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Open AccessArticle

Inhibition of the Alkali-Carbonate Reaction Using Fly Ash and the Underlying Mechanism

College of Materials Science and Engineering, Nanjing Tech University. Nanjing 210009, China
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Crystals 2020, 10(6), 484; https://doi.org/10.3390/cryst10060484
Received: 10 May 2020 / Revised: 29 May 2020 / Accepted: 3 June 2020 / Published: 5 June 2020
In this paper, fly ash is used to inhibit the alkali-carbonate reaction (ACR). The experimental results suggest that when the alkali equivalent (equivalent Na2Oeq) of the cement is 1.0%, the adding of 30% fly ash can significantly inhibit the expansion in low-reactivity aggregates. For moderately reactive aggregates, the expansion rate can also be reduced by adding 30% of fly ash. According to a polarizing microscope analysis, the cracks are expansion cracks mainly due to the ACR. The main mechanisms of fly ash inhibiting the ACR are that it refines the pore structure of the cement paste, and that the alkali migration rate in the curing solution to the interior of the concrete microbars is reduced. As the content of fly ash increases, the concentrations of K+ and Na+ and the pH value in the pore solution gradually decrease. This makes the ACR in the rocks slower, such that the cracks are reduced, and the expansion due to the ACR is inhibited. View Full-Text
Keywords: inhibit; alkali-carbonate reaction; fly ash; expansion; mechanism inhibit; alkali-carbonate reaction; fly ash; expansion; mechanism
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Ren, X.; Li, W.; Mao, Z.; Deng, M. Inhibition of the Alkali-Carbonate Reaction Using Fly Ash and the Underlying Mechanism. Crystals 2020, 10, 484.

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