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多因素下地铁混凝土耐久性试验
引用本文:乔宏霞,路承功,师莹莹,罗小博.多因素下地铁混凝土耐久性试验[J].重庆大学学报(自然科学版),2018,41(3):32-41.
作者姓名:乔宏霞  路承功  师莹莹  罗小博
作者单位:兰州理工大学 甘肃省土木工程防灾减灾重点实验室,兰州 730050;兰州理工大学 西部土木工程防灾减灾教育部工程研究中心,兰州 730050 陕西建筑产业投资集团有限公司,西安,710016 兰州理工大学 甘肃省土木工程防灾减灾重点实验室,兰州,730050
基金项目:国家自然科学基金资助项目(51168031,51468039);中铁一勘院科研开发基金(13-24-01)。
摘    要:综合考虑地铁沿线复杂的气候特点和腐蚀环境,在室内设计了考虑紫外线照射、干湿循环、冻融循环、硫酸盐及镁盐腐蚀的大循环试验,对3种水胶比和3种粉煤灰掺量共5种配合比的混凝土进行了耐久性试验,通过试件表观现象、抗压强度值、相对质量评价参数、相对动弹性模量评价参数及考虑质量和动弹性模量的综合损伤评价参数等评价指标,对地铁混凝土耐久性能进行了评价,同时,结合X射线衍射(XRD)和扫描电镜(SEM)分析了多因素下混凝土损伤劣化机理,结果表明:在室内大循环下混凝土试件发生了复杂的物理化学反应,生成膨胀性产物钙矾石、石膏晶体及无胶结性能的M-S-H,受到温度应力、胀缩应力、膨胀压力及盐结晶压力等复合力的共同作用,整个循环周期内呈现出初期强化、初步劣化及后期加速劣化的侵蚀特点,考虑质量和超声波波速的综合损伤评价指标,能够客观准确地反应混凝土宏观性能和内部微观结构,结果显示,水胶比为0.35,粉煤灰掺量30%的混凝土耐久性最佳。

关 键 词:地铁混凝土  干湿-冻融循环  硫酸盐腐蚀  镁盐腐蚀  耐久性
收稿时间:2017/9/27 0:00:00

Experiments on the durability of subway concrete under multi-factors
QIAO Hongxi,LU Chenggong,SHI Yingying and LUO Xiaobo.Experiments on the durability of subway concrete under multi-factors[J].Journal of Chongqing University(Natural Science Edition),2018,41(3):32-41.
Authors:QIAO Hongxi  LU Chenggong  SHI Yingying and LUO Xiaobo
Institution:Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province, Lanzhou University of Technology, Lanzhou 730050, P. R. China;Western Center of Disaster Mitigation in Civil Engineering of Ministry of Education, Lanzhou University of Technology, Lanzhou 730050, P. R. China,Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province, Lanzhou University of Technology, Lanzhou 730050, P. R. China;Western Center of Disaster Mitigation in Civil Engineering of Ministry of Education, Lanzhou University of Technology, Lanzhou 730050, P. R. China,Shanxi Construction Industry Investment Group Co., Ltd., Xi''an 710016, P. R. China and Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province, Lanzhou University of Technology, Lanzhou 730050, P. R. China
Abstract:Based on the comprehensive consideration of the complex climatic characteristics and corrosion environment along the metro line, simultaneously considering ultraviolet radiation, wet and dry cycles, freeze-thaw cycles, sulfate and magnesium salt corrosion, a large cycle indoor test is designed and durability tests are carried out on 5 kinds of concrete including 3 water binder ratio and 3 fly ash content. The durability of the subway concrete is evaluated through the apparent phenomenon, compressive strength value, the relative quality evaluation parameters, the relative dynamic elastic modulus evaluation parameters, and the comprehensive damage assessment parameters. The damage degradation mechanism of concrete under multi-factors is analyzed by means of X ray diffraction (XRD) and scanning electron microscopy (SEM) with considering the quality and dynamic elastic modulus and the micro image. The results show that concrete specimens under indoor large cycle have complex physical and chemical reactions, generate expansive products, i.e. ettringite and gypsum crystals, and products without cementing performance, i.e. M-S-H. And the same time, they are subjected to the combined action of temperature stress, expansion and contraction stress, swelling pressure and salt crystal pressure and take on the erosion characteristics of initial strengthening, preliminary deterioration and accelerated degradation later. The comprehensive damage evaluation index of quality and dynamic elastic modulus can more objectively and accurately demonstrate macro performance and microstructure of concrete. The durability of the specimen with water cement ratio of 0.35 and fly ash content of 30% is the best.
Keywords:subway concrete  wet and dry-freezing and thawing cycle  sulfate corrosion  magnesium salt corrosion  durability
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