土木工程專業(yè)英語課件u-文庫吧
2024-12-24 16:03 本頁面
【正文】 ave further increased the strength of steel and eliminated some of its problems, such as fatigue, which is a tendency for it to weaken as a result of continual changes in stress（ 連續(xù)的應(yīng)力變化） . 作為現(xiàn)代兩種最重要的建筑材料，鋼材與水泥在十九世紀(jì)得到了推廣。直到那個(gè)時(shí)候，鋼材才通過繁復(fù)的過程制造出來，基本上是鐵合金，并含有少量的碳，因而被限制在一些特殊的用途如刀刃。在 1856年發(fā)明了貝塞麥煉鋼法后，鋼材才得以大量低價(jià)獲得。鋼材巨大的優(yōu)勢即是它的抗拉強(qiáng)度，也就是當(dāng)它在適當(dāng)?shù)睦ο虏粫?huì)失去強(qiáng)度，正如我們所看到的，該力往往能夠?qū)⒑芏嗖牧侠_。新的合金進(jìn)一步提高了鋼材的強(qiáng)度，并消除了一些缺點(diǎn)，如疲勞，即在連續(xù)的應(yīng)力變化下導(dǎo)致強(qiáng)度減弱的趨勢。 Modern cement, called Portland cement, was invented in 1824. It is a mixture of limestone（石灰石） and clay, which is heated and then ground into a powder（磨成粉末） . It is mixed at or near the construction site （施工現(xiàn)場） with sand, aggregate (small stones, crushed rock, or gravel), and water to make concrete. Different proportions of the ingredients （配料） produce concrete with different strength and weight. Concrete is very versatile。 it can be poured, pumped, or even sprayed into （噴射成） all kinds of shapes. And whereas steel has great tensile strength, concrete has great strength under pression. Thus, the two substances plement each other（互補(bǔ)） . 現(xiàn)代水泥發(fā)明于 1824年，稱為波特蘭水泥。它是石灰石和粘土的混合物，加熱后磨成粉末。在或靠近施工現(xiàn)場，將水泥與砂、骨料（小石頭、壓碎的巖石或礫石）、水混合而制成混凝土。不同比例的配料會(huì)制造出不同強(qiáng)度和重量的混凝土?；炷恋挠猛竞芏啵梢詽仓?、泵送甚至噴射成各種形狀?；炷辆哂泻艽蟮目箟簭?qiáng)度，而鋼材具有很大的抗拉強(qiáng)度。這樣，兩種材料可以互補(bǔ)。 They also plement each other in another way: they have almost the same rate of contraction and expansion. They therefore can work together in situations where（在 … 情況下） both pression and tension are factors（主要因素） . Steel rods（鋼筋） are embedded in（埋入） concrete to make reinforced concrete in concrete beams or structures where tension will develop（出現(xiàn)） . Concrete and steel also form such a strong bond the force that unites（粘合） them that the steel cannot slip（滑移） with the concrete. Still（還有） another advantage is that steel does not rust in concrete. Acid（酸） corrodes steel, whereas concrete has an alkaline chemical reaction, the opposite of acid. 它們也以另外一種方式互補(bǔ)：它們幾乎有相同的收縮率和膨脹率。因此，它們?cè)诶?、壓為主要因素時(shí)能共同工作。在出現(xiàn)拉力的混凝土梁或結(jié)構(gòu)中，將鋼筋埋入混凝土而
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