The fundamental frequency of vibration (normally in transverse mode) is an excellent method of non-destructively evaluating the condition of concrete specimens subjected to repeated cycles of freezing and thawing in the laboratory. However, using fundamental frequency measurements has traditionally required prismatic specimens dimensioned so as to provide a clearly identifiable fundamental frequency in the selected mode of vibration. This works quite well for laboratory-molded specimens, but cutting prisms from field concrete is quite difficult. Fundamental frequency testing of cylindrical slices or disks provides a method of non-destructively evaluating specimens that could be easily prepared from drilled cores obtained from field concrete. Procedures for determining the fundamental frequencies and dynamic elastic moduli from disk specimens are presented, and comparisons between standard rectangular prisms and disk specimens are shown for a concrete mixture that showed deterioration in repeated freezing and thawing.
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