摘要
在速凝剂作用下,喷射混凝土水化硬化速度加快,其微观结构和力学性能与普通浇筑混凝土存在显著差异,继而对其耐久性能产生极大影响。试验采用X射线衍射分析、综合热分析及扫描电子显微镜等微观表征技术与方法,对隧道喷射混凝土的水化产物物相组成及其相对含量变化和喷射混凝土水化硬化过程进行研究。结果表明:喷射混凝土与浇筑混凝土水化产物的物相组成相同,但主要水化产物的衍射峰强度及其失重百分比的变化规律显著不同。速凝剂水解加速了水泥中石膏的溶解,铝酸三钙、铁铝酸四钙及硅酸三钙快速水化形成水化硫铝酸钙、水化铁铝酸钙及水化硅铝酸钙,其晶体相互交叉形成网络结构加快了喷射混凝土的凝结时间并产生初始强度。硅酸钙类熟料矿物持续水化及粉煤灰火山灰效应生成的水化硅酸钙填充网络空隙为喷射混凝土后期强度增长提供了动力。早龄期喷射混凝土力学性能高于浇筑混凝土,养护龄期大于1d,浇筑混凝土力学性能超过喷射混凝土且与喷射混凝土力学性能差距增大。喷射混凝土力学性能与养护龄期之间呈对数关系。
Under the effect of accelerators,shotcrete has a higher hydration rate and is significantly different from forming concrete in microstructure and mechanical properties,which in turn has significant influence on shotcrete’s durability.X ray diffraction,thermal analysis and scanning electron microscopy are employed to examine the mineral composition and the relative weight loss rate of thE-mailn hydration products as well as the hydration and hardening process of shotcrete.And also the relationship between the hydration process and curing age is analyzed.The results show that shotcrete and forming concrete are similar in mineral composition,but significantly different in the changing law of the diffraction peak’s relative strength and the relative weight loss rate of thE-mailn hydration products.The hydrolysis of accelerators accelerates the dissolution of CaSO 4 in cement,and rapid hydration of C 3A,C 4AF,and C 3S forms hydrated calcium sulfoaluminate,hydrated calcium alumino ferrite and hydrated calcium aluminosilicate.Their needle like crystals cross each other to form a network structure,which accelerates the setting time of shotcrete and produces initial strength.Furthermore,hydration products of C-S-H from the continuously hydration of calcium silicate clinker minerals and pozzolanic reaction of fly ash fill the voids and pores in the network,which enhances the strength of shotcrete at the later stage.The mechanical properties of early shotcrete are superior to those of forming concrete.As the curing age exceeds more than 1d,the mechanical properties of forming concrete becomes better than shotcrete’s,and the gap between them increases with the curing age.In addition,there is a logarithmic relationship between the mechanical properties of shotcrete and the curing age.
作者
刘东明
李合银
代磊
韩云飞
王家滨
LIU Dongming;LI Heyin;DAI Lei;HAN Yunfei;WANG Jiabin(CCCC SHEC Fourth Engineering Co.,Ltd.,Luoyang 471013,China;School of Civil&Architecture Engineering,Xi’an Technological University,Xi’an 710021,China)
出处
《西安工业大学学报》
CAS
2024年第5期556-565,共10页
Journal of Xi’an Technological University
基金
陕西省自然科学基金(2024JC-YBMC-268)。
关键词
隧道工程
喷射混凝土
微观结构
水化硬化过程
力学性能
tunnel engineering
shotcrete
microstructure
hydration process
mechanical properties
