J. Phys. IV France 107 (2003) 143
DOI: 10.1051/jp4:20030263

Evolution of Pb speciation in Portland cement during leaching

A. Bénard¹, J. Rose¹, J.-L. Hazemann², A. Masion¹, J.-Y. Bottero¹, A. Vichot³ and D. Lemarchand<sup>4

1</sup>  CEREGE Europole de l'Arbois, BP. 80, 13545 Aix-en-Provence cedex 04, France
²  Laboratoire de Cristallographie, CNRS, 38042 Grenoble cedex 9, France
³  ATILH, 7 place de la Défense, 92974 Paris-la-Défense cedex, France
⁴  SCORI, 54 rue Pierre Curie, ZI des Gâtines, 78370 Plaisir, France

Abstract
Heavy metals, coming from raw materials and combustibles, are present in trace amount in cement. This study aims at evaluating Pb long-term behaviour, linking the evolution of Pb speciation due to leaching, with changes in the structure of the bearing mineralogical phases of the cement. EXAFS experiments point out a Pb retention through calcium silicate phases, but also show changes in Pb atomic environment due to leaching. These changes would be due to evolution in calcium silicate hydrates (C-S-H) structure with alteration, as ²⁹Si NMR shows lengthening of the chains of silicon tetrahedron in the C-S-H.

© EDP Sciences 2003