Formulation of an equation for surface chloride content of concrete due to permeation of chloride.

Establishment of a diagnosing technology for the deterioration of reinforced concrete structures due to salt contamination is urgent, but few analytical methods based on measured data obtained from concrete structures have been presented so far. Chloride penetration into concrete from sea water is generally understood and analysed as diffusion of chloride ions. This paper presents a new method of predicting chloride penetration into concrete based on diffusion theory. From chloride concentration data of concrete structures, boundary conditions for diffusion equation are assumed to be a linear function of the square root of the age of the structure concerned. The constant coefficient for the linear function is assumed according to the environment of the structure. From the diffusion coefficient obtained from actual structures and the time dependent constant coefficient mentioned above, chloride concentration and initiation time of corrosion are predicted. (A)