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类型 基础研究 预答辩日期 2017-09-20
开始(开题)日期 2010-07-02 论文结束日期 2017-05-18
地点 九龙湖校区材料B楼523会议室 论文选题来源 973、863项目     论文字数 6.4 (万字)
题目 基于微结构的氯离子在混凝土中传输性能研究
主题词 耐久性,传输性能,扩散系数,微结构,多尺度模型
摘要 混凝土的耐久性一直是土木工程领域研究的热点,耐久性包括抗渗性、抗冻性、碳化性能、碱集料反应和抗侵蚀性等,其中环境中的侵蚀介质渗透到混凝土内部引起破坏是混凝土耐久性核心科学问题之一。影响混凝土耐久性的介质主要包括压力水、氯离子、二氧化碳和其他有害的酸碱盐溶液等,而氯盐环境下混凝土抵抗氯离子的渗透能力是关系到钢筋混凝土结构腐蚀问题的关键参数,因此研究氯离子在混凝土中的传输性能具有十分重要的理论意义和工程实用价值。 本课题研究氯离子在混凝土中的传输性能主要从水胶比、矿物掺合料、集料等对混凝土材料微结构的影响入手,建立宏观性能和微观结构之间的有机联系,在不同的尺度选择典型的代表性体积单元,利用均匀化理论通过多尺度过渡途径预测氯离子的传输性能。课题选择的水胶比为实际工程中常用的具有代表性的数值0.23、0.35、0.53;矿物掺合料为粉煤灰和硅灰,粉煤灰的掺量包含10%、30%、50%,硅灰的掺量4%、8%、12%。实验测试了水泥浆体、砂浆、混凝土的抗压强度等力学性能和氯离子扩散系数;通过等温量热实验、非接触式电阻率实验和压汞法研究了水泥浆体水化进程的变化情况;理论上通过Powers模型和J-T(Jennings-Tennis)模型计算了各种水化产物的体积分数,采用CEMHYD3D探究了水泥浆体水化三维结构。氯离子传输性能多尺度的预测模型主要包含四个尺度:第一尺度为水化产物尺度,第二尺度为水泥浆体尺度,第三的尺度为砂浆尺度,第四个尺度为混凝土尺度,利用均匀化理论从微观尺度向宏观尺度推进过渡预测宏观氯离子的传输性能。采用加载设备测试了拉伸荷载作用下氯离子扩散系数的变化。论文取得的主要研究结论和创新性成果包括如下几个方面: (1)水化进程与特征 采用等温量热实验研究了不同水胶比、掺加粉煤灰、硅灰的水泥浆体的放热过程,建立了放热速率和放热程度之间的关系。其中放热分为两部分:水泥的放热和矿物掺合料的后期介入放热,并定义了矿物掺合料的影响临界放热程度;采用非接触式电阻率仪测试了不同水胶比和不同矿物掺合料掺量电阻率随水化时间变化的情况;采用压汞法获得了不同水胶比和不同矿物掺合料掺量在不同龄期的孔隙情况,并通过二次退汞获得了有效孔隙率。 (2)水化产物与微结构演化 根据Powers模型和J-T(Jennings-Tennis)模型计算得到了水泥浆体材料中各相水化产物氢氧化钙、高密度水化硅酸钙、低密度水化硅酸钙、铝铁相、毛细孔和未水化水泥等的体积分数;采用CEMHYD3D模拟了水泥浆体水化过程,计算了水化产物和孔隙孔隙的数量,并重构了三维结构。 (3)多尺度氯离子传输性能预测模型 氯离子传输性能多尺度的预测模型主要包含四个尺度:第一尺度为水化产物尺度(高密度水化硅酸钙、低密水化硅酸钙、氢氧化钙、铝铁相等),第二尺度为水泥浆体尺度(水化产物、毛细孔),第三的尺度为砂浆尺度(水泥浆体、砂子),第四个尺度为混凝土尺度(砂浆、石子、界面过渡区);第一尺度中采用广义自洽理论计算HD C-S-H、LD C-S-H复合后的性能,采用Mori-Tanaka均匀化理论计算C-S-H夹杂了CH、AF混合物性能,采用采用广义自洽理论计算水化产物夹杂了未水化水泥颗粒混合物性能。第二尺度采用传并联模型计算了水化产物夹杂毛细孔的性能,考虑了毛细孔的逾渗效应和曲折度;第三尺度采用Mori-Tanaka均匀化理论计算了水泥浆体中夹杂了细集料砂子;第四尺度采用广义自洽理论计算了粗集料和界面过渡区的夹杂,采用串联模型计算了砂浆中粗集料和界面过渡区复合体的夹杂。 (4)拉伸荷载作用下氯离子传输性能变化 自行设计开发了拉伸加载与电加速氯离子扩散相结合的应力-传输耦合耐久性实验装置,采用该装置研究了不同拉应力水平下混凝土氯离子扩散系数的变化,应用损伤力学原理建立了扩散系数和应力水平的定量关系。
英文题目 The research on transport performance of chloride ion in concrete based on microstructure
英文主题词 durability,transport performance,diffusion coefficient; microstructure,multi-scale model
英文摘要 Durability of cement concrete material is always a major issues and hotspot of research in the field of civil engineering which includes impermeability,frost resistance,carbonation resistance,alkali aggregate reaction and corrosion resistance. In durability aspects impermeability of concrete is an important index to evaluate the durability of concrete which has a close relationship to other properties of durability. The resistance medium of concrete impermeability mainly includes pressure water,chloride ion,harmful gases and other harmful solution of acid,alkali,and alt. In chloride environment,permeability of chloride ion of concrete is a key parameter related to corrosion of reinforced concrete structure,so the study of transport performance of chloride ion in concrete is a project which has practical significance of civil engineering. In the research subject the impacts of transport performance of chloride ion in concrete concludes water binder,ratio,mineral admixture,aggregate which establish organic connections between micro structure and macro properties of cement concrete. The typical representative volume elements are selected in different scale to predict the transport performance of chloride ion using upscaling method and homogenization theory. According to the practical engineering the selection of water binder ratio includes 0.23,0.35,0.53, and the content of mineral admixture fly ash and silica fume includes respectively 10%,30%,50% and 4%,8%,12%. The compressive strength and diffusion coefficient of chloride ion of cement paste, mortar,concrete is tested in experiments. The changes of hydration process of cement pastes are studied by experiments of isothermal calorimetry,non-contact resistivity experiment and mercury porosimetry experiment. The volume fraction of various hydration products is calculated theoretically by Powers model and J-T (Jennings-Tennis) model. Three dimensional microstructures in hydration of cement paste are explored with the open procedures CEMHYD3D hydration program developed by the United States National Institute of standards and Technology (NIST). The prediction model of multi-scale transport performance of chloride ions mainly contains four scales: the first scale for the hydration product scale, second scale for cement paste scale,third scale for cement mortar scale, fourth scale for cement concrete scale. The transport performance of chloride ion is predicted using upscaling method and homogenization theory from microscopic to macroscopic scale. Changes of chloride ion diffusion coefficient of concrete are tested under tensile load by loading equipment specially designed. The main research conclusions and innovative results are as follows. (1)Experimental study of the hydration process An exothermic process of different water binder ratio, different dosage of fly ash, silica fume of cement paste is studied by isothermal calorimetric. The relationship between the hydration heat release rate and hydration heat release degree is established which hydration heat release of mineral admixture is divided into two parts: the hydration heat of cement and intervention of mineral admixture in later period. The critical exothermic degree is defined to describe the influence of mineral admixtures to cement hydration heat. The resistivity changes in hydration process of cement paste with different water binder ratios and different contents of mineral admixtures are tested by non contacting resistivity experiments. The changes of pore in hydration process of cement paste with different water binder ratios and different mineral admixtures are obtained by mercury porosimetry and effective porosity is obtained through two mercury withdrawal experiments in mercury porosimetry experiment. (2) Study on the microstructure of cement in hydration process The volume fraction of each phase of hydration products is obtained according to Powers model and J-T (Jennings- Tennis) model including calcium hydroxide, high density and low density hydrated calcium silicate, aluminum iron phase, pores and unhydrated cement. The volume fraction of hydration product of cement paste mixed with fly ash is calculated using the two component system hydration model proposed by Papadakis. The quantity of each phase in hydration process of cement is studied with the open procedures CEMHYD3D hydration program developed by the United States National Institute of standards and Technology to establish three dimensional microstructures of cement. (3)Prediction model of chloride ion transport performance using multi-scale calculation The multi-scale prediction model of chloride ion transport performance mainly contains four scales: the first scale for the hydration products including high density and low density of hydrated calcium silicate(HD C-S-H, LD C-S-H), calcium hydroxide(CH), aluminum iron phase(AF) etc,the second scale for cement paste including hydration products and capillary pores, third scale for cement mortar scale including cement paste and sand, fourth scale for cement concrete including cement mortar, stone and interfacial transition zone. On the first scale the composite property of HD C-S-H and LD C-S-H is calculated using generalized self consistent theory. The composite property of C-S-H and CH,AF is calculated using Mori-Tanaka homogenization theory. The composite property of hydration products and unhydrated cement particles is calculated by using the generalized self consistent theory. On second scale the composite property of hydration products and capillary pores is calculated by using pass parallel model considering percolation effect and tortuosity of capillary pores. On third scale the composite property of paste and fine aggregate is calculated by using Mori-Tanaka homogenization theory. On fourth scale the composite property of coarse aggregates and interface transition zone is calculated by using the generalized self consistent theory and the composite property of mortar, coarse aggregates and interface transition zone is calculated by using with the series model. (4) Changes of chloride transport performance under tensile load Tensile loading equipment combined with steady electric accelerated chloride ion diffusion instrument is specially designed to study the changes of chloride ion diffusion coefficient of concrete in different stress level and the relationship between stress level and diffusion coefficient by using application of damage mechanics principle.
学术讨论
主办单位时间地点报告人报告主题
东南大学材料学院 2009.06 材料楼225 马立国 硬化混凝土中的界面过渡区
东南大学材料学院 2009.10 材料楼225 马立国 Hydration development and pore structure of the cement-based paste
东南大学材料学院 2010.04 材料楼225 马立国 选择性溶解法研究复合水泥中粉煤灰反应程度
东南大学材料学院 2010.09 材料楼225 马立国 973项目2年工作总结
东南大学材料学院 2009.09 材料楼225 张文华 Experimental study on dynamic tensile behavior of ultra-high performance cementitious composite
东南大学材料学院 2009.09 材料楼225 张文华 Improved Resistivity Measurement
东南大学材料学院 2009.09 材料楼225 佘伟 he microstructure formation mechanism and dynamic behavior of ultra-high performance cementitious composites
东南大学材料学院 2010.09 材料楼225 重庆罗曼科技公司 重庆罗曼科技公司配方的改进
     
学术会议
会议名称时间地点本人报告本人报告题目
第七届全国土木工程研究生学术论坛 2009.10 东南大学榴园 水泥基材料氯离子稳态电迁移实验研究
第十三届纤维混凝土学术会议暨第二届海峡两岸三地混凝土技术研讨会 2010.10 江苏省建科院报告厅 荷载作用下混凝土渗透性能实验方法研究
     
代表作
论文名称
Microstructure-based prediction model for chloride on diffusivity in hydrated cement paste
Study on permeability of concrete under sustaining tension
Study on the effect of fly ash or silica fume to hydration heat of cement
Study on the effect of fly ash to properties of cement admixtures
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
蒋林华 正高 教授 博导 河海大学
高建明 正高 教授 博导 东南大学
朱海堂 正高 教授 博导 郑州大学
余红发 正高 教授 博导 南京航空航天大学
蒋金洋 正高 教授 博导 东南大学
      
答辩秘书信息
姓名职称工作单位备注
佘伟 其他 讲师 东南大学