The use of calcium aluminate cement (CAC) concrete in construction is increasing as the need for rapid repair solutions for deteriorating infrastructure rises.CAC is particularly useful because of its rapid strength gain property, even at low temperatures.However, the use of CAC in construction has been limited by a lack of understanding of the process of conversion, in which metastable hydrates convert to stable hydrates.This study examined two concrete mixtures, one containing a limestone aggregate and one containing a siliceous aggregate.The pore solution chemistry of each concrete system was determined, along with that of a CAC cement paste to determine the impact of aggregates.Pore solution chemistry of siliceous and limestone CAC concrete systems,as well as CAC paste was observed prior to and after conversion.Pore solution was expressed using mechanical methods, and the pore solution was analysed using inductively couple plasma optical emission spectrometry (ICP-OES).Results have shown that aluminium concentrations decreased and calcium concentrations increased in the limestone aggregate system and CAC paste system.Concentrations of aluminium and calcium remained constant prior to and after conversion in the siliceous aggregate system.These results indicate aggregate mineralogy does have a significant impact on pore solution chemistry and phase dissolution in CAC systems.