HIGH-STRENGTH CONCRETE - FREEZE-THAW TESTING AND CRACKING

Cracks due to rapid freezing and thawing in water (ASTM C666 procedure A) of non-air entrained high strength concretes have been investigate d using a procedure designed to avoid creating cracks during specimen preparation. Polished sections impregnated by immersing virgin water s aturated slices in ethanol containing fluorescent dye (Fluorescent Liq uid Replacement - FLR) were inspected in ultra violet light in an opti cal microscope. The fluorescent impregnated polished sections showed n o cracking in any of the concretes before frost exposure, and extensiv e cracking after deterioration. The amount of cracks on the polished s ections showed a good relationship to Durability Factors (DF) measured in the rapid freeze/thaw test. The crack volume calculated using a si mple square grid model of cracks correlated reasonably to measured vol ume increase at frost testing.