摘要
采用喷大板法制做C20喷射混凝土试件,使用压力试验机对经历不同冻融循环次数的试件进行了抗压和抗拉强度测试,分析冻融循环作用下其变化规律,采用共振法和超声波法对经历不同冻融循环次数的喷射混凝土进行动弹性模量测试,分析其抗冻耐久性,并对经历不同冻融循环次数下的试件外观进行了描述。研究结果表明:冻融对喷射混凝土的抗拉和抗压强度影响较大,随着冻融循环次数的增加,抗拉和抗压强度衰减程度增大,相对动弹性模量也逐渐衰减,呈线性降低趋势;C20喷射混凝土的相对耐久性指数非常低,经历50次冻融循环后的耐久性指数为10.1%,与C20普通混凝土相比,其相对耐久性指数更低,抗冻耐久性更差;C20喷射混凝土经历75次冻融循环后出现严重的酥碎剥落情况,不能满足工程抗冻性要求。
At a road tunnel construction site, C20 shotcrete samples were made by using the spray large panel. The compressive strength and tensile strength of the samples which experienced different times of freeze-thaw cycles were tested by pressure testing machine to analyze the compressive and tensile strength variation of the shotcrete under freeze-thaw cycles, and the dynamic modulus of elasticity of the samples experiencing different times of freeze-thaw cycles were tested by resonance method and ultrasonic method to analyze the frost resistance durability. Besides, there were descriptions about the appearance of samples experiencing different freeze- thaw cycles. The result indicates that the freeze-thaw has a great influence on the tensile strength and compression strength of shotcrete, the degree of attenuation of tensile strength and compression strength increases gradually with the increasing cycles, the relative dynamic elastic modulus of the shotcrete gradually decreases linearly with increasing cycles, and the relative durability index of C20 shotcrete is 10. 1% after 50 freeze-thaw cycles, which is lower than normal C20 concrete, so the frost resistance durability of shotcrete is worse. C20 shotcrete gets heavy spalling after 70 freeze-thaw cycles, which could not meet the freeze resistance demand of engineering.
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2012年第5期113-119,共7页
China Journal of Highway and Transport
基金
国家自然科学基金项目(51078040)
交通运输部西部交通建设科技项目(2007 318 812 67)
教育部新世纪优秀人才支持计划项目(NCET-07-0118)
关键词
隧道工程
喷射混凝土
冻融循环
动弹性模量
抗冻耐久性
tunnel engineering
shotcrete
freeze-thaw cycle
dynamic modulus of elasticity
frost resistance durability
