Bond durability of basalt FRP bars to fiber reinforced concrete in a saline environment

This study investigates the influence of basalt fiber reinforced concrete (BFRC) on the bond durability of helically wrapped basalt fiber reinforced polymers (HWBFRP) bars subjected to harsh saline environmental conditions. A total of 63 pullout specimens were fabricated and tested. Test parameters included conditioning duration (30, 60 and 90 days), conditioning temperature (35 and 60 degrees C), and the volume fraction of basalt macrofibers (BMF) added in the concrete mixture (0, 0.5 and 1%). Moreover, scanned electron microscopy (SEM) analysis was conducted to investigate the degradation of the HWBFRP bars. Additionally, two existing analytical models, the BPE and CMR models were calibrated using the experimental results for a better prediction of the bond-slip behavior of HWBFRP bars. The service life prediction of the bond strength after 50 years of service was also performed. Experimental results revealed that the addition of BMF to concrete improved the bond performance of HWBFRP bars and showed higher retentions in the bond strength compared to plain concrete specimens after 90 days of environmental conditioning, particularly at high temperatures. Moreover, the CMR model showed better reliability than the BPE model in describing the bond-slip behavior of HWBFRP bars in both plain and fiber reinforced concrete.