A Study on the Strengthening Performance of Concrete Beam by Fiber‐Reinforced Polyurea (FRPU) Reinforcement

Abstract

Polyurea coating helps improve the ductility and toughness of structural members. A fiber-reinforced polyurea (FRPU) composite provides high load-carrying capacity and is applied by simply spraying it onto the member surface. Unlike existing reinforcement approaches, the FRPU coating method can prevent the ductility of concrete beams from deteriorating and the concrete surface from debonding. In this study, 20 concrete beams were tested with respect to their load-carrying capacity and flexural ductility using polyurea or FRPU reinforcement. The test variables included the type of reinforcing fibers, coating thickness, and weight-to-content ratio of the fibers in the FRPU. Moreover, the load-carrying capacity and mechanical behavior of all specimens were compared according to the content of the steel fibers, milled glass fibers, or carbon nanotubes (CNTs). Specimens reinforced using polyurea or FRPU were confirmed to retain the load-carrying capacity and flexural ductility to a certain degree after concrete failure at the tension face of the midspan section. The concrete beams ultimately failed through the fracture of polyurea or FRPU without debonding. Experiments were conducted to illustrate the strengthening effect by FRPU and determine its superiority.

A review on the applications of polyurea in the construction industry

“…This system provides a high load‐bearing capacity and is easily applied by spraying on the surface of the structure and impedes the deterioration of the concrete rebars and the disintegration of the concrete surface. Reinforcement of the concrete specimens with the FRPU to maintain the load capacity and flexural flexibility has been confirmed to some extent after the concrete failure 83 …”

In-Plane Strengthening of Unreinforced Masonry Walls by Glass Fiber-Reinforced Polyurea

“…The initial cracks in all the specimens appeared in the displacement range of 0.2-0.8 mm, as presented in Table 2. FEMA 273 [25] and FEMA 306 [26] reported that a masonry wall subjected to an in-plane load fails by rocking, toe crushing, sliding, and diagonal tension. Diagonal tension and mortar cracks were evident in all the specimens.…”

“…By modifying the Triantafillou [7] and AC125 [25,26] models, this study proposed formulas to describe the degree of strengthening caused by GFRPU. It is not practical to construct a two-sided reinforcement using GFRPU, and the X-type reinforcement is rarely differentiated from the one-sided reinforcement of the wall when considering the construction and the experimental results.…”

Out-of-Plane Strengthening of Unreinforced Masonry Walls by Glass Fiber-Reinforced Polyurea

“…Wu et al [19] investigated the reinforcing effect based on the coating thickness and compared the reinforcement effect for nonreinforced and polyurea-reinforced clay brick walls against blast loads. The reinforcement effect on concrete beams and columns reinforced by glass fiber-reinforced polyurea (GFRPU) mixed with milled glass fiber to improve the tensile strength of polyurea [20][21][22][23] was investigated. The authors reported that GFRPU was effective in enhancing the strength and ductility of structural members.…”