Spalling of Partial-Depth Precast-Prestressed Bridge Deck Panel Investigation using GPR

This paper presents research in progress on spalling of partial-depth precast-prestressed concrete bridge deck panels. Recently it has been observed that several bridges in Missouri with this type of construction have experienced spalling of concrete at the edges of the panels revealing an extreme condition of corrosion in the prestressing tendons, some to the point of rupture. Ground penetrating radar (GPR) was used to assess the condition of an existing bridge deck experiencing severe spalling of concrete and corrosion of reinforcement, as well as to determine the reasons for spalling. The GPR technique of non-destructive evaluation was well-suited for determining the relative condition of the prestressing tendons as well as the relative condition of the concrete throughout the deck in order to identify areas of cracking and corrosion. The GPR method was also used in an attempt to identify areas of delamination at the interface between the precast panel and cast-in-place topping slab. Measurements were taken from the top and bottom surfaces of the bridge deck to obtain a better image of the cross section because the deck consists of two layers of concrete as well as multiple layers of reinforcement. The data obtained from the top of the bridge deck indicated less concrete degradation in areas with increased amounts of longitudinal reinforcement provided for negative moment. GPR was able to provide locations of deterioration, but it was unable to distinguish the type of deterioration