The effect of loading rate on fracture toughness of ice has been investigated using sharply edge-notched specimens by bending at -10°C. The loading rate KI ranged from 1 to about 103kPam1/2/s. The notch was made by molding a razor blade in the specimen in the ice growing process and removing it before the bending test. Two sizes of specimens, section sized 25×25mm (small size specimen) and 50×50mm (medium size specimen) respectively, were used. About thirty small size specimens or about ten medium size specimens were tested at each loading rate. The experimental results were as follows.
(1) The values of KIc were lower in the higher KI range, and there was a transition in the range of KI=10-100kPam1/2/s.
(2) The effect of KI was found to be very small in the range of KI larger than 100kPam1/2/s.
(3) The effect of loading rate on the minimum value of fracture toughness KIc was small in the whole range of KI tested for both small and medium size specimens.
(4) The minimum KIc values of small and medium size specimens seem to coinside each other approximately. The maximum and the median KIc values of medium size specimens were smaller than those of small size specimens.
(5) It was found that a vinyl silicone impression material being used for dentistry was suitable to make replica of the fracture surface for macrofractography.