摘要
为了探讨高温(600℃范围内)后不同冷却方式时石轻混凝土(GLWC)的物理力学性能变化规律,分别观察了色泽变化、裂纹分布特征和破坏形态,分析了电镜扫描照片,测试了超声波速和特征强度(抗压强度、轴心抗压强度和劈拉强度)。结果表明,石轻混凝土随温度升高,淋水冷却方式较自然冷却时的色泽变化更深、裂纹宽度更大,但其内部在200℃之前并没有裂纹产生(宏观试验时表现为抗压强度增加),而是在300℃以后,裂纹才首先从水泥砂浆内部萌生、扩展,400℃后开始逐渐贯通;除了质量损失率随温度变化规律在两种冷却方式下完全不同以外,超声波速衰减率、特征强度及其折减系数的变化规律则均相同,并具有一致性,但淋水冷却方式时的上述特征参数衰减更快,且仅在500℃以后,淋水冷却方式的强度才基本持平或略高于自然冷却方式时。
To investigate the change rules of physical-mechanical properties of gravel lightweight concrete( GLWC) under two cooling methods after high temperature( no more than 600℃) treatment,the color change,crack distribution characteristics and failure modes are observed,the photos of scanning electron microscope( SEM) are analyzed,and the ultrasonic velocity and the characteristic strength( including cubic compressive strength( fcu),axial compressive strength( fc) and split tensile strength( fts)) are tested. The results show that with the temperature increasing,the color of specimen is deeper and the crack width is larger under spray water cooling method than those under natural cooling method,but there is no inner crack before 200℃( the fcu increasing accordingly),the crack is initiation from the inside of the cement mortar and then expanding after300℃,and the crack starts to joint gradually after 400℃ . Except the change rules of mass loss rate( mL) are completely different under the two cooling methods,those of the ultrasonic velocity attenuation rate( ηv),the characteristic strength( fcu,fc,fts) and the strength reduction coefficient( αT) are same and have the consistency.But the above-mentioned parameters are attenuation much faster when used by spray water cooling method,only the strength is basically same or slightly higher than the natural cooling method after 500℃.
作者
蔺新艳
郭二帅
杨健辉
王钦亭
Lin Xinyan;Guo Ershuai;Yang Jianhui;Wang Qinting(Henan Province Engineering Laboratory for Eco-architecture and the Built Environment,Henan Polytechnic University,Jiaozuo 454000,China)
出处
《建筑科学》
CSCD
北大核心
2021年第7期80-87,共8页
Building Science
基金
国家自然科学基金项目(41172317)
国家“十三五”重点研发计划子课题(2016YF00702101-3)。
关键词
轻骨料混凝土
石轻混凝土
高温
冷却方式
电镜扫描
超声波速
强度折减系数
lightweight aggregate concrete(LWAC)
gravel lightweight concrete(GLWC)
high temperature
cooling method
scanning electron microscope(SEM)
ultrasonic wave velocity
strength reduction coefficient
