Concrete Beams Prestressed Using Carbon Fiber Reinforced Polymer

About the report:

Corrosion of reinforcement in reinforced concrete leads to damage in both the concrete and the reinforcement that requires costly repairs and inconvenience to the traveling public. When concrete is reinforced with steel prestressing strands that are under sustained tensile stress, corrosion is more critical than in non-prestressed concrete with non-prestressed steel reinforcement.  Corrosion-free carbon fiber reinforced polymer reinforcement may be used instead of prestressing steel and reinforcing bars to mitigate the corrosion problem in prestressed concrete elements such as beams. 

The Virginia Department of Transportation (VDOT) placed beams with carbon fiber reinforced polymer reinforcement in a two-span bridge in Halifax County, Virginia.  The bridge has two 84-ft spans, continuous for live load, and each span has four 45-in-deep prestressed bulb-T beams.  The first two beams were cast using a traditional concrete mixture with conventional slump.  The remaining six beams were cast with self-consolidating concrete to facilitate the placement operation.

The deck was cast with conventional concrete and corrosion-resistant reinforcing bars.  Concrete for both the beams and the deck was tested at the fresh and hardened states. The structure was inspected visually immediately after construction and 8 months and 3.5 years later.  The beams were performing well with no deficiencies. The deck was also performing well except that the continuity diaphragm over the pier had several longitudinal cracks. The continuity diaphragm concrete was placed, in accordance with normal VDOT practice, after the deck concrete had been placed on both sides of the pier.  Cracks at the deck level in the continuity diaphragms are generally attributed to restrained shrinkage when the diaphragm concrete is placed after the deck concrete.

The study recommends that VDOT’s Structure and Bridge Division use beams with self-consolidating concrete and carbon fiber reinforced polymer reinforcement as an option in severe environments since the fabrication and constructability challenges described herein were successfully overcome.

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