| Recently, test methods for evaluating the durability of concrete structures have attracted intense attention. Surface absorption tests for hardened concrete can be useful because some deterioration mechanisms in concrete structures are known to be facilitated by the supply of water. However, the amount of water absorbed by hardened concrete is significantly affected by the moisture content of the concrete. Therefore a long preconditioning time is needed to obtain stable results in a laboratory test. Such preconditioning methods cannot be used in the field. On the other hand, there are several in-situ non-destructive test methods in which the preconditioning of the test surface is generally omitted. Errors due to uncertainty in the water content are greater in non-destructive tests than in laboratory tests. To utilize the results of surface absorption tests as a durability index, a standard test condition applicable both in laboratory and in-situ will be useful. In this paper, a rapid preconditioning method for surface absorption tests that consists of a 24 h wetting period and 24 h drying period is discussed. The rapid preconditioning method is confirmed to reduce the effect of the original water content of concrete and it is especially effective when the water cement ratio of concrete is 0.4 or less. |
