Leaching assessment of Recycled Concrete Aggregates (RCA) containing hexavalent chromium

Ascribable to increasing environmental and health-related issues, the content of hexavalent chromium found in the cementitious pastes of old deconstructed concrete is under increasing scrutiny. This element is identified by... [ view full abstract ]

Ascribable to increasing environmental and health-related issues, the content of hexavalent chromium found in the cementitious pastes of old deconstructed concrete is under increasing scrutiny. This element is identified by the Environmental Priority Agency as a priority metallic pollutant. In Europe, there is a restriction on the amount of Cr (VI) in cement production, which is limited to 2 mg per kg due to its carcinogenic effects on human health. This heavy metal, unavoidably widespread in the environment, has very important solubility, mobility and high toxicity characteristics, which make the problematic of its presence in old deconstructed concrete dedicated for recycling challenging.   

In the French National Project RECYBETON context, an investigation about the potential leaching of the hexavalent chromium from recycled concrete aggregates (RCA) used in new cementitious matrix is realized. Indeed, the characterization of the leaching behavior of wastes is a crucial step in the environmental assessment for reuse or disposal scenarios. For this project, we are interested in the evaluation of the release potential of this pollutant from different cement mortars. This evaluation is based on the leaching experiments carried out on monolithic and granular materials. The results of this study are useful in predicting the leaching of chromium from cement products containing recycled concrete aggregates, so that can be safely applied in the environment.