Development of Anti-Moss and Anti-Fungal Coatings to Enhance Concrete Durability under Tropical Environmental Conditions

Biological colonization by moss and fungi poses a significant durability challenge for concrete structures in tropical regions, where high humidity and frequent rainfall promote moisture retention and surface deterioration. This study develops and evaluates a solvent-based anti-moss and antifungal coating formulated with Special Boiling Point solvent, Mineral Turpentine, Pegasol 150, and siloxane to enhance the durability-related performance of concrete. Concrete specimens were coated after 28 days of standard curing and assessed through water spray penetration, water absorption, rapid chloride permeability testing (RCPT), microstructural characterization (SEM), phase and chemical analysis (XRD and FTIR), and one-year outdoor exposure under tropical conditions. The water spray test identified the formulation containing 7% siloxane as optimal, exhibiting complete water beading and minimal surface absorption. The coated concrete showed a denser surface morphology with reduced pore presence compared to the control, as observed by SEM. RCPT results demonstrated a 28.6% reduction in total charge passed, from 2100 Coulombs to 1500 Coulombs, corresponding to an improvement in chloride permeability classification from moderate to low. After 12 months of outdoor exposure, the coated specimens remained free of visible moss and fungal growth, whereas uncoated concrete developed pronounced biological colonization. The effectiveness of the coating is attributed to its ability to restrict moisture and ion transport through the concrete surface, thereby limiting mechanisms associated with biological growth and surface degradation. The results indicate that the developed coating provides a practical and durability-oriented protection strategy for concrete infrastructure exposed to humid and tropical environments.