Performance of SFRC with varying surface texture and moisture conditions in overlay concrete

This paper presents a study carried out to assess the interfacial bond strength behaviour of Steel Fibre Reinforced Concrete (SFRC) and Plain Concrete (PC) substrate. Steel wire fibre was incorporated as reinforcing agent in the Fibre Reinforced Concrete (FRC) to determine its effect on bonding strength. To better understand the bonding mechanism at the interface, overlaid prism specimens were fabricated with three moisture conditions (air dry, saturated surface dry (SSD), and wet). Five different fibre volume fractions of 0%, 0.5%, 1.0%, 1.5%, and 2.0% were prepared and used as the overlay concrete on three different surface textures (As Cast surface, Grooved surface, and Wire brush surface). It was observed that the bond strength of the FRC samples at all moisture conditions is higher than that of the control specimens. The bond strength of FRC with 1% fibre volume was observed to have consequently improved. This improvement is influenced through grooved surface texture at SSD moisture condition of the old concrete surface. Steel fibre of 1.0% produced sample with the highest interfacial bond strength of 15.19N/mm2 . It was observed that, the bond strength of FRC was more than the control specimen. Based on American Concrete Institute (ACI) Concrete Repair Guideline, the roughened surface textures used in this study were able to meet the minimum bond strength it specified. Considering all inferences and appraisals from this research, 1% steel FRC, grooved surface treatment type and SSD surface condition are recommended in the production of retrofitting/repair concretes with the sole aim of achieving an enhanced interfacial shear bond strength.