Investigation of the effect of partial replacement of Portland cement by fly ash on carbonation using TGA and SEM-EDS

Author(s): Andres Belda Revert, Klaartje De Weerdt, Karla Hornbostel, Mette Geiker
Paper category: Proceedings
Book title: Proceedings of the International RILEM Conference
Materials, Systems and Structures in Civil Engineering 2016
Segment on Concrete with Supplementary Cementitious Materials
Editor(s): Ole M. Jensen, Konstantin Kovler and Nele De Belie
ISBN:978-2-35158-178-0
e-ISBN: 978-2-35158-179-7
Publisher: RILEM Publications SARL
Publication year: 2016
Pages: 426-435
Total Pages: 10
Language : English

Abstract: The aim of this paper is to investigate the effect of partial replacement of Portland cement by fly ash on the phase changes upon carbonation and the resulting CO2-binding capacity. Two mortars with water-to-binder ratio 0.55 and two different binders, Portland cement (CEM I) and Portland fly ash cement (CEM II/B-V) were cured sealed for 14 days at 20o C and subsequently exposed to accelerated carbonation (20o C, 60% RH and 1.5% CO2) for 4 weeks.The changes in the phase assemblage upon carbonation were studied by TGA and SEM-EDS.TGA allowed the quantification of changes in Portlandite and calcium carbonate content.SEM-EDS was used to investigate changes in the C-S-H composition and the microstructure. It was observed that both binders formed similar amounts of carbonates upon accelerated carbonation, even though their CaO content differed. This could be attributed to differences in the reaction degree of the Portland clinker and a larger contribution to the uptake of CO2 by C-S-H for the fly ash containing cement. Hence care should be taken when applying the CaO content as a measure for the CO2-binding capacity.

Online publication : 2016
Publication type : full_text
Public price (Euros) : 0.00