Synergistic integration of geopolymer coatings and concrete for enhanced corrosion protection: performance and economic assessment

Abstract

This study investigates the synergistic integration of geopolymer coatings and concrete for reinforcement corrosion protection. Fe500-grade steel rebars with four surface treatments (uncoated, red oxide, geopolymer, adhesive tape) were tested in conventional and geopolymer concrete environments (3 M and 5 M alkaline activators). The 5 M geopolymer concrete exhibited superior mechanical properties (38.42 MPa compressive strength, 35.0% higher than normal concrete), while geopolymer-coated rebars demonstrated enhanced bond strength (8.7–12.7% improvement) across all concrete environments. Corrosion testing revealed geopolymer coatings provided exceptional protection with 47% reduced corrosion current, 46.9% lower corrosion rates, and 47.1% decreased mass loss compared to uncoated specimens. Time-dependent analysis showed geopolymer-coated rebars in 3 M geopolymer concrete maintained currents below 20 mA for 12 days—a 300% improvement over normal concrete. The system exhibited industry-leading corrosion current densities (0.001279012–0.002427298 µA/cm²) and extended post-depassivation times (8–15 days). Economic analysis demonstrated the 3 M geopolymer system reduced life-cycle costs by 70.7% while extending maintenance intervals from 5 to 8 to 15 years. The integration of geopolymer coatings with 3 M geopolymer concrete provides an optimal performance-cost balance for sustainable infrastructure development.