Advanced analysis of published data on chloride binding in concrete

Chloride attack is a major cause of deterioration of reinforced and prestressed concrete structures. Chloride contamination can occur from the application of de-icing salts, from cast-in chlorides or from sea water as in marine structures. It has been found that chlorides are chemically bound mainly by tricalciumchloro-aluminate (C₃A) or Friedel's salt in cement. Chloride binding becomes of particular interest when a critical limit of chlorides in concrete for the initiation of corrosion is to be defined or for diffusion and migration processes of ions in concrete. Traditionally chloride binding is described using Boltzmann, Langmuir or other analytical reaction types. This paper is a survey of existing data on chloride binding in concrete. Attempts to employ empirical data to elucidate chloride binding in concrete are rare and never before have many sources been analysed. Using the data from over 20 different sources an empirical term was derived, which describes chloride binding in terms of total chloride content (TCL) and C₃A content (C₃A). Chloride binding in concrete is described through C₃A and TCL, therefore the term is applicable to any concrete.