Use of self-consolidating concrete to cast large concrete pipes.

An experimental study was carried out to develop a self-consolidating concrete (SCC) for casting large-sized concrete pipes and validate its performance at the pipe production plant. Four full-scale pipes were cast using different optimized SCC mixtures of various static stability levels (stable and highly-stable) coupled with different placing methods. The investigated SCC mixtures were proportioned with a water-cementitious materials ratio of 0.35. Initial slump flow of the SCC was fixed at 650 ± 20 mm. Two different casting methods were evaluated: conventional placement by bucket from the top and pumping from the bottom. Casting performance was evaluated in terms of filling capacity and flow into place, required duration of casting, segregation resistance, and surface finish. Cores were taken at different heights corresponding to 0.5, 3, and 5.5 m from the bottom of each pipe to evaluate the uniformity of in situ properties. The core samples were tested for water absorption and mercury intrusion porosimetry. Test results indicate that optimized SCC mixtures with adequate resistance to segregation cast from the top or pumped from the bottom can achieve excellent surface finish and uniform distribution of in situ properties. [ABSTRACT FROM AUTHOR]