Fingerprinting of a concrete mix proportion using the acid neutralisation capacity of concrete matrices

Due to the complexity of chemistry in the cement matrices, methods of identification of the concrete mix proportion have been restricted only in either binder type or water content. In this study, a new method for identifying the concrete mix proportion is developed by the acid neutralisation capacity (ANC) of concrete. The suspension of concrete was formed in still water and nitric acid to produce the variation in the pH. The molar concentration of the nitric acid ranged from 0 to 20 mol/kg. As a result, the pH of the suspension for concrete at a given concentration of the nitric acid was dramatically decreased at around 10 in the pH, depending on the aggregate content, of which characteristics was used to determine the aggregate content in a concrete mix. Simultaneously, an increase in the W/C resulted in decreased pH, of which the empirical equation was adopted to determine the W/C. The unique pattern of the ANC curve, including the peak intensity and location, and the fingerprinting spectrum were used to determine binder type in the concrete mix. As binders, OPC, 30% PFA, 60% GGBS and 10% SF were representatively used in this study.