Experimental Study on the Bearing Capacity of Reinforced Concrete Pipes with Corrosion-Thinning Defects Repaired by UHP-ECC Mortar Spraying

The in situ spraying method is widely used because of its advantages as a trenchless pipeline repair technology, including a fast construction speed and close bonding between the repair lining layer and the reinforced concrete pipe. However, current research on high-performance spray repair materials, the bearing capacity of pipelines before and after repair, and the failure modes between the two interfaces after repair is insufficient. Through laboratory tests designed with multiple sets of control tests, this paper outlines the bearing capacity of reinforced concrete pipelines with corrosion thinning defects repaired with ultra-high-performance concrete. The variation law of the residual bearing capacity of reinforced concrete pipes and the influence of different corrosion degrees, repair thicknesses, and interface forms on the bearing capacity of reinforced concrete pipes were studied following UHP-ECC for pipe repair. The results showed that the bearing capacity of the structure decreased with an increase in the corrosion thickness of the pipeline. After repair with ultra-high-performance concrete, the bearing capacity of corroded pipelines greatly improved. When the corrosion and repair thicknesses were the same, the bearing capacity of the repaired pipeline with different interface forms was very different. After the interface was implanted with nails, spray repair was carried out and the bearing capacity of the pipeline improved the most, followed by the naturally bonded interface. When plastic film was pasted on the repair interface, the bearing capacity of the pipeline improved the least.