Mechanistic Evaluation of Deicer Salt Scaling Damage Using Dynamic Elastic Young’s Modulus of Concrete Disks (05-1059)
Ufuk Dilek, MACTEC Engineering and Consulting, Inc.
Michael L. Leming, North Carolina State University, Raleigh

Frost deterioration in ASTM C 672 is assessed qualitatively. Test slabs are classified visually in one of six categories after 50 cycles of freezing and thawing cycles at realistic freezing rates. Frost deterioration in ASTM C 666 is assessed quantitatively using loss in the dynamic elastic (Young’s) modulus during at least 300 cycles of freezing and thawing at a very rapid rate. The quantitative approach based on dynamic elastic modulus was examined for evaluating frost durability under deicer salt exposure as an alternative to subjective, visually based evaluation techniques. This study was conducted in two phases. In one phase, cores were taken from slabs after the completion of the prescribed cyclic freezing and thawing regimen of ASTM C 672. Concrete disks consisting of the immediate surface, approximately 15 to 18 mm (0.6 to 0.7 in.) thick were removed from the top of the cores and used to determine the dynamic elastic modulus. The loss in dynamic elastic modulus of the surface disk removed from the test slab after 50 cycles was compared to the findings of the visual scaling evaluation. The second part of this study was the evaluation of a concrete scaling test performed on 25 mm (1 in.) thick concrete disks with a finished surface. The disk test permitted visual evaluation similar to ASTM C 672, although on a smaller surface area, and, in addition, the non-destructive determination of dynamic elastic Young’s modulus on the same specimen before and after frost exposure. Visual evaluation of disk scaling provided comparable results to scaling results of conventional specimens. While a decrease in Young’s modulus was found under salt scaling exposure for both the core and disk specimens the results were not directly comparable to visually evaluated deterioration. The use of thin, relatively small diameter, easily handled disk specimens, tested for only 15 cycles of freezing and thawing, was found to provide results similar to those of ASTM C 672.