Deterioration Mechanism of Protective Coating Materials for Anti-corrosion in Sewage Facilities Under Long-term Service Environment

Abstract

Surface protection methods are primarily employed to mitigate sulfuric acid-induced deterioration in sewerage facilities. While laboratory-scale accelerated testing has been conducted to examine the sulfuric acid resistance of surface protective coatings, little research has been done in actual facilities, and the mechanism of sulfuric acid penetration and structural deterioration remains unclear. This study investigated the effects of surface protective coatings in actual facilities with approximately 20 years of service to shed light on the long-term deterioration mechanism. A series of analyses revealed that, in environments where sulfuric acid is present, the acid can penetrate the protective coating material and gradually deteriorate the underlying concrete. Furthermore, the pH drop caused by sulfuric acid was observed to extend beyond the neutralization depth zone, affecting the structural integrity of the hardened concrete.