Research on alkali-carbonate reaction (ACR) and damage of freeze-thaw for pure dolomite as concrete coarse aggregate

Abstract

Alkali-carbonate reaction (ACR) is one of the important components of alkali aggregate reaction (AAR) in concrete structures, which may lead to a serious damage for the concrete construction and effect on the durability of concrete projects adversely. Previous research has systematically investigated the possibility of ACR in dolomitic limestone. However, there is limited literature available for ACR in pure dolomite aggregate specifically. Therefore, this paper aims to investigates whether pure dolomite occur ACR and the freeze-thaw resistance of pure dolomite coarse aggregate concrete (PDCAC) due to the raw materials produced in the southwest of China, which is cold in winter. To determine the alkali activity of pure dolomite, three methods were employed: lithofacies method (LM), rock-cylinder method (RCM), and rapid preliminary screening test for carbonate aggregates (AAR-5). Lithofacies method confirmed that the dolomite used in this paper was pure almost, and no SiO2 content, ruling out the possibility of alkali-silica reaction (ASR). The rock-cylinder method indicated a reduction in length during the 84-day test period, which indicates the absence of ACR. Subsequently, the AAR-5 method was used to test ACR, and the samples exhibited a length expansion rate of far less than 0.1% within 28 days, which further confirmed the absence of alkali activity in pure dolomite. Finally, the freeze-thaw cycles test was carried out on the concrete with pure dolomite as concrete coarse aggregate. The results revealed no significant spalling on the concrete surface after 200 freeze-thaw cycles, and pure dolomite coarse aggregate concrete can withstand freeze-thaw damage to a certain extent.