Field buried and laboratory investigation of Full-Scale eco-friendly Spun-Cast concrete pipes under various construction loading regimes

Reinforced concrete pipes are widely used under embankments for drainage purposes. Current design and construction guidelines for the reinforced concrete pipes are known to be overly conservative, putting reinforced concrete pipes at a disadvantage against flexible pipes. This study was designed to assess the structural performance of full-scale buried precast concrete pipes with shallow soil cover under the application of vehicular load representing commonly used construction equipment and daily routine vehicles. The concrete pipes incorporating fly ash were reinforced with double cage reinforcement with varying amounts of steel. Various types of vehicles including dump trucks, plain roller, asphalt-filled truck, and transit mixer were passed perpendicular to the longitudinal axis of the buried concrete pipe and the vertical displacement at the pipe's crown was monitored. Maximum deflection of 0.26 mm was observed due to the passage of dump truck over the buried pipe. No cracking or sign of distress was observed in the buried pipe under the action of tested vehicular loads. Therefore, pipes were transported to the laboratory and tested under three-edge bearing line load and patch load to mimic the application of wheel load and to investigate the cracking and ultimate capacities. The reduction in the steel reinforcement by 75 % and 50 % resulted in the decrease in the ultimate load capacities of the pipes by 83 % and 57 %, respectively. The 0.3 mm crack load in the patch load test was 0.82 to 0.89 times the 0.3 mm crack load in the three-edge bearing line load test. The 0.3 mm crack load in the laboratory test was around twice the maximum load applied to the pipe in the field buried condition. This study will help designers and contractors to better understand the field and laboratory performance of reinforced eco-friendly concrete pipes buried in shallow soil cover. Moreover, this study acts as a benchmark for evaluating the real field pipe capacities during the construction phase of various infrastructures development.