Title: Durability of Concrete Containing Fly Ash for Use in Highway Applications

Author(s): Peggy M. Carrasquillo

Publication: Symposium Paper

Volume: 100

Issue:

Appears on pages(s): 843-862

Keywords: abrasion resistance; admixtures; air-entraining agents; fly ash; bridges (structures); concrete durability; creep properties; shrinkage; freeze-thaw durability; Materials Research

DOI: 10.14359/1962

Date: 4/1/1987

Abstract:
The effect of fly ash content on the air entrainment, freeze-thaw durability, abrasion resistance, strength gain, shrinkage, and creep of concrete was studied. Two different fly ashes were used to replace 0, 20, and 35 percent of a portland cement by weight. A blended cement, containing 20 percent fly ash by weight, was also tested. Three different air entraining admixtures were used. It was found that the use of fly ash in concrete could reduce the effectiveness of air-entraining admixtures depending on properties of the fly ash, such as loss on ignition (LOI). However, concrete containing fly ash exhibited freeze-thaw resistance equal to or better than that of similar concrete containing portland cement only, provided both had similar entrained air contents. Similarly, concrete containing fly ash showed equal or better resistance to abrasion when compared to concrete of equal strength containing no fly ash. The strength gain characteristics of concrete containing fly ash are different from those of concrete containing no fly ash. The creep of concrete containing fly ash was found to be less than or equal to that of portland cement concrete when subjected to equal sustained loads, even though the 28 day compressive strength of the concrete containing fly ash was lower than that of concrete containing no fly ash. The shrinkage of concrete containing fly ash is highly dependent on the curing given to the concrete and on environmental conditions, such as temperature and relative humidity. Not only is the shrinkage of concrete containing fly ash affected by the previously mentioned conditions differently than that of concrete containing no fly ash, but concrete containing Class C fly ash is affected differently than concrete containing Class F fly ash.