Modeling and Measuring Chloride Ingress into Cracked Mortar

Published: August 08, 2016

Author(s)

Scott Z. Jones, Jeffery Davis, John L. Molloy, John R. Sieber, Dale P. Bentz

Abstract

Chloride ingress into reinforced concrete structures is responsible for initiating corrosion of steel embedded into concrete. To aide in the prediction of concrete service life, a chloride ingress model that includes chloride binding to the cement matrix and a time-dependent diffusivity is derived by a mass balance and solved by the finite element method. This model is validated through an experimental program where the chloride concentration around cracked specimens is measured with microbeam X-ray fluorescence (μXRF). Reinforced mortar beams are cast and cracked by three-point bending. The samples are submerged in a chloride solution for 7 d to 21 d. The data collected from the μXRF scans is processed using a support vector machine (SVM) algorithm to identify the cement paste matrix. The chloride counts in the matrix are input into a generalized additive model (GAM) to smooth the counts over the scan domain. The data is calibrated using standards with known chloride concentration and the results are compared to the finite element based model which shows good agreement between experiments and modeling. This demonstrates the necessity and usefulness of developing a chloride ingress model that accounts for both chloride binding and the timedependent behavior of the apparent diffusivity as well as crack geometry.
Conference Dates: August 7-11, 2016
Conference Location: Las Vegas, NV
Conference Title: Fourth International Conference on Sustainable Construction Materials and Technologies
Pub Type: Conferences

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Created August 08, 2016, Updated February 19, 2017