摘要
针对高温后混凝土力学性能衰弱的特性,采用递进循环式加热法对混凝土进行加热,分析高温后混凝土力学性能变化规律;并利用德国蔡司508体式显微镜,监测高温后混凝土表面孔隙直径、热膨胀裂纹扩展规律;最终从表观特征角度阐述其力学性能衰弱机理,结果表明:①混凝土的抗压强度随着温度升高而降低,且呈线性衰弱;②20-200、200-400 ℃阶段混凝土相对质量烧失率最大,均在3%左右;400-600、600-800 ℃阶段混凝土相对质量烧失率较小,均在1%左右;③导致强度降低的主要因素:20-200 ℃阶段,混凝土宏观表现为直径1-2 mm表面孔隙和长度4-10 mm孔隙周围裂纹增多;200-400 ℃,混凝土宏观表现为直径1-2 mm的表面孔隙、4-10 mm裂纹和长度大于10 mm的孔隙周围裂纹增多;400-600、600-800 ℃阶段,混凝土宏观表现为直径大于2 mm表面孔隙和长度大于10 mm孔隙周围裂纹增多。
Aiming at the characteristics of mechanical properties decay of concrete after high temperature fire,heated by progressive cyclic heating method to analyze the change law of mechanical properties of concrete after high temperature.Then using the German Zeiss 508 Body Microscope to monitor the change of pore diameter and thermal expansion crack length on concrete surface after high temperature.Finally,the mechanism of weakening mechanical properties is expounded from the aspect of apparent characteristics.The results showed that ①The compressive strength of concrete decreases with the increase of temperature,which is linear decay.②The relative mass loss rate of concrete is the largest in 20-200 ℃ and 200-400 ℃ stages,all at about 3%.The relative mass loss rate of concrete at 400-600 ℃ and 600-800 ℃ was relatively small,all around 1%.③Main factors of strength reduction:20-200 ℃ stage,the macroscopic performance of concrete is the increase of the surface porosity of 1-2 mm in diameter and the crack of 4-10 mm.200-400 ℃ stage,the macroscopic performance of concrete is the increase of the surface porosity of 1-2 mm in diameter,the crack of 4-10 mm and more than 10 mm.400-600,600-800 ℃ stage,the macroscopic performance of concrete is the increase of the surface porosity greater than 2 mm in diameter and the crack with a length greater than 10mm.
作者
戎虎仁
顾静宇
曹海云
王大路
王占盛
董浩
张佳瑶
RONG Huren;GU Jingyu;CAO Haiyun;WANG Dalu;WANG Zhansheng;DONG Hao;ZHANG Jiayao(Road College,Chang′an University,Xi′an 710061,China;Hebei Institute of Architecture and Civil Engineering,Hebei University of Architecture,Zhangjiakou 075000,China;Hebei Institute of Art and Architecture,Hebei University of Architecture,Zhangjiakou 075000,China;TieErYuan in Institute of Science and Technology,Chengdu 610000,China;Qinghai Provincial Institute of Transportation Science,Xining 810016,China)
出处
《混凝土》
CAS
北大核心
2019年第7期1-5,共5页
Concrete
基金
青海省自然科学青年基金（2018-ZJ-955Q,2018-ZJ-959Q）
河北省教育厅科技青年基金（QN2016066）
河北建筑工程学院校级基金（B-201602）
关键词
高温
混凝土
孔隙
裂纹
high temperature
concrete
pore
the crack
作者简介
第一作者: 戎虎仁(1986-),男,讲师,博士,博士后,硕士生导师,主要研究方向:固体材料微观结构损伤、隧道地质灾害突变防治等方面研究。联系地址: 河北省张家口市朝阳西大街13号 河北建筑工程学院土木工程学院(075000);通讯作者:顾静宇(1995-),女,硕士,硕士研究生,主要研究方向:桥梁与隧道工程、高温环境下混凝土灾变方向研究。联系电话:15532393397
