Skip to Main content Skip to Navigation
Journal articles

Modelling the Pb release during Portland cement alteration.

Abstract : Complex cementitious matrices undergo weathering with environmental exchange and can release metallic pollutants during alteration. The molecular mechanisms responsible for metal release are difficult to identify, though this is necessary if such processes are to be controlled. The present study determines and models the molecular mechanisms of Pb release during Portland cement leaching. As Pb release is strongly related to its speciation (i.e. atomic environment and the nature of bearing phases), the first objective of the present study was to investigate the evolution of Pb retention sites together with the evolution of the cement mineralogy during leaching. Complementary and efficient investigation tools were used, namely X-ray diffraction, micro-X-ray fluorescence and X-ray absorption fine structures. The second objective was to reproduce our results with a reactive transport code (CHESS/HYTEC) in order to test the proposed speciation model of Pb. Combined results indicate that in both the unaltered core and the altered layer of the leached cement, Pb(II) would be retained through C-S-H 'nano-structure', probably linked to a Q1 or Q2P silicate tetrahedra. Moreover in the altered layer, the presence of Fe atoms in the atomic environment of Pb is highly probable. Unfortunately little is known about Fe phases in cement, which makes the interpretation difficult. Can Fe- substituted hydrogranet (C3AH6) be responsible for Pb retention? Modelling results were consistent with Pb retention through C-S-H in layers and also in an additional, possibly Fe-containing, Pb-retention phase in the altered layer.
Complete list of metadatas

Cited literature [2 references]  Display  Hide  Download

https://hal.archives-ouvertes.fr/hal-00365127
Contributor : Agnès Birot <>
Submitted on : Wednesday, February 12, 2014 - 5:08:31 PM
Last modification on : Thursday, August 27, 2020 - 2:10:14 PM
Long-term archiving on: : Monday, May 12, 2014 - 10:05:43 PM

File

2009-046_post-print.pdf
Files produced by the author(s)

Identifiers

Citation

A. Benard, Jérôme Rose, Jean-Louis Hazemann, O. Proux, L. Trotignon, et al.. Modelling the Pb release during Portland cement alteration.. Advances in Cement Research, Thomas Telford, 2009, 21 (1), pp.1-10. ⟨10.1680/adcr.2007.00028⟩. ⟨hal-00365127⟩

Share

Metrics

Record views

1398

Files downloads

1057