Comparative Analysis of Precast and In situ Concrete and Their Effectiveness on Koga Irrigation Structures

Most construction projects in Ethiopia are built by using conventional cast in situ concrete. However, the latest technology reveals various priorities of the precast construction method over the cast in situ concrete. The main aim of this study is to analyze better irrigation lining concrete among two types of casting by conducting visual inspection methods and non-destructive tests to characterize defects. Koga irrigation main canal, which is found in Northwest Ethiopia, was used as a study area because it is made of both in situ and precast concrete linings. The study reveals that the lower strength, severe defects, and lower uniformity due to the high level of difficulty in pouring and vibrating the concrete on the side slopes of the canal were observed in the in situ lined canal. However, the growth of grass in the joints, and sealing of closely spaced and less water-tight joints are observed at the precast part of the canal lining. Providing reinforcement bars on the in situ canals and providing water-tight joints for the precast concrete part are viable solutions.