水泥专业外文翻译---波特兰水泥的制造

The contemporary cement cycle of the United StatesIntroductionHydraulic cement is one of the most important construction materials in modern society in terms of both value and volume. Portland cement, the most common type of hydraulic cement, is produced by heating limestone and other raw materials in a rotary kiln to produce an intermediate product called clinker. The clinker is then ground, along with about 5% (by weight) of gypsum, into a fine powder. When combined with water, cement forms a paste that binds sand and gravel (or other coarse aggregates) into a solid compound material known as concrete. Concrete usually contains about 11%–14% by weight of (dry) cement powder. Concrete is the most widely used manufactured material in buildings, bridges, streets, and highways.Cement production, especially to form clinker, is highly energy intensive；in the United States the average unit energy consumption for cement plants in 2000 was about 5.2 GJ per metric ton of cement. The critical environmental concerns associated with cement production are the large amount of raw materials required to make clinker, and the particulate and gaseous emissions (especially carbon dioxide which is a major greenhouse gas) from the clinker kilns. With respect to carbon dioxide, the cement industry is one of the two largest manufacturing industry sources in the United States, the other being the iron and steel industry.Concrete use in the United States reflects population growth and urbanization trends. Much of the concrete in use today (within buildings, roads, bridges, and other infrastructure) was installed several decades ago during early phases of growth and urbanization, and there are growing concerns about the condition and performance of this concrete. Various categories of infrastructure in the United States scored an overall grade of D (i.e., poor) in a recent assessment, and it was estimated that necessary replacement, rehabilitation, or both of infrastructure will require an investment of US$1.6 trillion by 2010.This work wil increase demand for cement. Apart from the environmental issues related to producing this extra cement, repair, replacement, or both of deteriorated infrastructure also commonly results in societal inconveniences and secondary environmental effects. For example, repair of transportation infra structure commonly causes delays and detours for vehicular traffic that may lead to greater fuel use and increased vehicular exhaust.To enhance the performance of concrete infrastructure in the United States and reduce environmental and economic impacts associated with deteriorating infrastructure, efforts are underway to develop advanced composite materials or concretes with greater strength and durability. A comparative evaluation of life-cycle costs and environmental management issues for conventional concrete and alternative materials can aid in the selection of the best building materials for repairing or replacing existing infrastructure. Material flow analysis of the cement cycle is a critical c omponent of such a comparative assessment and provides an understanding of resource supply, use, recovery, and recycling at a regional or national scale. Cement is chosen for the direct analysis instead of concrete itself because data on cement production and use are far more abundant and complete than those for concrete.This article undertakes a preliminary material flow anaysis of the contemporary cement cycle of the United State The objective is to characterize stocks and flows of cement(as a proxy for concrete) over its life cycle and to analyze the underlying environmental and resource use implictions. Material flow analysis is based on the universalla of mass conservation and is used to assess the current an future state of material flows and accumulation in the economy and in the environment. Many examples of material flow analysis models can be found in the literature.The present study is a component of the National Science Foundation MUSES Sustainable Concrete Infrastructure Materials and Systems project at the Center for Sustainable Systems, University of Michigan. This study provides an assessment of the flows of cement in the United States over the complete life cycle as characterized by three stages：production, use, and end-of-life disposal (see below for a detailed description of each life cycle stage). The intended purpose of this study to quantify cement flows is to understand the type and amount of raw materials extracted and consumed to produce cement and to estimate how much cement is added as new in-use stock every year, how much is discarded, and how much is disposed of in landfills. Previous material flow studies analyzing cement flows in the United Stateshave mainly focused on production-relatedflows, whereas this study provides a more integrated assess-ment, emphasizing the material flows for cement at the “end of life” of infrastructure systems.Production of cementRaw materials for the manufacture of cement are selected to provide the compositional requirements for modern portland cement clinker. Clinker is composed mainly of four oxides：calcium oxide (CaO – about 65% by weight), silica (SiO2 – about 22%), alumina (Al2O3 – about 6%), and iron oxide (Fe2O3 – about 3%). Raw materials for cement manufacture are mostly products from the mining industry. The calcium oxide is provided mostly by calcareous rocks such as limestone and marble. The alumina and silica are commonly provided by clay or shale；iron oxide by shale, iron ore, or mill scale；and silica sand is commonly used to remedy any remaining silica shortfalls in the other raw materials. Increasingly, industrial by-products such as ferrous slag and coal combustion fly ash are also being used as raw materials. The contemporary nonfuel raw materials consumption for the manufacture of cement and clinker in the United States is summarized in Table 1. Although Table does not distinguish between raw materials used to make clinker and those used subsequently in the finish mill to make finished cement, overall, about 1.7 metric tons of raw materials are required to produce 1 metric ton of clinker or portland cement. The majority of the apparent loss in mass is due to the emission of carbon dioxide, as will be discussed later. Not shown in Table 1 is the fact that about 0.2 metric tons of (mainly fossil) fuels are consumed per metric ton of clinker manufactured. Overall, cement manufacture also consumes about 100–160 kWh of electricity per metric ton of cement；in the United States, the vast majority of this electricity is purchased from the national grid.To minimize transportation costs, cement plants are generally located close to their limestone quarries. The limestone is transported from the quarry to the mill of the cement plant, where it is crushed and ground and then proportioned and mixed with vari ous other ground raw materials (as needed) to form the raw mix or feed for the kiln. At the high temperatures reached in the kiln, the rawmaterials react to produce several cement minerals, chiefly tricalcium silicate and dicalcium silicate, within a semifused nodular intermediate product called clinker.From an environmental standpoint, and that of the mass balance, the key reaction in the kiln is the highly energy intensive calcination (typically at about 750°–1000°C) break-down of the calcium carbonate (CaCO3) in the limestone to form calcium oxide (CaO) plus carbon dioxide (CO2). The subsequent formation of the actual clinker minerals and the clinker nodules typically requires yet higher temperatures, but the reactions actually require less thermal energy than does calcination, and there is little further change to the mass balance.The resulting clinker is interground with gypsum in the finishing mill to produce portland cement；the gypsum is added to control the setting rate of the concrete during cement hydration. More detailed descriptions of cement manufacture are given in the literature.In order to improve the performance of concrete and, increasingly, to minimize the environmental impacts of the manufacture of concrete, supplementary cementitious ma terials (SCM), such as fly ash, ground granulated blast furnace slag, silica fume, and pozzolana (a reactive volcanic ash), may be substituted for some of the portland cement in the finished cement (i.e., to make a blended cement) or in concrete. The extent to which SCM can substitute for portland cement depends mainly on the desired strength, durability, and other properties of the concrete, but substi-tution rates of 10%–30% or more are common. Apart from potentially improving the quality of the concrete, reducing the portland cement component of the concrete through incorporation of industrial by-products (fly ash and slag) as SCM also reduces the demand for virgin raw materials and the emissions associated with a given volume or mass of concrete. Likewise, the use of industrial by-product SCM in concrete decreases the need for disposal of these by-products, which conserves landfill space.Use of cementMost of the cement produced in the United States is portland cement (approximately 87 million metric tons per year). Portland cement is primarily utilized to make concrete, which has a wide spectrum of uses, including construction storage tanks. Compared to that of portland cement, the cement is primarily used in the construction of buildings. Detailed cement usage data are available only from the United States Geological Survey (USGS)and from the Portland Cement Association (PCA)；the former provides data on the distribution of portland cement shipments to different customer types, and the latter provides data on the end uses of cement. During the period 2000–2004, approximately 90% of portland cement shipments were made to ready-mixed concrete and concrete product producers, The data from the PCA averaged over the period 2000–2004 show that the cement end-use market was dominated by buildings (residential – 33%, commercial – 7%, public – 8%, and industrial – 4%) and streets and highways (29%), followed by water and waste management (6%) and other miscellaneous uses (12%).End-of-life management of cementConcrete in each of its uses has a certain useful lifespan. For example, streets and highways in the United States are expected to last 45 years, whereas residential buildings have an average lifetime of 80 years. The difference reflects thefact that streets and highways deteriorate more rapidly owing to their high degree of environmental exposure (to moisture, freezing and thawing, and chemicals such salt and sulfate) and the exposure to vehicular traffic. During the lifespan of each concrete structure, there are typically several cycles of repair and renovation. At their end of life, concrete structures are usually demolished. The further reuse of concrete construction and demolition debris depends on a number of factors such as its physical characteristics (porosity, density), the economic viability, and construction and material standards. The average material composition of construction and demolition debris fraction is higher in nonresidential buildings because the wall material in many of the residential bu ildings in the United States is not concrete. The amount of concrete debris from construction of new buildings is low because the amount of concrete to be poured is usually closely estimated using standard mix designs, and the amount of losses onsite are relatively small.In terms of reuse, it is more difficult to recover and recycle individual C&D materials from the demolition of buildings than from streets and highways because the debris from buildings is more heterogeneous. There are a number of advantages of in-place recycling of crushed concrete aggregate at highway sites, and a number of States in the United States are promoting such recycling. The reuse of crushed concrete aggregate from the existing pavement simplifies construction of new pavement at existing grade on highways. However,the specifications for construction materials do not promote reuse of materials already in use in the infrastructure.The concepts of material flow analysis were used to construct the contemporary cement cycle. The spatial boundary chosen for this study was the United States excluding Puerto Rico (so as to maintain data consistency as per USGS data). For the cement cycle, annual flow magnitudes for the production reservoir were averaged for the period 2000–2004 (data for use and end-of-life reservoirs are for 2002). The net cement flow can also be called the apparent consumption of cement. The flows to and from the production reservoir were broken down to three subreservoirs (mine mill complex, kiln, and finishing mill) to characterize the production and net trade (= import–export) flows of raw materials, clinker, and cement. Within the production reservoir, there could be net depletion or addition of material to clinker and cement stockpiles, depending on changes in inventory over the calendar year.Production residues consist of mine overburden (generally minor)；crushed limestone screenings (also known as stone dust or fines and are commonly used as a raw material for clinker production)；cement kiln dust (CKD)；carbon dioxide emissions from the calcination phase of the clinker production process；and other, volumetrically lesser, amounts of gaseous emissions from the kiln such as nitrogen oxides, sulfur oxides, and water vapor. In addition, there are carbon dioxide emissions from fuel combustion during clinker production. Mine overburden is the material moved during the extraction of the cement raw materials that is not used either for cement manufacture or for other purposes (e.g., sold as aggregates). Rock fines are materia l that passes through the smallest screen used in the raw materials processing circuits；of issue here are any fines not used as a raw material. CKD comprises fine particulate matter or dust that is generated in the kiln line；the material is essentially captured, but it may or may not be recycled to the kiln. If CKD is not recycled, it is generally land filled, although it can be used as a soil liming agent or as a fill material.This material flow analysis accounts for the flows and transformation of only the nonfuel materials used to make clinker and cement；the flows of energy resources and emissions related to fuel combustion are not evaluated in this study. Fuel tonnages and carbon dioxide emissions related to fuel combustion are discussed by van Oss andPado vani. Integrated assessment of energy and material flows are more data intensive and methodologically challenging and therefore the scope of this study is limited to material flows only.Estimates for cement cycle flow parametersFor this study, mine overbur den and (unused) stone fines were estimated as 6% and 1%, respectively, of crushed rock production from limestone quarries, following the findings of Matthews et al. Output of CKD was estimated at 0.2 metric ton per metric ton of clinker, based on the discussion by van Oss and Padovani；as noted by these authors, CKD data are subject to high uncertainties. Carbon dioxide emissions from calcination were estimated to be 0.51 metric ton of carbon dioxide per metric ton of clinker and are based on straightforward stoichiometric considerations. The data on production, imports, exports, and changes in stockpiles of clinker and cement are from USGS assessment of the cement industry and official trade data；The cement produced in the United States, as well as the net imports of cement, enter the use reservoir, and the cement flow within the use reservoir is divided into subflows：additions to stock (i.e., new construction)；repair/renovation；and retirement. Direct data on the breakout of cement sales (consumption) into new construction and repair/renovation are not available from USGS data on cement consumption；however, the PCA has developed indices that relate the tonnage of cement to the dollars spent, but mostly in terms of types of construction. The PCA’s tonnage rat io for new versus renovation residential construction (for the 5-year average of the period 2000–2004) is 75%–25%. Alternatively, this breakout between new and renovation construction can also be estimated by using the real dollar value of construction data and estimates of the cement intensity (tons per million dollars of spending) of different types of construction (Sullivan 2006, personal communication). The Construction Expenditures Branch of the U.S. Census Bureau (USCB) reports the annual total value of construction. However, only the data for private residential construction (current US$2200 billion total over the period 2000–2004) has any breakout for repair or renovation, i.e., new housing units (new single family current US$1400 billion；new multi family – current US$200 billion) and improvements (currentUS$600 billion). As part of its annual highway finance statistics, the FederalHighway Administration (FHWA) reported Federal and State funding for highways and bridges as totaling current US$279 billion for the period 2000–2004, split out as about 60% for new construction (current US$162 billion over 2000–2004) and about 40% for repair and rehabilitation (current US$117 billion over 2000–2004). Based on the weighted average of the USCB and FHWA data over the period 2000–2004, 70% of the total consumption tonnage of cement in the United States is estimated to have been used for new construction and the remaining 30% for repair and renovation activities. Although adoption of PCA or USCB/FHWA breakout ratios of cement consumption for new and renovation construction are significantly different, the likely error in using any one of the approximations would be in the range 5%–10%. Therefore, for this study, we assume that the breakout ratio between new and renovation construction is 65 ：35. It also can be anticipated the repair and rehabilitation of deteriorating highways currently in use would push the renovation component o cement consumption to a higher value. It is important to note that new construction projects are expected to consume more concrete overall than repair and renovation work, andthat unit prices for concrete will generally be lower for large.New construction, repair/renovation activities, and demolition of old infrastructure all generate C&D debris. Estimates of C&D debris from residential and nonresidential buildings were derived from a U.S. Environmental Protection Agency (USEPA) reportand modeling by Kapur et al.；the latter study also models roads, bridges, highways, and other civil infrastructure. The in-use cement stock was estimated as the difference between cement entering the use reservoir and cement discards in the form of C&D debris exiting the use reservoir. The net trade flows of cement within finished products (e.g., concrete tiles) were excluded owing to the lack of data on the cement content of these products.In the end-of-life reservoir, concrete can be either recycled to the use reservoir or disposed of to the environment (landfills). There also could be net import–export flows (likely minor) of C&D debris containing cement discards. Data on recycling of C&D debris are limited. The USGS reports that 9.5 million metric tons of concrete were recycled in the United States in 2000, but these data are likely to be incomplete. For ons ite C&D debris, the Associated General Contractors of America (AGC) conducted in 2004 a survey on the recycling practices of about 300 contractors. This survey showed that, depending onthe type of the project (building, highway, utility, or demolition), t he recycling rate for the concrete fraction of the C&D debris generated varied from 33% to 100% 。

水泥生产Fabrication ciment portlandLa fabrication de ciment se réduit schématiquement aux trois opérations suivantes: ∙préparation du cru∙cuisson∙broyage et conditionnementIl existe 4 méthodes de fabrication du ciment qui dépendent essentiellement du matériau: ∙Fabrication du ciment par voie humide (la plus ancienne).∙Fabrication du ciment par voie semi-humide (en partant de la voie humide).∙Fabrication du ciment par voie sèche (la plus utilisée).∙Fabrication du ciment par voie semi-sèche (en partant de la voie sèche).La composé de base des ciments actuels est un mélange de silicates et d’aluminates de calcium résultant de la combinaison de la chaux (CaO) avec la silice (SiO2), l’alumine(Al2O3), et l’oxyde de fer (Fe2O3). La chaux nécessaire est apportée par des roches calcaires, l’alumine, la silice et l’oxyde de fer par des argiles. Les matériaux se trouvent dans la nature sous forme de calcaire, argile ou marne et contiennent, en plus des oxydes déjà mentionnés, d’autres oxydes et en particulie r Fe2O3, l'oxyde ferrique.Le principe de la fabrication du ciment est le suivant: calcaires et argiles sont extraits des carrières, puis concassés, homogénéisés, portés à haute température (1450 °C) dans un four. Le produit obtenu après refroidissement rapide (la trempe) est le clinker.Un mélange d’argile et de calcaire est chauffé. Au début, on provoque le départ de l’eau de mouillage, puis au delà de 100 °C, le départ d’eau d’avantage liée. A partir de 400°C commence la composition en gaz carbonique (CO2) et en chaux (CaO), du calcaire qui est le carbonate de calcium (CaCO3).Le mélange est porté à 1450-1550 °C, température de fusion. Le liquide ainsi obtenu permet l’obtention des différentes réactions. On suppose que les composants du ciment sont formés de la façon suivante: un partie de CaO est retenu par Al2O3 et Fe2O3 en formant une masse liquide. SiO2 et CaO restant réagissent pour donner le silicate bicalcique dont une partie se transforme en silicate tricalcique dans la mesure où il reste encore du CaO non combiné.Fabrication par voie humideCette voie est utilisée depuis longtemps. C’est le procédé le plus ancien, le plus simple mais qui demande le plus d’énergie.Dans ce procédé, le calcaire et l’argile sont mélangés et broyés finement avec l’eau de façon, à constituer une pâte assez liquide (28 à 42% d’eau).On brasse énergiquement cette pâte dans de grands bassins de 8 à 10 m de diamètre, dans lesquels tourne un manège de herses.La pâte est ensuite stockée dans de grands bassins de plusieurs milliers de mètres cubes, oùelle est continuellement malaxée et donc homogénéisée. Ce mélange est appelé le cru. Des analyses chimiques permettent de contrôler la composition de cette pâte, et d’apporter les corrections nécessaires avant sa cuisson.La pâte est ensuite envoyée à l’entrée d’un four tournant, chauffé à son extrémité par une flamme intérieure. Un four rotatif légèrement incliné est constitué d’un cylindre d’acier dont la longueur peut atteindre 200 mètres. On distingue à l’intérieure du four plu sieurs zones, dont les 3 zones principales sont:∙Zone de séchage.∙Zone de décarbonatation.∙Zone de clinkerisation.Les parois de la partie supérieure du four (zone de séchage - environ 20% de la longueur du four) sont garnies de chaînes marines afin d’augm enter les échanges caloriques entre la pâte et les parties chaudes du four.Le clinker à la sortie du four, passe dans des refroidisseurs (trempe du clinker) dont il existe plusieurs types (refroidisseur à grille, à ballonnets). La vitesse de trempe a une influence sur les propriétés du clinker (phase vitreuse).De toutes façons, quelque soit la méthode de fabrication, à la sortie du four, on a unmême clinker qui est encore chaud de environ 600-1200 °C. Il faut broyer celui-ci très finement et très régulièrement avec environ 5% de gypse CaSO4 afin de «régulariser»la prise.Le broyage est une opération délicate et coûteuse, non seulement parce que le clinker est un matériau dur, mais aussi parce que même les meilleurs broyeurs ont des rendementsénergétiques déplorables.Les broyeurs à boulets sont de grands cylindres disposés presque horizontalement, remplis àmoitié de boulets d’acier et que l’on fait tourner rapidement autour de leur axe (20t/mn) et le ciment atteint une température élevée (160°C), ce qui nécessite l’arrosage extérieur des broyeurs. On introduit le clinker avec un certain pourcentage de gypse en partie haute et on récupère la poudre en partie basse.Dans le broyage à circuit ouvert, le clinker ne passe qu’une fois dans le broyage. D ans le broyage en circuit fermé, le clinker passe rapidement dans le broyeur puis à la sortie, est triédans un cyclone. Le broyage a pour but, d’une part de réduire les grains du clinker en poudre, d’autre part de procéder à l’ajout du gypse (environ 4%) pour réguler quelques propriétés du ciment portland (le temps de prise et de durcissement).A la sortie du broyeur, le ciment a une température environ de 160 °C et avant d'être transporter vers des silos de stockages, il doit passer au refroidisseur à force centrifuge pour que la température de ciment reste à environ 65 °C.Fabrication par voie sècheLes ciments usuels sont fabriqués à partir d’un mélange de calcaire (CaCO3) environ de 80% et d’argile (SiO2–Al2O3) environ de 20%. Selon l’origine des matières premières, cemélange peut être corrigé par apport de bauxite, oxyde de fer ou autres matériaux fournissant le complément d’alumine et de silice requis.Après avoir finement broyé, la poudre est transportée depuis le silo homogénéisateur jusqu’au four, soit par pompe, soit par aéroglisseur.Les fours sont constitués de deux parties:∙Un four vertical fixe, préchauffeur (cyclones échangeurs de chaleur).∙Un four rotatif.Les gaz réchauffent la poudre crue qui circule dans les cyclones en sens inverse, par gravité. La poudre s’échauffe ainsi jusqu’à 800 °C environ et perd donc son gaz carbonique (CO2) et son eau. La poudre pénètre ensuite dans un four rotatif analogue à celui utilisé dans la voie humide, mais beaucoup plus court.La méthode de fabrication pa r voie sèche pose aux fabricants d’importants problèmes techniques: ségrégation possible entre argile et calcaire dans les préchauffeurs. En effet, lesystème utilisé semble être néfaste et en fait, est utilisé ailleurs, pour trier desparticules. Dans le cas de la fabrication des ciments, il n’en est rien. La poudre restehomogène et ceci peut s'expliquer par le fait que l’argile et le calcaire ont lamême densité (2,70 g/cm3). De plus, le matériel a été conçu dans cet esprit et toutesles précautions ont été prises.2.Le problème des poussières. Ce problème est rendu d’autant plus aigu, que lespouvoirs publics, très sensibilisés par les problèmes de nuisance, imposent desconditions draconiennes. Ceci oblige les fabricants à installer des dépoussiéreurs, ce qui augmente considérablement les investissements de la cimenterie.Lesdépoussiéreurs sont constitués de grilles de fils métalliques portés à haute tension etsur lesquels viennent se fixer des grains de poussière ionisée. Ces grains de poussière s’agglomèrent et sous l’action de vibreurs qui agitent les fils retombent au fond dudépoussiéreur où ils sont récupérés et renvoyés dans le four. En dehors des pannes,ces appareils ont des rendements de l’ordre de 99%, mais absorbent une partimportante du c apital d’équipement de la cimenterie.3.Le problème de l’homogénéité du cru est délicat. Nous avons vu comment il pouvaitêtre résolu au moyen d’une préhomogénéisation puis d’une homogénéisation.。

混凝土工艺中英文对照外文翻译文献混凝土工艺中英文对照外文翻译文献混凝土工艺中英文对照外文翻译文献(文档含英文原文和中文翻译) Concrete technology and developmentPortland cement concrete has clearly emerged as the material of choice for the construction of a large number and variety of structures in the world today. This is attributed mainly to low cost of materials and construction for concrete structures as well as low cost of maintenance.Therefore, it is not surprising that many advancements in concrete technology have occurred as a result of two driving forces, namely the speed of construction and the durability of concrete.During the period 1940-1970, the availability of high early strength portland cements enabled the use of high water content in concrete mixtures that were easy to handle. This approach, however, led to serious problems with durability of structures, especially those subjected to severe environmental exposures.With us lightweight concrete is a development mainly of the last twenty years.Concrete technology is the making of plentiful good concrete cheaply. It includes the correct choice of the cement and the water, and the right treatment of the aggregates. Those which are dug near by and therefore cheap, must be sized, washed free of clay or silt, and recombined in the correct proportions so as to make a cheap concrete which is workable at a low water/cement ratio, thus easily comoacted to a high density and therefore strong.It hardens with age and the process of hardening continues for a long time after the concrete has attained sufficient strength.Abrams’law, perhaps the oldest law of concrete technology, states that the strength of a concrete varies inversely with its water cement ratio. This means that the sand content (particularly the fine sand which needs much water) must be reduced so far as possible. The fact that the sand “drinks” large quantities of water can easily be established by mixing several batches of x kg of cement with y kg of stone and the same amount of water but increasing amounts of sand. However if there is no sand the concrete will be so stiff that it will be unworkable thereforw porous and weak. The same will be true if the sand is too coarse. Therefore for each set of aggregates, the correct mix must not be changed without good reason. This applied particularly to the water content.Any drinkable and many undrinkable waters can be used for making concrete, including most clear waters from the sea or rivers. It is important that clay should be kept out of the concrete. The cement if fresh can usually be chosen on the basis of the maker’s certificates of tensile or crushing tests, but these are always made with fresh cement. Where strength is important , and the cement at the site is old, it should be tested.This stress , causing breakage,will be a tension since concretes are from 9 to 11times as strong in compression as in tension, This stress, the modulus of rupture, will be roughly double the direct tensile breaking stress obtained in a tensile testing machine,so a very rough guess at the conpressive strength can be made by multiplying the modulus of rupture by 4.5. The method can be used in combination with the strength results of machine-crushed cubes or cylinders or tensile test pieces but cannot otherwise be regarded as reliable. With these comparisons,however, it is suitable for comparing concretes on the same site made from the same aggregates and cement, with beams cast and tested in the same way.Extreme care is necessary for preparation,transport,plating and finish of concrete in construction works.It is important to note that only a bit of care and supervision make a great difference between good and bad concrete.The following factors may be kept in mind in concreting works.MixingThe mixing of ingredients shall be done in a mixer as specified in the contract.Handling and ConveyingThe handling&conveying of concrete from the mixer to the place of final deposit shall be done as rapidly as practicable and without any objectionable separation or loss of ingredients.Whenever the length of haul from the mixing plant to the place of deposit is such that the concrete unduly compacts or segregates,suitable agitators shall be installed in the conveying system.Where concrete is being conveyed on chutes or on belts,the free fall or drop shall be limited to 5ft.(or 150cm.) unless otherwise permitted.The concrete shall be placed in position within 30 minutes of its removal from the mixer.Placing ConcreteNo concrete shall be placed until the place of deposit has been thoroughly inspected and approved,all reinforcement,inserts and embedded metal properly security in position and checked,and forms thoroughly wetted(expect in freezing weather)or oiled.Placing shall be continued without avoidable interruption while the section is completed or satisfactory construction joint made.Within FormsConcrete shall be systematically deposited in shallow layers and at such rate as to maintain,until the completion of the unit,a plastic surface approximately horizontal throughout.Each layer shall be thoroughly compacted before placing the succeeding layer.CompactingMethod. Concrete shall be thoroughly compacted by means of suitable tools during and immediately after depositing.The concrete shall be worked around all reinforcement,embedded fixtures,and into the comers of the forms.Every precaution shall be taken to keep the reinforcement and embedded metal in proper position and to prevent distortion.Vibrating. Wherever practicable,concrete shall be internally vibrated within the forms,or in the mass,in order to increase the plasticity as to compact effectively to improve the surface texture and appearance,and to facilitate placing of the concrete.Vibration shall be continued the entire batch melts to a uniform appearance and the surface just starts to glisten.A minute film of cement paste shall be discernible between the concrete and the form and around the reinforcement.Over vibration causing segregation,unnecessary bleeding or formation of laitance shall be avoided.The effect spent on careful grading, mixing and compaction of concrete will be largely wasted if the concrete is badly cured. Curing means keeping the concretethoroughly damp for some time, usually a week, until it has reached the desired strength. So long as concrete is kept wet it will continue to gain strength, though more slowly as it grows older.Admixtures or additives to concrete are materials arematerials which are added to it or to the cement so as to improve one or more of the properties of the concrete. The main types are:1. Accelerators of set or hardening,2. Retarders of set or hardening,3. Air-entraining agents, including frothing or foaming agents,4. Gassing agents,5. Pozzolanas, blast-furnace slag cement, pulverized coal ash,6. Inhibitors of the chemical reaction between cement and aggregate, which might cause the aggregate to expand7. Agents for damp-proofing a concrete or reducing its permeability to water,8. Workability agents, often called plasticizers,9. Grouting agents and expanding cements.Wherever possible, admixtures should be avouded, particularly those that are added on site. Small variations in the quantity added may greatly affect the concrete properties in an undesiraale way. An accelerator can often be avoided by using a rapid-hardening cement or a richer mix with ordinary cement, or for very rapid gain of strength, high-alumina cement, though this is very much more expensive, in Britain about three times as costly as ordinary Portland cement. But in twenty-four hours its strength is equal to that reached with ordinary Portland cement in thirty days.A retarder may have to be used in warm weather when a large quantity of concrete has to be cast in one piece of formwork, and it is important that the concrete cast early in the day does not set before the last concrete. This occurs with bridges when they are cast in place, and the formwork necessarily bends underthe heavy load of the wet concrete. Some retarders permanently weaken the concrete and should not be used without good technical advice.A somewhat similar effect,milder than that of retarders, is obtained with low-heat cement. These may be sold by the cement maker or mixed by the civil engineering contractor. They give out less heat on setting and hardening, partly because they harden more slowly, and they are used in large casts such as gravity dams, where the concrete may take years to cool down to the temperature of the surrounding air. In countries like Britain or France, where pulverized coal is burnt in the power stations, the ash, which is very fine, has been mixed with cement to reduce its production of heat and its cost without reducing its long-term strength. Up to about 20 per cent ash by weight of the cement has been successfully used, with considerable savings in cement costs.In countries where air-entraining cement cement can be bought from the cement maker, no air-entraining agent needs to be mixed in .When air-entraining agents draw into the wet cement and concrete some 3-8 percent of air in the form of very small bubbles, they plasticize the concrete, making it more easily workable and therefore enable the water |cement ratio to be reduced. They reduce the strength of the concrete slightly but so little that in the United States their use is now standard practice in road-building where heavy frost occur. They greatly improve the frost resistance of the concrete.Pozzolane is a volcanic ash found near the Italian town of Puzzuoli, which is a natural cement. The name has been given to all natural mineral cements, as well as to the ash from coal or the slag from blast furnaces, both of which may become cementswhen ground and mixed with water. Pozzolanas of either the industrial or the mineral type are important to civil engineers because they have been added to oridinary Portland cement in proportions up to about 20 percent without loss of strength in the cement and with great savings in cement cost. Their main interest is in large dams, where they may reduce the heat given out by the cement during hardening. Some pozzolanas have been known to prevent the action between cement and certain aggregates which causes the aggregate to expand, and weaken or burst the concrete.The best way of waterproof a concrete is to reduce its permeability by careful mix design and manufacture of the concrete, with correct placing and tighr compaction in strong formwork ar a low water|cement ratio. Even an air-entraining agent can be used because the minute pores are discontinuous. Slow, careful curing of the concrete improves the hydration of the cement, which helps to block the capillary passages through the concrete mass. An asphalt or other waterproofing means the waterproofing of concrete by any method concerned with the quality of the concrete but not by a waterproof skin.Workability agents, water-reducing agents and plasticizers are three names for the same thing, mentioned under air-entraining agents. Their use can sometimes be avoided by adding more cement or fine sand, or even water, but of course only with great care.The rapid growth from 1945 onwards in the prestressing of concrete shows that there was a real need for this high-quality structural material. The quality must be high because the worst conditions of loading normally occur at the beginning of the life of the member, at the transfer of stress from the steel to theconcrete. Failure is therefore more likely then than later, when the concrete has become stronger and the stress in the steel has decreased because of creep in the steel and concrete, and shrinkage of the concrete. Faulty members are therefore observed and thrown out early, before they enter the structure, or at least before it The main advantages of prestressed concrete in comparison with reinforced concrete are :①The whole concrete cross-section resists load. In reinforced concrete about half the section, the cracked area below the neutral axis, does no useful work. Working deflections are smaller.②High working stresses are possible. In reinforced concrete they are not usually possible because they result in severe cracking which is always ugly and may be dangerous if it causes rusting of the steel.③Cracking is almost completely avoided in prestressed concrete.The main disadvantage of prestressed concrete is that much more care is needed to make it than reinforced concrete and it is therefore more expensive, but because it is of higher quality less of it needs to be needs to be used. It can therefore happen that a solution of a structural problem may be cheaper in prestressed concrete than in reinforced concrete, and it does often happen that a solution is possible with prestressing but impossible without it.Prestressing of the concrete means that it is placed under compression before it carries any working load. This means that the section can be designed so that it takes no tension or very little under the full design load. It therefore has theoretically no cracks and in practice very few. The prestress is usually applied by tensioning the steel before the concrete in which it isembedded has hardened. After the concrete has hardened enough to take the stress from the steel to the concrete. In a bridge with abutments able to resist thrust, the prestress can be applied without steel in the concrete. It is applied by jacks forcing the bridge inwards from the abutments. This methods has the advantage that the jacking force, or prestress, can be varied during the life of the structure as required.In the ten years from 1950 to 1960 prestressed concrete ceased to be an experinmental material and engineers won confidence in its use. With this confidence came an increase in the use of precast prestressed concrete particularly for long-span floors or the decks of motorways. Whereever the quantity to be made was large enough, for example in a motorway bridge 500 m kong , provided that most of the spans could be made the same and not much longer than 18m, it became economical to usefactory-precast prestressed beams, at least in industrial areas near a precasting factory prestressed beams, at least in industrial areas near a precasting factory. Most of these beams are heat-cured so as to free the forms quickly for re-use.In this period also, in the United States, precast prestressed roof beams and floor beams were used in many school buildings, occasionally 32 m long or more. Such long beams over a single span could not possibly be successful in reinforced concrete unless they were cast on site because they would have to be much deeper and much heavier than prestressed concrete beams. They would certainlly be less pleasing to the eye and often more expensive than the prestressed concrete beams. These school buildings have a strong, simple architectural appeal and will be a pleasure to look at for many years.The most important parts of a precast prestressed concrete beam are the tendons and the concrete. The tendons, as the name implies, are the cables, rods or wires of steel which are under tension in the concrete.Before the concrete has hardened (before transfer of stress), the tendons are either unstressed (post-tensioned prestressing) or are stressed and held by abutments outside the concrete ( pre-tensioned prestressing). While the concrete is hardening it grips each tendon more and more tightly by bond along its full length. End anchorages consisting of plates or blocks are placed on the ends of the tendons of post-tensioned prestressed units, and such tendons are stressed up at the time of transfer, when the concrete has hardened sufficiently. In the other type of pretressing, with pre-tensioned tendons, the tendons are released from external abutments at the moment of transfer, and act on the concrete through bond or archorage or both, shortening it by compression, and themselves also shortening and losing some tension.Further shortening of the concrete (and therefore of the steel) takes place with time. The concrete is said to creep. This means that it shortens permanently under load and spreads the stresses more uniformly and thus more safely across its section. Steel also creeps, but rather less. The result of these two effects ( and of the concrete shrinking when it dries ) is that prestressed concrete beams are never more highly stressed than at the moment of transfer.The factory precasting of long prestressed concrete beams is likely to become more and more popular in the future, but one difficulty will be road transport. As the length of the beam increases, the lorry becomes less and less manoeuvrable untileventually the only suitable time for it to travel is in the middle of the night when traffic in the district and the route, whether the roads are straight or curved. Precasting at the site avoids these difficulties; it may be expensive, but it has often been used for large bridge beams.混凝土工艺及发展波特兰水泥混凝土在当今世界已成为建造数量繁多、种类复杂结构的首选材料。

混凝土工艺中英文对照外文翻译文献混凝土工艺中英文对照外文翻译文献(文档含英文原文和中文翻译)Concrete technology and developmentPortland cement concrete has clearly emerged as the material of choice for the construction of a large number and variety of structures in the world today. This is attributed mainly to low cost of materials and construction for concrete structures as well as low cost of maintenance.Therefore, it is not surprising that many advancements in concrete technology have occurred as a result of two driving forces, namely the speed of construction and the durability of concrete.During the period 1940-1970, the availability of high early strength portland cements enabled the use of high water content in concrete mixtures that were easy to handle. This approach, however, led to serious problems with durability of structures, especially those subjected to severe environmental exposures.With us lightweight concrete is a development mainly of the last twenty years.Concrete technology is the making of plentiful good concrete cheaply. It includes the correct choice of the cement and the water, and the right treatment of the aggregates. Those which are dug near by and therefore cheap, must be sized, washed free of clay or silt, and recombined in the correct proportions so as to make a cheap concrete which is workable at a low water/cement ratio, thus easily comoacted to a high density and therefore strong.It hardens with age and the process of hardening continues for a long time after the concrete has attained sufficient strength.Abrams’law, perhaps the oldest law of concrete technology, states that the strength of a concrete varies inversely with its water cement ratio. This means that the sand content (particularly the fine sand which needs much water) must be reduced so far as possible. The fact that the sand “drinks” large quantities of water can easily be established by mixing several batches of x kg of cement with y kg of stone and the same amount of water but increasing amounts of sand. However if there is no sand the concrete will be so stiff that it will be unworkable thereforw porous and weak. The same will be true if the sand is too coarse. Therefore for each set of aggregates, the correct mix must not be changed without good reason. This applied particularly to the water content.Any drinkable and many undrinkable waters can be used for making concrete, including most clear waters from the sea or rivers. It is important that clay should be kept out of the concrete. The cement if fresh can usually be chosen on the basis of the maker’s certificates of tensile or crushing tests, but these are always made with fresh cement. Where strength is important , and the cement at the site is old, it should be tested.This stress , causing breakage,will be a tension since concretes are from 9 to 11times as strong in compression as in tension, This stress, the modulus of rupture, will be roughly double the direct tensile breaking stress obtained in a tensile testing machine,so a very rough guess at the conpressive strength can be made by multiplying the modulus of rupture by 4.5. The method can be used in combination with the strength results of machine-crushed cubes or cylinders or tensile test pieces but cannot otherwise be regarded as reliable. With these comparisons, however, it is suitable for comparing concretes on the same site made from the same aggregates and cement, with beams cast and tested in the same way.Extreme care is necessary for preparation,transport,plating and finish of concrete in construction works.It is important to note that only a bit of care and supervision make a great difference between good and bad concrete.The following factors may be kept in mind in concreting works.MixingThe mixing of ingredients shall be done in a mixer as specified in the contract.Handling and ConveyingThe handling&conveying of concrete from the mixer to the place of final deposit shall be done as rapidly as practicable and without any objectionable separation or loss of ingredients.Whenever the length of haul from the mixing plant to the place of deposit is such that the concrete unduly compacts or segregates,suitable agitators shall be installed in the conveying system.Where concrete is being conveyed on chutes or on belts,the free fall or drop shall be limited to 5ft.(or 150cm.) unless otherwise permitted.The concrete shall be placed in position within 30 minutes of its removal from the mixer.Placing ConcreteNo concrete shall be placed until the place of deposit has been thoroughly inspected and approved,all reinforcement,inserts and embedded metal properly security in position and checked,and forms thoroughly wetted(expect in freezing weather)or oiled.Placing shall be continued without avoidable interruption while the section is completed or satisfactory construction joint made.Within FormsConcrete shall be systematically deposited in shallow layers and at such rate as to maintain,until the completion of the unit,a plastic surface approximately horizontal throughout.Each layer shall be thoroughly compacted before placing the succeeding layer.CompactingMethod. Concrete shall be thoroughly compacted by means of suitable tools during and immediately after depositing.The concrete shall be worked around all reinforcement,embedded fixtures,and into the comers of the forms.Every precaution shall be taken to keep the reinforcement and embedded metal in proper position and to prevent distortion.Vibrating. Wherever practicable,concrete shall be internally vibrated within the forms,or in the mass,in order to increase the plasticity as to compact effectively to improve the surface texture and appearance,and to facilitate placing of the concrete.Vibration shall be continued the entire batch melts to a uniform appearance and the surface just starts to glisten.A minute film of cement paste shall be discernible between the concrete and the form and around the reinforcement.Over vibration causing segregation,unnecessary bleeding or formation of laitance shall be avoided.The effect spent on careful grading, mixing and compaction of concrete will be largely wasted if the concrete is badly cured. Curing means keeping the concretethoroughly damp for some time, usually a week, until it has reached the desired strength. So long as concrete is kept wet it will continue to gain strength, though more slowly as it grows older.Admixtures or additives to concrete are materials are materials which are added to it or to the cement so as to improve one or more of the properties of the concrete. The main types are:1. Accelerators of set or hardening,2. Retarders of set or hardening,3. Air-entraining agents, including frothing or foaming agents,4. Gassing agents,5. Pozzolanas, blast-furnace slag cement, pulverized coal ash,6. Inhibitors of the chemical reaction between cement and aggregate, which might cause the aggregate to expand7. Agents for damp-proofing a concrete or reducing its permeability to water,8. Workability agents, often called plasticizers,9. Grouting agents and expanding cements.Wherever possible, admixtures should be avouded, particularly those that are added on site. Small variations in the quantity added may greatly affect the concrete properties in an undesiraale way. An accelerator can often be avoided by using a rapid-hardening cement or a richer mix with ordinary cement, or for very rapid gain of strength, high-alumina cement, though this is very much more expensive, in Britain about three times as costly as ordinary Portland cement. But in twenty-four hours its strength is equal to that reached with ordinary Portland cement in thirty days.A retarder may have to be used in warm weather when a large quantity of concrete has to be cast in one piece of formwork, and it is important that the concrete cast early in the day does not set before the last concrete. This occurs with bridges when they are cast in place, and the formwork necessarily bends under the heavy load of the wet concrete. Some retarders permanently weaken the concrete and should not be used without good technical advice.A somewhat similar effect,milder than that of retarders, is obtained with low-heat cement. These may be sold by the cement maker or mixed by the civil engineering contractor. They give out less heat on setting and hardening, partly because they harden more slowly, and they are used in large casts such as gravity dams, where the concrete may take years to cool down to the temperature of the surrounding air. In countries like Britain or France, where pulverized coal is burnt in the power stations, the ash, which is very fine, has been mixed with cement to reduce its production of heat and its cost without reducing its long-term strength. Up to about 20 per cent ash by weight of the cement has been successfully used, with considerable savings in cement costs.In countries where air-entraining cement cement can be bought from the cement maker, no air-entraining agent needs to be mixed in .When air-entraining agents draw into the wet cement and concrete some 3-8 percent of air in the form of very small bubbles, they plasticize the concrete, making it more easily workable and therefore enable the water |cement ratio to be reduced. They reduce the strength of the concrete slightly but so little that in the United States their use is now standard practice in road-building where heavy frost occur. They greatly improve the frost resistance of the concrete.Pozzolane is a volcanic ash found near the Italian town of Puzzuoli, which is a natural cement. The name has been given to all natural mineral cements, as well as to the ash from coal or the slag from blast furnaces, both of which may become cements when ground and mixed with water. Pozzolanas of either the industrial or the mineral type are important to civil engineers because they have been added to oridinary Portland cement in proportions up to about 20 percent without loss of strength in the cement and with great savings in cement cost. Their main interest is in large dams, where they may reduce the heat given out by the cement during hardening. Some pozzolanas have been known to prevent the action between cement and certain aggregates which causes the aggregate to expand, and weaken or burst the concrete.The best way of waterproof a concrete is to reduce its permeability by careful mix design and manufacture of the concrete, with correct placing and tighr compaction in strong formwork ar a low water|cement ratio. Even an air-entraining agent can be used because the minute pores are discontinuous. Slow, careful curing of the concrete improves the hydration of the cement, which helps to block the capillary passages through the concrete mass. An asphalt or other waterproofing means the waterproofing of concrete by any method concerned with the quality of the concrete but not by a waterproof skin.Workability agents, water-reducing agents and plasticizers are three names for the same thing, mentioned under air-entraining agents. Their use can sometimes be avoided by adding more cement or fine sand, or even water, but of course only with great care.The rapid growth from 1945 onwards in the prestressing of concrete shows that there was a real need for this high-quality structural material. The quality must be high because the worst conditions of loading normally occur at the beginning of the life of the member, at the transfer of stress from the steel to the concrete. Failure is therefore more likely then than later, when the concrete has become stronger and the stress in the steel has decreased because of creep in the steel and concrete, and shrinkage of the concrete. Faulty members are therefore observed and thrown out early, before they enter the structure, or at least before it The main advantages of prestressed concrete in comparison with reinforced concrete are :①The whole concrete cross-section resists load. In reinforced concrete about half the section, the cracked area below the neutral axis, does no useful work. Working deflections are smaller.②High working stresses are possible. In reinforced concrete they are not usually possible because they result in severe cracking which is always ugly and may be dangerous if it causes rusting of the steel.③Cracking is almost completely avoided in prestressed concrete.The main disadvantage of prestressed concrete is that much more care is needed to make it than reinforced concrete and it is therefore more expensive, but because it is of higher quality less of it needs to be needs to be used. It can therefore happen that a solution of a structural problem may be cheaper in prestressed concrete than in reinforced concrete, and it does often happen that a solution is possible with prestressing but impossible without it.Prestressing of the concrete means that it is placed under compression before it carries any working load. This means that the section can be designed so that it takes no tension or very little under the full design load. It therefore has theoretically no cracks and in practice very few. The prestress is usually applied by tensioning the steel before the concrete in which it is embedded has hardened. After the concrete has hardened enough to take the stress from the steel to the concrete. In a bridge with abutments able to resist thrust, the prestress can be applied without steel in the concrete. It is applied by jacks forcing the bridge inwards from the abutments. This methods has the advantage that the jacking force, or prestress, can be varied during the life of the structure as required.In the ten years from 1950 to 1960 prestressed concrete ceased to be an experinmental material and engineers won confidence in its use. With this confidence came an increase in the use of precast prestressed concrete particularly for long-span floors or the decks of motorways. Whereever the quantity to be made was large enough, for example in a motorway bridge 500 m kong , provided that most of the spans could be made the same and not much longer than 18m, it became economical to usefactory-precast prestressed beams, at least in industrial areas near a precasting factory prestressed beams, at least in industrial areas near a precasting factory. Most of these beams are heat-cured so as to free the forms quickly for re-use.In this period also, in the United States, precast prestressed roof beams and floor beams were used in many school buildings, occasionally 32 m long or more. Such long beams over a single span could not possibly be successful in reinforced concrete unless they were cast on site because they would have to be much deeper and much heavier than prestressed concrete beams. They would certainlly be less pleasing to the eye and often more expensive than the prestressed concrete beams. These school buildings have a strong, simple architectural appeal and will be a pleasure to look at for many years.The most important parts of a precast prestressed concrete beam are the tendons and the concrete. The tendons, as the name implies, are the cables, rods or wires of steel which are under tension in the concrete.Before the concrete has hardened (before transfer of stress), the tendons are either unstressed (post-tensioned prestressing) or are stressed and held by abutments outside the concrete ( pre-tensioned prestressing). While the concrete is hardening it grips each tendon more and more tightly by bond along its full length. End anchorages consisting of plates or blocks are placed on the ends of the tendons of post-tensioned prestressed units, and such tendons are stressed up at the time of transfer, when the concrete has hardened sufficiently. In the other type of pretressing, with pre-tensioned tendons, the tendons are released from external abutments at the moment of transfer, and act on the concrete through bond or archorage or both, shortening it by compression, and themselves also shortening and losing some tension.Further shortening of the concrete (and therefore of the steel) takes place with time. The concrete is said to creep. This means that it shortens permanently under load and spreads the stresses more uniformly and thus more safely across its section. Steel also creeps, but rather less. The result of these two effects ( and of the concrete shrinking when it dries ) is that prestressed concrete beams are never more highly stressed than at the moment of transfer.The factory precasting of long prestressed concrete beams is likely to become more and more popular in the future, but one difficulty will be road transport. As the length of the beam increases, the lorry becomes less and less manoeuvrable until eventually the only suitable time for it to travel is in the middle of the night when traffic in the district and the route, whether the roads are straight or curved. Precasting at the site avoids these difficulties; it may be expensive, but it has often been used for large bridge beams.混凝土工艺及发展波特兰水泥混凝土在当今世界已成为建造数量繁多、种类复杂结构的首选材料。

外文资料译文Portland cement of its Types and Manufacture of Portland cement Portland cement is made by heating a mixture of limestone and clay, or other materials of similar bulk composition and sufficient reactivity, ultimately to a temperature of about 1450°C. Partial fusion occurs, and nodules of clinker are produced. The clinker is mixed with a few percent of gypsum and finely ground to make the cement. The gypsum controls the rate of set and may be partly replaced by other forms of calcium sulfate. Some specifications allow the addition of other materials at the grinding stage. The clinker typically has a composition in the region of 67% CaO, 22% SiO2, 5% Al2O3, 3%Fe2O3, and 3% of other components,and normally contains four major phases,called alite , belite , aluminate phase and ferrite phase . Several other phases, such as alkali sulfates and calcium oxide, are normally present in minor amounts.Alite is the most important constituent of all normal Portland cement clinkers,of which it constitutes 50%--70%.It is tricalcium silicate (Ca3SiO5)modified in composition and crystal structure by incorporation of foreign ions, especially Mg2+, Al3+ and Fe3+. It reacts relatively quickly with water, and in normal Portland cement is the most important of the constituent phases for strength development at ages up to 28 days, it is by far the most important.Belite constitutes 15%---30% of normal Portland cement clinker. It is declaim silicate (Ca2SiO4) modified by incorporation of foreign ions and normally present wholly or largely as theβ polymorph. it reacts slowly with water , thus contributing little to the strength during the first 28 days ,but substantially to the further increase in strength that occurs at later ages .By one year, the strength obtainable form pure alit and pure belite are about the same under comparable conditions.The aluminates phase constitutes 5%--10% of most normal Portland cement clinkers. it is Tricalcium aluminates (Ca3Al2O6), substantially modified in composition and sometimes also in structure by incorporation of foreign ions , especially Si4+, Fe3+, Na+and K+. It reacts rapidly with water and can cause undesirably rapid setting unless a set-controlling agent, usually gypsum, is added.The ferrite phase makes up 5%-15% of normal Portland cement clinkers. It is tetra calcium aluminoferrite (Ca4AlFeO7) substantially modified in composition by variation in Al/Fe ratio and incorporation of foreign ions. The rate at which it reacts with water appears to be somewhat variable, perhaps due to differences in composition or other characteristics, but in general is high initially and intermediate between those of Alite and Belite at later ages.The great majority of Portland cements made throughout the world are designed for general constructional use. The specifications with which such cements must comply are similar, but not identical, in all countries and various names are used to define the material, such as OPC (Ordinary Portland Cement) in the UK, or Type IPortland Cement in the USA.Specifications are, in general based partly on chemical composition or physical properties such as specific surface area, and partly on performance tests, such as setting time or compressive strength developed under standard conditions. The content of MgO is usually limited to either 4 or 5%, because quantities of this component in excess of about 2% are liable to occur as periclase (magnesium oxide), which through slow reaction with water can cause destructive expansion of hardened concrete. Free lime (calcium oxide) can behave similarly, and its potential formation sets a practical upper limit to the Alite content of a clinker. Excessive contents of SO3 can also lead to delayed expansion, and upper limits of 2.5%-4% are usually imposed. Alkalis (K2O and Na2O) can undergo expansive reactions with certain aggregates, and some national specifications limit the content, e.g. to 0.6% equivalent Na2O (Na2O+0.66K2O) .other upper limit of composition widely used in specifications relate to matter insoluble in dilute acid, and loss on ignition. Many other minor components are limited in content by their effects on the manufacturing process, or the properties, or both, and in some cases the limits are defined in specifications.Rapid-hardening Portland cement have been produced in various ways , such as varying the composition to increase the alite content , finer grinding of the clinker , and improvements in the manufacturing process , e.g. finer grinding or better mixing of the raw materials . The alite contents of Portland cements have increases steadily over the one and a half centuries during which the latter have been produced, and many presentday cements that would be considered normal today would have been described as rapid hardening only a few decades ago. In USA specifications, rapid-hardening Portland cements are called high early strength or Type III cements.Destructive expansion from reaction with sulfates can occur not only if the latter are present in excessive proportion in the cement, but also form attack on concrete by sulfate solutions. The reaction involves the Al2O3 containing phases in the hardened cement, and in sulfate-resisting Portland cements, its effects are reduced by decreasing the proportion of the aluminates phase, sometimes to zero. This is achieved by decreasing the ratio of Al2O3to Fe2O3in the materials. In the USA, sulfate-resisting Portland cements are called Type V cements.White Portland cements are made by increasing the ratio of Al2O3 to Fe2O3, and thus represent the opposite extreme in composition to sulfate-resisting Portland cements. The normal, dark color .of Portland cement is due to the ferrite phase, formation of which in white cement must thus be avoided. It is impracticable to employ raw materials that are completely free from Fe2O3 and other components, such as Mn2O3, that contribute to the color. The effects of these components are therefore usually minimized by producing the clinker under slightly reducing conditions and by rapid quenching. In addition to alite, belite and aluminates phase, some glass may be formed.Portland cement is made from some of the earth's most abundant materials .about two-thirds of it is derived from calcium oxide, whose source is usually some form of lime-stone(calcium carbonate),marls, chalk, or shells(for example, oyster).the other ingredients-silica,SiO2,about20％;alumina ,Al2O3,about5％; and iron oxide,Fe2O3,about 3％are derived from sand shale, clays, coal ash, and iron ore metal slag. Because the individual ingredients must be fused and sintered to produce new compounds they must de ground to pass a 200 mesh screen in order to react within a reasonable time in the kiln .in addition, the composition of the raw materials must be held within narrow limits of the above oxides to produce a useful product. Other elemental oxides which can be detrimental to the cement must be limited: these include magnesium MgO; potassium oxide, K2O; sodium oxide, and phosphorus oxide, P2O5.after blending to the proper composition, the raw materials are interground in ball mills, rod mills, or roller millers. Depending on the raw materials characteristics, they are ground either dry (dry process) or in water (wet process). The resultant raw feed is introduced into the kiln system, usually a rotary kiln, where the material is heated to about 2700°F. The material progressively loses first the water, then the carbon dioxide CO2, at about 1750°F, and at about 2300°F, a small amount at liquid phase forms. This liquid is the medium through which the higher-melting phases are formed. The resultant product, called clinker because the whole never truly melts, is cooled and again ground, in ball mills to such a fineness that about 90％will pass a screen having 325 openings per linear inch. The final product has a texture much like face powder. During grinding, about 5％of calcium sulfate(gypsum or anhydride) is added to control setting time, strength development, and other properties.The major trend in manufacture of Portland cement has shifted to a greater emphasis on the reduction of the energy consumed for its production and increasing use of coal to replace gas and oil, which were the major fuels for burning the clinker. Energy consumption is generally greater for the wet process; therefore most new plants use the dry process. The characteristics of the final product are not any different for either process. The world's largest kiln (as of 1957) produced about 7500 tons (6750 metric tons) per day of clinker. An average kiln produces about 1800 tons (1620 metric tons) per day. The latest kilns utilize some form of preheating system, which fully utilizes the hot exit gases to warm the incoming raw materials; In addition, decarbonation of the limestone can be done on the raw feed prior to its entrance to the rotary kilns by use of auxiliary burners. These techniques enable much shorter rotary kilns for equal production and save much energy. Because of these developments, the world's longest kiln (760 ft or 228 m long, 25 ft or 7.5 m in diameter) will probably remain the longest. Another trend is toward a newer type of grinding mill, called a roller mill. This mill can use waste heat for drying, lends itself readily to automatic control, and uses less energy. These mills can grind up to 400 tons (360 metric tons) per hour. Several employees in a control room can operate a whole plant except for the quarry. Control is exercised by means of television monitors, sensors, computers, and automatic continuous chemical analysis.Other types of kilns which have been used or are in the process of being developed are vertical or shaft kilns, fluid-bed furnaces, and swirl calciners.波特兰水泥的分法及生产波特兰水泥是通过加热石灰岩和粘土的混合物，或者其他具有相似组成并具有活性的块状物来生产的，加热的最高温度可以达到大约1450摄氏度。

水泥专业词汇英语翻译矿渣硅酸盐水泥（矿渣水泥）slag cement硅酸盐水泥portland cement粉煤灰硅酸盐水泥（粉煤灰水泥）fly-ash portland cement火山灰质硅酸盐水泥（火山灰水泥）portland-pozzolana cement普通硅酸盐水泥（普通水泥）ordinary portland cement复合硅酸盐水泥(复合水泥)composite Portland cement主导产品leading product年产量annual output基准reference体系system完全燃烧complete combustion不完全燃烧incomplete combustion机械不完全燃烧mechanical incomplete combustion化学不完全燃烧chemical incomplete combustion雾化atomization雾化介质atomizing medium物料平衡material balance实际空气量amount of actual air for combustion理论空气量amount of theoretical air for combustion理论烟气量amount of theoretical burned gas；amount of theoretical flue gas 形成热heat of formation information 信息formation 形成单位热耗unit heat consumption标准煤Standard coal标准煤耗standard coal consumption实物煤耗raw coal consumption窑炉的余热利用waste heat utilization of kiln干燥周期drying cycle焙烧周期firing cycle热损失thermal loss；heat loss燃烧热heat of combustion有效热effective heat热效率heal efficiency燃烧效率combustion efficiency一次空气primary air二次空气secondary air系统漏入空气量false air空气系数air coefficient废气含尘浓度dust content in stack gas热平衡表heat balance table热流图heat balance diagram回转窑rotary kiln窑胭体内容积inside volume of kiln shell窑胴体有效内表面积effective inside surface of kiln shell窑或预热器排出飞灰量dust emit out from the Kiln or preheater system 入窑回灰量dust fed back into kiln system飞损飞灰量amount of flying loss of dust生料中可燃物质combustible components in raw meal生料带入空气量air volume carrying by raw meal冷却机烟囱排灰量dust content emitting from stack of cooler煤磨从窑系统抽出的热气体量hot gas volume from Kiln system for coal mill入窑回灰脱水及碳酸盐分解耗热heat consumption for dehydration and decarbonation for dust fed back into kiln system回转窑用煤应用基coal used in rotary kiln system立窑shaft Kiln漏风系数false air coefficient普通立窑cement shaft Kilt / ordinary shaft Kiln机械化立窑mechanized cement shaft kiln立窑喇叭口inversed cone inlet of shaft kiln立窑单位截面积产量production of shaft kiln for unit cross section立窑单位容积产量production of shaft Kiln for unit volume白生料common meal干白生料耗consumption of drying raw meal立窑断面平均风速average velocity in cross section of shaft kiln卸料管漏出风量amount of leaked out air for discharging tube窑面废气成分composition of combustion gas at the upper in surface of shaft Kiln黑生料black meal入磨煤量internal fuel amount of raw meal半黑生料semi－black meal入窑煤量external fuel amount of raw meal隧道窑tunnel Kiln倒焰窑down draft kiln检查坑道inspection pit预热带preheating zone烧成带firing zone；burning zone冷却带cooling zone窑车kiln car匣钵sagger棚板deck气幕air curtain直接冷却direct cooling间接冷却indirect cooling窑尾冷风cooling gas in the kiln outlet窑内断面温差difference of temperature in cross section of kiln 进车间隔时间kiln car time schedule坯体内结构水含量structural water content in body坯体的入窑温度inletting body temperature零压面neutral margin轮窑annular Kilt / ring Kilt circular kiln窑门wicket隧追式干燥室tunnel dryer湿坯wet green干坯dried green绝干坯absolute dried green普通砖common brick窑的部火数number of fire travels in annular kiln内掺燃料（简称内燃料）carbonaceous materials added to raw materials外投燃料（简称外燃料）external fuel added into firing－hole of a kiln焙烧反应热heat of burning reaction操作放热损失heat losses in the opening and closing of kiln wicket and firing holes 隧道式干燥室－轮窑（隧道窑）体系热效率（简称体系热效率）（ηtx）the fmal efficiency of tunnel dryer－annular kiln （tunnel kiln）system隧道式干燥室－轮窑（隧道窑）体系单位热耗（简称体系单位热耗）unit heat consumption of tunnel dryer－annular Kiln（tunnel kiln）system隧道式干燥室，轮窑（隧道窑）体系单位煤耗（简称体系单位煤耗）（mtxm）unit coal consumption of tunnel dryer－annular Kiln（tunnel kiln）system cardanshaft万向联轴节companionflange成对法兰结合法兰配对法兰screw螺丝钉packinglist装箱单hydraulic液压的rollerpress液压机bearing活动轴承bore钻孔thread穿线hexagonnut六角螺母springlockwasher螺丝弹簧垫片handpump手动泵grease润滑油file锉screwclamp螺丝钳slidingcaliper游标卡尺vice抬物架hose胶皮管tubefitting管接头cyl.rollerbearing轴承thrustroll.bear.spherical轴承spheric.pl.bearing球面轴承slidingplate滑板tyre轮带flatpacking密封shaftlipseal密封v-sealv-密封o-ringo形圈compressionspring弹簧垫片pumpingelement泵件progr.distributor分配器gasketset密封圈装置rubberplate橡胶板bellows橡胶防尘罩风箱transm.pressure压力表,压力传动器filterelement过滤芯gearedpump齿轮泵prop.contr.valve阀gasket密封pressuregauge压力表sightglass量位计einbaruventil阀hose管子liftcheckvalve阀diff.pressuregaue压力表diaph.accumulator气串瓶speicherblase气串temperaturesensor传感器gas-valveinsert阀芯ventileinheit阀芯clutch/coupling连轴带srppressorplug插座levelswitch开关sandwichplate夹层板direct.contr.valve直控阀ventilatingfilter滤芯flowcontrolvalveby-passvalve旁通阀,辅助阀,回流阀tubularcoredele.焊丝cored-wire焊丝plug-inconnector插座接头pulsegenerator脉冲发生器proximityswitchinductive非接触式电感开关sensor传感器pick-up传感器monitoringtransd.变送器hexagonbolt六角螺栓springlockwasher弹簧锁架垫片resist.thermometeroilleak-proof油封式变阻温度计resist.thermometer变阻温度计screwflatcountersunknibbolt螺旋平头垫头螺栓heatingcable耐热电缆connectionset连接装置controllerelectronic电子调节器,电控装置alum.adjesovetape胶带threadedjoint螺纹接合hoseassembly软组件twinnipple双喷嘴measuringinstrument计量工具bracket支座support支座hydr.cyl.flattype液压缸板型,水平水压气缸rotaryseal回转密封threadedrod螺纹杆hexagonnut六角螺母pressionhose压力软管hoseclip软管卡l-section组装列表controlblockhydraulicunitwithcontrol液压控制部件pumpset泵机组levelcontrol水平控制,水准控制press.reliefvalve安全阀tubefitting管接头progr.distributor程序寄存器crane龙头retainingplate固定板,支撑板directionalsign定向信号screwingarmature螺纹电枢variab.displ.motor可旋转电机shim薄垫片sprocketwheelforrollerchain链轮simpl.rollerchain单缸棍子链sliderail滑轨rerainingwasher固定垫片stickelectrodecovered焊条ratingplate标牌notchednail凹槽钉threadcutt.screw旋转螺纹distancepiece隔板screwhexagonsocketheadcapscrew六角螺钉locatingwasher定位垫片liningring衬垫clip压板o-sealo形密封圈flatiron扁铁floorplate地板elbow弯头hydraulichose水力管screwnipple螺纹连接管settingtool安装工具socketwrenchsquaredrive套筒扳手extensionbar加长杆handle.spintypemalesquare销式手柄lineal线pin销子adapter转接器clevispinu形夹销nitrogenload.dev.负载氮气wrench扳手shackle钩环chaintrackguard护链槽lateralwall单侧墙roundsteel圆钢intermed.piece中圆片discspring盘簧studscrew柱螺栓螺钉thrustwasher止推拴片rotationallock旋转锁定air exhaust 排气air exhaust opening 排气口clampingbox夹紧盒clampingsocket夹紧插座controlbox操纵台,控制箱,操作箱dowels销子squarekey方键lubricatingequipmentowge润滑用具setsofsuction抽水机,抽水泵shrinkdisc缩紧盘allowance补贴air cooled condenser空冷式冷凝器水泥行业常用英语会话水泥英语1 How do you do? Mr. Jensen . Welcome to Guangdong.你好，Jensen先生，欢迎到广东来。

1水泥的历史中英文对照资料外文翻译文献外文翻译History of cementEarly usesThe earliest construction cements are as old as construction, and were non-hydraulic. Wherever primitive mud bricks were used, they were bedded together with a thin layer of clay slurry. Mud-based materials were also used for rendering on the walls of timber or wattle and daub structures. Lime was probably used for the first time as an additive in these renders, and for stabilizing mud floors. A “daub” consisting of mud, cow dung and lime produces s tough coating, due to coagulation by the lime, of proteins in the cow dung. This simple system was common in Europe until quite recent times. With the advent of fired bricks, and their use in larger structures, various cultures started to experiment with higher-strength mortars based on bitumen (in Mesopotamia), gypsum (in Egypt) and lime (in many parts of the world). It is uncertain where it was first discovered that a combination of hydrated non-hydraulic lime and a pozzolan produces a hydraulic mixture, but concrete made from such mixtures was first used on a large scale by the Romans. They used both natural pozzolans ( trass or pumice) and artificialpozzolans (ground brick or pottery) in these concretes. Many excellent examples of structures made from these concretes are still standing, notably the huge monolithic dome of the Pantheon in Rome. The use of structural concrete disappeared in medieval Europe, although weak pozzolanic concretes continued to be used as a core fill in stone walls and columns.Modern cementModern hydraulic cements began to be developed from the start of the Industrial Revolution (around 1800), driven by three main needs:Hydraulic renders for finishing brick buildings in wet climates.˙Hydraulic mortars for masonry construction of harbor works etc, in contact with sea water.˙Development of strong concretes.In Britain particularly, good quality building stone became ever more expensive during a period of rapid growth, and it became a common practice to construct prestige buildings from the new industrial bricks, and to finish them with a stucco to imitate stone. Hydraulic limes were favored for this, but the need for a fast set time encouraged the development of new cements. Most famous among these was Parker’s “Roman cement.” This was development byJames Parker in the 1780s, and finally patented in 1796. It was, in fact, nothing like any material used by the Romans, but was a “Natural cement” made by burning septaria-nodules that are found in certain clay deposits, and that contain both clay minerals and calcium carbonate. The burnt nodules were ground to a fine powder. This product, made into a mortar with sand, set in 5—15 minutes. The success of “Roman cement” led other manufacturers to develop rival products by burning artificial mixtures of clay and chalk.John Smeaton made an important contribution to the development of cements when he was planning the construction of the third Eddystone Lighthouse (1755-9) in the English Channel. He needed a hydraulic mortar that would set and develop some strength in the twelve hour period between successive high tides. He performed an exhaustive market research on theavailable hydraulic limes, visiting their production sites, and noted that the “hydraulicity” of the lime was directl directly y related to the clay content of the limestone from which it was made. Smeaton was a civil engineer by profession, and took the idea no further. Apparently unaware of Smeaton’s work, the same principle was identified by Louis Vicat in the first decade of the nineteenth century. Vicat went on to devise a method of combining chalk and clay into an intimate mixture, and, burning this, produced an “artificial cement” in 1817. James Frost, working in Britain, produced what he called “British cement” in a similar manner around the same time, but did not obtain a patent until 1822. In 1824, Joseph Aspdin patented a similar material, which he called Portland cement, because the render made from it was in color similar to the prestigious Portland stone.All the above products could not compete with lime/pozzolan concretes because of fast-setting (giving insufficient time for placement) and low early strengths(requiring a delay of many weeks before formwork could be removed). Hydraulic limes “natural” cements and “artificial” cements all rely upon their belite content for strength development. Belite develops strength solely. Because they were burned at temperatures below 1259℃, they contained no alite, which is responsible for early strength in modern cements. The first cement to consistently contain alite was that made by Joseph Aspdin’s son William in the early 1840s. This was what we call today “modern” Portland cement. Because of the air of mystery with which William Aspdin surrounded his product, others (e.g.Vicat and I C Johnson) have claimed precedence in this invention, but recent analysis of both his concrete and raw cement have shown that William Aspdin’s products made at Northfleet, Keen was a true alite-alite-based based cement. However, Aspdin’s methods were “rule “rule-of-th -of-th -of-thumb”:Vicat is responsible for establishing the mix in the kiln.umb”:Vicat is responsible for establishing the mix in the kiln. William Aspdin’s innovation was counter counter-intuitive -intuitive for manufacturers of “artificial cement”, because they required more lime in the mix ( a problem for his father ), because they required a much higher kiln temperature ( andtherefore more fuel ) and because the resulting clinker was very hard and rapidly wore down the millstones which were the only available grinding technology of the time. Manufacturing costs were therefore considerably higher, but the product set reasonably slowly and developed strength quickly, thus opening up a market for use in concrete. The use of concrete in construction grew rapidly from 1850 onwards, and was soon the dominant use for cements. Thus Portland cement began its predominant role.水泥的历史早期应用早期应用最早的建筑水泥是和建筑一起起步的，但是这种水泥在水中不会硬化。

外文资料Manufactre of Portland CementPortland cement is made from some of the Earth's most abundant materials.About two - thirds of it is derived from calcium oxide, whose source is usually some form of lime - stone (calcium carbonate),marls,chalk, or shells(for exam-ple oyster).The other ingredients - silica SiO2,about 20% ; alumina,Al2O3,about 5%; and iron oxide, Fe2O3 about 3%-are derived from sand shales, clays, coal ash, and iron ore metal slags. Because the individual ingredients must be fused and sintered to produce new compounds, they must be ground to pass a 200- mesh screen in order to react within a reasonable time in the kiln. In addition, the composition of the raw materials must be held within narrow lim-its of the above oxides to produce a useful product. Other elemental oxides which can be detrimental to the cement must be limited, these include magne-siumMgO ; potassium oxide K2O ; sodium oxide, and phosphorus oxide, P2O5.After blending to the proper composition, the raw materials are interground in bail mills, rod mills,or roller mills. Depending on the raw material characteris-tics, they are ground either dry (dry process) or in water(wet process). The re-sultant raw feed is introduced into the kiln system usually a rotary kiln, where the material is heated to about 2700'F(1482℃). The material progressively loses first the water then the carbon dioxide CO2, at about 1750'F(954℃), and at about 2300'F(1260℃), a small amount at liquid phase forms. This liquid is the medium through which the higher - melting phases are formed. The resultant product, called clinker because the whole never truly melts, is cooled and again ground,in ball mills to such a fineness that about 90% will pass a screen having 325 openings per linear inch. The final product has a texture much like face pow-der. During grinding, about 5% of calcium sulfate (gypsum or anhydride) is added to control setting time,strength development, and other properties.The major trend in manufacture of Portland cement has shifted to a greater emphasis on the reduction of the energy consumed for its production and an in-creasing use of coal to replace gas and oil; which were the major fuels for burn-ing the clinker. Energy consumption is generally greater for the wet process; therefore most new plants use the dry process. The characteristics of the final product are not any different for either process. The world's largest kiln ( as of 1957)produced about 7500 tons (6750 metric tons) per day of clinker. An aver-age kiln produces about 1800tons (1620 metric tons) per day. The latest kilns utilize some form of preheating system which fully utilizes the hot exit gases to warm the incoming raw materials ; in addition decarbonation of the limestone can be done on the raw feed prior to its entrance to the rotary kiln by use of aux-iliary burners. These techniques enable much shorter rotary kilns for equal production and save much energy. Because of these developments, the world's longest kiln (760 ft or 228 m long, 25 ft or 7. 5 m in diameter) will probably re-main the longest. Another trend is toward a newer type of grinding mill, called a roller mill. This mill can use waste heat for drying, lends itself readily to auto-matic control, and uses less energy. These mills can grind up to 400 tons(360 metric tons) per hour. Several employees in a control room can operate a whole plant except for the quarry. Control is exercised by means of television monitors, sensors 9 computers 9 and automatic continuous chemical analysis.Other types of kilns which have been used or are in the process of being developed are vertical or shaft kilns, fluid-bed furnaces, and swirl calciners.Storage of Cement. Portland cement is a moisture-sensitive material; if kept dry, it will retain its quality indefinitely. When stored in contact with damp air or moisture, portland cement will set more slowly and has less strength than portland cement that is kept dry. When storing bagged cement, a shaded area or warehouse is preferred. Cracks and openings in storehouses should be closed. When storing bagged cement outdoors, it should be stacked on pallets and covered with a waterproof covering.波特兰水泥的制造波特兰水泥是由一些地球上最丰富的原料组成。

Portland cementPortland cement(often referred to as OPC, from Ordinary Portland Cement) is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout. It is a fine powder produced by grinding Portland cement clinker (more than 90%), a limited amount of calcium sulfate (which controls the set time) and up to 5% minor constituents as allowed by various standards such as the European Standard EN197.1ASTM C 150 defines portland cement as "hydraulic cement (cement that not only hardens by reacting with water but also forms a water-resistant product) produced by pulverizing clinkers consisting essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an inter ground addition." Clinkers are nodules (diameters：0.2-1.0 inch [5–25 mm]) of a sintered material that is produced when a raw mixture of predetermined composition is heated to high temperature. The low cost and widespread availability of the limestone, shales, and other naturally occurring materials make portland cement one of the lowest-cost materials widely used over the last century throughout the world. Concrete becomes one of the most versatile construction materials available in the world.Portland cement clinker is made by heating, in a kiln, a homogeneous mixture of raw materials to a sintering temperature, which is about 1450 °C for modern cements. The aluminium oxide and iron oxide are present as a flux and contribute little to the strength. For special cements, such as Low Heat (LH) and Sulfate Resistant (SR) types, it is necessary to limit the amount of tricalcium aluminate (3CaO.Al2O3) formed. The major raw material for the clinker-making is usually limestone (CaCO3) mixed with a second material containing clay as source of alumino-silicate. Normally, an impure limestone which contains clay or SiO2 is used. The CaCO3 content of these limestones can be as low as 80%. Second raw materials (materials in the rawmix other than limestone) depend on the purity of the limestone. Some of the second raw materials used are: clay, shale, sand, iron ore, bauxite, fly ash and slag. When a cement kiln is fired by coal, the ash of the coal acts as a secondary raw material HistoryPortland cement was developed from natural cements made in Britain in the early part of the nineteenth century, and its name is derived from its similarity to Portland stone, a type of building stone that was quarried on the Isle of Portland in Dorset, England.The Portland cement is considered to originate from Joseph Aspdin, a British bricklayer from Leeds. It was one of his employees (Isaac Johnson), however, who developed the production technique, which resulted in a more fast-hardening cement with a higher compressive strength. This process was patented in 1824. His cement was an artificial cement similar in properties to the material known as "Roman cement" (patented in 1796 by James Parker) and his process was similar to that patented in 1822 and used since 1811 by James Frost who called his cement "British Cement". The name "Portland cement" is also recorded in a directory published in 1823 being associated with a William Lockwood, Dave Stewart, and possibly others.Aspdin's son William, in 1843, made an improved version of this cement and he initially called it "Patent Portland cement" although he had no patent. In 1848 William Aspdin further improved his cement and in 1853 he moved to Germany where he was involved in cement making. Many people have claimed to have made the first Portland cement in the modern sense, but it is generally accepted that it was first manufactured by William Aspdin at Northfleet, England in about 1842. The German Government issued a standard on Portland cement in 1878.ProductionThere are three fundamental stages in the production of Portland cement:1.Preparation of the raw mixture2.Production of the clinker3.Preparation of the cementTo simplify the complex chemical formulae which describe the compounds present in cement, a cement chemist notation was invented. This notation reflects the fact that most of the elements are present in their highest oxidation state, and chemical analyses of cement are expressed as mass percent of these notional oxidesRawmix preparationThe raw materials for Portland cement production are a mixture of minerals containing calcium oxide, silicon oxide, aluminium oxide, ferric oxide, and magnesium oxide, as fine powder in the 'Dry process' or in the form of a slurry in the 'Wet process'. The raw materials are usually quarried from local rock, which in some places is already practically the desired composition and in other places requires the addition of clay and limestone, as well as iron ore, bauxite or recycled materials. The individual raw materials are first crushed, typically to below 50 mm.Formation of clinkerThe raw mixture is heated in a cement kiln, a slowly rotating and sloped cylinder, with temperatures increasing over the length of the cylinder up to a peak temperature of 1400-1450 °C. A complex succession of chemical reactions takes place (see cement kiln) as the temperature rises. The peak temperature is regulated so that the product contains sintered but not fused lumps. Sintering consists of the melting of25-30% of the mass of the material. The resulting liquid draws the remaining solid particles together by surface tension and acts as a solvent for the final chemical reaction in which alite is formed. Too low a temperature causes insufficient sintering and incomplete reaction, but too high a temperature results in a molten mass or glass, destruction of the kiln lining, and waste of fuel. When all goes according to plan, the resulting material is clinker. On cooling, it is conveyed to storage. Some effort is usually made to blend the clinker because, although the chemistry of the rawmix may have been tightly controlled, the kiln process potentially introduces new sources of chemical variability. The clinker can be stored for a number of years before use. Prolonged exposure to water decreases the reactivity of cement produced from weathered clinker.The enthalpy of formation of clinker from calcium carbonate and clay minerals is about 1500 to 1700 kJ/kg. However, because of heat loss during production, actual values can be much higher. The high energy requirements and the release of significant amounts of carbon dioxide makes cement production a concern for global warming.Cement grindingIn order to achieve the desired setting qualities in the finished product, a quantity(2-8%, but typically 5%) of calcium sulfate (usually gypsum or anhydrite) is added to the clinker and the mixture is finely ground to form the finished cement powder. This is achieved in a cement mill. The grinding process is controlled to obtain a powder with a broad particle size range, in which typically 15% by mass consists of particles below 5 μm diameter, and 5% of particles above 45 μm. The measure of fineness usually used is the "specific surface area", which is the total particle surface area of a unit mass of cement. The rate of initial reaction (up to 24 hours) of the cement on addition of water is directly proportional to the specific surface area. Typical values are 320–380 m2·kg−1 for general purpose cements, and 450–650 m2·kg−1 for "rapid hardening" cements. The cement is conveyed by belt or powder pump to a silo for storage. Cement plants normally have sufficient silo space for 1–20 weeks production, depending upon local demand cycles. The cement is delivered to end-users either in bags or as bulk powder blown from a pressure vehicle into the customer's silo. In industrial countries, 80% or more of cement is delivered in bulkUseThe most common use for Portland cement is in the production of concrete. Concrete is a composite material consisting of aggregate (gravel and sand), cement, and water. As a construction material, concrete can be cast in almost any shape desired, and once hardened, can become a structural (load bearing) element. Users may be involved in the factory production of pre-cast units, such as panels, beams, road furniture, or may make cast-in-situ concrete such as building superstructures, roads, dams. These may be supplied with concrete mixed on site, or may be provided with "ready-mixed" concrete made at permanent mixing sites. Portland cement is also used in mortars (with sand and water only) for plasters and screeds, and in grouts (cement/water mixes squeezed into gaps to consolidate foundations, road-beds, etc.).When water is mixed with Portland Cement, the product sets in a few hours and hardens over a period of weeks. These processes can vary widely depending upon the mix used and the conditions of curing of the product, but a typical concrete sets in about 6 hours and develops a compressive strength of 8 MPa in 24 hours. The strength rises to 15 MPa at 3 days, 23 MPa at 1 week, 35 MPa at 4 weeks and 41 MPa at3 months. In principle, the strength continues to rise slowly as long as water is available for continued hydration, but concrete is usually allowed to dry out after a few weeks and this causes strength growth to stop.Cement plants used for waste disposal or processingDue to the high temperatures inside cement kilns, combined with the oxidizing (oxygen-rich) atmosphere and long residence times, cement kilns are used as a processing option for various types of waste streams: indeed, they efficiently destroy many hazardous organic compounds. The waste streams also often contain combustible materials which allow the substitution of part of the fossil fuel norma lly used in the process.Waste materials used in cement kilns as a fuel supplement∙Paint sludge from automobile industries∙Waste solvents and lubricants∙Meat and bone meal - slaughterhouse waste due to bovine spongiform encephalopathy contamination concerns∙Waste plastics∙Sewage sludge∙Rice hulls∙Sugarcane waste∙Used wooden railroad ties (railway sleepers)Portland cement manufacture also has the potential to remove industrialby-products from the waste-stream, effectively sequestering some environmentally damaging wastes∙Slag∙Fly ash (from power plants)∙Silica fume (from steel mills)∙Synthetic gypsum波特兰水泥硅酸盐水泥(OPC),通常是指从普通硅酸盐水泥)是最常见的一种水泥在世界各地的一般用途,因为它是一种基本成分的混凝土、砂浆、粉刷、最非专业浆液。

外文翻译---波特兰水泥的原料准备外文资料翻译Portland Cement Preparation of Raw Materials1. CrushingThe raw materials as received from the mines are in lump form and have to be crushed before fine grinding. The size of the lumps would depend upon the raw material and the method of mining, so the size of the crushing equipment used would depend primarily upon the size of the lumps received. In a modern cement factory, manufacturing 1000 to 2000 tonnes of cement per day, the limestone is mined by mechanical means and hence the size of individual pieces may be 1 meter or so. In smaller factories, the mining of limestone may be manual and the size of individual pieces may be 200 mm or so. Similarly, clay, shale, bauxite, laterite, sandstone, coal, gypsum, etc. may be received in sizes not larger than 300 mm.(a) Limestone Crushers: The requirement of limestone per day for a 2000 TPD factory may be about 2600 to 3000 TPD, for a 1000 TPD factory 1300 to1500 TPD and for a 300 TPD factory 400 to 450 TPD. As the mining operation has to be carried out in daylight hours only, the crushing operation should also be carried out in the 10 or 12 hours of light per day. The capacity of a limestone crusher for a 2000 TPD factory may be 300 TPH, for a 1000 TPD factory 150 TPH and for a 300 TPD factory 50 TPH. The decision on the type of limestone crusher would depend upon the physical properties of the limestone; however, for smaller factories using manually mined limestone, single stage Hammer Crushers are most suitable; but for larger factories two stage crushing is always more economical and more efficient. The first stage may be a Jaw Crusher, Gyratory Crusher or Impact Crusher and the second stage a Hammer Crusher or Cone Crusher. If possible, a screen of suitable size may be introduced after the secondary crusher to allow only undersize to go for further processing while oversize is returned to the crusher. A typical flowsheet for a limestone crushing plant in a 2000 TPD factory may be.Dumpers--Feed Hopper with Laminated conveyor at the bottom 300 TPH Jaw Crusher (feed size 1000 mm - product size 200 mm ) 300 TPH Hammer Crusher or Impact Crusher or Cone Crusher (feed size 200 mm -- product size 20mm 300 THP Vibrating screen accepts minus 20 mm -- oversize back to crusher.Proper dedusting arrangements must be made at the crushers, the vibrating screen and the transfer points and a Dust Collector with fan installed. Power consumed for the crushing operation may vary from 3 to 6 Kwh per tonne of limestone. (b) Other Crushers. Crushers required for crushing shale, gypsum, coal, etc. may be of suitable design, preferably Hammer Mills, and of suitable size. For the 2000 TPD factory requiring 10 % addition of shale to the raw mix,using the dry process and using 6 % gypsum for cement grinding, the shale required would be about 3000 TPD, coal 4000 TPD and gypsum 100 TPD. The preferable size of the crushers would be 30 TPH, 50 TPH and 20 TPH respectively. The feed size may be specified minus 300 mm, and product size 20 or 25mm.2.Storage of Raw MaterialsLimestone in lump form is generally not stored at the factory, it is crushed as soon as it is received at the factory or even crushed at the mine itself and only crushed limestone is store at the factory. Shale or other corrective materials, coal and gypsum are generally stored in lump form as well as in crushed form. It would, therefore be advisable to have a common covered storage space for all types of crushed materials with proper partitions and proper reclaiming arrangements, Shale, gypsum, coal, etc., received in lump form, should be stored suitably and arrangements made to feed the same to the respective crushers mechanically. Two types of storage for crushed material are common:(a) crane gantry with Electric Overhead Travelling (EOT) cranes and(b) Storage bins with overhead feed belt conveyors and underground reclaiming belt conveyors, the second alternative may be more economical both in first costs and operating costs. The latest development in the storage of crushed raw materials, especially for factories with annual capacities of 0.5 million tonnes or more, is the "Bed Blending System" in which crushed limestone from different faces of the mines and correctives are spread in predetermined layers at one end and the material reclaimed with the help of cutter blades at the other end, so that a preblended raw mix of approximately the desired chemical composition is fed to the raw mill hoppers.the system can be housed either in the open or under cover, depending upon the climatic conditions of the location. Lump materials are generally stored in the open and reclaimed with the help of Pay Loaders or Scraper Haulers or Bull Dozers.3.Fine GrindingIn the manufacture of Portland Cement types, the calcareous constituent have to combine with the argillaceous constituents are ground and the more intimately they are mixed, the more efficient would be combination. If the limestone is of cement grade composition, the argillaceous constituents are intimately dis-seminated in the calcareous matrix, such a raw material can be ground coarse; but if the calcareous constituent is very pure and considerable amount of clay or shale has to be added, the raw mix must be ground much finer.A few tests carried out in a pilot plant can indicate the optimum degree of grinding required for a particular raw mix. It must be remembered that the raw materials fed to the grinding equipment are generally minus 20 mm and the product size may be 13±7% on 90 micron sieve. Intimate mixing is anotherimportant factor; the raw mix has to be brought to a very precise oxide composition, which in the manufacture of cement is generally gauged determining the total carbonates (TC) by simple acid/alkali titration. For example, if at a factory the holding point of TC is 78%, the TC from batch to batch should not vary more than 78±0.1%, and this can be achieved only by thorough mixing.4.storage of Ground MaterialIn the wet process the ground slurry is stored either in silos or in basins with continuous mixing. The storage capacity should be 2 to 3 days' consumption for the factory. In the dry process, tall silos are used for storage of the dry raw meal. It is now the general practice that mixing silos or "homogenising silos" are placed above the storage silos, so that the ready mixed and corrected raw mix is fed to the storage silos by gravity, result in a saving in power. The various methods of feeding the slurry and the dry raw meal to the burning equipment will be discussed in the next section, dealing with burning operation.5.Coal GrindingAs coal has been considered a raw material, grinding of coal should also considered in this section. Coal has to be ground dry. Raw coal always contains 2% to 10% moisture; during the rainy season the moisture content always goes up, sometimes even up to 15% to 20%. Therefore, coal has to be dried suitably before grinding. In early days rotary driers were used, but some forty years ago, mills were designed in which the coal could be dried and ground simultaneously with the help of hot air, in air swept ball mills. In separate drying and grinding systems the raw is dried in suitable driers with the help of hot air generated in an oil fired or coal fired or coal fired furnace; the spent air is vented to the atmosphere through suitable dust collectors. The dry coal is then ground, either in an open circuit coal mill in which the ground coal is transported to the coal firing hopper with the help of a bucket elevator, other dry coal may be ground in an air swept close circuit mill, and air used to transport the ground coal to the cyclone over the coal firing hopper; the same air is used as primary air in the coal firing pipe. In a simultaneous drying and grinding system, the front portion of the mill; fitted with lifters and chains, acts as the rotary drier and the back portion, filled with steel balls, acts as the closed circuit mill; hot air, either from the rotary kiln or from an auxiliary furnace, is used as air for drying and transporting the coal. The spent air, in this case also, is used as primary air in the coal firing pipe. The power consumption in separate drying and grinding units may work out to 25 to 30 kW·h per tonne fine coal and in the simultaneous drying and grinding units to about 20 to 25 kW·h per tonne fine coal.6.BurningA mixture of pure lime and silica in the proportion of 2. 8:1 should give 100% tricalcium silicate on burning, but it will require a very prolonged heating at 1600℃or more, to obtain a perfect combination. It is not possible to obtain such prolonged heating conditions in actual plant practice; it is, therefore, necessary to add some fluxing materials to bring about the combination at a lower temperature and in a shorter time. Alumina, iron oxide and, to some extent, magnesia and alkalies present in the raw mix act as the fluxing agents. By judicious inclusion of these oxides in the raw mix it is possible to shorten the reaction time to reasonable limits within the range of temperatures available in actual plant practice. In the process of burning in the manufacture of cement, the raw mix is first heated to about 100℃where the moisture present in the dry raw meal or in the semi -dry process nodules or in the wet process slurry is removed. The dry raw mix is further heated and at about 400℃to 500℃the combined moisture present in the clay matter of the raw mix is dissociated and removed and magnesium carbonate, if present, is dissociated. On further heating to about 900℃the calcium carbonate (the main ingredient of the raw mix) is dissociated, carbon dioxide evolved and simultaneously combination between the lime (CaO) and the Silica (SiO2), alumina (Al2O3) and iron-oxide (Fe2O3) starts. Presumably, first all the Fe z O3 present in the raw mix and a part of Al2O3 combine with lime to form C4AF at about 1200℃. This point may be termed as the start of the burning zone of the rotary kiln. The C4AF being the liquid form, the loose powdery mass starts becoming more coherent, and the movement of the material in the rotary kiln becomes more sluggish. At the same time, a part of the SiO2 present starts combining with CaO to form C2S. Then the remaining Al2O3 present combines with lime to form C3A, and now because the material has more liquids proper clinker nodule formation starts. As the mass passes further down the kiln, all the SiO2present combines with lime (CaO) to form C2S and the remaining lime (CaO) starts combining with C2S to form C3S. This point may be called the beginning of the actual clinkering zone which extends to the point where practically all the lime present combines with C2S to form C3S and very little free lime is left. At this point the clinker leaves the burning zone and cooling of the clinker starts.Clinker burning takes place in the above mentioned sequence in all the processes of burning, viz. , Long Dry Process Kiln, Long Wet Process Kiln, Short Dry Process kiln with suspension preheaters and Short Kilns with great heat exchangers. Lime silicates (C2S and C3S) are the true cementations materials, C3S contributing towards early strength and C2S towards late strength, so the Process Chemist tries to obtain the highest possible C3S and lowest possible free lime in his clinker commensurate with:波特兰水泥的原料准备破碎作为从矿山得到的原料以块状形式（存在），必须在研磨之前被破碎。