Title: Service-Life Model Bench Marking Using Data Collected from Marine-Exposure Sites

Author(s): Michael Thomas

Publication: Web Session

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Date: 10/25/2020

Abstract:
This paper presents data from two marine-exposure sites to validate the predictive model Life-365; the author was a co-developer of the original (Version 1) model. Chloride-profile data were collected from large blocks (1 x 1 x 3 feet) exposed in the tidal-zone of the Treat Island Marine-Exposure Site near Eastport, ME; the site is owned and operated by the US Army Corps of Engineers. Concrete blocks were exposed for 20 to 25 years prior to sampling. The concretes examined include mixes with a range of water-to-cementing-materials ratios (w/cm) and various levels of SCM including ternary blends. Over 30 different mixes were included in the study. The Life-365 model was able to closely predict the profiles for most mixes, the exception being mixes with relatively high w/cm that exhibited some level of deterioration mainly attributed to freeze-thaw damage at the surface. Data were also collected for smaller samples (4 x 4 x 16 inches) exposed in the tidal zone of a marine-exposure site in the Thames Estuary, UK. Approximately 12 mixes were included in this study; the variable included w/cm and fly ash content. These concretes were 10 years old at the time of sampling. In this case, the model did not always correctly predict the profile, mainly because the measured surface concentration, Cs, was not correctly predicted by the model. The predicted profiles generally provided a good fit when C¬s was corrected based on the measured value. The paper discusses the importance of models being able to properly account for other deterioration processes and to better predict surface chloride concentrations.