Synergistic integration of geopolymer coatings and concrete for enhanced corrosion protection: performance and economic assessment
Chava Venkatesh, T. Muralidhara Rao, Takkellapati Sujatha, Chereddy Sonali Sri Durga, Ramamohana Reddy Bellum, Meseret Getnet Meharie, Bypaneni Krishna Chaitanya
Abstract
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.