Non-destructive testing for assessing the tightness of cover concrete

Three specific in-situ tests to assess the air tightness and water tightness of the surface layer of concrete were examined. Test methods for the tightness are the rapid air permeability, the water absorption applying Figg's method and the rapid water permeability by author's method. In the experiments, specific parameters obtained in three different in-situ tests corresponded well to air permeability coefficient and coefficient of water diffusion in the firms indoor tests, and those parameters satisfactorily reflect the change in the tightness of the surface layer caused by the water to cement ratio, age of test and cement type. In addition, those parameters also sensitively reflected the change of the permeability due to the existence of the model crack, In conclusion, three test methods are promising for providing air tightness or water tightness of the surface layer of concrete from the view points of the use of simple testing devices and convenient procedures.