Influence of air entraining agents on deicing salt scaling resistance and transport properties of high-volume fly ash concrete

摘要

Based on laboratory tests, the deicing salt scaling resistance of high-volume fly ash (HVFA) concrete is usually reported as less than satisfactory. Therefore, we developed a HVFA composition with an air entraining agent (AEA) that should meet the European salt scaling criterion (≤1 kg/m~2). This paper presents a full characterization of its air void system from the moment of casting until the freeze/thaw test on cast surfaces, and evaluates the influence of air entrainment on its transport properties. The minimum air content of 6-7% was achieved with 7.0 ml AEA/kg binder (versus 2.0 ml AEA/kg binder for traditional concrete). However, with very fine fly ash (45 μm fineness: 13.2% retained), it was more difficult to maintain an adequate air void system and control the salt scaling resistance at later age (91 days). With coarser fly ash (45 μm fineness: 26.6% retained), salt scaling after 28 severe freeze/thaw cycles equaled only 0.5 kg/m~2. Nevertheless, AEA use increased the water sorption under vacuum and the apparent gas permeability.