Abstract

Porosity is possibly an important parameter with respect to leaching of constituents from cement monoliths. During its lifetime, the pore structure of cementitious matrices changes due to carbonation and leaching. This paper discusses the effects of both accelerated carbonation and continuous leaching on the porosity, and, conversely, how porosity affects leaching properties. Two sample types are investigated: a mortar with MSWI-bottom ash substituting the sand fraction and a cement paste with 30 wt% of the cement substituted by a flue gas cleaning residue. The samples have been intensively carbonated in a 20% CO2 atmosphere for up to 60 days and were subsequently leached. The porosity was investigated by mercury intrusion porosimetry.Accelerated carbonation decreases total porosity by 12% in the case of 60 days of treatment of bottom ash mortars, whereas continuous leaching during 225 days increases it by 16%. Both carbonation and leaching decrease the amount of smaller capillary pores.Carbonation decreases both porosity and pH. Decreasing porosity diminishes leaching of sodium and potassium, while the decrease in pH increases leaching. However, the former process dominates the latter, resulting in a net decreasing effect of carbonation on the release of sodium and potassium from these cement matrices. (c) 2006 Elsevier Ltd. All rights reserved.

Published in

Waste Management
2007, Volume: 27, number: 7, pages: 977-985
Publisher: PERGAMON-ELSEVIER SCIENCE LTD

UKÄ Subject classification

Other Environmental Engineering


Publication identifier

DOI: https://doi.org/10.1016/j.wasman.2006.05.008

Permanent link to this page (URI)

https://res.slu.se/id/publ/80961