Chloride, ingress into concrete

R. B. Polder, Simulated de-icing salt exposure of blended cement concrete - chloride penetration , Proc. 2nd International RILEM Workshop Testing and Modelling the Chloride Ingress into Concrete, C. Andrade,... 

Redistribution of chloride in blended cement concrete during storage in various climates , 3rd RILEM Int. Workshop Testing and Modelling Chloride Ingress into Concrete, Madrid, 9-10 September 2002, to be published. 

L. Bertolini, M. Gastaldi, M. Carsana, M. Berra, "Gomparison of resistance to chloride penetration of concretes and mortars for repair , 3 Rilem Workshop Testing and Modelling Chloride ingress into Concrete,... 

Rilem Workshop Testing and Modelling the Chloride Ingress into Concrete,... 

Chloride ingress into concrete follows Pick s second law of diffusion, forming a chloride profile with depth into the concrete ... 

The chloride ingress into concrete follows Pick s law of difiusion for cured concretes. Concrete mixtures and admixtures affect the diffusivity of chloride ions. Figure 12.7 shows the transport of chloride ions through the concrete deck under moderate corrosion environment. The surface chloride concentration is assumed to be equal to 3.56 kg/m, which corresponds to moderate corrosive conditions. Chloride diffusion follows an exponential decay into the concrete. Chloride concentration at the rebar surface increases with time. 

L. Pel, K. Kopinga, H.P. Huinink and E.F. Kaasschieter, RILEM Proc., 2000, PRO 19(Second International RILEM Workshop on Testing and Modelling the Chloride Ingress into Concrete, 2000), 211. 

Hydrophobic surface treatments, based mainly on silanes or siloxanes, are applied in order to reduce water (and chloride) ingress into concrete. The success of the treatment depends on the concrete moisture and on the quantity applied to ensure formation of a continuous water repellent layer in the pore system and on the surface tension in order to ensure a penetration of at least 2 mm (Polder, 1996). Hydrophobic treatments cannot protect concrete in permanently wet conditions. 

A sacrificial or consumed anode can be used instead of coated titanium. Copper was tried in the early 1970s trials but copper (or its salt,s) may accelerate corrosion if it gets into concrete. Steel mesh has been used more recently but has fallen out of favour as it may be completely consumed in some areas before the treatment process is over. It also causes rust staining, although this is not a serious problem as the structure is usually cleaned by water or abrasive blasting after treatment for the application of a protective coating or sealer to prevent further chloride ingre,ss,... 

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