Flexural Behavior of Reinforced Concrete Slabs Strengthened with High Elastic Modulus Polyurea

This study experimentally investigates the strengthening performance and failure behavior of reinforced concrete slabs coated with high elastic modulus polyurea(HEPU). To address the limited strengthening effect of conventional polyurea due to its low elastic modulus and strength, HEPU was applied to slab specimens with varying coating thicknesses (1, 2, and 3 mm). To evaluate the effectiveness of the HEPU reinforcing method, experiments were conducted with varying coating thicknesses, and the results were compared with those of unstrengthened specimens. The results showed that HEPU strengthening significantly enhanced flexural strength and stiffness, with improvements increasing proportionally with coating thickness. Additionally, the polyurea coating enhanced crack resistance and adhered well to the concrete, preventing delamination or detachment up to final failure. The slabs maintained ductile behavior even after HEPU rupture, although load resistance decreased post-rupture. However, the strengthening effect diminished due to the rupture of the HEPU, indicating limited effectiveness in improving ductility. These findings provide insights into the design and application of polyurea-based strengthening techniques for reinforced concrete structures.