993
4384.017
Khayat, Kamal Henri; Discussion by V.R. Sturrup
Journal - ACI
Article
ACI
1991
May-June
233-239
Y
Although the mechanical properties of a high-strength lightweight concrete containing fly ash were shown to improve at cryogenic temperatures, its susceptibility to repetitive cryogenic frost cycles still must be evaluated. Longitudinal thermal strains of water-saturated and air-dried concretes were monitored between 65 and -250 F (18 and -157 C). Cumulative drops in compressive and splitting tensile strengths were measured after each of five gradual freeze-thaw cycles ranging from a high of 65 F (18 C) to two low temperatures of -40 and -100F (-40 and -73C). This was done to evaluate the concrete’s frost durability at liquified petroleum and natural gas temperatures, respectively.As expected, moist concrete exhibits larger dilation and residual strains than air-dried concrete. The compressive strengths of both moist and air-dried concretes cycled five times to -40 F (-40 C) are virtually unchanged; however, maximum losses of 10 percent may result when the extreme freezing temperature drops to -100 F (-73 C). The splitting tensile strength of air-dried concrete cycled to either cryogenic temperature does not undergo any significant damage, whereas the splitting tensile strength of moist concrete may exhibit up to a 20 percent loss. This sharp drop in splitting tensile strength of moist concrete can be caused by debonding observed at the interface between aggregate and cement paste.