Modeling Chloride Penetration into Concrete with Lightweight Aggregates

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Title: Modeling Chloride Penetration into Concrete with Lightweight Aggregates

Author(s): M. Maage, S. Helland, and J. E. Carlsen

Publication: Special Publication

Volume: 192

Issue:

Appears on pages(s): 451-470

Keywords: chlorides; concretes; corrosion; lightweight aggregates; models; slags

Date: 4/1/2000

Abstract:
A model for predicting the initiation period of reinforcement corrosion for marine concrete structures was presented at the CANMET/ACI Int. Confr. On Durability, Sydney, Australia 1997. The theory has been refined to be valid also for short time curing and exposure. The objective of the program aimed at giving input data to the model for estimating the initiation period of reinforcement corrosion. Furthermore, the programmed should document the chloride ingress into various practical concretes made with lightweight aggregates, depending on a number of variables in curing and exposure conditions as well as concrete composition and materials. The most important variable were 1) curing time before exposure, 2) curing temperature, 3) exposure temperature, 4) exposure time, 5) type of exposure, 6) salt concentration in exposure medium and 7) type of binder. The most important conclusion was that the results fitted very well to the earlier presented hypothesis for the prediction of the initiation period independent of type of aggregate. Additionally the following main conclusions shall be mentioned: Surface chloride content, C is the environmental load, and it increases with the exposure time during the first years, and reduces with increased curing time and the introduction of slag, and independent of curing and exposure temperature. The achieved diffusion coefficient, D is independent of curing and exposure temperature, and decreases with an increase of the exposure time and the introduction of slag. The parameter a expresses the time dependency of D with exposure time. a is independent of curing time, curing and exposure temperature, and it increases somewhat with increased salt concentration in the exposure water and introduction of slag.