Structural performance of full-scale spun-cast concrete pipes incorporating hybrid reinforcement for resilient infrastructure: laboratory and field investigations

The efficient structural performance of precast concrete pipes under various loadings is the key factor responsible for its long-term behavior. This study was undertaken in an attempt to reduce the steel consumption in concrete pipes without compromising performance, particularly in developing countries using spun-cast technology. The study investigated the structural performance of full-scale spun-cast concrete pipes in laboratory and field settings. The conventional steel rebar reinforcement was reduced to 50% and the incorporation of locally cut steel fibers at dosages of 30 kg/m3, 60 kg/m3 and 80 kg/m3 as secondary reinforcement in pipes was explored. Higher crack and ultimate loads were observed for pipe having higher amount of reinforcement tested for both three edge bearing and patch loadings. Tested pipe having 80 kg/m3 of steel fibers showed 50% and 43% higher 0.3 mm crack and ultimate D-loads compared to identical pipe having 30 kg/m3 of steel fibers owing to a greater number of fibers restricting the crack propagation and widening by the crack bridging action. No cracks were observed for all the buried pipes tested under various types of vehicles. This study provides experimental evidence for the adequate structural performance of the hybrid reinforced spun-cast concrete pipes through laboratory and field testing and thus paving the way for the commercialization of the more economical hybrid reinforced concrete pipes.