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类型 基础研究 预答辩日期 2018-03-27
开始(开题)日期 2015-01-09 论文结束日期 2017-12-20
地点 东南大学 榴园宾馆会议室 论文选题来源 国家自然科学基金项目     论文字数 8.0 (万字)
题目 大掺量工业废渣混凝土早期开裂行为研究
主题词 大掺量粉煤灰,大掺量矿渣粉,混凝土,早期开裂,多场耦合
摘要 粉煤灰和矿渣粉是产量较大的工业废渣,在混凝土中大量利用不仅能节约水泥熟料、降低能耗,而且能够减少对环境的污染。然而,大掺量粉煤灰和矿渣粉对混凝土早期开裂的影响机理非常复杂,研究发现存在着正负效应和较大争议;如何正确评价此影响对大量有效的利用工业废渣,促进低碳绿色社会发展具有重要的意义。 目前多数研究是从单一因素,标准条件下的水泥基材料收缩性能角度分析混凝土早期开裂。实验室研究结果与工程实践之间存在很大差异。主要原因在于实际应用中,浇筑成型的混凝土处于水化-温度-湿度-约束多场耦合作用的环境,其早期开裂风险是多因素共同作用的结果。对此,本文开展基于水化-温度-湿度-约束多场耦合机制的大掺量工业废渣混凝土早期开裂行为研究。 重点研究了大掺量粉煤灰和矿渣粉水泥基材料在硬化阶段“水化-温度-湿度”交互作用对其早期性能的影响规律;基于“水化-温度-湿度-约束”多场耦合作用机制建立模型,对大掺量工业废渣混凝土早期开裂风险进行分析。 一、温-湿度场耦合下大掺量工业废渣水泥基材料的早期水化历程研究 通过不同温度、水胶比和掺量条件下微量热试验,热重试验(TG)以及扫描电镜(SEM)分析了大掺量粉煤灰和矿渣粉对于水泥早期水化的影响;大掺量粉煤灰和矿渣粉能有效的促进水泥早期水化。揭示了胶凝体系中粉煤灰和矿渣粉的早期水化机理;7天内矿渣粉水化发展迅速水化度20%左右,而粉煤灰的水化度<5%。 研究了温度-湿度耦合条件下,大掺量粉煤灰和矿渣粉水泥基体系的水化度;高温能够有效的提高大掺量粉煤水泥基材料早期水化度;对于低水胶比大掺量粉煤灰和矿渣粉水泥基材料,提高水胶比对胶凝材料早期水化没有明显促进作用。修正了大掺量粉煤灰和矿渣粉水泥材料早期水化的活化能;建立了温-湿度耦合大掺量粉煤灰和矿渣粉水泥基材料水化模型。 二、多场耦合条件下大掺量工业废渣混凝土早期开裂抗力研究 通过立方体抗压、劈裂抗拉和超声波试验研究了大掺量粉煤灰和矿渣粉对混凝土早期抗压强度、抗拉强度和弹模发展的影响规律;矿渣粉早期水化对混凝土早期强度增长起到了明显促进作用。揭示了温度促进大掺量粉煤灰混凝土早期强度发展的机理;结合修正后的早期水化活化能,基于等效龄期和水化度,修正了大掺量工业废渣混凝土早期强度发展模型。 三、多场耦合条件下大掺量工业废渣混凝土早期变形及驱动力研究 通过自收缩试验、高精度内部湿度仪及毛细管负压试验的同步测试揭示了大掺量粉煤灰和矿渣粉对混凝土早期自收缩的影响机理。大掺量粉煤灰水化度低,延迟了混凝土内部湿度下降时间,减少自收缩;矿渣粉水化度高,消耗相对较多的毛细孔水,导致混凝土内部湿度加速下降,增加自收缩。 试验分析了混凝土早期热变形和热膨胀系数。采用POWERS模型计算大掺量粉煤灰和矿渣粉混凝土早期毛细孔饱和系数,基于温度-湿度-水化耦合机制,修正了多场耦合条件下大掺量工业废渣混凝土自收缩模型。通过温度-应力试验机验证,模型能够较好的模拟多场耦合下大掺量粉煤灰和矿渣粉混凝土早期变形。 通过圆环约束试验分析了大掺量粉煤灰和矿渣粉对混凝土早期应力松弛的影响;大掺量粉煤灰更加明显降低混凝土早期应力松弛系数。建立了指数模型可较准确的得到大掺量粉煤灰和矿渣粉混凝土早期应力松弛系数。 四、温-湿度场耦合下混凝土早期开裂评价模型及开裂行为模拟 在等效应力等理论的基本框架下,结合约束条件及应力松弛,建立了多场耦合作用下大掺量工业废渣混凝土早期开裂的评价模型,对大掺量工业废渣混凝土早期开裂风险进行定量评价。采用有限元分析建模,对实际工程中大掺量工业废渣混凝土侧墙和底板的开裂风险进行评估,并对不同厚度不同浇筑长度条件下的构件开裂风险进行定量分析,为实际工程提供参考。
英文题目 Studies on Cracking Behaviour of High Volume Slag and Fly Ash Concrete at Early Age
英文主题词 high volume fly ash, high volume slag, concrete, early-age cracking, hygro-thermo-chemo-mechanical modelling
英文摘要 Fly ash and slag are two of the largest amount of industrial residue production, and the industrial residue aforementioned could be utilized widely in concrete, not only which could save the cement clinker and decrease the energy consumption, but also could decline the environmental pollution. However, the mechanism of the effect of industrial residue on the cracking behaviour of concrete is very complex and the disputes of researches exist in positive and negative effects. Correctly evaluating the impact of the superposition effect is meaningful to use the industrial residue effectively and promote the development of low carbon green society. From the perspectives of single factor, most researches published in journals focused on the early cracking behaviour of concrete under standard condition. But, there is a great difference between the laboratory research results and the practice of projects because the cast concrete of projects is in the environment coupled temperature, humidity and restrain, the cracking behaviour of that results from the these coupling factors. It is pointed that this study mainly investigates the effect of “hydration-temperature-humidity “coupled factor on the hardened properties of high volume industrial residue concrete. On the basis of the multi-field coupling “hydration – temperature - humidity - constraint” model, the cracking risk of high volume industrial residue concrete is analyzed. 1. Study on the hydration process of high volume slag and fly ash cementitious system under coupling temperature and humidity field Using calorimeter, TG and SEM experimental methods, the effect of high volume of slag and fly ash under different temperature, water to binder ratio and replacement amount condition on cement hydration is studied and results show that the cement hydration is accelerated by the high volume slag and fly ash. Hydration mechanism of slag and fly ash in cementitious system is summarized, it can be seen that the hydration degree of slag can reach to around 20% in age of 7 days while that of fly ash is less than 5%. The investigation of hydration degree of high volume slag and fly ash indicates that the hydration degree of high volume slag and fly ash can be increased but there is no obvious influence on hydration degree of cementitious materials when increasing the ratio of water to cement. On the basis of hydration degree of high volume slag and fly ash cementitious system and the modified hydration activation energy, the high volume slag and fly ash cement system hydration model coupling temperature and humidity is put forward. 2. Study on the early cracking resistance of large volume fly ash and slag under coupling multi-fields The study investigate the impact of high volume slag and fly ash on the evolution of compressive strength, flexural strength and the elastic modulus by cube compression, splitting tensile and ultrasonic testing methods. The results show that the hydration process of slag has played a significant role in promoting the compressive strength of high volume fly ash concrete in early period. Based on the experimental results, the mechanism of promoted early compressive strength is disclosed. Combining the modified early hydration activation energy, equivalent age and the hydration degree are utilized to modify the strength evolution model of high volume industrial residue concrete. 3. Study on the early deformation and its driving force of large volume fly ash and slag under coupling muti fields The effect of high volume slag and fly ash addition on autogenous shrinkage is investigated using non-contact electriceddy transducer, internal humidity and capillary pressure. And the results indicate that the autogenous shrinkage of high volume slag cement paste is reduced because of the decrease hydration degree of fly ash which can delay the occurrence of decreased internal humidity. On the other hand, slag can increase the autogenous shrinkage which can be attributed to the reason that the higher hydration degree results in higher consumption amount of capillary water and the decreased internal humidity. Early thermal deformation and thermal expansion coefficient of concrete was analyzed based on experiments. In order to modify the autogenous shrinkage model of high volume slag and fly ash concrete under the multi-field condition, on the basis of coupling mechanism of temperature and hydration, the early saturation coefficient of capillary is adopted by POWERS model and the multi-field deformation model of concrete is verified by the temperature stress tester experiments. To evaluate the influence of high volume fly ash and slag on early stress relaxation, the steel- ring tests are applied, which shows that large amount of fly ash obviously reduces the early stress relaxation coefficient of concrete. The exponential model is proposed based on the experimental results and it can be used to predict the stress relaxation coefficient of high volume slag and fly ash in early period. 4. Study on evaluation model of early cracking of concrete and the simulation of cracking behaviour of concrete under coupled temperature and humidity field Under the theoretical framework of equivalent stress, an evaluation model taking the restraint and the stress relaxation condition into consideration for early cracking of high volume slag and fly ash concrete is established. It is used to evaluate cracking risk of high volume industrial residue concrete in practical projects.
学术讨论
主办单位时间地点报告人报告主题
江苏苏博特股份有限公司 2012.10.07-10.12 江苏博特研发中心(南京) RILM 2012 混凝土多尺度模拟国际博士课程
东南大学材料学院 2013.02.26 东南大学材料学院A楼601 许国东 Time-dependent mechanics of cement concrete composites
东南大学材料学院 2013.07.27 东南大学材料学院B楼432 许国东 Developing infiltration testing methods for pervious concrete
中国工程院化工、冶金与材料工程学部 2013.12.21 金陵江滨国际酒店(南京) 中国工程院化工、冶金与材料工程学部专家 “基础设施耐久性与可持续发展工程前沿技术研究”学术研讨会
东南大学土木工程院 2014.05.27 东南大学土木学院701 许国东 红外热成像检测技术在工程中的应用
东南大学土木工程院 2014.11.27 东南大学土木学院701 许国东 孔隙湿度对混凝土弹性模量的影响
东南大学 2016.10.24-10.26 金陵江滨国际酒店(南京) RILM The 3rd International Conferences on Microstructure Related Durability of Cementitious Composites
混凝土外加剂专业委员会 2014.11.13-14 金陵江滨国际酒店(南京) 混凝土外加剂专业委员会 “第十二届混凝土外加剂专业委员会年会”暨“混凝土外加剂新技术及其应用学术交流会”
     
学术会议
会议名称时间地点本人报告本人报告题目
CONSEC 2016 2016.09.11-09.16 意大利米兰 The Interaction of C-S-H and Chlorides——Experimental and Molecular Dynamics Studies
23rd Plenary Meeting of ISO/TC 71 2017.09.25-09.28 日本札幌 The Performance Tests of Pervious Concrete
     
代表作
论文名称
Early-age hydration and mechanical properties of high volume slag and fly ash concrete at different
 
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
陆采荣 正高 教授 博导 南京水利科学研究院
高建明 正高 教授 博导 东南大学
钱春香 正高 教授 博导 东南大学
白云 正高 教授 博导 伦敦大学学院(UCL)
肖鹏 正高 教授 博导 扬州大学
      
答辩秘书信息
姓名职称工作单位备注
冯攀 其他 讲师 东南大学