Bridges, as a core component of transportation infrastructure, are not only physical hubs connecting geographical spaces but also vital carriers supporting economic development, promoting social integration, and ensuring smooth traffic flow for people's livelihoods.

With continuously increasing traffic volume and an increasingly urgent need for the reconstruction and expansion of existing bridges, bridge splicing technology has become a key means of expanding traffic capacity, and bridge splicing adhesive is the core material for ensuring the safety and reliability of the spliced structure.

Segment construction of newly constructed bridges is a core construction method in the construction of large bridges (especially continuous box girder bridges). By precisely prefabricated segments into a complete structure, the spanning capacity and overall stress performance of the bridge can be optimized. Its core objective is to ensure seamless connection and coordinated stress distribution between segments, thereby ensuring the smoothness of the bridge deck and structural safety.

The process must be strictly carried out in the following logical sequence: "acceptance and cleaning of precast segments—positioning and fixing of the first segment—trial assembly and precise positioning of subsequent segments—connection of internal and external steel reinforcement in the box girder—formwork erection (including internal formwork)—application of segmental bridge adhesive—construction of splicing materials—gradual application of prestress."

Bridge segmental adhesive: a "key link" in structural connections.

In precast segmental bridges, the segmental bridge adhesive is the core material for achieving bonding and sealing between segments and stress transfer. Its performance directly determines the durability and safety of the spliced structure. High-quality segmental adhesive must possess three core advantages: mechanical properties, construction adaptability, and durability, making it an indispensable "industrial adhesive" in bridge segmental construction projects.

(I) The Core Functions of the Segmental Bridge Adhesive: Multiple Functions Ensuring Structural Stability

The role of the joint adhesive goes far beyond simple "adhesion," encompassing four core functions: bonding and sealing, lubrication and positioning, stress transfer, and waterproofing and corrosion prevention.

Firstly, its bonding and sealing function ensures a tight fit between precast segments, effectively transferring shear force and part of the bending moment, achieving coordinated structural stress distribution.

Secondly, its viscous state before curing provides lubrication, compensating for slight deviations in the segment shear keys and facilitating assembly and positioning.

Thirdly, by filling the pores on the concrete surface with pre-pressure, it forms a "rivet-like" effect after curing, enhancing structural resistance.

Fourthly, it fills the gaps in the joints, preventing moisture penetration, preventing corrosion of prestressed cables, and ensuring the long-term waterproof performance of the bridge.

(II) Core Performance Requirements of the Segmental Bridge Adhesive: Adaptability to the Harsh Environment of Bridge Engineering

Bridges endure complex loads from vehicles, temperature variations, and weathering over extended periods, placing extremely high demands on the performance of the joint adhesive. From a mechanical performance perspective, it must possess high strength, high elastic modulus, and low creep characteristics to ensure it can withstand various loads during bridge operation and resist deformation over long-term use. Simultaneously, it must exhibit high thixotropy, be a paste-like consistency, easy to mix and apply, and not drip or sag at high temperatures, ensuring stability during construction.

From an adhesion performance perspective, it must possess extremely strong wetting and bonding capabilities with concrete, achieving cohesive failure within the concrete (i.e., failure occurs within the concrete rather than at the adhesive interface), ensuring reliable bonding. From a durability perspective, it must possess excellent waterproof, corrosion-resistant, fatigue-resistant, and aging-resistant properties. Modified epoxy resins optimize the molecular structure to prevent moisture penetration and damage to the bonding interface, meeting the 50-year design life requirement of bridges.

In addition, construction adaptability is also crucial: it needs to have a reasonable workable time (generally 40~120 minutes) and a bonding time (≥60 minutes) to ensure that the processes of applying adhesive, positioning, and applying prestress are completed in an orderly manner; at the same time, it should be able to adapt to damp surfaces and low-temperature construction environments to reduce the impact of weather on construction.

The application of segmental construction technology for new bridges has significantly improved the construction efficiency and quality of large bridges, providing an efficient and feasible solution for the construction of long-span, complex-structure bridges. In the future, with continuous innovation in materials technology and construction processes, segmental splicing engineering for new bridges will become even more efficient and reliable, providing stronger support for the high-quality development of transportation infrastructure.