高性能混凝土外文翻译.doc

On The Application of High-Performance ConcreteSummary The high-performance concrete is a main direction of the technical development of recent concrete, the foreign scholar has called that the concrete in 21st century. Norway carried on research to this at first in 1986, named formally from American National Standard, technological research institute (NIST) and a seminar hosted together of American Concrete Institute (ACI) in 1990. Conference stipulate high-performance concrete to have whom some performance require homogenize the concrete, must adopt the strict construction craft, adopt high-quality material formulate, easy to water smash, emanate, mechanics performance steady, early intensity high, with performance such as toughness and volume stability durable concrete, especially suitable for the skyscraper, bridge and open to the building structure of the harsh environment. Key words concrete; performance; engineering; application1 Introduction Recent high-performance concrete is the main direction of the development of concrete technology, foreign scholars have called the 21st century concrete. Norway in 1986, this was the first study in 1990 by the National Institute of Standards and Technology (NIST) and the American Concrete Institute (ACI) at a seminar co-hosted a formal naming. The General Assembly for high-performance concrete is a certain performance requirements of the uniform quality of concrete, it must adopt a strict construction technology, using high-quality materials, preparation, ease of pouring pound, non-segregation, mechanical properties and stability, high early strength with toughness and size stability durability performance of concrete, especially for high-rise buildings, bridges, and exposure to harsh environments in architectural structures. As an integrated high-performance concrete with excellent technical characteristics of materials at home and abroad has aroused world wide attention with the engineering and concern. 10 years, the world, many countries have invested a great deal of manpower, financial and material resources to conduct the research and development applications, to enable high-performance concrete technology has made great progress in the selection of raw materials, mix design, physical and mechanical properties of , durability, workability, structure and performance as well as application of technology have made both theoretical basis and its practical value of scientific and technological achievements. In 1993, the technical committee under American Concrete Institute proposed a new high-performance concrete was defined: Meet project special various performance of requirement, but including easy to water, smash instead of emanating, high long-term mechanics performance, high early intensity, high and tough and tensile and high volume stability, or the service life in the harsh environment is for a long time, and homogenizing good concrete. In recent years, American Concrete Institute provides more concise definition on a piece of characters again: The high-performance concrete is that one kind can accord with special performance and synthesize the concrete with the homogeneity requirement, the concrete can get with regular concrete component material and common mixing, habit method smashed and maintained to water often. High-performance concrete, it is used for signifying the concrete with high work degree, high strength and high durability beginning. This kind of concrete must be designed and possessed high volume stability. For reduce concrete shrink and do fracture produced to contract with temperature, must limit the grout content in the concrete mixture. The high-performance concrete amount of total grout limited of design method of match ratio that Mehta and Actcin put forward is 1/3 of the concrete volume; Allow some silicate cement spend volcanic ash or have glue person who congeal to mix, shut material replace. AcTcin has been prophesied: Mix slay, fly ash, silica flour, inferior clay, the rice husks dust and three yuan of the lime stone powder and mix cement besides can make the preparation of the high-performance concrete more economic ing, still can give play to exceeding a pile of function of them, improve its property while mixing and hardening newly. 2.High performance concrete in modern engineering High performance concrete technology is successfully used in many parts of the world of offshore structures and grew up across the bridge construction, Langley, who described growing up across a few bridges in Canada with the workability.They are used in the girder, mound department and mound base, it is 450 Kg/m3 that silica flour mix cement consumption, water 153L/ m3, guide angry pharmaceutical 160mL/ m3 and high-efficient water-reducing agent 3L/ m3. Its slump is probably in 200mm; Includes 6.1% of tolerance; 1d, 3d, 28d compression strength are 35, 52 and 82 MPa respectively; The foundation and other big mixed cement consumption of pieces of concrete are 307 Kg/m3, fly ash 133 Kg/m3, water consumption is close, but guide the angry pharmaceutical and mixing amount of high-efficient water-reducing agent to reduce by a large margin, make an appointment in 185mm in slump; Includes 7% of tolerance; 1d, 3d, 28d and 90d compression strength are 10, 20, 50 and 76 MPa respectively. And water permeability of U.S.A. and chlorine ion fast to permeate standard method experimental result indicate according to Canada: Both part of concretes present very low permeability. To high-performance concrete construction of structure, need, put emphasis on, strengthen on-the-spot laboratory test and inspection of quality very much. Another area of development of high performance concrete is a high performance lightweight concrete, as opposed to steel, ordinary concrete strength / weight ratio is very low, mixed with high-strength concrete superplasticizer is significantly enhanced the ratio; with a large number of tiny holes lightweight aggregate to replace part of the normal aggregate, will be able to further improve this ratio. As the aggregate quality of different density of 2000 Kg/m3, compressive strength at 70 80 MPa high-performance lightweight concrete in a number of countries have already commercialized and used in component production. In Australia, Canada, Japan, Norway and the United States, high-performance lightweight concrete has been used in fixed and floating drilling platform; because of mud and water, the interface between the aggregate bond strength, it can be impermeable, so the erosion of the environment able is very durable. -Doped silica powder 10 15% or even higher superplasticizer prepared mixture of cement concrete, with excellent adhesion, so the spray applied to the wet spraying the structural repair of concrete, which is one of the areas of high performance concrete applications . 2.1 High-performance concrete in high-rise building applications. High-performance concrete ( 40MPa) over the first 30-story high-rise buildings used for reinforced concrete structures, because such buildings in the lower third of the columns, using ordinary concrete when the great cross-section. In addition to savings in material costs, as compared with the steel structure, speeding up the adoption of concrete structures is an important feature, since the United States in Chicago in 1965 with 50 MPa concrete pouring Lake Point Tower some of the pillars has been everywhere in North America and other countries using high-performance concrete to build high-rise building. Chicago 79-story Water Tower Place building columns using 60MPa concrete; Torontos Scotia Plaza Building and Seattles Two union Square Building 2 Buildings then 90 and 120MPa respectively intensity of high-performance concrete pillars. Application examples: a. high-performance concrete application of C80 high-strength and high-performance concrete in Shenyang Fangyuan Building, Onishi Electric Park, and many other high-rise building in the application of concrete filled steel tubular columns. b. Shanghai Research in the field of high performance concrete in a large number of promising results obtained, of which representative results are: Chinas tallest building - 88 C40 floor Jinmao Tower once pumped to 382.5m; Tomorrow Square slag pumping C80 concrete; in Shanghai education TV station based on complex building mass concrete, cement consumption accounted for only 46% of the total cementitious materials, preparation of the full amount of concrete slurry, concrete work, cohesiveness and resistance to segregation are very excellent performance, strength of C40 high-performance concrete.2.2 High-performance pavement concrete a. High-performance pavement concrete significance of the study With the increasing traffic and transport requirements to develop the long-life low-maintenance road, With high-performance pavement concrete, to improve the flexural strength and durability of concrete is the current trend of development of concrete pavement. b. Overseas developments Held in 1997 at the XVI International Conference on Concrete Pavement, pavement design proposed not only to raise the average intensity of demand, but also make the durability requirements. Made in the direction of future development of ultra-high tensile strength up to 17MPa strength concrete, for paving continuous concrete pavement. Improve the concrete pavement surface compactness and impermeability are very important, and this is through high-performance concrete to achieve. c. High-performance pavement concrete strength High-performance concrete pavement important feature is a high flexural strength. Using high-performance pavement concrete can significantly improve the bearing capacity of pavement, extend service life, or thinning the thickness of pavement to reduce the project cost. d. High-performance durability of concrete pavement High-performance concrete pavement main feature is a sufficient durability, resistant to climatic and environmental effects of long-term damage to ensure that the design of pavement and within the concrete can work properly. e. High deformation characteristics of concrete pavement (1) Shrinkage Road panel surface area of great evaporation, shrinkage may be caused by Tao panel surface of shrinkage cracks, the need to increase conservation. (2) The flexural modulus of elasticity High-performance pavement concrete flexural elastic modulus E, by measurement, one for 4.305104Mpa, 2 grade 4.845104Mpa, 3 grade 4.605104Mpa. Intensity of three high-performance pavement concrete mix, the aggregate amount of less coarse aggregate maximum particle diameter is smaller. f. The application of Application of high-performance pavement concrete yield significant benefits: (1) increase pavement strength; (2) extend the pavement service life; (3) reducing the project cost; g. Applications (1) in the U.S. about 70% of the road pavement using high-performance concrete: one in North Dakota, 1988 and 1989 in the summer, with 20000m3 of concrete paving thickness of 200 mm of the surface, its water-cement ratio of 0.43, cement consumption 100 Kg/m3, fly ash 220 Kg/m3; the road Texas demonstration project has successfully adopted this new material. (2) The Qinghai-Tibet railway construction project fully promote the use of h. Conclusion Three intensity levels of high-performance pavement concrete is extremely good quality, cost of materials basically does not increase or increased marginally, for the different requirements of the project choose to use, the construction of low-maintenance long-life pavement, road, its social, economic benefits are enormous, and worth promoting and continued research to promote the countrys airports cement concrete pavement construction and road pavement engineering is entering a new stage of development to meet the growing demand for aviation and transportation needs. 2.3 Marine Concrete Structures - Durability of hydraulic structures to enhance port study and propose technical and economic rational, easy to promote the use of a new marine engineering high-performance concrete Span bridges, undersea tunnels and offshore oil platforms, is an instance of this application. Such as: a, Shantou, Hong Kong outside the Deepwater Channel Regulation Project; b Lingdingyang Pearl River Estuary Deepwater Channel Regulation Project; c, Qingdao, Ningbo Beilun and other ports that can berth 200,000-ton class built tankers and ore ships deep-water berths 2.4 Free Vibration of Self-compacting Concrete Due to vibration-free self-compacting concrete has a very good work, making the concrete filling, compactness, uniformity has been significantly improved, becoming a new concrete technology, progress is listed as a family of high performance concrete. Vibration-free self-compacting concrete is the first study from Japan over the last decade to develop and put into a modern concrete engineering technology. Since vibration-free self-compacting concrete in engineering applications can be made to improve concrete quality, improve concrete construction operations, to support the construction noise and improve labor productivity, speed up the construction cost reduction and other technical and economic effect, in recent years have given the world great pay attention to. Japan is expected by 2003 there will be 1 / 2 works with the free vibration of concrete self-compacting concrete pouring.As the name suggests, vibration-free self-compacting concrete is poured concrete, when self-gravity alone without any external force tamping to achieve self-compacting, self-leveling of a concrete. Vibration-free Self-compacting concrete should have three characteristics: (1) Mobility; (2) Good stability - does not disintegrate; (3) Reinforcement and templates in any gap, with a good through capacity, does not produce blocking. According to the requirements of these three characteristics, vibration-free preparation of self-compacting concrete principles and methods section are as follows: Fresh concrete phase is a particle suspended solids, the continuous medium is a cement paste, which is liquid and Concrete Aggregates, compared with solid-phase. All the particles in suspension, mobility and particle balance between segregation is necessary. Free vibration of fresh self-compacting concrete in the absence of external force to be real concrete formwork to give full fill all the gaps and achieve the compact, more importantly, to both good fluidity and stability. In order to obtain high mobility, we must first reduce the friction between the particles. Incorporation of superplasticizer to reduce the surface tension of particles of course is necessary, but vibration-free performance requirements of self-compacting of view, alone doped superplasticizer was also difficult to achieve, needs to mixed with a certain amount of ultra-fine material. To obtain good stability, so that materials are not disintegrate, the liquid must have the appropriate rheology, can not produce bleeding and prevent particle segregation. To achieve this request, also be mixed with an appropriate amount of particle size 0.25mm fine filler and in some cases mixed with viscosity modifying agent (tackifier). In order to be able to flow through the reinforcement of concrete and templates in the gap without creating any obstruction, in addition to the design of engineering structures be selected according to the appropriate particle size and morphology of aggregates, the liquid volume is the amount of its rheological properties important parameters. The rheological properties is based on the Bingham rheological model used to evaluate the viscometer, and should have a low yield stress and plastic viscosity appropriate. By rheological point of view, vibration-free matrix of self-compacting concrete is a free flow of ultra-fine paste, the paste is made of cement and composed of fine material, the liquid surrounding the solid particles with the thickness of the serosal layer increases with the increase, while the serosal layer thickness of solid particles in the paste has been filled before the gap between the formation, therefore, the thickness of the slurry affects the shapes by solid particles. For the paste, apart from the requirements of high liquidity, the need of sufficient high viscosity, must be a high-viscosity Newtonian fluid, in order to prevent segregation.Vibration-free self-compacting concrete preparation process as shown. Cement Ultra-fine admixture of water superplasticizer The free flow of slurry of fine aggregate The free flow of mortar of coarse aggregate Self-compacting Concrete Vibration-free self-compacting concrete mix design, first make sure the gap under the aggregate liquid volume of content needed. The composition of the liquid cement, water, additives, and 0.25mm ultra-fine material. Super fine materials and the total aggregate volume ratio (S / A) is free of vibration of self-compacting concrete mix design in an important parameter. Zhen-ming, the mobility of self-compacting concrete will be with the S / A increased with the increase, while the elastic modulus of no significant impact. Basically, according to the required water-cement ratio to determine the compressive strength of concrete. Vibration-free self-compacting concrete due to the rheological behavior of volume and composition of the material has a very close relationship, therefore, vibration-free self-compacting concrete mix design is recommended rather than weight ratio of the volu