Protrusions designs of AFRP to eliminate slippage of bonding adhesive

A presentation of a new innovative smart designs of protrusions in Aramid Fiber Reinforced Polymer (AFRP) which could lead the manufacturing industry of AFRP to a new era. The classic straight AFRP strips has a major disadvantage when externally bonded with other engineering materials using bonding adhesive. When exposed to high temperatures, the bonding adhesive slides causing a weak bondage or a complete debonding in some cases between the AFRP and engineering material surfaces. Thus, the purpose of protrusions in AFRP laminates is to eliminate the slippage of the bonding adhesive between the AFRP strips and other engineering material surfaces. This takes place by eliminating the frictional factor between the surfaces of AFRP laminate and bonded engineering material.

Influence of Externally Bonded CFRP on the Shear Behavior of Strengthened and Rehabilitated Reinforced Concrete T-Beams Containing Shear Stirrups

This study aims to investigate the effect of using externally bonded carbon fiber reinforced polymer (CFRP) on the strengthening and rehabilitation of reinforced concrete (RC) T-beams reinforced with steel stirrups. Three configurations of CFRP were used: 45° inclined strips, horizontal straight strips, and U-wrapped sheets. A total of 19 specimens of strengthened and preloaded RC T-beams were experimentally tested. The experimental results were compared with the theoretical values determined according to the ACI 440.2R−17 code. The results proved that all beams containing CFRP recorded higher strength than the control sample, regardless of whether the beams were tested for strengthening or rehabilitation purposes. The horizontal straight strips of the CFRP schemes recorded the highest enhancement in the shear capacity, followed by the U-wrapped sheets and inclined strips. Moreover, the ACI 440.2R−17 code overestimated the capacities of some samples.

Bond Tests on Clay Bricks and Natural Stone Masonry Externally Bonded with FRP

Nowadays, the solution of durability problems of existing buildings has a key role in civil engineering, in which there is an ever-increasing need for building restorations. Over the past 50 years, there is a growing interest in a new composite material, fibre-reinforced polymer (FRP), suitable for increasing the resistance and the stability of existing buildings and, consequently, for extending their service life. In this context, the effectiveness of the strengthening system is related to the bond behaviour that is influenced by several parameters such as bond length, the stiffness of the reinforcement, the mechanical properties of the substrate, environmental conditions, etc. This paper aims to analyse the main experimental results from shear tests performed on two kinds of masonry substrates and different types of FRP reinforcements. The purpose is to highlight the role played by many parameters to the bond behaviour of these systems: the mechanical properties of substrates; the stiffness of reinforcements; the type of supports (i.e., unit or masonry unit). The obtained experimental results underlined that the specimens realised with masonry unit show an increase in debonding load and different stress transfer mechanisms along the bonded length with respect to the specimens with a unit substrate. The analysis of the data revealed that the presence of mortar joints cannot be neglected because it influences the interface global performance.