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Description: This 75-page report describes a laboratory testing program to determine the freeze-thaw durability and scaling resistance of 18 portland cement concretes with six different water-cement ratios (0.25, 0.30, 0.35, 0.40, 0.45, and 0.50) and three air entrainment levels (non-air-entrained, 4%, and 6%). The results are compared to the current recommendations for producing frost resistant concrete outlined in ACI 318. This report is also found on DVD021.
The primary purpose of this work was to assess the effect of air entrainment on the frost durability and scaling resistance of high strength concrete.
The laboratory program consisted of the production of six concrete mixtures with water/cement ratios of 0.50, 0.45, 0.40, 0.35, 0.30, and 0.25; each at three levels of air content: non-air-entrained, 4%, and 6%. No supplementary cementitious materials were used.
Frost resistance was investigated as a bulk or interior concrete property, via modified ASTM C 666, and as a surface property, via ASTM C 672.
For the mixtures investigated here, it was possible to obtain frost resistance based on the modified ASTM C 666 at w/c less than 0.40 without air entrainment. As far as scaling resistance is concerned, no air entrainment was necessary for mixtures with w/c of 0.25 or less.
It was observed that the ACI 318 provisions for frost durability are somewhat conservative. While ACI 318 requires air entrainment for all mixtures subject to freezing and thawing, all mixtures studied here with w/c of 0.25 and no air can be considered frost resistant. Further, properly air-entrained mixtures with w/c of 0.50 were frost resistant, even though the w/c was in excess of the 0.45 required by the ACI 318 provisions for freeze-thaw durability.
This report was developed as part of the educational requirements under a fellowship grant from PCA.
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