The exposure time at which a threshold Cl— concentration, Ct, is initially achieved at the reinforcement depth in concrete, Ti, is an important service life determinant for reinforced concrete structures. However, there is no consensus in the literature of a value for Ct, as reported concentrations extend over one order of magnitude; and it has become increasingly apparent that Ct is distributed even for apparently identical specimens. In this research, models of randomly arranged coarse aggregate (CA) particles in concrete cover were generated for different aggregate types (particle size and size distribution), CA volume fraction, and cover; and, by finite element analysis, the effect of these factors on the time and location along the reinforcement at which Ct is initially achieved was investigated as a function of Ct. The results are discussed within the context of factors that contribute to the reported variability in Ct.
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