Concrete structures are responsible for a substantial share of the total global CO2 emissions. This has led to the establishment of the Betonakkoord in the Netherlands, which aims to significantly reduce the emissions from concrete structures.

Reinforcement bars made from Basalt Fibre Reinforced Polymer (BFRP) offer a potential solution for making concrete structures more sustainable. Firstly, the Environmental Cost Indicator (ECI) of BFRP rebar is 43% lower than that of steel rebar. Additionally, BFRP does not corrode, which eliminates the requirement for a thick concrete cover to meet environmental class standards. Consequently, the use of BFRP reinforcement instead of steel could potentially reduce the amount of concrete needed, further enhancing the sustainability of concrete structures.

This study investigates the feasibility of enhancing the sustainability of a bridge deck in an inverted T-girder bridge by using BFRP rebars. BFRP differs from steel in several material properties. Although its strength, at approximately 1200 N/mm², is significantly higher than that of B500B steel, the much lower E-modulus of BFRP presents challenges. Additionally, BFRP behaves in a fully linearly elastic manner until failure in the absence of a yield plateau. The lower stiffness results in higher deformations and crack widths. The hypothesis is that this could potentially be problematic for shear capacity, as the concrete compression zone is reduced, aggregate interlock decreases, and dowel action is less effective due to the low transverse strength of the rebar.

In this study, various design variants for a bridge deck in an inverted T-girder bridge were modeled to assess the impact of different design parameters. A reference design variant with steel reinforcement was used as a baseline and compared with several variants incorporating BFRP rebars. The BFRP design variants differed in terms of reinforcement quantity, concrete cover, and effective depth.

A quasi-linear model of an inverted T-girder bridge was developed using the numerical software SCIA Engineer. The bridge deck design alternatives were modeled as an orthotropic plate with centroidal ribs. The numerical model clearly demonstrated that, due to the less stiff nature of the BFRP-reinforced bridge decks, there is less distribution of traffic loads compared to relatively stiff steel-reinforced bridge deck. Ultimately, the model showed that shear force is indeed the critical failure mechanism for BFRP-reinforced bridge decks. Reducing the effective depth of the BFRP reinforced bridge deck variants, decreases the shear force distribution in transverse direction by 5% and further decreases the shear capacity by 23% to 30%, depending on the adjusted parameters for each design variant.
The application of BFRP rebar in a bridge deck and the reduction of concrete cover to 25 mm, instead of the usual 50 mm used with steel reinforcement, is shown to be feasible in this study. An optimization was conducted to develop a bridge deck design, that meets the structural performance criteria of shear force while minimizing concrete usage. This resulted in an optimized design with a bridge deck height of 215 mm, compared to the conventional 250 mm.

A sustainability study based on the LCA cradle-to-gate life cycle phases (A1-A3) has demonstrated that BFRP reinforcement can significantly enhance the sustainability of a bridge deck. For the optimized design variant that meets all the structural requirements, the ECI reductions range from 27% to as much as 32%, depending on the cement type used in the concrete mixture. This study has shown that the application of BFRP rebars in a concrete bridge deck is certainly feasible and results in significant sustainability improvements.