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Chloride penetration into cementitious mortar at early age

J. Caballero 1, R.B. Polder1,2, G.A. Leegwater2, A.L.A. Fraaij1
1 Delft University of Technology, Section of Materials and Environment, Faculty of Civil Engineering and Geosciences, Delft, the Netherlands
2 TNO Technical Sciences, Structural Reliability, Delft, the Netherlands

Modern service life design methods for concrete structures use chloride diffusion data as an input parameter. Abundant data exist for concrete at 28 days and, to a lesser extent, at later ages. This paper presents chloride diffusion data for mortar at ages between 1 day and 28 days age. Rapid Chloride Migration (RCM) and natural diffusion tests are performed on mortar specimens made with Portland (CEM I) and Blast Furnace Slag (CEM III/B) cement with w/c 0.50. The results show that mortar at a young age has a relatively high chloride migration coefficient. The value for CEM I at day 1 is one order of magnitude larger than at 28 days age, for CEM III/B this value is even two orders of magnitude larger. In the first two weeks, the value drops rapidly and more strongly for Blast Furnace Slag cement. The experimental data was used to model the chloride ingress up to 50 years with and without exposure to chloride at young ages. Modelling shows that the effect of exposure at young age is significant but relatively small when compared to the chloride ingress during the whole service life of concrete.