Frost Damage to Bricks Observed in Kitami City, Hokkaido

At two different locations in Kitami City, Hokkaido, cracks have been found in bricks, seemingly due to frost damage. In this research, the mechanism of the occurrence of the cracks in the bricks has been looked into through field investigations and exposure experiment. The field investigations have revealed that some bricks located in sun-exposed areas have a higher frequency to crack and cracks occur in the protruded part of bricks. From the exposure experiment, cracks in the bricks have been found to occur in late winter from the end of February to the end of March. It has also been confirmed that the following unique temperature distribution exists when cracks occur in bricks; in late winter, bricks melt due to the daytime heat. If bricks do not melt completely during the daytime leaving some frozen parts and these remain overnight, the melted areas created during the daytime then refreeze surrounded by the frozen parts due to the low night temperatures. In this research, this frost damage caused by such temperature distribution has been defined as closed-type freeze-thaw phenomenon.From the above results, this article describes the mechanism of frost damage to bricks in Kitami City. The research results are considered useful when brick structures are built in cold regions like Hokkaido, ensuring the appropriate use of bricks.