Journal article

Natural carbonation of aged alkali-activated slag concretes

Susan A Bernal, Rackel San Nicolas, John L Provis, Ruby Mejia de Gutierrez, Jannie SJ van Deventer



Alkali-activated slag concretes stored for 7 years under atmospheric conditions are assessed, and the structural characteristics of naturally carbonated regions are determined. Concretes formulated with a 400 kg/m 3 and water/binder (w/b) ratio between 0.42 and 0.48 present similar natural carbonation depths, although these concretes report different permeabilities after 28 days of curing. The inclusion of increased contents of binder leads to a substantial reduction of the CO2 penetration in these concretes, so that negligible carbonation depth values (2 mm) are identified in concretes formulated with 500 kg/m3 of binder. Calcite, vaterite, and natron are identified as the main carbonation ..

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Funding Acknowledgements

This study was sponsored by the Australian Research Council (ARC) through a linkage grant between University of Melbourne and Zeobond Pty, including partial funding through the Particulate Fluids Processing Centre, a Special Research Centre of the ARC. The participation of R. Mejia de Gutierrez was funded by Universidad del Valle (Colombia) and the GEOCERAM Project. The authors would like to express their gratitude to William Valencia and Jherson Diaz (Univalle) for carbonation depth data collection, and Brant Walkley (UniMelb) for his assistance in the difficult task of obtaining the carbonated paste from the hardened concretes for the XRD analysis.