Title:
Deicer Salt Scaling Resistance, Chloride Permeability and Code Requirements for Air Content, Spacing Factor
Author(s):
Colin D. Johnston
Publication:
Concrete International
Volume:
16
Issue:
8
Appears on pages(s):
48-55
Keywords:
air entrainment; deicers; fly ash; permeability; salts; silica fume; high-range water-reducing admixtures; standards; water-cement ratio; water-cementitious materials ratio; Materials Research
DOI:
Date:
8/1/1994
Abstract:
Concrete durability under exposure to deicing salts is discussed in terms of how to insure proper air entrainment and consolidation throughout the duration of the placement process, especially when superplasticizing admixtures or fly ash produce significant time-dependent losses of entrained air and slump during the process. The validity of recent revisions to the CAN/CSA A23.1 and ACI 318 codes that replace limits on water-cement ratio (w/c) with limits on water-cementitious materials ratio (w/c+m) is discussed in terms of quantitative measurements of deicer salt scaling resistance and chloride permeability. The prescriptive code limits on w/c+m are shown to be in some cases not sufficient to insure satisfactory durability, even with proper air entrainment. They need to be augmented by performance-based requirements for scaling resistance and chloride permeability, particularly for concretes containing fly ash or silica fume.