The competitiveness of weathering steel-concrete composite bridges in the Dutch market

Abstract

In the coming decades, Rijkswaterstaat faces the challenge of replacing and renovating a large number of Dutch highway bridges built in the 1950’s and 1960’s. These structures must be renewed in a sustainable, cost-efficient manner while minimizing traffic disruption. The objective is to retain the existing substructure and replace only the superstructure of the bridges, which are in need of replacement. This study investigates the competitiveness of weathering steel concrete composite bridges in the Netherlands, for small-span bridges (15–30 m). Hereby the following bridge variants will be considered for determining the competitiveness:

Variant 1: Existing full reinforced concrete superstructure
Variant 2: conventional painted steel–concrete composite superstructure
Variant 3 : weathering steel–concrete composite superstructure

The research is structured into four phases: (1) a literature review on material behavior, corrosion performance, and durability of unpainted weathering steel under Dutch environmental conditions; (2) structural verification using a real bridge case study to assess Eurocode compliance; (3) a sustainability assessment using Life Cycle Assessment (LCA) and Environmental Cost Indicator (MKI) values for life-cycle stages A1–A5; and (4) an economic evaluation of construction, maintenance, and lifecycle costs.
The literature review highlighted that weathering steel offers substantial maintenance and sustainability advantages but faces environmental constraints in the Netherlands due to high humidity (≥76%) and frequent de-icing salt exposure. The standard Dutch vertical clearance of approximately 4.5 m is below the 6.1 m recommended in international guidelines (ASTM and ECCS) to prevent chloride spray contamination. Effective use of weathering steel thus requires sacrificial thicknesses, optimized detailing, and preventive maintenance to ensure long-term durability. Mechanically, weathering steel behaves comparably to conventional painted steel.
Structural verifications confirmed that variant 2 and variant 3 satisfy Eurocode requirements for bending moment, shear force, and deflection, considering different configurations of the superstructure. Accounting for a 1 mm sacrificial thickness in weathering steel reduces bending moment resistance by 3.5–6%, a small but measurable effect.
The sustainability assessment showed that Variant 3 achieved the lowest environmental impact for A1–A5 stages. The use of low-carbon XCarb® steel reduced total MKI by 50–55% compared to conventional NMD steel in Variant 2, and the elimination of paint provided an additional ~9% reduction. Variant 2 performed better than Variant 1, but worse than Variant 3, while Variant 1 (full concrete) had the highest MKI.
Life-cycle cost analysis indicated up to 30% savings over 100 years for Variant 3 compared to variant 2, mainly due to reduced maintenance and minimized traffic disruptions. Structural mass comparisons showed that Variants 2 and 3 are 53–56% lighter than Variant 1, reducing loads on existing abutments and facilitating replacement while preserving substructures.
Overall, weathering steel–concrete composite bridges are technically feasible, sustainable advantageous, and economically competitive for small-span superstructure replacement in the Netherlands. These findings support the potential of integrating weathering steel into Rijkswaterstaat’s sustainable bridge renewal strategy, offering a robust pathway toward low-maintenance, low-impact, and long-lasting infrastructure.