Coal Ash Pavement Technology to Mitigate Heat Island Effect

Tokyo Electric Power Co. (TEPCO) announced on October 4, 2005, that it has developed what it calls "Heat Island Effect Inhibiting Pavement" technology, a first in Japan. Coal ash produced by coal thermal power plants is recycled as paving material, and this new technology helps keep roads cool, ameliorating the urban heat island effect.

TEPCO has succeeded in attaining a 100 percent recycling rate for coal ash by turning it into a resource material for land formation and cement. In the course of this effort, the company worked to develop technology for paving materials that can control heat in asphalt, one of the contributing factors to the urban heat island effect.

The new pavement consists of two layers; an upper layer of water-retentive coal asphalt and a lower layer of water-retentive ash roadbed. Moisture in the lower layer rises to the upper layer through capillary action, and the water cools off the road surface by absorbing heat as it evaporates. The lower layer has a water-retention capacity about 10 times greater than regular roadbeds, so it can sustain the cooling effect for longer periods.

Field experiments at TEPCO's laboratory confirmed that the new technology lowers the road surface temperature by about 10 degrees Celsius compared to normal pavement. TEPCO plans to promote verification of the stability, durability and economic efficiency of these cooling effects through full-scale testing, aiming for practical application in FY 2007.

http://www.tepco.co.jp/en/index-e.html

Posted: 2006/02/02 09:53:24 AM
Japanese version