【作者】 曾俊杰；

【导师】 水中和；

【作者基本信息】 武汉理工大学 ， 材料学， 2012， 博士

【摘要】 预应力高强混凝土管桩(prestressed high-strength concrete pipe pile,简称PHC管桩)是现阶段最常用于建筑基础的混凝土构件,其具有高强度、高密实性、高承载力等优点,被广泛地应用于工业与民用建筑、公路与铁路交通、港口与码头等各类工程建设。目前的PHC管桩生产主要采用先常压蒸汽养护后高温高压蒸养的养护工艺,生产过程中养护能耗高。与此同时,随着经济社会的迅速发展,资源短缺与环境污染日趋严重,节能减排成为建筑行业乃至整个社会关注的焦点。另外,随着混凝土工程环境的复杂化,传统的PHC管桩能否适用于海洋、盐碱、寒冷等恶劣环境下的土建工程,有待深入系统的研究。鉴于此,本文针对PHC管桩养护能耗高、耐久性不足等问题,开展高强高性能管桩混凝土节能制备技术研究。作者对PHC管桩混凝土材料体系进行了优化设计,探索适用于该体系的免压蒸节能养护工艺,并系统研究了蒸汽养护条件下高强管桩混凝土的凝结硬化性能,揭示了蒸养条件下混凝土耐久性形成机理,掌握了高强高性能管桩混凝土节能制备的关键技术。论文进行的主要工作和取得的主要成果如下：(1)研究了偏高岭土对混凝土凝结硬化性能的影响,结果认为偏高岭土能缩短混凝土凝结时间,显著提高混凝土早期和后期强度,其合理掺量为10%～15%,偏高岭土的应用会增加混凝土的用水量,因此不宜作为唯一矿物掺合料进行高强管桩混凝土的制备。(2)分别采用胶凝材料复合化和颗粒密实堆积模型两种手段进行高强高性能管桩混凝土胶凝材料体系设计,结果表明以水泥和偏高岭土、矿粉、粉煤灰、石粉等矿物掺合料组成的多元胶凝体系具有良好的火山灰活性和密实作用,凝结硬化性能良好,满足高性能管桩混凝土工作性及高、早强力学性能要求。(3)系统研究了静停时间、升温速率、养护温度、保温时间等工艺参数对蒸养高强混凝土凝结硬化性能的影响：延长静停时间、降低升温速率、控制合理的养护温度和保温时间能有效提高蒸养混凝土抗压强度,其中静停时间和升温速率对混凝土强度影响较为显著,养护温度和保温时间次之。通过以上研究,掌握了满足高强高性能管桩混凝土免压蒸生产的蒸汽养护工艺。(4)对高强高性能管桩混凝土整体材料体系进行了设计,探索了适用于节能养护工艺的高强管桩混凝土配合比参数和混凝土制备工艺,掌握了满足PHC管桩性能要求的高强高性能管桩混凝土节能制备新技术。(5)分别对蒸汽养护和标准养护条件下高强混凝土耐久性进行了对比研究,探明了胶凝体系组成和养护条件对高强混凝土耐久性的影响规律：蒸汽养护对高强混凝土耐久性有不良影响,表现为增加混凝土渗透性,降低混凝土抗冻和耐侵蚀性能等。采用多元复合胶凝体系能显著改善高强混凝土的各项耐久性能,所制备的高强高性能管桩混凝土耐久性良好。(6)系统研究了蒸汽养护条件下高强混凝土的显微结构特征,揭示了多元复合胶凝材料体系对蒸养高强管桩混凝土显微结构的影响规律,揭示了高强管桩混凝土强度和耐久性形成机理：复合矿物掺合料促进了蒸养条件下混凝土早期水化进程,改善了水化产物的物相组成和结构特征；优化了混凝土的孔结构,细化了孔径,降低了蒸汽养护对混凝土孔结构造成的热致损伤；改善了蒸养高强混凝土的界面过渡区性能,提高了界面区结构的完整性,优化了浆体与集料的结合状态,降低了高强混凝土界面孔隙率。(7)将所研究的高强高性能管桩混凝土节能制备技术应用到实际生产中,中试结果表明：该节能制备技术工艺流畅,所生产的产品外观质量良好,满足PHC管桩力学性能要求,理论计算表明,可降低PHC管桩养护能耗70%以上,具有较好的推广应用前景。更多还原

【Abstract】 Prestressed high-strength concrete (PHC) pipe piles are the most widely used concrete members in building foundations nowadays. They are widely used in all kinds of engineering projects, such as industry and civil buildings, highway and railway, port and wharf constructions, due to the advantages of high strength, high density and high bearing capacity. In traditional manufacturing process, the curing condition of PHC piles is consist of steam curing and autoclaved curing, which requires large amount of energy. At the same time, the resources shortage and environmental pollution are more and more serious due to the development of economy and society. Energy conservation and pollution reduction become the focus of the construction industry and society. In addition, the concrete engineering environment is becoming more and more complex. Further investigation is needed about whether PHC piles can be applied to some harsh environmental conditions, such as sea water, saline-alkali and cold.Therefore, the paper focuses on the high energy consumption and insufficient durability of PHC piles, and an energy-saving manufacturing technique of high performance piles concrete with high strength is studied. A new concrete materials system and energy-saving curing process of PHC are designed. The setting and hardening performance and durability development of PHC under steam curing condition are investigated. An energy-saving manufacture technique of high performance PHC is obtained.The main work and results of the paper may be summarized as follows.(1) The influence of metakaolin to the setting and hardening performance of concrete is investigated, and the results indicate that concrete setting time is shortened by metakaolin and the early and latter strength can be enhanced. The appropriate dosage of metakaolin is between10%and15%. In addition, the water demand of concrete is increased by metakaolin and it is not appropriate to use metakaolin as the only mineral admixture in the preparation of high performance PHC.(2) Cementitious materials composite technique and particles density packing model are adopted to design the high performance PHC materials system. It is concluded that the complex cementitious material systems, consist of cement, metakaolin, slag, flay ash and limestone powder, may exhibit satisfied pozzolanic activity and filler effect. Concrete with the complex cementitious material systems perform high and early strength. Meanwhile, the workability of the concrete is satisfied.(3) Influence of steam curing parameters such as delay time, heating-up rate, thermostatic period and thermostatic temperature on hardening performance of high-strength concrete is studied. The results reveal that concrete strength can be improved with a longer delay time, a lower heating-up rate, an appropriate thermostatic period and thermostatic temperature. Furthermore, it is noted that the influence of delay time and heating-up rate on concrete strength are prominent, followed by thermostatic period and thermostatic temperature. Based on the systematic research, a non-autoclaved energy-saving curing technique for the manufacture of PHC piles is obtained.(4) The whole materials system of high performance PHC is designed in the paper. The mixture parameters and preparation process under energy-saving curing condition are researched. Based on the research above, a new energy-saving manufacture technology of high performance PHC is conducted.(5) The durability of high-strength concrete subjected to steam curing and standard curing is investigated comparatively. The influence of cementitious system and curing conditions on high-strength concrete durability is studied. It is concluded that permeability resistance, frost resistance and sulphate resistance of concrete is decreased by steam curing. However, the application of complex cementitious materials system can improve the durability of steam cured high-strength concrete and the durability of the PHC prepared with the energy-saving technique is satisfied.(6) The microstructure of steam cured high-strength concrete is researched systematically. The influence of the complex cementitious materials system on microstructure of steam cured concrete is investigated. The results show that the complex mineral admixtures promote concrete hydration, improve the composition and structure of hydration products. Pore structure is refined and improved while the damage to pore structure caused by steam curing is eliminated. The ITZ performance is improved and the bong performance of the pate and aggregate is enhanced. Meanwhile, the porosity of interface between paste and aggregate is decreased.(7) The energy-saving manufacture technique of high performance PHC was adopted in the practical production. The pilot test shows that the energy-saving manufacture technique can be conducted successfully. The mechanical properties and appearance quality of the energy-saving produced PHC piles are satisfied. The energy consumption in the curing process is decreased by70%, compared with the traditional curing condition. The promotion and application prospect of the new technique is optimistic.更多还原