Ultra-high-performance concrete (UHPC) is a form of cementitious composite that has been the most innovative product in concrete technology over the last three decades. Ultra-high-performance concrete has been broadly employed for the design of numerous forms of construction owing to its excellent mechanical characteristics and durability, and studies on its behavior have grown fast in the last decades. While the utilization of ultra-high-performance concrete in bridge engineering (BE) is limited owing to its high costs, little is recognized about the utilization of UHPC in various BE elements. As a result of these issues, a comprehensive review of the current UHPC development trends should be conducted to determine its present state and perspective. This study presents a review of the state-of-the-art UHPC applications in BE. This review also discusses the current status, limitations, challenges, and areas for the further investigation of UHPC in BE. The aim of this research to help various construction stakeholders understand the distinctive characteristics, benefits, and barriers to the broad utilization of ultra-high-performance concrete applications. The understanding of UHPC will aid in increasing its entire market share in both the national and worldwide building sectors.

The goal of this research is to identify the impact of microsilica and polypropylene fibers (PF) on the mechanical characteristics of an ultra-high performance geopolymer concrete (UHP-GPC). The workability, compressive strength, modulus of elasticity, and splitting tensile strength of a total of 20 concrete mixtures were evaluated experimentally. To produce the mixtures, PF was utilized at four different volume fractions: 0%, 0.75%, 1.75%, and 2.75%. Moreover, five microsilica levels were employed in terms of the total mass of the binder: 0%, 7.5%, 15%, 25%, and 35%. The findings showed that when 15% microsilica was added to UHP-GPC, the mechanical characteristics were significantly degraded, but then enhanced when more than 15% microsilica was added. Furthermore, PF contributes significantly to the mechanical characteristics of UHP-GPC and introducing 2.75% PF minimizes a significant drop in the characteristics of UHP-GPC when 15% microsilica is employed. ‎