埃及人主要对如何建造感兴趣；他们对为什么这么使用没有什么太多的兴趣。相反，在公元前六世纪到公元前三世纪希腊人取得了巨大的进步于工程理论的推广。他们发展了线、角度、面，和实体的抽象的知识，而不是与特定的对象产生联系。 希腊建筑施工的几何基础包括数字如正方形、矩形和三角形。
The Greek architekton was usually the designer, as well as the builder, of architectural and engineering masterpieces. He was an architect and engineer. Craftsmen, masons, and sculptors worked under his supervision. In the classical period of Greece all important buildings were built of limestone or marble; the Parthenon, for example, was built of marble.
希腊建筑师 通常是建筑工程杰作的设计师同时也是建造师。 他既是一个建筑师也是工程师。工匠、石匠和雕塑家在他的监督下工作。在希腊古典时期所有重要建筑物是由石灰石或大理石建造的；以帕台农神庙为例，由大理石建成的。


UNIT 3
The principal construction materials of earlier times were wood and masonry-brick, stone, or tile, and similar materials. The courses or layers（砖层）were bound together with mortar or bitumen, a tarlike substance, or some other binding agent. The Greeks and Romans sometimes used iron rods or clamps to strengthen their building. The columns of the Parthenon in Athens（雅典的帕台农神庙）, for example, have holes drilled（钻孔） in them for iron bars that have now rusted away（锈蚀殆尽）. The Romans also used a natural cement called pozzolana, made from volcanic ash, that became as hard as stone under water.
            早期主要的建筑材料是木材和砌体，如砖、石、瓦以及类似的材料。砖层之间通过砂浆、沥青（一种焦油状的物质）或其他一些粘合剂粘合在一起。希腊人和罗马人有时用铁条或夹子来加固他们的房屋。例如，雅典的帕台农神庙柱子中曾钻孔以便加入铁条，如今都已锈蚀殆尽。罗马人也用称作白榴火山灰的天然水泥，它用火山灰制作，在水中会变得与石头一样坚硬。
     Both steel and cement, the two most important construction materials of modern times, were introduced（推广） in the nineteenth century. Steel, basically an alloy of iron （铁合金）and a small amount of carbon, had been made up to that time（到那个时候） by a  laborious（繁复的） process that restricted it to such special uses as sword blades（刀刃）. After the invention of the Bessemer process （贝塞麦炼钢法）in 1856, steel was available in large quantities at low prices. The enormous advantage of steel is its tensile strength; that is, it does not lose its strength when it is under a calculated degree (适当的) of  tension, a force which, as we have seen, tends to （往往）pull apart many materials. New alloys have 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（连续的应力变化）.
            作为现代两种最重要的建筑材料，钢材与水泥在十九世纪得到了推广。直到那个时候，钢材才通过繁复的过程制造出来，基本上是铁合金，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年发明了贝塞麦炼钢法后，钢材才得以大量低价获得。钢材巨大的优势即是它的抗拉强度，也就是当它在适当的拉力下不会失去强度，正如我们所看到的，该力往往能够将很多材料拉开。新的合金进一步提高了钢材的强度，并消除了一些缺点，如疲劳，即在连续的应力变化下导致强度减弱的趋势。
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 （施工现场）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 （喷射成）all kinds of shapes. And whereas steel has great tensile strength, concrete has great strength under compression. Thus, the two substances complement each other（互补）.
        现代水泥发明于1824年，称为波特兰水泥。它是石灰石和粘土的混合物，加热后磨成粉末。在或靠近施工现场，将水泥与砂、骨料（小石头、压碎的岩石或砾石）、水混合而制成混凝土。不同比例的配料会制造出不同强度和重量的混凝土。混凝土的用途很多，可以浇筑、泵送甚至喷射成各种形状。混凝土具有很大的抗压强度，而钢材具有很大的抗拉强度。这样，两种材料可以互补。
         They also complement each other in another way: they have almost the same rate of contraction and expansion. They therefore can work together in situations where（在…情况下） both compression and tension are factors（主要因素）. Steel rods（钢筋） are embedded in（埋入）concrete to make reinforced concrete in concrete beams or structures where tension will develop（出现）. 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（还有） 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.