There are several causes, fatigue, the percussion from the exterior, the decline of capacity by circumstances, the crack occured in the interior, the carbonation and so on, that can shorten the span of life of concreted construction.
First of all, the life of R-C construction can be predicted to understand the connection between appearance status index, fatigue life and used life
The study of the life of R-C construction has been developed deeply at the inside and outside of the country and several experimental formulae have been presented. Forther more, these formulae have been utilized as the index of making the prediction of life of R-C construction and maintenance. However, it's very difficult to predict accurately the span of life, because of circumstance of a field experimentation, reliance of Data and so on.
Finally, in this report, I think that the status evaluation found out by the outside investigation with timeworn R-C bridge can be utilized for deciding bridge's life and danger with analysis of appearance status index, fatigue-life and used-life.