土木工程英语教案

1、Unit One CementIntroduction Cement, any material that hardens and becomes strongly adhesive after application in plastic form. The term cement is often used interchangeably with glue and adhesive; in engineering and building construction the term usually refers to a finely powdered, manufactured sub

2、stance consisting of gypsum plaster or portland cement that hardens and adheres after being mixed with water. Cements are used for various purposes, such as binding sand and gravel together with Portland cement to form concrete, for uniting the surfaces of various materials, or for coating surfaces

3、to protect them from chemical attack. Cements are made in a wide variety of compositions for a wide variety of uses. They may be named for the principal constituents, such as calcareous cement, which contains silica, and epoxy cement, which contains epoxy resins; for the materials they join, such as

4、 glass or vinyl cement; for the object to which they are applied, such as boiler cement, or for their characteristic property, such as hydraulic cement, which hardens underwater, or acid-resisting cement, or quick-setting cement. Cements used in construction are sometimes named for their commonly re

5、ported place of origin, like Roman cement, or for their resemblance to other materials, such as Portland cement, which produces a concrete resembling the Portland stone used for building in England. Cements that resist high temperatures are called refractory cements. Cements set, or harden, by the e

6、vaporation of the plasticizing liquid such as water, alcohol, or oil, by internal chemical change, by hydration, or by the growth of interlacing sets of crystals. Other cements harden as they react with the oxygen or carbon dioxide in the atmosphere. Portland Cement Typical Portland cements are mixt

7、ures of tricalcium silicate, tricalcium aluminate, and dicalcium silicate, in varying proportions, together with small amounts of magnesium and iron compounds. Gypsum is often added to slow the hardening process. Portland cement is manufactured from lime-bearing materials, usually limestone, togethe

8、r with clays, shales, or blast-furnace slag containing alumina and silica, in the approximate proportions of 60 percent lime, 19 percent silica, and 8 percent alumina, 5 percent iron, 5 percent magnesia, and 3 percent sulfur trioxide. Some rocks, called cement rocks, are naturally composed of these

9、elements in approximately suitable proportions and can be made into cement without the use of large quantities of other raw materials. In general, however, cement plants rely on mixed materials. In the manufacture of cement the raw materials are ground together, the mixture is heated until it fuses

10、into a clinker, and the clinker is ground into a fine powder. A number of tests are used to check the quality of the cement. A common one is to use a mortar specimen of one part of cement and three parts of sand and measure its tensile strength after a week in air and underwater. A good cement will

11、show a tensile strength of 19.4 kg per sq cm (2751 b per sq in) under these conditions. Special Cements By varying the percentage of its normal components or adding others, portland cement can be given various desirable characteristics, such as rapid hardening, low heat during hydration, and resista

12、nce to alkalis. Rapid-hardening cements, sometimes called high-early-strength cements, are made by increasing the proportion of tricalcium silicate or by finer grinding, so that up to 99.5 percent will pass through a screen with 16,370 openings per sq cm (105,625 per sq in). Some of these cements wi

13、ll harden as much in a day as ordinary cement does in a month. They produce much heat during hydration, however, which makes them unsuitable for large structures where such heat may cause cracks. Special low-heat cements, which usually have a large proportion of dicalcium silicate, are generally use

14、d for massive pourings. Where concrete work must be exposed to alkaline conditions, which attack concretes made with ordinary portland cement, resistant cements with a low aluminum content are generally employed. Cements for use under salt water may contain as much as 5 percent iron oxide, and those

15、 with as much as 40 percent aluminum oxide are used to resist the action of sulfate-bearing waters.简介水泥，是一种物质，在以塑性形式使用后会硬化，成为强烈的粘合剂后。水泥这个术语往往可以和胶水和粘合剂交替使用；在工程和建筑工程，这个术语通常指的是一种细粉末，工厂化生产的一种物质，含有石膏灰分或者波特兰水泥，与水混合会变硬。变粘。水泥用于各种目的，如结合沙和砾石与波特兰水泥形成混凝土，用于连接各种材料表面或表面涂层，保护他们免受化学侵蚀。水泥是由多种成分制造，用于为多种用途。他们可能以主要成分被命

16、名，如石灰水泥，其中包含二氧化硅，环氧水泥，其中包含环氧树脂；也可以以它们加入的材料命名，如玻璃或塑料水泥；为也可以以它们所用于的对象命名，如锅炉水泥，或以他们的特性命名，水硬性水泥，在水的作用下硬化，或耐酸水泥，或速凝水泥。水泥用于建筑，有时以原产地被命名，如罗马水泥，或以其与其他材料的相似点命名，如波特兰水泥，会产生类似波特兰石的混凝土，用于英国建筑。能抵抗高温的水泥被称为耐火水泥。水泥凝固或硬化，是通过蒸发塑化液体比如水，酒精，或油，通过内部的化学变化，水化作用，或晶体交织凝固作用的增长实现的。其他水泥当他们与氧气或大气中的二氧化碳发生反应时硬化。波特兰水泥典型的波特兰水泥是不同的比例的

17、硅酸三钙，铝酸三钙，和硅酸二钙以及少量镁和铁的化合物的混合物。石膏是经常添加减缓硬化过程。波特兰水泥是用含石灰的材料制成，通常是石灰岩，连同粘土，页岩，或含氧化铝和二氧化硅的高炉矿渣，以60%的石灰，19%的二氧化硅8%的氧化铝，5%的氧化铁，5%的氧化镁和3%的氧化硫的近似比例。一些岩石，称为水泥石，天生是由这些元素在大约相当比例下组成的，可以制成水泥，不需要大量使用其他原材料。然而，一般来说，水泥厂依靠混合材料。制造水泥的原材料一起混合后被加热到融合成熟料，熟料在磨成细粉。一些测试是用来检查水泥质量。常见的一种是测量用一分水泥和三分的沙子制成的砂浆标本在空气和水中养护一周后的抗拉强度，好的

18、水泥在这些条件的坑拉强度为19.4公斤/平方厘米（2751每平方英寸）。特种水泥通过改变正常组成部分的比例，或者添加替他的成分，波特兰水泥可具有不同的理想的特点，如快速硬化，低水化热，和抗碱。快硬水泥，有时被称为早强水泥，是通过增加硅酸三钙的比例或更细的研磨，使多达百分之99.5的成分将通过一个每平方厘米有16370个筛孔的筛网。其中的一些水泥将在1天内硬化，而普通水泥则需要一个月。他们在水化过程中产生大量的热，但是，这使得它们不适合大型结构，这种热量可能导致裂缝。特殊低热水泥，通常有一个硅酸二钙的大的比例，一般用于大规模浇筑。在具体工作中必须暴露在碱性条件下，这种条件会腐蚀有普通波特兰水泥混

19、凝土，通常使用含少量铝的耐碱水泥。用于盐水条件下的水泥可含有高达百分之5的铁氧化物，那些有高达百分之40的氧化铝的水泥是用来抵御含硝酸的水的作用。AggregatesAggregate is inert material (chemically inactive) such as sand，slag，pebbles, gravel, broken stone, broken bricks, industrial by products etc., which is mixed with cement and water and concrete or mortar is prepared. T

20、he aggregate is added to cement paste to increase the bulk Seventy to seventy-five percent of the volume of the hardened mass of concrete consists of aggregates. The remaining thirty to twenty five percent consists of hardened cement paste, uncombined water (i.e., water not involved in the hydration

21、 of the cement) and air voids. (2)Aggregate must be clean, dense,hard,durable,structurally sound,capable of developing good bond with cement, weather resistant and unaffected by water. )Sand. gravel and broken stone are natural available materials most commonly used as aggregates. Blast furnace slag

22、 (air-cooled and crushed) and broken bricks are the artificial and processed aggregates used in concrete. Natural aggregates are generally classified as coarse and fine aggregates. Natural materials having uniform shear strength in all directions are ideal for use as aggregates. Other natural materi

23、als having pronounced planes of weakness or cleavage (e.g., slate, shale,and micaceous materials) are usually undesirable. The aggregates used for concrete should conform to IS:383-1970 (specifications for coarse and fine aggregate from natural sources for concrete). Coarse aggregate Broken stones,

24、pebbles and gravel retained on IS:4.75 mm sieve is called as coarse aggregate. Coarse aggregate is prepared by crushing igneous stone (e.g., granite, gneiss), sedimentary stone (e.g., sand stones), and metamorphic stone (e.g., crystalline lime). f3Koarse aggregates prepared from very fine grained gr

25、anite stone is used for high strength concrete. Coarse aggregates obtained from crushing of hard sand stone are also suitable for use in concrete, Coarse aggregates made from the soft sand stone cracks when there is high degree of shrinkage in concrete, and it should be used with care. Coarse aggreg

26、ates (if prepared from close grained crystalline lime stone) is also suitable for use in plain cement concrete. Coarse aggregate made from broken bricks is also used for plain cement concrete only. It makes the concrete weak in strength. In structural concrete, the reinforcement is likely to be rust

27、ed when the broken brick aggregates are used. Coarse aggregates are separated in two or three size groups for use in concrete for large and important constructions. Each size group of aggregate is separately weighed according to grade charts and then combined to result in densely packed concrete. Fo

28、r construction of less importance, aggregates brought from the pits or river beds (called as all in aggregate) are directly used. Fine aggregate Sand and any other aggregates which pass through IS: 4.75 mm sieve is called fine aggregate. Sand is brought from lakes, pits, rivers and sea-shores. (4)ga

29、nd is thoroughly washed so that there remain no clay films over the surface of the aggregate. It prevents adhesion ofcement to the aggregate. Clay and silt are fine materials which pass through 75 micron IS: sieve. Clay and silt materials (if present) will increase water content. Dust is also detrim

30、ental material to concrete. As such the fine aggregates should be free from dust, organic impurities and silts. Chlorides (present in seashore sand) cause efflorescence and rusting and corrosion of reinforcement in structural concrete. In order to prepare strong concrete, angular grained sand (havin

31、g good interlocking property) is used. Round grained particles of sand lack in interlocking property. In order to prepare the concrete to have good strength, weather resistance and durability, the aggregates are closely packed. For this reason, the gradation of particle sizes of the aggregates is of

32、 considerable importance. Grading of aggregates (5)Gradation of particle sizes of the aggregate vary with the nature and course of material and the requirements in this respect depend upon the type of structure. The particle sizes of fine and coarse aggregates are properly graded. Use of well graded

33、 aggregates reduces the air voids. The cement fills up the air voids of fine aggregates. The cement and sand both together fill up the air voids of the coarse aggregate. The finishing, workability and uniformity of concrete are considerably affected by the grading of fine aggregates. 集料（1）集料是惰性材料（化学

34、活性不灵敏）如沙，渣，卵石，砾石，碎石，碎砖，工业产品等，它与水泥、水混合制备混凝土或砂浆。骨料添加到水泥浆中来增加块状物，混凝土硬化后百分之七十到百分之七十五的体积由骨料组成。其余三十至二零五%是由硬化水泥浆体，游离水（即水，不参与水化的水泥）和空隙。（2）骨料必须是干净的，致密，硬，耐用，结构性强，能够和水泥形成良好连接，具有耐候性和不受水的影响。沙，砾石、碎石是天然材料，是最常用的骨料。高炉渣（风冷和破碎）和破砖是人工加工骨料，在混凝土中的应用。自然骨料一般分为粗、细集料。天然材料在所有方向具有均匀的剪切强度，用作骨料是是理想的。其他天然材料具有明显的薄弱面或劈理（例如，板岩，页岩，云母

35、材料）通常是不可取的。用于混凝土的骨料应符合：383-1970（用于混凝土的天然的粗、细集料规范）。粗骨料 保留在4.75毫米筛径上的碎石，卵石和砾石称为粗骨料。粗集料是经过粉碎火成岩石（如花岗岩片麻岩），沉积岩（例如，沙石），和变质石（例如，石灰晶）制备的，用细粒花岗岩石材制备的粗骨料是用于高强度混凝土。从破碎中硬石砂制备的粗集料也适用于水泥，软沙石料制成的粗集料当时混凝土发生高程度的收缩时会裂纹，并应小心使用。粗集料（用紧密粒状的结晶石灰岩制备）也适用于普通水泥混凝土。用碎砖制备粗骨料也用于普通的水泥混凝土。它使混凝土强度下降。在混凝土结构中，当使用碎砖骨料是钢筋可能锈蚀。大型和重要的建筑

36、用于混凝土的粗骨料可分成二或三个粒组。每一个粒组组按及配图分别称重，然后混合制造密实填充的混凝土，对于不太重要建筑，骨料可以从洼地或河床（称为所有骨料）直接使用。细骨料能通过4.75毫米筛子的沙和任何其他骨料叫做细骨料。沙可取自湖泊，河流和海滨。（4）沙需彻底清洗，使骨料表面不会覆盖粘土薄膜。粘土薄膜会组织水泥骨料粘接。粘土和淤泥的好材料，粘土和淤泥是你通过75微米筛是的细粒料。粘土和淤泥材料（如果存在）会增加水含量。粉尘也是对混凝土的有害材料这样，细骨料应无灰尘，有机杂质和淤泥。氯化物（目前在海滨砂存在）会造成结构混凝土风化和钢筋生锈和腐蚀。为了制备强混凝土，采用角粒砂（具有良好的联锁性）。

37、圆粒沙石缺乏合适的联锁特性。为了准备具有良好的强度、耐候性和耐久性的混凝土，骨料需紧密堆积。为此，骨料颗粒的级配是相当重要的。骨料级配（5）骨料颗粒的级配随着特性和材料的层位变化，关于这方面的需求取决于结构的类型，粗细集料的颗粒尺寸需合理级配，使用良好级配的骨料会减少孔隙，水泥填充细集料的孔隙。水泥和沙共同填充粗集料的孔隙，细骨料的级配在很大程度上影响着混凝土的表面平整性、和易性好均匀性。Concrete Concrete (construction), artificial engineering material made from a mixture of cement, water,

38、fine and coarse aggregates, and a small amount of air. It is the most widely used construction material in the world. Concrete is the only major building material that can be delivered to the job site in a plastic state. This unique quality makes concrete desirable as a building material because it

39、can be molded to virtually any form or shape. Concrete provides a wide latitude in surface textures and colors and can be used to construct a wide variety of structures, such as highways and streets, bridges, dams, large buildings, airport runways, irrigation structures, breakwaters, piers and docks

40、, sidewalks, silos and farm buildings, homes, and even barges and ships. Other desirable qualities of concrete as a building material are its strength, economy, and durability. Depending on the mixture of materials used, concrete will support, in compression, 700 or more kg/sq cm (10,000 or more Ib/

41、sq in). The tensile strength of concrete is much lower, but by using properly designed steel reinforcing, structural members can be made that are as strong in tension as they are in compression. The durability of concrete is evidenced by the fact that concrete columns built by the Egyptians more tha

42、n 3,600 years ago are still standing. The two major components of concrete are a cement paste and inert materials. The cement paste consists of Portland cement, water, and some air either in the form of naturally entrapped air voids or minute, intentionally entrained air bubbles. The inert materials

43、 are usually composed of fine aggregate, which is a material such as sand, and coarse aggregate, which is a material such as gravel, crushed stone, or slag. In general, fine aggregate particles are smaller than 6.4 mm in size, and coarse aggregate particles are larger than 6.4 mm. Depending on the t

44、hickness of the structure to be built, the size of coarse aggregate particles used can vary widely. In building relatively thin sections, a small size of coarse aggregate, with particles about 6.4 mm in size, is used. At the other extreme, aggregates up to 15 cm or more in diameter are used in large

45、 dams. In general, the maximum size of coarse aggregates should not be larger than one-fifth of the narrowest dimensions of the concrete member in which it is used. When Portland cement is mixed with water, the compounds of the cement react to form a cementing medium. In properly mixed concrete, eac

46、h particle of sand and coarse aggregate is completely surrounded and coated by this paste, and all spaces between the particles are filled with it. As the cement paste sets and hardens, it binds the aggregates into a solid mass. Under normal conditions, concrete grows stronger as it grows older. The

47、 chemical reactions between cement and water that cause the paste to harden and bind the aggregates together require time. The reactions take place very rapidly at first and then more slowly over a long period of time. In the presence of moisture, concrete continues to gain strength for years. For i

48、nstance, the strength of just-poured concrete may be about 70,307 g/sq cm after drying for a day, 316,382 g/sq cm in 7 days, 421,842 g/sq cm in 28 days, and 597,610 g/sq cm after 5 years. Concrete mixtures are usually specified in terms of the dry-volume ratios of cement, sand, and coarse aggregates

49、 used. A 1:2:3 mixture, for instance, consists of one part by volume of cement, two parts of sand, and three parts of coarse aggregate. Depending on the applications, the proportions of the ingredients in the concrete can be altered to produce specific changes in its properties, particularly strengt

50、h and durability. The ratios can vary from 1:2:3 to 1:2:4 and 1:3:5. The amount of water added to these mixtures is about 1 to 1.5 times the volume of the cement. For high-strength concrete, the water content is kept low, with just enough water added to wet the entire mixture. In general, the more w

51、ater in a concrete mix, the easier it is to work with, but the weaker the hardened concrete becomes. Concrete can be made to have any degree of watertightness. It can be made to hold water and resist the penetration of wind-driven rains. On the other hand, for purposes such as constructing filter be

52、ds, concrete can be made porous and highly permeable. Concrete can also be given a polished surface that is as smooth as glass. By using heavy aggregates, including steel fragments, dense concrete mixtures can be made that weigh 4005 or more kg/m3. Concrete that weighs only 481 kg/m3 can be made by

53、using special lightweight aggregates and foaming techniques. Forms consisting of such lightweight aggregates can be floated on water, sawed into pieces, or nailed to another surface. After exposed surfaces of concrete have hardened sufficiently to resist marring, they should be cured by sprinkling o

54、r ponding (covering) with water or by using moisture-retaining materials such as waterproof paper, plastic sheets, wet burlap, or sand. Special curing sprays are available. The longer concrete is kept moist, the stronger and more durable it will become. In hot weather, it should be kept moist for at

55、 least three days. In cold weather, drying concrete must not be allowed to freeze. This can be accomplished by covering the cement with a tarpaulin or some other material that helps trap the heat generated by the chemical reactions within the concrete that cause it to harden.单元2混凝土混凝土，由水泥，水，细和粗骨料，和少

56、量的空气制成的一种人工工程材料。它是世界上最广泛使用的建筑材料。混凝土是唯一的主要建筑材料，可以在塑性状态运送到工作现场。这种独特的品质使混凝土作为理想的建筑材料，因为它可以被塑造成几乎任何形式或形状。混凝土在表面纹理和颜色方面提供了很宽的界限，可用于构建各种结构，如公路和街道，桥梁，堤坝，大型建筑物，机场跑道，灌溉结构，防波堤，桥墩和码头，人行道，筒仓和农场建筑，房屋，甚至驳船和轮船。混凝土作为一种建筑材料，其他可取的性质是它的强度和耐久性，经济性。取决于所用的材料的混合物，混凝土能承受超过700公斤/平方厘米（10000个或更多的磅/平方英寸）的压力。混凝土的抗拉强度很低，但使用适当设计的

57、钢结构构件加固，这种结构在抗拉方面可以具有和抗压一样的强度，混凝土耐久性已经由超过3600年前埃及人建筑的混凝土柱仍然站立的事实证明。混凝土的两种主要成分是水泥净浆和混凝土惰性材料。水泥浆含有波特兰水泥，水，和一些空气，或者是以天然的空气孔隙形式或者是有意携带的少量的空气气泡的形式。惰性材料通常包括细集料，比如沙子和粗骨料如砾石，碎石，或渣。一般来说，细骨料颗粒小于6.4毫米大小，粗骨料颗粒大于6.4毫米。根据建筑的结构的不同厚度，粗骨料颗粒的尺寸可以有很大的不同。在截面相对薄的建筑中，采用颗粒尺寸大约6.4毫米的小材料粗集料。在另一个极端，大型大坝采用粒径达到或超过15厘米粗集料。一般来说，

58、粗集料的最大粒径不应大于五分之一混凝土构件的最窄的尺寸。当波特兰水泥与水混合，该水泥化合物就会反应形成一种水泥介质。以适当比例搭配混合的混凝土，每一粒砂和粗骨料完全被砂浆包围和包覆，和所有颗粒之间的间隙充满了砂浆。当水泥浆凝固和硬化时，它就把这些寂寥凝固形成一个坚实整体。正常情况下，混凝土会随着凝固而逐渐强硬，水泥和水间的化学反应使得砂浆硬化并且胶结骨料成一体，这需要时间，这种反应在开始的时候很快，然后在很长的一段时间内会变慢，在有水分存在的条件下，混凝土可以持续几年增长强度，。例如，刚刚浇筑的混凝土在干燥一天后的强度大约为70307克/平方厘米，7天后大约为316382克/平方厘米，28天后

59、大约为421842克/平方厘米，5年后大约597610克/平方厘米，。通常混凝土混合物中所用的水泥，砂，粗骨料的干体积比例通常是特别规定的。例如1 : 2 : 3的混合物，有体积比为1分水泥，两份沙，三部分的粗骨料。根据不同的应用，混凝土成分的比例可以改变，来制造一些性能方面，特别是强度和耐久性方面有特殊改变的混凝土。比例变化从1 : 2 : 3到 : 2 : 4和1:3:5。向混合料中添加的水的数量大约是1至1.5倍数量的水泥体积。高强混凝土，水含量保持在较低水平，只有足够的水加入以洒湿整个混合物。一般来说，在混凝土配合比中更多的水，使混凝土的制造更加容易，但会产生硬化不好的混凝土。混凝土可

60、有任何程度的不透水性。它可以用来持水并且低于暴风雨的渗透，另一方面，也可以用于过滤床，可使混凝土多孔和高渗透。混凝土也可以给予一个抛光的表面，如玻璃般平滑。通过使用重型骨料，包括钢铁碎片，可以制成重4005以上公斤/立方米的密实的混凝土混合物。可通过使用特殊的轻骨料和发泡技术制造重量只有481千克/立方米的混凝土，含有轻型集料的混凝土骨架可以浮在水面上，锯成小片，或钉的另一面。混凝土的暴露面经过足够的硬化后能够耐污染，可以通过喷水或浸泡在水里养护混凝土，或者使用含水材料如防水纸，塑料片，湿麻袋，或砂，可用专门的养护喷剂。混凝土养护时间越长他就会越强，月耐用，在炎热的天气，它应保持湿润，至少三天