DETERIORATION OF REINFORCED CONCRETE STRUCTURES DUE TO CHLORIDE EXPOSURE IN WATER: A CASE STUDY, THAILAND

Abstract

Saline soils in Northeast Thailand, particularly in Nakhon Ratchasima Province, significantly threaten the durability of reinforced concrete structures. Chloride infiltration from these soils accelerates steel corrosion, shortening the service life of concrete. This study investigates the penetration of chloride into concrete in saline areas and examines the oxidation states of iron when exposed to varying chloride levels. Using X-ray Absorption Spectroscopy (XAS), the research analyzes changes in iron phases before and after exposure to brine. Concrete samples were immersed in chloride solutions simulating local conditions in Nakhon Ratchasima, aiming to calculate the chloride diffusion coefficient and predict concrete deterioration. The findings will assist in selecting appropriate cement types to enhance durability in saline environments and guide efforts to mitigate reinforced concrete corrosion in the region.The study also examines chloride penetration in reinforced concrete immersed in chloride solutions for 30, 60, and 90 days at different chloride concentrations. Chloride levels were measured at depths of 2, 4, and 6 cm from the concrete surface, following ASTM C1152 standards. Results show the highest chloride concentration near the surface, decreasing with depth, and that prolonged exposure increases chloride infiltration. Microstructural analysis using Scanning Electron Microscopy (SEM) revealed voids and perforations caused by chloride corrosion, altering the concrete's crystalline structure. XAS analysis of deformed bar samples identified iron oxides such as FeO(OH) and Fe₂O₃, which are crucial in the corrosion process. The study emphasizes that chloride concentrations above 30% in saline environments significantly accelerate reinforced concrete corrosion, affecting the durability and service life of these structures.