摘要
对比选取C25喷射混凝土与C30模筑混凝土作为混凝土基体层,制作混凝土基体层-混凝土喷射层的模拟单层衬砌组合试件,通过界面抗压强度、钻芯拉拔及恒压水渗试验及界面水化微观分析,系统地探究了单层衬砌混凝土层间的力学特性及渗透行为。试验结果表明:采用双层湿法喷射工艺成型的单层衬砌组合试件界面粘结区存在力学薄弱区或裂缝缺陷,整体力学强度低于混凝土喷射层;与素喷层体系相比,纤维喷射层体系表现出更高的界面粘结强度(大于1.2 MPa),并与养护龄期遵循良好的抛物线发展规律,这是因为垂直界面粘结区方向纤维分布较多,并通过重排、桥接等方式改善了界面粘结区及组合混凝土整体的抗弯韧性;模筑混凝土基体层后期水化产物中存在丰富的氢氧化钙物相,为混凝土喷射层前期水化物相钙矾石的生成提供了充足的反应物,改善了界面区水化结构的致密性。
By choosing shotcrete with C25 grade and molded concrete with C30 grade as concrete matrix layer,the combined specimens of simulative single-shell lining were prepared and composed of concrete matrix layer and shotcrete layer.Interlayer mechanical characteristics and water permeation behavior of combined shotcrete in single-shell lining were evaluated systematically including compressive strength,pull-cracking strength,water penetration test with constant pressure and interlayer hydration microstructure analysis.The results show that weakened mechanical zones and crack defects among interface bonding area of combined specimens conducted with double wet-mix spraying method are observed,behaving lower mechanical strength integrally compared to that prepared with shotcrete only.Interfacial bond strengths of fiber reinforced combined concrete specimens are higher than that for plain shotcrete,measured with over 1.2 MPa and follow parabolic law with increasing curing age.Flexural toughness and interfacial bonding properties are improved with fiber component introduced because that much more fiber are distri-buted,rearranged and bridged together along vertical direction toward interlayer zones.Massive portlandite phases of C30 molded concrete are observed and promote the initial hydration process of ettringite crystals in shotcrete type,inducing a compact hydration microstructure of interlayer bonding zones.
作者
王伟
霍建勋
曾鲁平
刘伟
王育江
WANG Wei;HUO Jianxun;ZENG Luping;LIU Wei;WANG Yujiang(School of Materials Science and Engineering,Southeast University,Nanjing 211189,China;China Railway Economic and Planning Research Institute,Beijing 100038,China;Jiangsu Sobute New Materials Co.,Ltd.,Nanjing 211103,China;Sichuan-tibet Railway Co.,Ltd.,Linzhi 860000,Xizang,China)
出处
《材料导报》
CSCD
北大核心
2023年第15期86-92,共7页
Materials Reports
基金
中国国家铁路集团有限公司科技研究开发计划(N2020G046,K2020G035)
国家重点研发计划(2020YFC1909900,2021YFB2601000)
江苏省自然科学基金(BK20211030,BK20211031,BK20221199)
国家自然科学基金(52178213)。
关键词
单层衬砌
钢纤维喷射混凝土
界面粘结强度
抗渗性能
single-shell lining
steel fiber reinforced shotcrete
interfacial bond strength
anti-penetrability performance
