以往,好些国家不能修造现代化的飞机场,其中一个原因就是因为现代的飞机越造越大,对机场的要求也越来越高。如波音747在普通混凝土跑道上,经几百次碾压,就得破裂报废。美国70年代采用一种新型混凝土铺筑了一条机场跑道,虽经千多次碾压竟未出现一条裂缝。原来,这种混凝土是在普通混凝土中掺入与缝衣针长短相仿的短细钢丝,这种混凝土称为钢丝混凝土。钢丝混凝土不但耐磨、抗震、抗冲击,还 In the past, many countries could not build modern airports. One of the reasons was that the more modern airplanes were created, the more demanding the airport was. If the Boeing 747 is rolled on ordinary concrete runways after several hundred times of rolling, it will be broken and scrapped. The United States used a new type of concrete to build an airport runway in the 1970s. Although it had been rolled over more than a thousand times, there was no crack. Originally, this kind of concrete was mixed with short and fine steel wires similar to the length of sewing needles in ordinary concrete. Such concrete is called steel wire concrete. Steel wire concrete is not only wear-resistant, shock-resistant, impact-resistant, but also