砂浆抹灰层对混凝土耐高温性能的影响  

Effects of mortar plastering layer on high temperature resistance of concrete

作　　者：刘炽豪 吴波[2] 陈嘉健[1] 吴沛林 王健 LIU Chihao;WU Bo;CHEN Jiajian;NG Pui-Lam;WANG Jian(Department of Civil Engineering, Foshan University, Foshan 528200, China;State Key Laboratory of Subtropical Architectural Science, South China University of Technology, Guangzhou 510000, China;Department of Civil Engineering, The University of Hong Kong, Hong Kong 999077, China;School of Civil Engineering, Sun Yat-Sen University, Guangzhou 510000, China)

机构地区：[1]佛山科学技术学院土木工程系,广东佛山528200 [2]华南理工大学亚热带建筑科学国家重点实验室,广东广州510000 [3]香港大学土木工程系,香港999077 [4]中山大学土木工程学院,广东广州510000

出　　处：《南京工业大学学报（自然科学版）》2021年第3期329-336,共8页Journal of Nanjing Tech University(Natural Science Edition)

基　　金：广东省重点领域研发计划(2019B111107003);广东省绿色建材与装配式建筑工程技术研究中心开放基金(ZCZX201803);广东省高校省级重点平台和重大科研项目(2018GXJK197)。

摘　　要：混凝土经历高温后会出现不同程度的劣化,并且劣化程度会随着温度的上升而加剧,具体体现为混凝土开裂以及强度下降。混凝土表面的砂浆抹灰层能提高混凝土的耐高温性能,但缺乏针对性研究。为探索抹灰层对混凝土耐高温性能的影响及作用机制,本文通过观察不同抹灰层厚度的混凝土试样在高温环境下的裂缝发展,并测定剩余质量比率、耐高温试验温度、红外温升、超声波脉冲速度、抗压强度及傅里叶变换红外光谱(FTIR),证明抹灰层可以延缓混凝土高温劣化,其效果随着抹灰层厚度增加而增大。砂浆抹灰层通过降低混凝土升温、降温速率和混凝土试件各点的最高温度,进而延缓因高温蒸气压、温度应力以及水化产物热分解导致的高温劣化。试验结果表明:厚度为10和20 mm的抹灰层在600℃下可分别将混凝土强度提升23.65%和50.94%;在800℃下可分别将混凝土强度提升46.72%和161.63%。通过回归分析获得抗压强度与耐高温试验温度、抹灰层厚度的关系式,证明砂浆抹灰层厚度为影响混凝土高温抗压强度的重要因素。因此,在混凝土结构的耐高温研究中,不宜单纯考虑混凝土基体的耐高温性能,应同时考虑抹灰层的保护作用。Deterioration occurs in concrete subject to high temperature and is more serious with temperature rising,which causes cracking and decrease in strength of concrete.The mortar plastering layer on concrete surface may have the ability to improve the resistance to high temperature,whereas little research has been conducted about its effectiveness.In order to systematically reveal this effect and explore the mechanisms behind,experiments are conducted to observe the crack development in concrete samples with various plastering layer thickness,and to measure their residual mass ratio,temperature variation curve,infrared temperature rise,ultrasonic pulse speed,FT-IR(Fourier-tranform infrared spectroscope and compressive strength.Experimental results show that the mortar plastering layer has the effect of mitigating the deterioration of concrete at high temperature,and its effectiveness increases with its thickness.By reducing the rate of temperature change and maximum temperature in concrete specimen,the deterioration caused by high temperature vapor pressure,thermal stress and thermal decomposition of hydration products can be alleviated.The compressive strength increases by 23.65%and 50.94%at 600℃,when the thickness of plastering layer is 10 and 20 mm,respectively.The compressive strength will increase by 46.72%and 161.63%at 800℃,respectively.The relationship between the compressive strength,test temperature and mortar plastering layer thickness is obtained by regression analysis.It is proven that the mortar plastering layer thickness is an important factor affecting the strength of concrete subject to high temperature.Therefore,not only the high temperature performance of concrete matrix but also the effect of protective mortar plastering layer as well,should be considered in the fire resistant design of concrete structure.

关 键 词：水化硅酸钙(CSH)凝胶 混凝土 砂浆抹灰层 耐高温性能 高温劣化 

分 类 号：TU541[建筑科学—建筑技术科学]