Chloride binding capacity and binding isotherms of OPC pastes and mortars

Abstract

A method for evaluating chroride binding capacity of concrete was proposed based on the adsorption from solution and chloride binding isotherms of OPC pastes and mortars with water-cement ratio 0.4, 0.6 and 0.8. The experimental results show that the chloride binding capacity of concrete strongly depends on the content of CSH gel in the concrete, regardless of the water-cement radio and the addition of aggregate. The relationship between the bound chloride and the free chloride can be described by Freundlich isotherm at high free chloride concentrations and Langmuir isotherm at low free chloride concentrations.