Eur. Phys. J. Special Topics 224, 1985-1994 (2015)
https://doi.org/10.1140/epjst/e2015-02515-7

Regular Article

Reactivity of NO₂ and CO₂ with hardened cement paste containing activated carbon

¹ Lafarge Centre de Recherche, 95 rue Montmurier, 38291 Saint Quentin Fallavier, France
² Université de Poitiers, Institut de Chimie des Milieux et Matériaux de Poitiers, UMR 7285 CNRS, 4 rue Michel Brunet, 86022 Poitiers, France

^a e-mail: matthieu.horgnies@lafarge.com

Received: 6 November 2014
Revised: 21 May 2015
Published online: 30 July 2015

Abstract

The development of building materials to reduce the concentration of NO₂ is growing interest in a world where the air quality in urban areas is affected by the car traffic. The main binder in concrete is the cement paste that is partly composed of calcium hydroxide. This alkaline hydrate composing the hardened cement paste shows a high BET surface area (close to 100 m².g⁻¹) and can absorb low-concentrations of NO₂. However, the presence of CO₂ in the atmosphere limits the de-polluting effect of reference cement paste, mainly due to carbonation of the alkaline hydrates (reaction leading to the formation of calcium carbonate). The results established in this paper demonstrate that the addition of activated carbon in the cement paste, because of its very high BET surface area (close to 800 m².g⁻¹) and its specific reactivity with NO₂, can significantly improve and prolong the de-polluting effect in presence of CO₂ and even after complete carbonation of the surface of the cement paste.