英语翻译Concrete is a man-made material created by the proper mi

英语翻译
Concrete is a man-made material created by the proper mixing of coarse aggregate,such as gravel ,fine aggregate ,such as sand ,and cement ,with adequate and controlled amounts of water.Concrete is very strong in compression,and ultimate strengths of 5000psi(34.5N/mm2)to 6000psi(41.4N/mm2)can be otbtained.But concrete is very weak in tension,and so has to be adequately reinforced with steel bars .The concrete then takes the compression,and the steel takes all the tension.Both materials work together as a composite material.This material is then called reinforced concrete.
Concrete sets ,or hardens ,into a dense,stonelike substance.Unlike stone ,however,it does not have be cut and shaped into individual blocks that are then fitted together to make a wall.Instead ,it can be poured into woooden forms to make solid,one piece structures of almost any shape.