§ Mr. CorbynTo ask the Secretary of State for the Environment, Transport and the Regions what research he has commissioned or evaluated on the chemical content of bottom ash from incinerators; if its use as road-making material complies with his Department's specifications; and if he will make a statement. [90356]
§ Ms Glenda JacksonResearch carried out in 1993 for the Department of Transport looked into the chemical content of bottom ash from the incineration of municipal waste and its possible use in road construction. This concluded that due to the high concentration of soluble metals (eg. lead, zinc and arsenic) and sulphates, incinerator wastes are not suitable for use in road works in their unbound state. In certain circumstances it was suitable when combined with cement.
The specification used by the Highways Agency currently permits incinerator bottom ash to be used for road maintenance and construction in cement bound, lower strength road materials. High strength concrete 20W made with incinerated municipal waste, even when sintered with clay, has not proved to be of suitable quality for use in road pavements.
Research is continuing to extend the use of incinerator bottom ash in construction.