英语翻译Modern cement,called Portland cement,was invented in 182

英语翻译
Modern cement,called Portland cement,was invented in 1824.It is a mixture of limestone and clay,which is heated and then ground into a power.It is mixed at or near the construction site with sand,aggregate small stones,crushed rock,or gravel,and water to make concrete.Different proportions of the ingredients produce concrete with different strength and weight.Concrete is very versatile; it can be poured,pumped,or even sprayed into all kinds of shapes.And whereas steel has great tensile strength,concrete has great strength under compression.Thus,the two substances complement each other.
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 both compression and tension are factors.Steel rods are embedded in concrete to make reinforced concrete in concrete beams or structures where tensions will develop.Concrete and steel also form such a strong bond─ the force that unites them─ that the steel cannot slip within the concrete.Still another advantage is that steel does not rust in concrete.Acid corrodes steel,whereas concrete has an alkaline chemical reaction,the opposite of acid.

现代水泥,又叫波特兰水泥,是在1824年发明的.这种水泥是石灰石和粘土被加热并且被碾碎成粉末的混合物.（这边power是powder吧~我按powder翻的）.在建筑工地上或者周边,水泥和沙子、小石头、碎石或砂砾,水混合来制造混凝土.不同的成分比例可以制造出不同强度和不同重量的混凝土.混凝土有多种用途：倒入,用泵输入,或者喷成不同的形状.不同于钢有很大的抗张强度,混凝土有很大的抗压强度.所以,这两种材料是互补的.
钢和混凝土在另一种方式上也是互补的：它们有基本相同的膨胀和收缩的比率.所以它们可以在有压力和张力的情况下一起工作.当有张力的情况下,把钢管嵌入混凝土梁可以来加固混凝土.混凝土和钢管同样可以紧密的联结在一起（两者之间有力来联结）,这样钢就不会滑出混凝土了.另外一个优势是钢在混凝土中不会腐朽.钢会被酸腐蚀,但是混凝土有碱性的化学反应,和酸正好相反.
完全自己翻译,不是翻译机~