摘要
为了研究火灾后轻骨料混凝土的长期稳定性,对经过不同高温煅烧后的混凝土试样开展单轴压缩试验、核磁共振(NMR)扫描试验和扫描电子显微镜(SEM)试验,旨在获取高性能轻骨料混凝土的强度和微观结构损伤特征的关系。结果表明:不同热破裂温度的混凝土试样的强度随温度升高呈指数型衰减;由核磁共振扫描试验测得的试样的T2分布曲线谱面积在100℃~800℃范围内保持增长趋势,且增长的速率随温度升高而逐渐下降;混凝土的抗压强度与T2分布曲线谱面积之间存在负相关的线性关系;由SEM扫描试验表明高温热破裂作用使得混凝土陶粒骨料之间的水泥水化物逐渐分解消失,在混凝土内部逐渐形成尺寸较大的孔隙,进而导致孔隙分布的变化以及强度的渐进衰减。
In order to study the long-term stability of lightweight aggregate concrete after fire,uniaxial compression tests,NMR scanning test and SEM scanning test were carried out on concrete samples calcined at different temperatures.The relationship between the strength and microstructure damage characteristics of high performance lightweight aggregate concrete was studied.The results show that the shear strength of concrete samples decreases exponentially with the increase of fire temperatures.The spectral area of distribution curves of concrete samples measured by nuclear magnetic resonance tests keeps increasing in the temperature range of 100℃~800℃,and the growth rate gradually decreases.A negative linear relationship between the compressive strength of concrete and the spectrum area of T2 distribution curves was observed.The SEM scanning tests show that high temperature thermal fracture causes gradual decomposition and disappearance of the cement hydrate between concrete ceramsite aggregates,and larger pores in the concrete are gradually formed,leading to the change of pore distribution and the attenuation of strength.
作者
刘思勤
李家稳
LIU Siqin;LI Jiawen(North China University of Technology,Beijing 100093,China)
出处
《防护工程》
2019年第5期53-57,共5页
Protective Engineering
关键词
高性能轻骨料混凝土
耐火性
压缩试验
NMR
SEM
high performance lightweight aggregate concrete
fire resistance
uniaxial compression test
NMR
SEM
