建筑畢業(yè)設(shè)計外文翻譯---建筑材料—混凝土與砂漿

1、<p>　　CONCRETE AND MORTAR</p><p>　　1. Early History of Cement and Concrete</p><p>　　Shelter from the very beginning of man/ existence, has demanded the application Of the best , available t

2、echnology of the contemporary era. In the earliest ages, structures consisted of rammed earth, or stone blocks laid one on another without benefit of any bonding or cementing medium. Stability of the stone structures dep

3、ended on the regular setting of the heavy stones , The earliest masonry probably consisted of sun-dried clay bricks, set in regular courses in thin layers of moist mud. When t</p><p>　　Burnt gypsum as a ceme

4、nting material was developed early in the Egyptian period and was apparently used in construction of some of the pyramids. Later the Greeks and Romans discovered methods of burning limestone to produce quicklime which wa

5、s subsequently slaked for use in making mortar. Both the Greeks and the Romans learned that certain fine soil or earth, when mixed with the lime and the sand, produced a superior cementing material. The Greek material, a

6、 volcanic tuff from the island of Sant</p><p>　　The cement produced by the Romans was a hydraulic cement, that is, it had the capability of hardening under water. Many of the Roman structures were constructe

7、d of a form of concrete, using these materials, and stone masonry was bonded with a mortar similarly composed.</p><p>　　During the Middle Ages of history, the art of making good mortar was nearly lost, the l

8、ow point having been reached in about the llth century, when much inferior material was used. Quality of the lime started to improve at this time and in the 14th century or later the use of pozzolans was again practised.

9、</p><p>　　One of the most famous projects of the comparatively recent period was the construction of the new Eddystone Lighthouse off the coast of England in 1757--59. John Smeaton, the engineer and designer

10、 of the structure, investigated many materials and methods of bonding the stones for the building.</p><p>　　Engineering and scientific development was beginning to move rapidly at this time, and many researc

11、hers in several countries were investigating cementing agents made from gypsum, limestone and other natural materials. One discovery was a method of making a cement by burning a naturally occurring mixture of lime and cl

12、ay. properties of the natural cement were very erratic because of variations in the proportions in the natural material, although use of this natural cement continued for many years</p><p>　　In 1824 Joseph A

13、spdin , a brickmason of Leeds, England, took out a patent on a material he called Portland cement, so called because concrete made with it was supposed to resemble the limestone quarried near Portland, England. Aspdin is

14、 generally credited with inventing a method of proportioning limestone and clay, burning the mixture at high temperature to produce clinkers, then grinding the clinkers to produce a hydraulic cement. His small kiln, pro

15、ducing about 16 tons of clinker at a time, r</p><p>　　Shipments to the United States were started in 1868 and reached a peak about 1895, at which time production was well under way in the United States.</

16、p><p>　　Meanwhile the United States production of natural cement had been started early in the 19th century as a result of the demand for cement for construction of the Erie Canal and related works. Subsequent

17、development of the rotary kiln led to large scale production of cement throughout the world.</p><p>　　The use of concrete was expanded by the construction of railroads, bridges ,buildings and street pavement

18、s. Research in reinforcing concrete with steel rods had been started in France, and the year 1875 saw first use of reinforced concrete in the United States. Much'of the concrete at this time contained barely enough w

19、ater to enable the concrete to be rammed into place by the application of much hand labor. There then ensued a period of wet concrete in which the concrete was flowed into place. </p><p>　　2. Advantages and

20、Disadvantages of Concrete and Its Water-Cement Ratio</p><p>　　Concrete is a mixture of Portland cement, water, sand, and crushed gravel or stone. The water and cement form a cement paste in which the sand an

21、d stone or gravel are mixed. The sand and stone or gravel together make up the aggregate of a concrete mixture. The aggregate serves no structural function. It is merely ,a filler that adds low-cost bulk to the cement pa

22、ste; it usually makes up about 75 percent of a given mass of concrete, by volume, although a poor aggregate can reduce the strength of </p><p>　　The two principal advantages of concrete as a construction mat

23、erial are its relative cheapness and the ease with which it can be handled and placed while it is in the plastic state.</p><p>　　The principal structural advantages of concrete are its great compressive stre

24、ngth and its durability , Concrete can withstand very high compressive loads. This is what makes concrete so suitable for the foundations, walls, and columns of buildings, and for driveways and walks as well.

25、 </p><p>　　The principal structural disadvantage of concrete is its poor tensile strength. That is, it cannot withstand pulling or bending l

26、oads without cracking or breaking. For this reason, steel rods, or reinforcement steel, are often embedded in concrete, the reinforcement steel providing the tensile strength the concrete lacks. Concrete with reinforceme

27、nt steel embedded in it is reinforced concrete.</p><p>　　In addition to its poor tensile strength, concrete, like most construction materials, expands in hot weather and when wet and contracts in cold weathe

28、r and as it dries out. Unless these movements are allowed for during construction, the concrete will crack.</p><p>　　And, contrary to common belief, solid concrete is not impervious to water. Some moisture w

29、ill migrate into the best-made concrete. But if the concrete should be excessively porous ,which can happen if too much water has been used in mixing it, moisture can easily enter the concrete after it has cured. If this

30、 moisture should be present within the concrete when cold weather comes, the moisture may freeze, which may result in serious frost damage to the structure.</p><p>　　Despite these limitations, concrete is an

31、 inherently strong and durable construction material. If the proportions of water, cement, and aggregate are carefully calculated and if the concrete is placed and allowed to cure according to simple but definite rules,

32、it is possible to obtain from the concrete all the strength and durability that is inherent in it.</p><p>　　The ratio of water to cement in a batch of concrete is the principal determinant of the concrete

33、9;s final strength. At one time the instructions for preparing a batch of concrete would have contained proportions such as 1:2:4, indicating that 1 part of Portland cement to 2 parts of sand to 4 parts of gravel by volu

34、me were to be mixed together, after which sufficient water was to be added to obtain a workable mixture. This procedure ignored entirely the importance of the water-cement ratio. It als</p><p>　　In theory, i

35、t takes only 3 gal of water to hydrate completely 1 cu ft of cement. (A sack of cement contains 1 cu ft exactly, and the sack weighs 94 lb). But this water-cement ratio produces a mixture that is too stiff to be worked.

36、In practice, therefore, additional water, between 4 and 8 gal per sack of cement, is used to obtain a workable mixture.</p><p>　　But the greater the proportion of water in a water-cement ratio, the weaker th

37、e final concrete will be. The additional water that is necessary to achieve a workable batch will only evaporate from the concrete as the concrete sets, and it will leave behind in the concrete innumerable voids. This is

38、 the reason there will always be some porosity in concrete. When an excessive amount of water has been used, there will be an excessive number of voids, which may cause the concrete to leak badly. If th</p><p&

39、gt;　　As a general rule, therefore, 6 gal of water per sack of cement should be the maximum amount used for making concrete; and the less the amount of water that is used, the stronger the concrete will be. Also include

40、d in the 6 gal is whatever surface moisture is contained in the sand that is part of the aggregate. </p><p><b>　　3.Mortar</b></p><p>　　Mortar is a mixture of a cementitious material

41、(which may be portland cement or lime or both) and sand. When water is added to these ingredients, the result is a plastic substance that is used to bind together bricks, tiles, concrete blocks, and other kinds of mas

42、onry units. After the mortar has set, the masonry units are bound together by the ,mortar in such a way that they form a single structural unit.</p><p>　　Mortar is closely related to other cementitious mate

43、rials such as concrete, plaster, and stucco, but it would be a mistake to confuse mortar with these other materials or attempt to use them as a substitute for mortar; the properties required of each are distinctive and d

44、iffer from the others.</p><p>　　By a mistaken analogy with a chain and its weakest link, it is a common belief that for any masonry construction to be strong, the mortar must be strong also. Very often, for

45、example, a person who is familiar with concrete will infer that mortar, being a cementitious material like concrete, should have properties similar to those of concrete and be mixed and used in much the same way. w Since

46、, for example, concrete has, or should have, a high compressive strength, mortar should have a high compr</p><p>　　A great many tests have been made of brick walls built with mortars having a wide range of s

47、trength characteristics. ~ These tests show uniformly that a brick wall is strongest when the mortar used to bind the brick is weaker than the brick. Indeed, the mortar can be substantially weaker than the brick Without

48、much affecting the overall strength of the construction. As long as the mortar is strong enough to resist the erosive effects of the weather and of freezing water, it is strong enough for </p><p>　　But suppo

49、se for the sake of argument that a brick wall has been built using a mortar that does have a compressive strength greater than that of the brick. ~Any stress this wall may be subjected to-the result of the settlement of

50、the soil under the wall, say-will cause the brick to fracture along the line of greatest stress. This fracture will run in a single jagged crack right through the brick, from the top of the wall to the bottom.</p>

51、<p>　　But when the mortar is weaker than the brick, as it should be, any stresses in the construction will be absorbed entirely by the mortar. The mortar will absorb these stresses in the form of a multitude of min

52、ute cracks invisible to the eye that leaves the basic strength of the construction unimpaired. The overall appearance of the wall and its structural integrity will be unchanged.</p><p>　　Masonry construction

53、s can, however, suffer from another type of failure. Sometimes stresses are relieved by a separation of the mortar from the brick. The result is a zig-zag crack through the mortar that follows the brick pattern. What has

54、 happened here is that the bond between the brick and the mortar was too weak, a consequence either of ignorance or poor workmanship, or both, since the last thing that should happen in a well-made masonry wall is for th

55、ere to be a poor bond between the masonr</p><p>　　Freshly prepared mortar in which the cement, lime, and sand are accurately proportioned and mixed with the requited amount of water has a quality called work

56、ability or, sometimes, plasticity. Workability is as difficult to describe in words as the consistency of pancake batter or soft butter, but fresh mortar that doesn't have this quality will be incapable of bonding ma

57、sonry units together as tightly as they should be, A workable mortar can be spread with a trowel smoothly, evenly, and without </p><p>　　建筑材料—混凝土與砂漿</p><p>　　一、水泥與混凝土的早期歷史</p><p>　　

58、自從人類開始存在時起，人的住處一直要求應(yīng)用每個時代所能提供的最好的技術(shù)。在最初時期，建筑物是由土夯實而成，或者在沒有任何連接或粘接物的情況下，用石頭一塊一塊地壘砌而成。石材建筑的穩(wěn)定性依賴于重石塊有規(guī)則的排放。最早的磚石建筑可能是由陽光曬干后的土磚，有規(guī)則地一層一層砌在薄泥漿上而構(gòu)成。泥漿變干后，就成為堅實的土墻。這種建筑結(jié)構(gòu)在世界上一些干燥的沙漠地區(qū)曾經(jīng)很常見。</p><p>　　燒制過的石膏作為一種膠凝材料

59、，最早產(chǎn)生于古埃及時期,并顯然曾用于建造金字塔。后來，希臘人和羅馬人發(fā)現(xiàn)了用石灰石來燒制生石灰，然后把它熟化制作灰泥的方法。希臘人和羅馬人都懂得，用某種細(xì)土與石灰和砂子混合即可生產(chǎn)優(yōu)質(zhì)的膠凝材料。希臘人用的材料是一種取自圣多林島的火山灰，至今仍在世界的那個地區(qū)使用。羅馬人使用的膠凝材料中，最好的那種是取自維蘇威山附近波佐利地區(qū)的一種火山灰。因此，直到現(xiàn)在，用于混凝土中的某種礦物摻合劑仍然稱為火山灰。</p><p&g

60、t;　　羅馬人生產(chǎn)的水泥是一種水硬水泥，就是說這種水泥在水的作用下會變硬。很多古羅馬建筑都是用某種混凝土建造的，使用的就是這些材料，石材建筑物也是用含有類似成分的砂漿粘合的。</p><p>　　中世紀(jì)期間，調(diào)制優(yōu)質(zhì)砂漿的技術(shù)幾乎失傳，大約十一世紀(jì)達(dá)到最低點，那時使用的材料質(zhì)量很差。后來石灰的質(zhì)量開始改進(jìn)，十四世紀(jì)或稍后，又開始使用火山灰水泥。</p><p>　　比較近期，最著名的工程項

61、目之一是在1757—1759年間在英格蘭海岸外面建造的新的渦石燈塔。該工程的設(shè)計師及工程師約翰·斯米頓為該建筑研究過多材料和多種粘結(jié)右塊的方法。</p><p>　　那時工程學(xué)和科學(xué)研究開始迅猛發(fā)展。一些國家的研究人員當(dāng)時都在研究用石膏、石灰石和其他天然材料制成的膠凝劑。通過燒制石灰與粘土的天然混合物來制造水泥的方法便是其中的一項發(fā)現(xiàn)。盡管這種天然水泥的使用繼續(xù)了好多年，但由于天然材料的配比變化不定，使

62、這種天然水泥的性能非常不穩(wěn)定。</p><p>　　1824年，一位英國里茲的瓦匠約瑟夫·艾斯波丁取得了他稱之為波特蘭水泥的一種材料的專利權(quán)。之所以如此命名是因為用這種水泥制成的混凝土被認(rèn)為很象是從英國波特蘭附近采集來的石灰石。艾斯波丁被公認(rèn)為發(fā)明了一種制造水泥的方法，先把石灰石與粘土按比例摻合在一起，放在高溫中焙燒成熟料，再將熟料磨細(xì)即成為水硬水泥。他的小水泥窯每窯要燒幾天時間，一次可生產(chǎn)大約16t熟

63、料。水泥制造業(yè)的擴(kuò)大與發(fā)展在其后的若干年相當(dāng)緩慢。然而，大約在1850年，這門工業(yè)不僅在英國，而且在德國和比利時都已牢固確定。</p><p>　　水泥運銷美國開始于1868年，大約在1895年達(dá)到高峰。此時美國的水泥生產(chǎn)也已初具規(guī)模。 </p><p>　　在進(jìn)口水泥的同時，由于修建伊利運河及其配套工程對水泥的需求，美國生產(chǎn)天然水泥在十九世紀(jì)初就已開始。?其后，水泥回轉(zhuǎn)窯的開發(fā)致使

64、大規(guī)模的水泥生產(chǎn)遍及全世界。 鐵路、橋梁、樓房的建設(shè)以及城市街道路面的鋪設(shè)，使得混凝土的應(yīng)用得以推廣。用鋼筋來增強混凝土的研究工作始于法國。1875年美國首次應(yīng)用鋼筋混凝土。這個時期大多數(shù)混凝土含水量很低，要用大量手工作業(yè)才能使之夯實就位。接著有一段時間使用濕混凝土，這種濕混凝土可以流淌就位。然而，許多混凝土的使用者認(rèn)識到，使用濕混凝土是件蠢事。大約1920年，達(dá)夫·亞布拉姆斯公布了他的研究及觀測結(jié)果。他說明：混凝土的質(zhì)

65、量直接受到用水量與水泥量之比的影響。在一定范圍內(nèi)，混凝土的質(zhì)量隨其水灰比的升高而降低。這已成為混凝土工藝的基本法則之一。</p><p>　　二、混凝土的優(yōu)缺點及其水灰比</p><p>　　混凝土是波特蘭水泥、水、砂子與卵石或碎石的拌合物。水與水泥調(diào)制成水泥漿，在水泥漿中把砂子和碎石或卵石混合在一起。砂子和碎石或卵石共同構(gòu)成混凝土拌合物的骨料。骨料不起結(jié)構(gòu)作用，它僅僅是加入到水泥漿中來降

66、低成本的一種填充物。骨料通常占一塊特定混凝土體積的百分之七十五。劣質(zhì)骨料可以極大地降低混凝土的強度，可是優(yōu)質(zhì)骨料對于增加水泥的強度卻沒有多大影響。</p><p>　　作為建筑材料，混凝土有兩大主要優(yōu)點，—是比較便宜，二是當(dāng)它處于塑性狀態(tài)時容易操作和澆注?；炷恋闹饕Y(jié)構(gòu)優(yōu)點是它抗壓強度高、耐久性能好。它能承受很高的壓力荷載。這使它非常適用于建造基礎(chǔ)、墻壁、樓房的支柱，也適用于修筑公路及街道。</p>

67、<p>　　混凝土的主要結(jié)構(gòu)缺點是它抗拉強度低。就是說，它承受拉伸或彎曲荷載時容易斷裂。 因此，常常將鋼筋埋人混凝土中。加固鋼筋給混凝土提供了它所缺乏的抗拉強度。置人鋼筋的混凝土叫做鋼筋混凝土。</p><p>　　除了抗拉強度差之外，像大多數(shù)建筑材料一樣，混凝土還會熱脹冷縮，濕脹干縮。在施工中，如果這些脹縮運動超出允許限度，混凝土就會開裂。</p><p>　　與常識相反，

68、硬化后的混凝土并不是不透水的。一些濕氣會遷移到加工最好的混凝土 中。在拌合中加入了太多的水會使混凝土內(nèi)出現(xiàn)過多的氣孔。萬一這種現(xiàn)象出現(xiàn)，混凝土養(yǎng)護(hù)完后，濕氣會很容易地進(jìn)入其內(nèi)。當(dāng)冷天到來時，萬一水分還存在于混凝土內(nèi)，便會凍結(jié)，這會給建筑物帶來嚴(yán)重的結(jié)凍損傷。 </p><p>　　盡管混凝土有這些缺點，它仍不失為一種天生具有堅固與耐久性的建筑材料。如果水、 水泥和骨料的比例經(jīng)過認(rèn)真計算，如果混凝土的澆注

69、與養(yǎng)護(hù)按照簡明的規(guī)章來進(jìn)行，完全 可能獲得它固有的全部強度與耐久性。</p><p>　　混凝土的水灰比是它最終強度的決定因素。曾經(jīng)有一段時間，混凝土的配料比例規(guī)定為l：2：4。它表示從體積上一份波特蘭水泥、二份砂子和四份卵石拌合在一起，之后加人足夠的水來獲得和易性良好的拌合物。這種作業(yè)過程完全忽視了水灰比的重要性。其結(jié)果 是經(jīng)常調(diào)配出強度非常低的混凝土。因為就工人而言，自然傾向于多加水，足以使混凝土的澆注盡

70、可能容易，越稀滑越好。這種規(guī)定混凝土成分比例的做法現(xiàn)已淘汰，不應(yīng)該再遵循。</p><p>　　從理論上講，僅有3加侖水便可完全水化1立方英尺水泥(1袋水泥正好1立方英尺，重94磅)?？墒前凑者@種水灰比加工出來的拌合物太干不能操作。因此，在實踐中需要再多加些水來獲得和易性良好的拌合料，每袋水泥加水在；4—8加侖之間為宜。</p><p>　　但是在水灰比中，水的比例越大，最終制成的混凝土的

71、強度越低。為了得到和易性好的混凝土而需要多加人的水將隨著混凝土的硬化從混凝土中蒸發(fā)掉，這將在混凝土內(nèi)留下無數(shù)的氣孔。這便是為什么在混凝土內(nèi)總存在一些孔隙的原因。當(dāng)超量的水使用后，就會產(chǎn)生超量的孔隙，這會使混凝土嚴(yán)重滲漏。萬一當(dāng)冷天到來，這些孔隙充滿了水分，它們會引起上述的結(jié)凍損傷。</p><p>　　因此，作為一般規(guī)定，每袋水泥加人6加侖水應(yīng)該被視為配制混凝土的最大加水量，并且所用的水量越少，混凝土強度越高。作

72、為骨料組成部分的砂子所含表面水分也應(yīng)包括在6加侖加水量之內(nèi)。 </p><p><b>　　三、 砂漿</b></p><p>　　砂漿是一種膠凝材料(可能是硅酸鹽水泥或石灰或是二者兼有)．和砂子的混合物。當(dāng)把水加入到這些成分中時，就形成了一種可塑性物質(zhì)，這種物質(zhì)可用來粘結(jié)磚、瓦、混凝土砌塊和其他種類的砌塊。砂漿硬化后，砌塊就被砂漿牢牢地粘結(jié)起來，形成了一個結(jié)構(gòu)

73、單元。</p><p>　　砂漿與其他膠凝材料，如混凝土、熟石膏和灰泥有著密切的關(guān)系，但是若把砂漿和這些材料混同起來，或是想用這些材料來替代砂漿是錯誤的，因為每一種材料均具有各自的特點，互不相同。</p><p>　　由于“一環(huán)薄弱，全局必垮”的錯誤推論，人們普遍認(rèn)為，要想使砌體結(jié)構(gòu)堅固，砂漿也必須是堅固的。例如：熟悉混凝土的人常會推斷，作為一種類似混凝土的膠凝材料，砂漿應(yīng)具有與混凝土類似

74、的特性，并應(yīng)按照同樣的方式進(jìn)行調(diào)制和使用：又比如：既然混凝土有或是應(yīng)該有很高的抗壓強度，那么，砂漿也應(yīng)該有很高的抗壓強度。但是砂漿的主要作用是粘結(jié)砌塊，而不是抵抗壓力，也不是增加砌塊的強度。</p><p>　　對由各種不同強度的砂漿建成的磚墻已經(jīng)做了大量的實驗。這些實驗一致表明，當(dāng)用來粘結(jié)磚塊的砂漿比磚塊的強度低時，磚墻的強度最高。實際上，在不影響結(jié)構(gòu)整體強度的情況下，砂漿實質(zhì)上可以比磚的強度低很多。只要砂漿強

75、度能夠抵抗天氣和凍結(jié)水的侵蝕作用，它就堅固得足以用于一般外墻。 </p><p>　　但為了論證，假定一面磚墻是用比磚的抗壓強度還高的砂漿砌成的，這面墻所承受的任何應(yīng)力一比如說由墻下土的沉陷而導(dǎo)致的應(yīng)力，將導(dǎo)致磚塊沿最大應(yīng)力方向斷裂，這種斷裂將形成一條從墻頂?shù)綁δ_，貫穿墻體的鋸齒狀裂縫。</p><p>　　但是，當(dāng)砂漿像應(yīng)該的那樣比磚的強度低時，結(jié)構(gòu)中的任何應(yīng)力將全部被砂漿所吸收，

76、砂漿吸收這些應(yīng)力后將形成許多肉眼看不見的微小裂縫，這樣，結(jié)構(gòu)的基本強度沒有受到損壞，墻的整體外觀及其結(jié)構(gòu)的完整性不變。 </p><p>　　然而，砌體結(jié)構(gòu)還可能出現(xiàn)另一種斷裂現(xiàn)象。有時應(yīng)力是通過砂漿與磚的分離得以釋放的，結(jié)果，沿著磚的砌筑模式穿過砂漿出現(xiàn)了鋸齒形裂縫。由于在砌筑完好的磚墻中最不應(yīng)出現(xiàn)的就是砌塊與砂漿粘結(jié)薄弱，而導(dǎo)致砌塊和砂漿粘結(jié)薄弱的是由于疏忽或是工藝較差，也可能是二者兼而有之，或是由于砂

77、漿配合的比例和調(diào)制方法有誤，或是由于向磚上抹砂漿方式不當(dāng)，也可能是二者共同導(dǎo)致的結(jié)果。 </p><p>　　以適當(dāng)比例的水泥、石灰和砂子加入適量的水剛調(diào)制成的砂漿具有一種特性叫和易性，有時也稱為可塑性。就像很難說明煎薄餅用的面糊或者軟化了的奶油的稠度一樣，砂漿的和易性很難用語言來描述，但不具備這一特點的新砂漿是不能將砌塊緊緊地粘結(jié)在尸起的。和易性好的砂漿，可用一把瓦刀毫不費力，光滑而均勻地涂抹在砌塊表面上。