Behavior of Externally Fiber-Reinforced Polymer Reinforced Shrinkage-Compensating Concrete Beams

The major cause of cracking in bridge decks, concrete pavements, and slabs-on-ground is restrained shrinkage of concrete. Shrinkage-compensating concrete (SHCC) and fiber-reinforced polymer (FRP) are explored to develop a hybrid slab system as one possible method of eliminating this cracking. To achieve this objective, the behavior of hybrid FRP-SHCC beams was studied in this paper as the first-stage development. The expansion property of SHCC is used to decrease cracks in concrete. A series of coffee can tests were carried out to measure and compare the expansion of SHCC from two candidate materials. The selected SHCC candidate mixture was then optimized to achieve the maximum expansion and a decent concrete strength. The optimized SHCC mixture was used to make FRP-SHCC beams. The expansion was measured through strain gauges on the FRP sheets during curing. Both glass fiber-reinforced polymer (GFRP) sheets and carbon fiber-reinforced polymer (CFRP) sheets were used for comparison. A series of third-point loading experiments were conducted to study the behavior of the proposed hybrid FRP-SHCC beams. The results indicate that the proposed system is promising in terms of its ability to develop a residual prestressing effect. Tests also show that the prestressing effect from the expansion of SHCC increases as the axial stiffness of the FRP reinforcement increases.