Rate controls on silicate dissolution in cementitious environments
The dissolution rate of silicate minerals and glasses in alkaline environments is of importance in cementitious systems due to its influences on: (a) early-age reactivity that affects the rate of strength gain and microstructure formation, and/or, (b) chemical durability of aggregates; compromises in which can result deleterious processes such as alkali-silica reaction (ASR). In spite of decades of study, quantitative linkages between the atomic structure of silicates and their dissolution rate in aqueous media (i.e., chemical reactivity) has remained elusive. Recently, via pioneering applications of molecular dynamics simulations and nanoscale-resolved measurements of dissolution rates using vertical scanning interferometry, a quantitative basis has been established to link silicate dissolution rates to the topology (rigidity) of their atomic networks. Specifically, an Arrhenius-like expression is noted to capture the dependence between silicate dissolution rates and the average number of constraints placed on a central atom in a network (nc, i.e., an indicator of the network’s rigidity). This finding is demonstrated by: (i) ordering fly ashes spanning Ca-rich/poor variants in terms of their reactivity, and, (ii) assessing alterations in the reactivity of albite, and quartz following irradiation due to their potential to induce ASR in concrete exposed to radiation, e.g., in nuclear power plants.
Copyright (c) 2017 Tandre Oey, Yi-Hsuan Hsiao, Erika Callagon, Bu Wang, Mathieu Bauchy, Gaurav N. Sant
This work is licensed under a Creative Commons Attribution 4.0 International License.
Authors retain copyright of the articles published in RILEM Technical Letters and grant the journal right of first publication with open access. The work is simultaneously licensed under Creative Commons Attribution 4.0 International License (CC BY 4.0) that allows others to share and adapt the work under the following terms: 1) a proper attribution is given in a form of a reference to the original work's authorship and initial publication in RILEM Technical Letters (bibliographic record with a DOI link); 2) a link to the license is provided; 3) the possible changes are indicated.