DETERMINATION OF CHLORIDE DIFFUSION COEFFICIENT IN CARBONATED CONCRETE CONTAINING SILICA-FUME

The deterioration of concrete structures is a non-linear and complex phenomenon which is caused by different phenomena. Carbonation is known as one of the major reasons of concrete deterioration. Carbonation has two different effects on concrete structures. Carbonation may have a positive effect against corrosive materials because of its effect in reducing the concrete porosity by changing calcium hydroxide to calcium carbonate. On the other hand, carbonation may have a major role in improving corrosion by reducing the pH of concrete and omitting of passive layer. Although literatures on carbonation have been vast, there are so few studies in carbonation of concrete containing silica fume. In this research the effect of carbonation in reducing of the porosity of concretes containing silica fume was studied. For this reason, concrete specimens with different water to binder ratios (w/c = 0, 0.35 and 0.5) and silica fume percentage (S.F = 0%, 5% and 10%) were made and carbonated in different ages (28 and 90 days). The porosity of carbonated concretes compared with control specimens by different experiments. Finally, a mathematical model for concrete porosity reduction under carbonation phenomena was developed based on experimental results.