《瘋狂英語》精選輯:古羅馬的故事
The Pantheon here was built by the Emperor Haydrian in the 2nd century AD and its 1)dome is still one of the largest 2)concrete domes in the world. It's 50 yards across and its concrete is up to 20 feet thick.
The word "concrete" comes from the Latin "concretus", meaning grown together or harden. Romanconcrete was a mixture of sand, powdered 3)limestone and stone 4)rubble, pretty well what it is today. To construct 5)arches and 6)vaults, the Romans also developed a lightening. And the higher they went the lighter they made the concrete. In this way they could roof over much larger areas than would be possible with stone.
But one of the problems with concrete is that even after it's hardened, it still absorbs water. So the Romans added a mix of 7)volcanic 8)cinders and clay called "Potsularna". Potsularna reacts with the 9)lime in the 10)mortar and sets quickly. And most important of all, it's resistant to water.
The Romans had invented damp proof concrete, and they used it for the foundations of buildings like the pantheon, for lining reservoirs and for constructing harbors. Concrete allowed the Romans to build big and fast, and thus 11)impose their authority on tribes still living in simple structures of wood or mud. Concrete may well have been one of the secret weapons of the Roman Empire.
古羅馬的故事
萬神殿是哈第安皇帝在公元2世紀(jì)時建立的，它的圓頂至今仍是世界上最大的混凝土圓頂之一。寬有50碼，混凝土厚達(dá)20英尺。
"混凝土"一詞來自拉丁語"concretus"，意思是粘合在一起或硬化。羅馬的混凝土是把沙子、石灰粉和碎石摻合到一塊來，和今天的做法很相似。為了建造拱門與拱頂結(jié)構(gòu)，羅馬人還發(fā)展了減壓技術(shù)。建得越高，所用的混凝土也就越輕。他們用此辦法搭建的屋頂面積比用石頭搭建的要大得多。
可混凝土的一個問題是，即使變硬以后，它仍然吸水。所以羅馬人又添加進(jìn)一種火山灰與黏土的混合物，稱為"波修拉那"。波修那拉與灰泥中的石灰產(chǎn)生反應(yīng)，可以快速定型。最重要的是它還防水。
羅馬人發(fā)明出防濕混凝土，用它來建造萬神殿這樣的建筑基礎(chǔ)，用來圍水庫、起港口?；炷潦沽_馬人的建筑宏大、建筑速度更快，并加強(qiáng)了他們對依然居住在泥木搭建的簡單結(jié)構(gòu)里的部族的統(tǒng)治?；炷烈苍S一直是羅馬帝國的秘密武器之一。
1) dome n. 圓屋頂
2) concrete n. 混凝土
3) limestone n. 石灰石
4) rubble n. 碎石
5) arch n. 拱門
6) vault n. 拱頂
7) volcanic a. 火山的
8) cinder n. 灰
9) lime n. 石灰
10) mortar n. 灰泥
11) impose v. 加強(qiáng)
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