Behavior of High-Performance Pull - out Bond Strength of Fibers Reinforced Concrete Structures

The influence of steel fibers in bond strength attributes of fiber reinforced concrete is examined in this research. Concrete specimens with fiber contents of 0%, 1.0%, 2.0% and 2.5% by volume were tested. Thirty pull-out bond half-cylinder concrete mixes were prepared in order to examine the discrepancy in bond resistance owing to the disparity in percentage volume of steel fibers and the aspect ratio of the fibers. Each of the 30 half-cylinders were comprised of two matching half-cylinders; one with steel-fiber reinforced concrete containing different volumes of fibers with various aspect ratios and one containing plain concrete using reinforcement by placing a medium tensile steel bar in the center. Employing fiber-reinforced concrete instead of plain concrete showed a tangible increase in the interfacial force at the surface of the steel bar. The influence of steel fibers in augmenting the interfacial forces is assessed in percentage increase over plain concrete. A thorough experimental scheme has confirmed the proposed method using several variations of steel-fiber reinforced concrete samples

Assessment of the Strength of Remixed Concrete Structures

This work presents an experimental investigation to study the effect of remixing on the strength of concrete. The compressive strength, the splitting tensile strength, the shear strength as well as the flexural strength for 6 different concrete mixes have been measured. The results of investigation showed that the strength of concrete may be improved by remixing, provided that the time between remixing and casting does not exceed 0.7 the initial setting time of cement. Further improvement is achieved when remixing is associated with adding fresh concrete. The results showed that the improvement in strength can be as high as 20%. The improvement in strength was found to be affected by the blend ratio