Detailed investigation of ACR in concrete with silica-free dolomite aggregateŠtukovnik, Petra (Avtor) Bokan-Bosiljkov, Violeta (Avtor) Marinšek, Marjan (Avtor) alkali carbonate reaction - ACR in concretesilica-free dolomite aggregatemicrostructure investigationreaction mechanismThe progress of the alkali-carbonate reaction (ACR) in NaOH or an aqueous environment at elevated tem-perature (60°C) was investigated in concrete prepared with silica-free dolomite aggregate. The resultsobtained 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 completededolomitisation process. Additionally, new Mg-Al, Mg-Si and Mg-Al-Si phases were recognized at theaggregate-cement paste interface. The less alkaline environment in the case of H2O-aged samplesresulted in substantially decelerated ACR reaction. Based on observed long-term microstructural andphase changes, a detailed scheme of the ACR in concretes with silica-free dolomite aggregates was pro-posed. It turned out that the soluble Si-source does not necessarily originate from the aggregate itself butrather through the Pozzolanic reaction of cement binder decomposition/regeneration cycle.20192021-03-15 09:12:21Članek v reviji125411sl