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To understand the conditions surrounding frost damage of concrete, freezing and thawing tests were executed on microchips containing microchannels of various geometries. The straight channels remained intact, and the channels having ink bottle geometries suffered frost damage. The channels with ink bottle profiles avoided frost damage when air remained in their cavities. After water permeation, air remained in channels having a large ratio of cavity to neck volume. Often, air is entrained to fresh concrete as a means of improving frost damage resistance. The results of this study indicate the importance of air entrapment during water permeation. Based on the results of the microchannel study, cement paste specimens were cured under reduced pressure to investigate the hypothesized improvement in resistance to frost damage. Freezing and thawing of hardened cement paste specimens containing AE water reducing agent resulted in surface deterioration. On the other hand, vacuumed cement paste specimens suffered almost no damage. These results indicate, under our experimental condition, vacuum curing as an effective means of reducing frost damage and also support the observations and results of the microchannel study.

Freezing Damage Mechanism in Model Microchannels and Vacuum Curing on Cement Paste to Improve Frost Damage Resistance