DEICER SALT SCALING RESISTANCE OF SUPPLEMENTARY CEMENTING MATERIAL CONCRETE: LABORATORY RESULTS AGAINST FIELD PERFORMANCE

摘要

In North-America, the de-icer salt scaling resistance of concrete containing supplementary cementing materials (such as fly ash and granulated blast-furnace slag) has been a matter of concern over the past decade. In order to provide more information on the real durability of these mixtures, nine test sections were cast in the City of Quebec (Canada). The test site was selected for its harsh winter climate that combines low temperatures and regular exposure to de-icing salts. As part of this program, three sources of fly ash and one source of slag were tested. In addition, a reference concrete mixture made of an ordinary Portland cement was also tested. Test sections were cast as sidewalks and cured with a white membrane curing compound. After 60 days and five years of exposure to natural conditions, cores were extracted from the sections and brought back to the laboratory for testing. In addition, specimens were also cast on site in PVC moulds and moist cured in the laboratory for a minimal period of 14 days. The salt scaling resistance of all field and laboratory samples was evaluated using ASTM C672. Additional porosity measurements and chloride content determinations were performed on the five-year old samples. Cores extracted from the test sections were much more resistant to de-icer salt scaling than the specimens cured under laboratory conditions, confirming the importance of casting and finishing operations on the behavior of concrete. Furthermore, the good performance of the test sections after 10 years of exposure to natural conditions clearly emphasizes the severity of the ASTM C 672 procedure.