Assessing the potential environmental hazards of concrete made using recycled aggregates (RAs)

Abstract : This chapter starts with widely recommended and used methodologies for environmental assessment, with an overview of their application to construction materials. The concept of pollutant emission by leaching and its dependence on the materials involved is introduced, along with the parameters influencing the leaching process. The manner in which water contact with materials causes transfer, transport and dispersion of the contained contaminants is explained. Then the most relevant experimental tools dedicated to hazard identification and environmental performances are presented. These tools comprise laboratory leaching tests whose suitability for future standardisation in the field of construction materials is considered. Ecotoxicology tests could potentially be adapted to this standard testing method. The second part discusses recent research and discoveries concerning the leaching properties and potential hazards of materials of concern. The chemical behaviour of several pollutants in cement matrix is explained and examples of results obtained by leaching studies on concrete materials are discussed. Examples of studies on recycled aggregates (RA) from demolition as well as new concrete materials containing these wastes are also presented.