道路桥梁专业论文汉译英.doc

高性能混凝土的研究与发展现状1 引 言从1824年波特兰水泥发明开始，混凝土材料至今已有100多年的历史，以水泥为胶结材的混凝土也取得了具大的发展，由普通混凝土向高性能混凝土发展。从20世纪以来，混凝土就己成为房屋建筑、桥梁、水利、公路等现代工程结构首选材料，混凝土作为土木工程中最大宗的人造材料，其用量巨大。据统计，当今我国每年混凝土用量约109m3，并且随着我国近年来工业化、城市化进程的加快，其用量将继续快速增长。人类进入21世纪，随着科学技术的快速发展，一种又一种新型混凝土涌现出来。混凝土能否长期作为最主要的建筑结构材料，其本身必须具有高强度、高工作性、高耐久性等性能，因此高性能混凝土是现代混凝土技术发展的必然结果，是混凝土的发展方向。高性能混凝土(High Performance Concrete，HPC)是20世纪80年代末90年代初，一些发达国家基于混凝土结构耐久性设计提出的一种全新概念的混凝土，它以耐久性为首要设计指标，这种混凝土有可能为基础设施工程提供100年以上的使用寿命。区别于传统混凝土，高性能混凝土由于具有高耐久性、高工作性、高强度和高体积稳定性等许多优良特性，被认为是目前全世界性能最为全面的混凝土，至今已在不少重要工程中被采用，特别是在桥梁、高层建筑、海港建筑等工程中显示出其独特的优越性，在工程安全使用期、经济合理性、环境条件的适应性等方面产生了明显的效益，因此被各国学者所接受，被认为是今后混凝土技术的发展方向。2 高性能混凝土产生的背景和研究现状2.1 背景 当代大跨、高层、海洋、军事工程结构的发展对混凝土提出的更高的要求;处在恶劣环境下既有建筑不断劣化、退化导致过早失效、退役甚至出现恶性事故造成巨大损失的严重后果;原材料生产、开采造成的生态环境恶化以及砂石料枯竭、资源短缺严重影响进一步发展的严酷现实。这就要求混凝土不断提高以耐久性为重点的各项性能, 多使用天然材料及工业废渣保护环境, 走可持续发展的道路, 高性能混凝土就是在这种背景下出现并逐步完善与发展的。混凝土作为用量最大的人造材料，不能不考虑它的使用对生态环境的影响。传统混凝土的原材料都来自天然资源。每用1t水泥，大概需要0.6t以上的洁净水，2t砂、3t以上的石子；每生产1t硅酸盐水泥约需1.5t石灰石和大量燃煤与电能，并排放1tCO2，而大气中CO2浓度增加是造成地球温室效应的原因之一。尽管与钢材、铝材、塑料等其它建筑材料相比，生产混凝土所消耗的能源和造成的污染相对较小或小得多，混凝土本身也是一种洁净材料，但由于它的用量庞大，过度开采矿石和砂、石骨料已在不少地方造成资源破坏并严重影响环境和天然景观。有些大城市现已难以获得质量合格的砂石。另一方面，由于混凝土过早劣化，如何处置费旧工程拆除后的混凝土垃圾也给环境带来威胁。因此，未来的混凝土必须从根本上减少水泥用量，必须更多地利用各种工业废渣作为其原材料；必须充分考虑废弃混凝土的再生利用，未来的混凝土必须是高性能的，尤其是耐久的。耐久和高强都意味着节约资源。“高性能混凝土”正是在这种背景下产生的。2.2 研究现状及发展方向针对混凝土的过早劣化，发达国家在20世纪80年代中期掀起了一个以改善混凝土材料耐久性为主要目标的“高性能混凝土”开发研究的高潮，并得到了各国政府的重视。从20世纪80年代开始，各国混凝土结构设计规范中逐渐突出了耐久设计的考虑，从只重视强度设计向强度与耐久性并重。进入20世纪90后代以后，混凝土结构耐久性设计方法成为土木工程领域中的研究重点。针对不同环境类别的侵蚀作用，提出材料性能劣化的理论或经验模式，并据此估算结构的使用寿命，成为发展和研究耐久性设计方法的主流。目前，高性能混凝土的发展有以下几个方向：(1)绿色高性能混凝土水泥混凝土是当代最大宗的人造材料，对资源、能源的消耗和对环境的破坏十分巨大，与可持续发展的要求背道而驰。绿色高性能混凝土研究和应用较多的是粉煤灰混凝土，粉煤灰混凝土与基准混凝土相比，大大提高了新拌混凝土的工作性能，明显降低混凝土硬化阶段的水化热，提高混凝土强度特别是后期强度。而且，节约水泥，减少环境污染，成为绿色高性能混凝土的代表性材料。(2)超高性能混凝土超高性能混凝土，如活性粉末混凝土（Reactive Powder con-crete,RPC）,其特点是高强度，抗压强度高达300MPa，且具有高密实性，已在军事、核电站等特殊工程中成功应用。(3)智能混凝土智能混凝土是在混凝土原有的组分基础上复合智能型组分，使混凝土材料具有自感知、自适应、自修复特性的多功能材料，对环境变化具有感知和控制的功能。随着损伤自诊断混凝土、温度自调节混凝土、仿生自愈合混凝土等一系列机敏混凝土的出现，为智能混凝土的研究、发展和智能混凝土结构的研究应用奠定了基础。高性能混凝土是近20余年发展起来的一种新型混凝土。欧洲混凝土学会和国际预应力混凝土协会将HPC定义为水胶比低于0.40的混凝土；在日本，将高流态的自密实混凝土（即免振混凝土）称为HPC；中国土木工程学会高强与高性能混凝土委员会将HPC定义为以耐久性和可持续发展为基本要求并适合工业化生产与施工的混凝土。虽然在不同的国家，不同的学者或工程技术人员，对HPC的理解有所不同。比如美国学者更强调高强度和尺寸稳定性，欧洲学者更注重耐久性，而日本学者偏重于高工作性。但是他们的基本点都是高耐久性，这方面的认识是一致的。Research and development of high performance concrete1 IntroductionFrom the beginning of the 1824 invention of Portland cement, concrete has been 100 years of history, to cement concrete has also been made to develop a large, composed of ordinary concrete and high performance concrete development to. Since twentieth Century, it has become a modern engineering concrete structure buildings, bridges, water conservancy, highway concrete material of choice, as the largest civil engineering synthetic materials, its huge amount. According to statistics, Chinas annual consumption of concrete in about 109m3, and with Chinas industrialization, city to speed up the process in recent years, its consumption will continue to grow rapidly. Entering the twenty-first Century, along with the rapid development of science and technology, a novel concrete emerge. Concrete can long as structural material in the main, it must have high strength, high performance, high durability and performance, so the high performance concrete is the inevitable result of the development of modern concrete technology, is the development direction of concrete.High performance concrete (High Performance Concrete, HPC) is the late nineteen eighties and early 90s, some developed countries based on a new concept of the concrete structure durability design of concrete, its durability as the main design index, this kind of concrete may provide the service life of 100 years for infrastructure projects. Different from the traditional concrete, high performance concrete with high durability, high workability, high strength and high volume stability of many excellent properties, is considered the worlds most comprehensive performance of concrete, has been adopted in many important projects, especially shows its unique superiority in bridge, high-rise building, harbor construction and other projects, has significant benefits in terms of time, economic rationality, environmental conditions using the engineering safety adaptability, therefore accepted by scholars, is considered to be the development direction of concrete technology in the future.2 The background of the high performance concrete production and research status2.1 backgroundThe development of modern large span, tall, marine, military engineering of concrete structure put forward higher requirements; in the harsh environment of existing building continuous deterioration, degradation, resulting in serious consequences, and even the emergence of premature failure of retired malignant accidents have caused huge losses; harsh realities of raw material production, the ecological environment caused by the exploitation of deterioration and sand and stone resources, shortage seriously affected the further development of the. This requires continuously improve the performance of concrete durability as a focus, the use of natural materials and industrial waste to protect environment, take the road of sustainable development, the high performance concrete is in this context the emergence and gradual improvement and development.Materials for artificial concrete as the largest amount, can not consider the impact of its use on the ecological environment. The raw material of traditional concrete from natural resources. Each with 1t cement, probably need clean water more than 0.6T, 2T, 3T above the sand pebbles; each producing 1t Portland cement about 1.5T limestone and large amounts of coal and electricity, and the emission of 1tCO2, and the concentration of CO2 in the atmosphere is one of the causes of increased greenhouse effect on the earth. Compared with steel, aluminum, plastic and other building materials, required to produce concrete energy and pollution caused by the relatively small or much smaller, concrete itself is a kind of clean material, but because of its large amount, excessive mining ore and sand, stone aggregate has in many places, resulting in destruction of resources and serious environmental impact and the natural landscape. Some big city has been difficult to obtain the qualified sand. On the other hand, because the concrete deterioration, how to dispose of garbage fees after the removal of old concrete project also to environmental threats.Therefore, the future of the concrete must be radically reduce the dosage of cement, must be more use of industrial waste residue as the raw material; must fully consider the recycling of waste concrete, the concrete must be of high performance, especially the durable. Endurance and strength are meant to save resources. High performance concrete is produced in this context.2.2 the research status and development directionAccording to the concrete premature deterioration, the developed countries in the nineteen eighties medium set off a concrete to improve the durability of materials as the main target of high performance concrete research and development of high tide, and got the attention of governments. Starting from the nineteen eighties, national design specification for concrete structure gradually highlighted the durability design considerations, from only attach importance to strength design strength and durability. After entering the twentieth Century post-90s generation, design method of durability of concrete structure has become a research focus in the field of civil engineering. According to the different environment types of erosion, the material performance degradation theory or empirical mode, and then estimating the service life of the structure, has become the mainstream of development and Research on durability design method. At present, there are the following the direction of the development of high performance concrete:(1) the green high performance concreteConcrete is the largest man-made materials, resources, energy consumption and environmental damage is very great, draw further apart and the requirements of sustainable development. Green high performance concrete research and the application is more than fly ash concrete, fly ash concrete and reference concrete, greatly improving the workability of fresh concrete, significantly reduce the heat of hydration stage of hardened concrete, improve the strength of concrete especially the later strength. Moreover, saving cement, reduce environmental pollution, become the representative materials green high performance concrete.(2) ultra high performance concreteUltra high performance concrete, such as reactive powder concrete (Reactive Powder con-crete, RPC), which is characterized by high strength, high compressive strength is up to 300MPa, and has the advantages of high compactness, has been successfully applied in the military, nuclear power and other special projects.(3) the intelligent concreteSmart concrete is concrete in the original component based on composite intelligent components, the concrete material has since self-healing properties of multifunctional materials, adaptive, perception, with perception and control of environment function. With the damage diagnosis of concrete, temperature control of concrete, biomimetic self-healing concrete and a series of smart concrete appearance, laid the foundation for the application of intellige