ABSTRACT
Abstract This paper presents findings from a review of laboratory and field studies related to the salt scaling resistance of concrete containing fly ash. Laboratory studies using accelerated scaling tests, such as ASTM C 672, invariably show that the partial replacement of Portland cement with fly ash reduces the scaling resistance of concrete, particularly at high levels of replacement and in lean concretes (low cementitious materials content). This apparent drawback has been a barrier to the wider use of fly ash concrete in highway structures in northern climates. However, the poor performance of fly ash concrete in laboratory tests is not corroborated by field experience. A field survey including more than 20 sites (mainly highway structures) where fly ash concrete had been exposed to freezing and thawing in the presence of deicing salts was recently completed by the author. Observations from these field studies indicated no problem due to salt scaling of the concrete even after more than 20 winters in some cases. Fly ash concrete samples taken during a number of field placements showed poor performance in accelerated laboratory tests hi contrast to excellent field performance. It is concluded that the ASTM salt scaling test is not appropriate for evaluating the scaling resistance of fly ash concrete. Keywords: Concrete, de-icing salts, field studies, fly ash, laboratory studies, scaling.
