The irrigation structures in Songphinong operation and maintenance project are at the age between 2 8 - 3 2 years old.
These are reinforced concrete structures. The deterioration of several structures are effected by many factors. In this research,
visual inspection was conducted to evaluate the concrete deterioration of 3 2 irrigation structures. In addition, the soil samples were collected at the position adjacent to these structures and concrete powder from 5 large irrigation structures
in the project area. All samples were tested at Soil Science Laboratory of Kasetsart University and Central Laboratory of
Kasetsart University. The results reveal that structures of 5 3 . 6 percent have the level of the moderate damage in class 3
with some of structures have crack parallel to reinforcing steel and need for more examine in details . While the results of
soil and concrete chemical testing, the most of soil in the area have amount of sulfate between 0. 0004- 0. 084 percent by
weight which less than minimum value of allowable sulfate, the amount of chloride in soil between 0-0.04 percent by weight
off concert. From results of testing concrete, there were found that sulfate in concrete of irrigation structures have between
0.53-1.90 percent by weight which were higher than the minimum value of allowable sulfate for severe condition. Moreover
amount of chloride higher results more than maximum value of allowable chloride. It may affect the service life of the
structures in future.
Keywords
failure, water conveyance structure, severe environment, chloride, sulfate