Calibration of a bond law for sand-coated BFRP

Abstract Within the scope of this paper, the bond behaviour of reinforcement made of basalt fibre reinforced polymers (BFRP) with a helically wrapped and sand coated surface is investigated in an experimental test program to evaluate the bond stress - slip relationship. Due to the strongly varying surface condition and material properties, the bond behaviour is expected to be very different compared to the conventional ribbed steel reinforcement. Therefore, the standard vertical pull-out test specimen will be adjusted according to the described bond length. Based on the obtained experimental results, a bond law for the non-linear increasing branch of the bond stress - slip relationship will be formulated and calibrated for the investigated reinforcement type. The goal of this research program is to use this precise bond law to adjust the analytical model for the calculation of crack spacing and crack width. This adjustment can be made by merging the bond law with the analytical model of bond and slip to obtain a more reliable crack width design for reinforcement types with varying bond properties.