Beam End Repair for Prestressed Concrete Beams-TR715

One of the primary concerns of the use of precast prestressed concrete beam (PPCB) bridges is cracking and spalling of the concrete towards the ends of the beams due to contamination from water and deicing chemicals, which results in exposure and corrosion of the beams’ reinforcement and prestressing strands. If allowed to progress, this deterioration will compromise the capacity of the beams, which can affect the integrity of the entire bridge and raise safety and durability concerns. To address this issue, the efficacy of ultra-high performance concrete (UHPC) and high early strength concrete (HESC) for strengthening and repairing damaged prestressed concrete beams ends was evaluated. First, a review of current repair strategies was conducted to determine the key qualities of effective repair methods. The use of unique materials with enhanced properties to perform patch repairs was ultimately selected as the repair method evaluated in this research project. Small-scale laboratory testing was conducted to evaluate the bond strength of various potential patching materials in terms of shear stress and tensile stress. Full-scale laboratory testing was conducted to determine the properties and performance of UHPC and HESC as beam patching materials. Six artificially damaged prestressed concrete beams were tested in full-scale experiments: two without repair, two repaired with UHPC, and two repaired with HESC. Observations indicated excellent patch bonding by the two materials tested in the full-scale portion of this research. Failure of one of the unrepaired beams due to confinement failure demonstrated one consequence of the loss of concrete cover and damage to the reinforcing steel caused by the beam-end damage. The outcome of this study is a set of recommendations regarding the most effective repair methods and appropriate retrofit materials for rehabilitating prestressed concrete beam ends