高温环境下堆坑混凝土劣化行为研究  

Investigation on the degradation behaviors of pit concrete exposed to high temperature

作　　者：陈森 李浩 王振 张昆桥 张文斌 罗华清 张伟 CHEN Sen;LI Hao;WANG Zhen;ZHANG Kunqiao;ZHANG Wenbin;LUO Huaqing;ZHANG Wei(China Nuclear Power Operation Technology Co.,Ltd.,Wuhan 430000,China)

机构地区：[1]中核武汉核电运行技术股份有限公司,湖北武汉430000

出　　处：《混凝土》2023年第11期53-57,共5页Concrete

基　　金：国家重点研发计划(2019YFB1900903)。

摘　　要：为有效评估高温条件下核电基础设施的服役安全性,研究了不同温度(25~400℃)及持续时间(0.5~30 d)对堆坑混凝土水化产物、孔结构、质量损失及力学性能的影响。结果表明:试验温度与持续时间的增加会促进堆坑混凝土中钙矾石(AFt)和C-S-H等特征水化产物分解,提升有害孔含量;堆坑混凝土的质量损失率随试验温度和龄期增加而增加;当热老化温度不高于80℃时,随试验温度和龄期增加,混凝土的抗压强度有小幅提升的趋势;当温度为300℃、400℃时,混凝土的抗压强度与温度和龄期呈反比,降低趋势明显;水化产物分解以及孔结构特征变化与混凝土力学性能降低具有较高的相关性。最后基于试验结果,建立了考虑温度和持续时间耦合作用的堆坑混凝土本构模型,可为高温条件下混凝土力学性能的预测评估提供基础。In order to effectively evaluate the service safety of nuclear power infrastructure under high temperature conditions,it studies the effects of temperature from 25℃to 400℃and durations from 0.5 d to 30 d on the hydration products,pore structure,mass loss and mechanical properties of the concrete applied in the reactor pit.The results show that the increase of temperature and duration promote the decomposition of typical hydration products such as AFt and C-S-H,and increase the content of harmful pores.The mass loss of concrete increases with the increase of test temperature and age.When the temperature is no higher than 80℃,the compressive strength of concrete slightly increases with the increase of the test temperature and age,and when the temperature is 300℃and 400℃,the compressive strength is negatively related with temperature and age,and the strength reduction becomes more obvious.The decomposition of hydration products and the change of pore structure characteristics exhibit high correlations with the decrease of mechanical properties of concrete.Finally,based on the test results,a constitutive model of concrete considering the coupling effect of temperature and duration is established,which can provide a reference for the prediction of concrete performance under complicated high temperature conditions.

关 键 词：高温环境 堆坑混凝土 物相组成 抗压强度 本构模型 

分 类 号：TU528.01[建筑科学—建筑技术科学]