75°N, -49°C: THE INVESTIGATION AND REPAIR OF ARCTIC STRUCTURES DAMAGED BY THAUMASITE

摘要

Two structures with reinforced concrete foundation components comprise the Polar Continental Shelf Project in Resolute, on Cornwallis Island, the northernmost outpost in Arctic Canada. One is an accommodation building, and the other is a converted hangar for laboratories and equipment. This is a base for scientific expeditions in the Arctic. The foundations were constructed in 1988 and within two years severe deterioration of the concrete was seen. Sampling was carried out under severe Arctic conditions. Investigation determined that the cause of the damage was the formation of thaumasite in the mature concrete. The determination of the cause, the first instance recorded in Canada, involved tests by an international multi-disciplinary team. Since the disease was progressive and could destroy all the foundations, and because suitable materials were not available on site, innovative and different repairs were devised for the two structures, and made in 1993. In the accommodation building the piers supporting the building were isolated from further contact with the sulphate waters present during the summer thaw. The foundations in the laboratory building were replaced by resin concrete designed specifically for low temperature applications. The components of the materials used for grout and concrete on both buildings had to be flown to Resolute. Deficiencies in the execution of the repair contract led to the resin concrete foundations being replaced in 1995 by the repair contractor at no expense to the owner.