The use of ultra high performance fiber reinforced concretes (UHPFRCs) is spreading rapidly. Their outstanding mechanical and durability properties and castability enable very innovative and efficient structural and architectural applications. Both prefabrication and cast-on-site applications are now well established, for new structures as well as for the rehabilitation and reinforcement of existing ones. This book sets out the basis and provides a state-of-the-art review of the mechanical and physical properties of UHPFRCs and measurement methods. It highlights the differences between the various UHPFRCs available worldwide, giving guidance on the design of sustainable mixes which make ample use of supplementary cementing materials and local components. The environmental assessment of construction systems using UHPFRC is also examined.