pressure.Obtained from the CT scan test,the 2D/3D images of concrete show that the porosity and average pore radius of concrete gradually increase with increasing temperature.The residual strength of concrete has obvious degradation effect with increasing temperature,the reason is that the higher the temperature acting on the concrete specimen.The more obvious the high-temperature cracking effect inside the concrete,the more the pore volume increases,and the lower the residual strength after thermal cracking.The results of this experiment provide a reference for in-depth understanding of the characteristics of the fire resistance of fly ash concrete.

关 键 词：粉煤灰混凝土 火灾高温 三轴试验 CT扫描试验 

分 类 号：TU43[建筑科学—岩土工程]