Frost testing of HP/HVFA concrete for severe offshore conditions

In the rim of DaCS (Durable advanced Concrete Solutions) project, financed by Norwegian research council and the industry partners, one of the work packages is associated with production and documentation of frost durable low-carbon concrete suitable, in addition, for offshore and arctic exposures conditions. A number of freeze-thaw experiments with high-volume fly ash concrete were carried out. This paper presents some preliminary results made to proceed in the understanding of : 1.how internal and superficial frost damage occur in ASTM C666 procedure A, rapid freeze-thaw testing in fresh water (by far the most common way of frost testing concrete), 2. how this is related to water uptake during curing and during subsequent freeze-thaw, and 3. how the air entrainment contributes to frost resistance in this test. The results show that the water uptake during curing, presumably due to self-desiccation and air void filling, is much lower than the accelerated uptake due to the wet freeze/thaw. Furthermore, air voids in FA-concrete seem to be filled less than inwet curing. A surprisingly high scaling was observed for FA-concrete in these fresh water tests even without any internal damage and cracking and scaling were accelerated as both occurred. Key words: Frost resistance, Fly ash, Air voids, Freshwater, Scaling, Cracking