Every vehicle needs tires, but eventually they wear out. Roads wear out too, and they often need repairing. But new research by a pair of teens suggests the rubber from worn-out tires could lengthen the lifetime of asphalt   pavement. Also roads made with this material might need fewer patches  .   The young researchers presented their findings in May, 2014, as finalists at the International Science and Engineering Fair (ISEF). The 64th annual Intel ISEF shows some of the best high school science projects from around the globe.    Many roads are made with asphalt, which requires much petroleum. But Jordan is a country that has very few oil wells or other sources of petroleum, notes Mohammad Salameh, who is a 10th-grader at the International School in Amman, Jordan.   For Jordan, having to import most of the country's petroleum adds greatly to its cost, the teen notes. The extra expense means that there's less money to build and maintain roads. That has resulted in poorer quality roads. As a result, those roads need to be patched almost constantly.   Therefore, 16-year-old Mohammad and his research partner, 15-year-old classmate Adam Belaid, came up with the idea of adding rubber to asphalt. But that rubber can come from old tires. Even a worn-out tire contains much rubber, which means the material should be plentiful, says Mohammad. Drivers in Jordan replaced 9 million tons of tires between 2006 and 2010, and only 0.3% of that rubber was recycled. That leaves much rubber that could possibly go into road construction.   But first the teens had to show adding rubber to asphalt resulted in better roads. To test their idea, they created several different asphalt-rubber recipes. They also tried out different temperatures at which the mix was heated. And their tests suggested that when the surfacing material includes 8% rubber, it should hold up for 10 to 15 years of traffic instead of the normal 5 years. And their recipe should reduce the need for patching worn areas from once a year, to maybe once every 5~7 years in the future. We can know from the passage that in Jordan     .
the roads are the worst across the world many people are interested in recycling old tires a typical road is replaced every five years or so most roads require patching once every five years