To properly evaluate watertightness of field concrete is extremely important from the standpoint of design and construction of watertight structures. In this research, permeability tests are performedon small standard specimens and cores sampled from field concrete with the purpose of seeking a method of evaluatingwatertightness of field concrete from the watertightness test values of small standard specimens of concrete used for evaluation of watertightness of field concrete, and comparison studies are made of the relations of the watertightness of the two. As a result, it is found that watertightness of field concrete are more reductions than small standard specimens.
