Search Results (3)

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. Full article

Ultra-High-Performance Fibre-Reinforced Cementitious Composite (UHPFRC) has been developed to design lightweight structures and enhance existing designs. As the environmental footprint of the construction industry must be significantly reduced, the potential to lower environmental impacts of structures using UHPFRC needs to be explored. While the greenhouse gas emissions of a volume of UHPFRC are higher than that of the same volume of concrete, UHPFRC enables the reduction in the amount of material required in structural designs and improves the durability of structures. The environmental impacts of structural designs must thus be compared on the cradle-to-grave use cycle of the design at a project scale. In this study, a methodology is proposed to evaluate the ecological burdens of several bridge designs involving various structural elements in UHPFRC. The method proposes an analysis over three time horizons: first, the construction phase, then including the scheduled maintenance, and finally, adding the elimination. A case study of a short-span bridge in Switzerland is used to assess three alternatives of bridge designs: a conventional reinforced-concrete structure, a composite timber–UHPFRC bridge, and a full-UHPFRC solution. The results show that timber–UHPFRC structures can significantly reduce the environmental impacts of bridge designs, showing promising results in terms of sustainable development. The use of the methodology supports bridge owners in assessing the environmental impacts of structural designs. Full article

This paper provides an overview of the use of the magnetic NDT method for estimating the fibre content, and fibre orientation and efficiency factors in thin UHPFRC elements/layers, along any two orthogonal directions. These parameters are of utmost importance for predicting the post-cracking tensile strength in the directions of interest. After establishing meaningful correlations at the lab-specimen scale, this NDT method can be effectively implemented into quality control protocols at the industrial production scale. The current study critically addresses the influence of key factors associated with using this NDT method in practice and provides recommendations for its efficient implementation. Full article