Bar surface treatment effect on the bond-slip behavior and mechanism of basalt FRP bars embedded in concrete

Abstract

This study aims to explore the bond-slip behavior of BFRP bars. A series of standard pull out tests was conducted in order to examine the bond behavior of BFRP bars with 4 different surface treatments (smooth, wounded, wrapped, and sand-coated) compared to deformed steel bars. The investigated parameters included the bar diameter, the concrete compressive strength, in addition to the surface treatment of the bar. The results showed the significant effect of the bar surface treatment on the bond behavior of BFRP bars. Different surface treatments resulted in different failure mechanisms and behavior. Sand coating BFRP bars showed its advantage in enhancing the bond stiffness while wounding BFRP bars was proved to be very effective in increasing the bond strength. In addition, the bond behavior of BFRP bars can be represented using BPE bond-slip model. Increasing concrete compressive strength caused an increase in the bond strength with a minor effect on other bond-slip behavior characteristics. Bond specimens reinforced by bars with different bar diameters exhibited different failure modes. The bond-slip relationship of wounded BFRP bars is strongly dependent on the geometry of the bar surface profile. Moreover, the geometric details of the bar rib spacing, width, and height can be utilized to produce bars with desirable bond-slip features.