Release of dangerous substances from construction and demolition recycled materials used in road pavements - Laboratory and field leaching tests

The use of Construction and Demolition Recycled Materials in road pavements is envisaged as a recycling solution with environmental and economic benefits, allowing the incorporation of large amounts of those materials from different sources. The environmental concerns regarding the potential contamination of surface and ground waters and soil forces the evaluation of the leaching behavior of the recycled materials. In Portugal the application of Construction and Demolition Waste (CDW) in civil engineering works demands their compliance with the requirements of leachability for waste admissible in landfills for inert waste. Nevertheless some issues concerning this criterion and the leaching procedure should be better studied whereby leaching tests, laboratorial batch and column leaching tests and in situ lysimeter leaching tests, were performed, or are still ongoing, on recycled aggregates – crushed mixed concrete, crushed reclaimed asphalt and milled reclaimed asphalt – and on a natural aggregate to provide a comparison with the results obtained with recycled materials. Crushed and milled reclaimed asphalt aggregates do not fulfill the criteria to be disposed at landfill for inert waste owing to the content of the hydrocarbons C10-C40. Nevertheless, based only on the thresholds for leachability defined in the Portuguese technical specifications no restrictions apply for their use from an environmental perspective.