高温历程对碱矿渣混凝土残余抗压强度的影响  

Influence of temperature elevation on residual compressive strength of alkali activated slag concretes

作　　者：马倩敏 刘倩 李黎山 秦枭宇 张淼 史天尧 MA Qianmin;LIU Qian;LI Lishan;QIN Xiaoyu;ZHANG Miao;SHI Tianyao(Faculty of Civil Engineering and Mechanics,Key Laboratory of Yunnan Province for Disaster Prevention in Civil Engineering,Kunming University of Science and Technology,Kunming 650500,P.R.China;Yunnan Institute of Industrial Administrators,Kunming 650500,P.R.China)

机构地区：[1]昆明理工大学建筑工程学院,云南省土木工程防灾重点实验室,昆明650500 [2]云南工业干部学院,昆明650500

出　　处：《土木与环境工程学报（中英文）》2024年第5期168-174,共7页Journal of Civil and Environmental Engineering

基　　金：国家自然科学基金(52068038);云南省科技厅基础研究专项-面上项目(202101AT070089);昆明理工大学分析测试基金(2020M20192210078)。

摘　　要：为了探明高温历程对碱矿渣混凝土残余抗压强度的影响,对不同升温速率(5、10℃/min)、恒温时间(1、2 h)和冷却方式(自然冷却、浇水冷却)作用后的碱矿渣混凝土残余抗压强度进行表征,并通过胶凝材料基体微观结构的高温变化对上述强度变化进行分析。结果表明:升温速率较快的情况下,当温度低于400℃时,热应力影响不明显,由于受热时长较短,残余强度较高;随着温度升至800℃,热应力影响显著,混凝土残余强度持续显著降低;800℃之后,热应力达到一定程度,较短的受热时长保证了较高的残余强度。恒温时间的延长会加剧胶凝材料基体结构及基体-骨料界面过渡区的劣化效应,从而引起混凝土残余强度的降低。浇水冷却降低了水化产物C-S-H凝胶的分解温度,并在混凝土内产生热应力,残余强度损失明显。This paper studied the influence of temperature increase rates(5,10 ℃/min),duration at target temperatures(1,2 hours) and cooling methods(natural cooling,water cooling) on the residual compressive strength of alkali activated slag concretes after high temperature.The microstructural change of the alkali activated slag matrix with temperature elevation was also studied to analyze the strength change.The results show that when the higher temperature increase rate was used,within 400 ℃,the influence of thermal stress was not sufficient,and a shorter duration in heat could remain the strength of concretes at a considerable level;with temperature elevation to 800 ℃,residual strength decreased dramatically with the increase of thermal stress;afterwards,thermal stress has achieved a certain extent,and a shorter duration in heat remained the strength.Increase in duration at target temperature has intensified the deterioration of alkali activated slag matrix and matrix-aggregates ITZ,resulting in the decrease of the residual strength.Water cooling has lowered the temperature of C-S-H hydrates to decompose,as well as resulted in thermal stress in concretes,and consequently limited the remain of the residual strength.

关 键 词：碱矿渣混凝土 抗压强度 高温历程 胶凝材料 微观结构 

分 类 号：TU501[建筑科学—建筑技术科学]