英語聽力 學(xué)英語,練聽力,上聽力課堂! 注冊(cè) 登錄
> 在線聽力 > 英語高級(jí)聽力 > 英語時(shí)差 >  第1262篇

英語時(shí)差:自動(dòng)復(fù)原的混凝土

所屬教程:英語時(shí)差

瀏覽:

2022年06月15日

手機(jī)版
掃描二維碼方便學(xué)習(xí)和分享
https://online2.tingclass.net/lesson/shi0529/10000/10183/1293.mp3
https://image.tingclass.net/statics/js/2012

Have you ever been driving down a pothole filled street, thinking, "I wish the city, someone, anyone would fix the roads!" Soon, roads and streets may be able to fix themselves. Researchers at the University of Michigan have developed a type of concrete that heals itself when it cracks. Regular concrete is like ceramic when it breaks. It really breaks, opening a wide chasm that requires serious mending. Self healing concrete behaves more like metal. It bends without breaking thanks to special fibers holding it together. Bending or stressing the new concrete creates hairline fractures instead of gaping holes. All it takes to mend the tiny fissures is exposure to water and carbon dioxide. Chemicals in the concrete mix with water and carbon dioxide to form a healing scar. In the lab, the concrete was able to heal itself back to nearly full strength after a slab was stretched to three times its normal size. Self healing concrete could help cut costs for rebuilding not only new roads but also bridges and other structures that use the material. You won’t find self healing concrete on roads just yet. The researchers are working on bringing it to market in the next few years. And when it’s ready for widespread use, self healing concrete could make potholes a thing of the past.

用戶搜索

瘋狂英語 英語語法 新概念英語 走遍美國(guó) 四級(jí)聽力 英語音標(biāo) 英語入門 發(fā)音 美語 四級(jí) 新東方 七年級(jí) 賴世雄 zero是什么意思保定市華僑宿舍英語學(xué)習(xí)交流群

網(wǎng)站推薦

英語翻譯英語應(yīng)急口語8000句聽歌學(xué)英語英語學(xué)習(xí)方法

  • 頻道推薦
  • |
  • 全站推薦
  • 推薦下載
  • 網(wǎng)站推薦