Comparative study of the alkali-silica reaction (ASR) in granitic aggregates

Velasco-Torres, A.; Alaejos, P.; Soriano, Jesús

doi:10.3989/egeol.40133.091

Cited by 13 publications

(4 citation statements)

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“…However, although the criterion in LNEC E 461 [20] uses the lowest expansion limits and a shorter test period (twelve weeks), the interpretation of the aggregates' behaviour in RILEM AAR-4.1 shows that this criterion is effective in the detection of almost all the aggregates classified as potentially reactive by the criterion in Lindgård et al [19], which uses a test period of twenty weeks. The potential reactivity detected for aggregates GR3, GR19 and GR20 in RILEM AAR-4.1 can be, probably, justified by the great abundance of microcracks in those aggregates, which was pointed out by Velasco-Torres et al [29] as the main responsible for the interstitial fluid intake to the siliceous components in the aggregates. The assumption in LNEC E 461 [20] that petrographic characterization is not sufficient for the classification of granitic aggregates seems to be justified, since some potentially reactive behaviours that were observed in RILEM AAR-4.1 were not identified by the petrographic characterization.…”

Section: Ramos | I Fernandes | a S Silva | D Soares | F Noronhamentioning

confidence: 79%

Potential reactivity of granitic rocks. Petrographic characterization vs accelerated expansion tests

Ramos

Fernandes

Silva

et al. 2016

Rev. IBRACON Estrut. Mater.

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ResumoSeveral cases of alkali-silica reaction involving granitic aggregates have been diagnosed in damaged concrete structures in Portugal. Nonetheless, this kind of rock is usually regarded as slow/late reactive or even non-reactive to alkalis. Granitic rocks are widely exploited in Northern and Central Portugal, representing almost half of the produced aggregates in this country. Project IMPROVE rose from the need to accurately diagnose the potential reactivity of granites to alkalis. The study involved about forty granites collected from different regions in Portugal, from which the results of eight samples are being presented in this paper. The tests carried out include the petrographic analyses of the aggregates and mortar and concrete expansion tests. It was concluded that the content of microcrystalline quartz correlates better with the results of AAR-4.1 than with the other expansion tests.Keywords: alkali-silica reaction; granites; petrography; expansion tests; performance.Diversos casos de reação álcalis-sílica têm sido diagnosticados em estruturas de concreto nas quais foram utilizadas rochas graníticas. No entanto, este tipo de rocha é geralmente considerado como inócuo ou de reactividade pouco provável aos álcalis. As rochas graníticas são amplamente exploradas no norte e centro de Portugal, representando quase metade da produção total de agregados no país. O Projeto IMPROVE surgiu da necessidade de diagnosticar corretamente a potencial reatividade aos álcalis de granitos. No âmbito desse projeto foram estudadas diversas amostras colhidas em diferentes regiões de Portugal, apresentando-se neste artigo os resultados de oito destas. Os ensaios realizados incluem a caracterização petrográfica dos agregados e ensaios de expansão de barra de argamassa e prisma de concreto. Concluiu-se que o conteúdo em quartzo microcristalino se correlaciona melhor com os resultados do ensaio em prisma de concreto RILEM AAR-4.1 do que com os outros ensaios de expansão.Palavras-chave: reação álcalis-sílica, granito, petrografia, ensaios de expansão, desempenho.

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Section: Ramos | I Fernandes | a S Silva | D Soares | F Noronhamentioning

confidence: 79%

Potential reactivity of granitic rocks. Petrographic characterization vs accelerated expansion tests

Ramos

Fernandes

Silva

et al. 2016

Rev. IBRACON Estrut. Mater.

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“…Velasco-Torres et al (38) carried out a comparative study of two granitic rocks extracted from two dams affected by alkali-silica reaction, with slow and fast reactions, respectively, classifying the reactivity of the rocks according to their geological term. They concluded that the reaction can be slow or fast for any given type of rock depending on its components and/or its microstructural characteristics.…”

Section: Introductionmentioning

confidence: 99%

Study of the alkali-silica reaction rate of Spanish aggregates. Proposal of a classification based in accelerated mortar bars tests and petrographic parameters

et al. 2021

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The alkali-silica reaction has been studied in depth due to the evolution in the knowledge of the expansive phenomenon. One of its most important aspects is the reaction rate of the aggregates. In Spain, at the early 90s of the 20th century, aggregates were considered almost non-reactive. However, the use of accelerated curing and other environmental factors revealed that there were potentially reactive siliceous aggregates. Nevertheless, there are several siliceous and limestone aggregates with siliceous inclusions that show reactivity over long period. In the present work, open porosity, expansion and petrography with quartz reactivity index have been determined, in 68 siliceous, limestone and dolomitic aggregates, from quarries located in areas with diagnostic reactivity. Based on these parameters and their interrelation, a classification method is proposed to detect slow-reacting aggregates.

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“…Gogte 1973;Grattan-Bellew 1992;Kerrick and Hooton 1992;Shayan 1993;Wenk et al 2008). However, microcracks in the aggregate particles also provide easy access to quartz grains in the interior, as suggested by Velasco-Torres et al (2010).…”

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confidence: 99%