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.

Ultra-High-Performance Fibre Reinforced Cementitious Composite (UHPFRC) has recently been used to design lightweight structures and strengthen existing ones, with more than 300 applications in Switzerland. Several composite timber-UHPFRC bridges have been built in Switzerland, also to reduce the environmental impact of the construction. Girders are typically made of timber girders, while the deck slab is in UHPFRC. This high-performance material reduces, typically by 3, the deck weight compared to traditional reinforced-concrete slabs. Using UHPFRC also improves the durability of the timber elements as the UHPFRC deck slab remains crack-free under service conditions, meaning that the timber, located underneath the deck, remains dry and protected from direct water contact. This paper proposes a methodology to compare UHPFRC structures with traditional reinforced-concrete designs by evaluating the environmental impact and life-cycle costs over the expected bridge service duration. The first timber-UHPFRC bridge built in Switzerland is used as an example. Results show that composite structures can significantly reduce the environmental impact and costs of short-span bridge design. Timber-UHPFRC composite structures are thus promising to enhance sustainability of the construction sector, especially in the infrastructure domain. Moreover, the methodology supports bridge owners in assessing the life-cycle costs and environmental impacts of structural designs involving UHPFRC with their associated maintenance scheme, leading to better decision-making.