Experimental Study on the Bond Performance of Steel-Basalt Fiber Composite Bars in Concrete

Steel-basalt fiber composite bars (SBFCBs) exhibit excellent strength, elastic modulus, toughness, corrosion resistance, and low cost. Understanding the bond performance between SBFCBs and concrete is important for evaluating the mechanical behavior of SBFCB-reinforced concrete structures. In this study, the bond-slip performance of SBFCB in concrete was experimentally assessed via pullout and beam bond tests. The influence of various factors on the bond performance was discussed, and the bond mechanism between SBFCB and concrete was analyzed. The results indicate that reducing the thread pitch ratio in the SBFCB can reduce slippage at the postpeak bonding stress-slip curve. The bond strength of the SBFCB was significantly improved by sandblasting. Longer bond lengths correspond to smaller average bond strengths in SBFCB. The load corresponding to the maximum bond strength of a specimen with a bond length of 10d was determined as the ultimate load value for the SBFCB. An increase in the SBFCB diameter had a negative impact on the bond strength. Moreover, an increase in the concrete cover thickness was conducive to improving the bond strength; if the thickness of the concrete cover was sufficiently increased, failure occurred owing to SBFCB tension rather than bonding. Based on the test results and the existing bond-slip model, a simple bond-slip constitutive model of the SBFCB embedded in concrete was proposed to simulate the pullout process of the SBFCB. Subsequently, the established bond-slip model can be used to analyze the mechanical performance of SBFCB-reinforced concrete structures.