Bond Stress-Slip Models and Behavior of Aluminum Alloys-Concrete Interface

Abstract

In the last few decades, different techniques have been used for strengthening reinforced concrete (RC) structures to increase their strength and stiffness. One of these techniques involves the use of steel and fiber reinforced polymers (FRP) as externally bonded reinforcing (EBR) materials. The use of FRP and steel as EBR materials has many advantages and disadvantages. Recently developed aluminum alloys (AA) have many desirable characteristics that may overcome some of these disadvantages making them an attractive candidate as EBR materials. This research aims to examine and evaluate the use of AA as a new EBR material. Achieving a strong bond between AA and concrete is crucial to the success of AA as an EBR material. Several parameters affect the bond strength and behavior. Such parameters include concrete compressive strength, effective bond length, stiffness and surface of the EBR material, concrete surface, thickness and width of the EBR material and adhesive type. In this study the bond strength, effective bond length and bond-slip models for AA-concrete interface were determined. A comprehensive experimental investigation including 96 specimens was conducted to evaluate the bond strength and behavior using adhesive as bonding material. Concrete strength, bond length and plate type were used as variables while other parameters were kept constant. It was observed that the bond stress, loading capacity, and failure modes vary with AA surface roughness and bonded length. The load capacity and maximum bond stress increased by 254.7% and 253.7%, respectively for randomly grinded AA surface compared with those of normal AA surface indicating that AA plates with scratched surface could be used in practical applications. Moreover, AA scratched plates exhibits higher ultimate loads compared with CFRP plates. The load capacity for AA scratched plates increases by 5.6% for the short bonded length up to 22.5% for the long bonded length when compared to the CFRP plates. In addition, the bond-slip models of the AA plates were developed, with reasonable level of accuracy. Moreover, finite element (FE) models were developed for a number of tested specimens. The results of the FE modeling showed a great agreement with the corresponding experimental results.