The emergence of innovative construction materials is dawning a new era of ambition within the civil engineering community. Among these innovative materials, Basalt Fibre Reinforced Polymer (BFRP) has recently surfaced with promising potential as a reinforcing material in concrete. Currently, in the Dutch concrete construction industry, the choice for reinforcement steel has remained unchanged for the past decades. However, the increasing availability of innovative alternatives could help the transition to a more sustainable concrete industry. Although BFRP has promising potential for application in concrete structures, the global application has not been established yet. One of the reasons for this limited research into the structural behaviour of concrete structures reinforced with BFRP-bars. Furthermore, the limited development of codes specifically designed for concrete reinforced with BFRP-bars and the modest availability compared to reinforcement steel also play into the unknowns about the material.

BFRP-bars contain certain qualities that reinforcement steel does not. One of the most prominent is resistance against corrosion due to environmental influences on concrete structures. This eliminates the requirement for the concrete cover to protect the reinforcement from corrosion. Hence, the concrete cover only serves its purpose to ensure effective bond action between the reinforcement bars and the concrete. This inherent quality of BFRP-bars eases the crack width control requirements in the codes for the design of structures reinforced with BFRP-bars to a range of 0.5 mm to 0.7 mm. Although this is a significant increase in comparison to the Eurocode for concrete structures (0.2 mm to 0.4 mm), the properties of BFRP-bars cause larger crack width development.

The aim of the experiment is to investigate the flexural behaviour of concrete beams reinforced with BFRP-bars as tensile reinforcement. The flexural behaviour of concrete structures reinforced with BFRP-bars is studied both experimentally and numerically. The research program contains 6 beams differing in reinforcement material, concrete covers, reinforcement ratio and bar diameters. To investigate the effects of the concrete cover, 2 beams are designed with concrete covers of 31 mm and 11 mm containing 3 BFRP-bars with a diameter of 8 mm in
the tension zone. To compare the behaviour of these beams, 2 identical beams with reinforcement steel are designed. To determine the effects of the reinforcement bar diameter, 1 beam is designed with 2 bars with a diameter of 10 mm. The reinforcement ratio in beams remains approximately equal, hence the only changing parameter is the bar diameter. The effects reinforcement ratio is investigated by a beam designed with 2 bars with a diameter of 8 mm. By keeping the bar diameter and the concrete cover the same, the reinforcement ratio is the only changing parameter for this beam. By subjecting the beams to a 4-point bending test, a fully developed crack pattern can be established over a certain length. By using digital image correlation (DIC), the flexural behaviour is monitored and analysed. This includes both crack width development and overall pattern forming. The results are verified with linear variable differential transformers (LVDT‘s) and a laser measuring vertical displacements. This procedure is devised to evaluate the stiffness behaviour of the beams as well as the cracking behaviours. In addition, the experimental program includes a series of direct tensile tests with reinforcement bars to determine the stress-strain behaviour of the reinforcement bars themselves...

This thesis investigates the potential of Basalt Fibre-Reinforced Polymer (BFRP) as an alternative to traditional steel reinforcement in concrete structures, with a focus on enhancing shear capacity. BFRP offers advantages such as higher tensile strength, superior corrosion resistance, and environmental sustainability. The study compares two alternative BFRP stirrup designs—braided BFRP rods and laminated unidirectional (UD) BFRP strips—with traditional steel stirrups through uniaxial tensile testing and displacement-controlled three-point bending tests on reinforced concrete beams. The results show that while BFRP stirrups improve the shear capacity of concrete beams, they do not yet match the performance of steel stirrups due to issues like reduced stiffness and stress concentrations in corner sections. However, BFRP stirrups demonstrated potential advantages in terms of weight efficiency, suggesting a promising role in sustainable construction. The findings underscore the need for further refinement in BFRP production methods to achieve consistent quality and better performance in structural applications.