Design, Characterization, and Performance of Reinforced Waterproof Gradient Coating for Steel Bridge Decks

Addressing the issues of insufficient flexibility, high construction energy consumption, and susceptibility to interface failure in traditional waterproof bonding layers, a gradient coating system that integrates bonding and waterproofing functions was proposed. Organic silicon modified acrylic copolymers (MBMS1–MBMS3) were synthesized by a solution polymerization method and blended with high-adhesion epoxy resin E51 in proportion to achieve controllable phase separation and form a gradient structure. The chemical composition, thermal properties, phase separation behavior, and road performance were analyzed by various techniques. The characterization results indicated that the MBMS2/E51 exhibited optimal performance, with a tensile strength of 6.5 MPa and a fracture elongation of 97.5%. At the optimal spray density of 2.4 kg/m2, the bonding strength between the coating and the steel bridge deck reached 6.5 MPa. Accelerated durability tests confirmed robust performance, with tensile strength and elongation retention rates maintained above 85% and 78%, respectively. This study validates the effectiveness of gradient coatings as a multifunctional solution for steel bridge deck waterproofing, addressing critical challenges in interlayer adhesion and durability.