FAILURE OF IRRIGATION STRUCTURES IN SEVERE ENVIRONMENT

Abstract

The irrigation structures in Songphinong operation and maintenance project are at the age between 28-32 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 32 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 53.6 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.