Atomistic Modelling for the Study of Dissolution and Carbonation of Lime

Ball, Richard, Pesce, Giovanni, Molinari, Marco, Grant, James, Parker, Steven and Fletcher, Ian (2016) Atomistic Modelling for the Study of Dissolution and Carbonation of Lime. In: 36th Cement and Concrete Science Conference, 5th - 6th September 2016, Cardiff.

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Abstract

At the 35th Cement and Concrete Science conference, we provided an example of how advances in computing power make atomistic modelling a viable approach for the study of chemical processes relevant to the construction industry. This paper describes developments of this work and how the combination of stable isotopes, atomic force microscopy (AFM), secondary ion mass spectrometry (SIMS) and atomistic modelling can provide new insights into the dissolution and carbonation mechanisms of lime. In this research AFM and atomistic modelling were used to investigate the dissolution mechanism of nano-sized Portlandite (Ca(OH)2) crystals. Experimental and computational results highlight differences in the solubility of {100}, {010} and {001} crystallographic faces. The {001} faces were shown to be the most stable. SIMS and Raman spectroscopy of 18O-labelled calcium hydroxide and computational techniques have allowed investigation of previously unknown details of the carbonation mechanism. Experimental results provide the first evidence of the theory proposed by Letolle and colleagues in 1990 regarding the formation of the carbonate ion (CO32-) by direct reaction of the hydroxyl ions (OH-) with carbon dioxide (CO2) dissolved in water. New insights into the transformation of meta-stable carbonates into stable phases in the first few minutes of carbonation are also reported.

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