Hawaiian and Azorean volcanic aggregates: a preliminary study of the potential alkali-silica reaction

Autor: Violeta Ramos, Benoit Fournier, João Carlos Nunes, Sara Medeiros, Isabel Fernandes
Rok vydání: 2020
Předmět:
Zdroj: Bulletin of Engineering Geology and the Environment. 80:8949-8960
ISSN: 1435-9537
1435-9529
DOI: 10.1007/s10064-019-01702-z
Popis: The alkali-silica reaction (ASR) is a chemical deterioration of concrete that involves reactive forms of silica. Volcanic glass is one of the potentially reactive forms of silica that can be present in volcanic rocks such as basalts. The aggregates used for concrete purposes from the Azores and Hawaiian Archipelagos are mainly of basic composition (basalts s.l.). In general, there is no report of ASR damaged structures in both archipelagos. However, in order to evaluate the behavior of these rocks regarding ASR and to compare the rocks from the two archipelagos, a set of methodologies were performed on a total of twenty-one volcanic aggregates. Geochemical analysis, total alkali-silica diagram, CIPW norm calculation, and petrographic analysis are some of the methods used for the assessment and analysis of rocks. The study was also complemented by electron probe microanalysis (EPMA) in order to identify the composition of volcanic glass and by X-ray diffractometry (XRD) for the Hawaiian aggregates. The results obtained from the studied aggregates showed that there are some differences between the two archipelagos. The rocks from the Azores are alkaline while the majority of the rocks from Hawaiian Archipelago are tholeiitic. The petrographic study revealed that the analyzed rocks from the Hawaiian Islands contain a higher quantity of interstitial volcanic glass than those from the Azores Archipelago. The EPMA carried out in some samples from the Hawaii showed that the volcanic glass has a composition of silica higher than 65%, value that is considered in the literature as potentially reactive.
Databáze: OpenAIRE
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