Two concretes were made in the Canadian Arctic at sub-freezing temperature using an unusually high amount of calcium chloride, about 9% of the cement mass. Calcium chloride in such a high dosage was mainly used as an antifreezing admixture, because it was impossible to heat the cement and the aggregates prior to the batching and cure the concrete properly after its pouring.
One of these two concretes was cast inside a mine, where the temperature is about −10°C all year round. After one year of service, the strength of this concrete was determined to be 39 MPa at room temperature. The second one was cast outside the mine at −30°C during winter and was exposed to temperatures above 0°C the following summer. After one winter of service the strength of this was 5 MPa.
These two concretes were examined under the SEM and show quite a dense microstructures containing chloroaluminates.