Ultra-High-Performance Fibre-Reinforced Concrete for Rehabilitation and Strengthening of Concrete Structures: A Suitability Assessment

Abstract

Ultra-high-performance fibre-reinforced concrete (UHPFRC) is a cementitious composite which contains fibres. UHPFRC has emerged as an effective structural retrofitting material due to its superior mechanical properties. In addition, UHPFRC has outstanding durability, ductility and workability; a low permeability; and a high abrasion and fire resistance. These improved characteristics of UHPFRC are obtained by reducing the content of free water in the concrete matrix (leading to less air voids), introducing high strength ductile steel fibres, replacing coarse aggregates with well graded fine aggregates and introducing highly active pozzolanic materials. UHPFRC has excellent bonding with normal strength concrete and it eliminates the issue of debonding which is common in other retrofitting techniques employing fibre-reinforced polymers or externally bonded steel plates. Therefore, considering various aspects, UHPFRC-based structural retrofitting possesses a number of advantages. This paper presents a review of previous studies employing UHPFRC for structural retrofitting applications, highlighting its advantages, limitations and challenges. Aspects of flexural strengthening, combined axial and flexural strengthening, shear strengthening, impact resistance and torsional strengthening are considered for this review. Altogether, the paper aims to enhance the awareness of UHPFRC for structural retrofitting as a step forward towards effective field applications and to outline the potential future directions of research.