Journal
CONSTRUCTION AND BUILDING MATERIALS
Volume 216, Issue -, Pages 325-336Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.conbuildmat.2019.04.260
Keywords
Alkali carbonate reaction (ACR) in concrete; Silica-free dolomite aggregate; Microstructure investigation; Reaction mechanism
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Funding
- Slovenian Research Agency [P1-0175, P2-0185, J2-8194]
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The progress of the alkali-carbonate reaction (ACR) in NaOH or an aqueous environment at elevated temperature (60 degrees C) was investigated in concrete prepared with silica-free dolomite aggregate. The results obtained show that chemical reactions characteristic for the ACR progressed in all aged concrete systems. In NaOH aged samples, dolomite grains smaller than 2 mm in diameter went through a complete dedolomitisation process. Additionally, new Mg-Al, Mg-Si and Mg-Al-Si phases were recognized at the aggregate-cement paste interface. The less alkaline environment in the case of H2O-aged samples resulted in substantially decelerated ACR reaction. Based on observed long-term microstructural and phase changes, a detailed scheme of the ACR in concretes with silica-free dolomite aggregates was proposed. It turned out that the soluble Si-source does not necessarily originate from the aggregate itself but rather through the Pozzolanic reaction of cement binder decomposition/regeneration cycle. (C) 2019 The Authors. Published by Elsevier Ltd.
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