Influence of data acquisition and processing on surface chloride concentration of marine concrete

•Data acquisition and processing on chloride profile of marine concrete was studied.•Method of measurement affects the fitting of surface chloride concentration (Cs).•Selection of convection zone thickness alters the result of fitting of Cs.•The applicability of time-dependent Cs models of various function types were analyzed. The apparent surface chloride concentration (Cs) of marine concrete is a key parameter in durability design. Based on data in the literature, this study aims to analyze the influences of data acquisition and processing to Cs, including measurement methods of chloride concentration in concrete powder samples, the processing strategy for the thickness of convection zone (Δx), and effect of the exposure duration of concrete. The influence of function types on the time-dependent Cs models was discussed. The results indicate that: using total or free chloride concentrations in marine concrete for chloride concentration profile plotting could affect Cs, though it does not significantly affect the apparent chloride diffusion coefficient (Da). It is more rational to take the half thickness of concrete core slice, rather than the full thickness, as the initial point of chloride concentration curve. The evaluation strategy of the Δx have significant impact to the Cs and Da for chloride concentration curve with unobvious maximum chloride concentration. Exposure duration of marine concrete determines the function type of the time-dependent Cs model and the beginning time of the stable period of Cs according to 481 datasets from field tests. The time-dependent Cs model developed based on short-term Cs datasets should only be used to for short-term prediction, while more long-term data are needed to develop and testify reliable models for predictions of Cs and service life.