An image‐based non‐destructive technique for condition assessment of concrete exposed to chemical attacks using chromaticity analysis

Abstract Durability is a crucial concern for the long‐term maintenance of reinforced concrete structures, which are often expensive to repair and must account for environmental damage and safety risks. Challenges in accessibility and the subjective nature of visual inspections can result in inaccurate damage assessments. Identification and quantification of the extent of deterioration can be achieved using digital image processing methods. In the current study, image analysis is performed on concrete cube samples of M25 and M50 grades of concrete cast and cured in water for 7, 28, 56 and 90 days then exposed to acid (hydrochloric acid, sulphuric acid), chloride (sodium chloride) and sulphate (magnesium sulphate) at 5% concentration exposed for a period of 7, 28, 56 and 90 days. The surface images are captured using a digital single‐lens reflex camera then analysis is performed in the CIE‐XY colour plane. The colour profiles of deteriorated surfaces are analysed in CIE‐XY colour space and the respective chromaticity diagrams are investigated. The study concludes that the colour profile changes in samples immersed in hydrochloric acid and sodium chloride are like those observed in samples exposed to sulphuric acid and magnesium sulphate. Key properties, such as loss factor based on the mass loss factor, strength loss factor, attacking factor and durability loss factor, are determined. The greatest strength loss occurs with hydrochloric acid exposure, and the acid durability loss factor increases linearly with prolonged exposure to sulphuric acid. Thus, sulphuric acid has the most severe effect, followed by hydrochloric acid, while sodium chloride and magnesium sulphate have the least impact on the strength and durability of both M25 and M50 concrete.