Chromium trapping in the cement matrix: potential of leaching from RCA and stabilization

Author(s): Oumeima Ben Maaouia, Rabah Hamzaoui, Abdelkrim Bennabi, Johan Colin, Horacio colina
Paper category: Proceedings
Book title: Proceedings of the 2nd International RILEM/COST Conference on Early Age Cracking and Serviceability in Cement-based Materials and Structures Volume 2
Editor(s): Stéphanie Staquet and Dimitrios Aggelis
ISBN: 978-2-35158-200-8
e-ISBN: 978-2-35158-198-8
Publisher: RILEM Publications SARL
Publication year: 2017
Pages: 805-810
Total Pages: 6
Language : English

Abstract: Considering economic and social interests, deconstruction concretes are studied more closely to be recycled into new concretes. However, these materials (Recycled Concrete Aggregates RCA) are generally old and may contain considerable amounts of heavy metals like Chromium element for example. The Chromium was not controlled before the late 2000. It is a toxic element in its hexavalent form, which is stable in alkaline media, as in the case of cementitious matrix. In this work, we are interested in the presence of chromium in the cementitious matrix of RCA and their environmental characterization. The latter is performed via leaching test carried out according to the Dutch standard NEN 7347:2006 for granular materials and the conformity standard NF EN 12457-2. In addition, structural characterization has been performed. It has been found that RCA are inert wastes, despite the demonstration of the presence of chromium in its two stable forms, trivalent and hexavalent, in the cement matrix, more specifically in the ettringite system. KEYS WORDS: deconstruction, recycled concrete aggregates, environmental assessment, leaching, ettringite.

Online publication : 2017
Publication type : full_text
Public price (Euros) : 0.00