| Time-to-corrosion estimates typically do not account for variations of diffusion coefficients with depth into the concrete, which may be caused by imperfect curing. A method, which involved using specimens that were sliced perpendicular to the exposed surface of a concrete slab, was used to estimate diffusion coefficients with depth using the Rapid Migration test. Eight different concrete mixtures were used and were subjected to six different curing regimes, which include moist curing for 0 days, 1 day, 3 days, 7 days, and 28 days and a curing compound. The chloride diffusion coefficients at the surface generally decreased as moist curing increased for each concrete. There was also a depth at which the chloride diffusion coefficient remains constant and unaffected by external curing. Service life estimates using this constant chloride diffusion value, which was unaffected by external curing were higher than estimates using variable diffusion values and were not conservative. |
