Use of Steel Fibres in Bridge Decks to Improve Serviceability and Reduce Top Mat Reinforcement Requirements

Abstract

This study examined a practical strategy to enhance the long-term performance of bridge deck slabs, which are highly susceptible to deterioration due to corrosion of conventional steel reinforcement. While glass fibre reinforced polymer (GFRP) bars offer corrosion resistance, their low stiffness often necessitates increased reinforcement ratios to meet serviceability requirements, diminishing their economic and practical benefits. To address this limitation, the study investigated the use of steel fibre reinforced concrete (SFRC) with steel macrofibres to improve service performance and reduce top mat reinforcement demands. The research program integrated concrete mixture development, material characterization, and large-scale structural testing. Practical SFRC mixtures were developed to evaluate material properties including workability, compressive strength and direct tensile response to support mixture selection for structural testing. Six large-scale one-way bridge deck slab strip specimens were tested to failure, simulating deck overhang behaviour. The test variables included GFRP reinforcement ratios of 0.6% and 0.8% and steel fibre volume fractions of zero, 0.5%, and 1.0%. A conventionally steel reinforced slab without fibres served as a control. The results demonstrated that the incorporation of steel fibres significantly improved crack control, stiffness, and flexural capacity in GFRP reinforced slabs. Fibre reinforced specimens exhibited service and strength performance comparable to or exceeding that of the steel-reinforced control slab, with improvements increasing with fibre dosage. Notably, comparable serviceability was achieved even with reduced flexural reinforcement when steel fibres were present. Collectively, the findings indicated that SFRC can effectively mitigate the serviceability limitations of GFRP reinforcement enabling more durable, efficient, and lower maintenance bridge deck construction.