Bond performance of basalt FRP bar against aggressive environment in high-strength concrete with varying bar diameter and bond length

Concrete is a porous material and prone to attacks by aggressive media such as sulphates, carbonates, and alkalisilica reactions. These aggressive media penetrate the reinforced concrete members and not only damage the concrete but also the steel reinforcement. It has been observed that the bond between the ordinary steel rebars and concrete degrades significantly over time besides reducing the mechanical properties of the rebar. As a result, the service life of concrete structures reduces significantly and adversely impacts their overall structural behavior, hence, raising safety issues that are expensive to repair. Recently, Basalt Fiber Reinforced Polymer (BFRP) bars are found to be an emerging solution that could alleviate the issue of steel reinforcement corrosion in aggressive environments. This research comprises a detailed investigation of bond strength reduction between concrete and BFRP bars through pull-out testing. Since FRP rebar's bond behavior is expected to differ from that of steel, therefore, to evaluate the bond performance of BFRP bars, the concrete specimens reinforced with BFRP bars having varying parameters, i.e., different bar diameters and development lengths, were exposed to the alkaline solution and sea water for three months. The results showed that both aggressive media triggered the bond strength reduction between the concrete and BFRP bars, however, a slightly higher bond strength retention was observed in comparison to steel rebars, i.e., 86% and 82% of bond strength retention was observed in the case of alkaline and seawater exposure, for three months respectively. The future bond strength retention for BFRP bars was lastly evaluated using the Fib bulletin model.

Automated summary

This article investigates the reduction of bond strength between concrete and BFRP bars. The results show that both alkaline solution and seawater trigger bond strength reduction between concrete and BFRP bars, with slightly higher bond strength retention compared to steel rebars.