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Measurement and Modeling of the Ability of Crack Fillers to Prevent Chloride Ingress into Mortar

Published

Author(s)

Scott Z. Jones, Dale P. Bentz, Jeffrey Davis, Daniel S. Hussey, David L. Jacobson, John L. Molloy, John R. Sieber

Abstract

One of the most common repair procedures applied to damaged concrete is the filling of cracks by the application (injection) of an organic polymer. This operation is performed to increase the service life of the concrete by removing a preferential pathway for the ingress of water, chlorides, and other deleterious species. To effectively fulfill its mission of preventing chloride ingress, the polymer must not only fully fill the macro-crack, but must also intrude the damaged zone surrounding the crack perimeter. Here, the performance of two commonly employed crack fillers, one epoxy and one methacrylate, are investigated using a combined experimental and computer modeling approach. Neutron tomography and microbeam X-ray fluorescence spectrometry (µXRF) measurements are employed on pre-cracked and chloride-exposed specimens to quantify the crack filling and chloride ingress limiting abilities, respectively, of the two polymers. A two-dimensional computer model using a finite element-based method is employed to simulate the experiments, with the (crack) images provided by the µXRF technique being used to provide the input microstructures for the simulations. When chloride binding and a time-dependent mortar diffusivity are both included in the computer model, good agreement with the experimental results is obtained. Both crack fillers significantly reduce chloride ingress during the 21 d period of the present experiments. However, the epoxy itself contains a significant level of chlorine (≈ 4 %) whose leaching has been evaluated to assess their availability as a source of deleterious ions for initiating corrosion of the steel reinforcement in concrete structures.
Citation
Cement and Concrete Composites
Volume
81

Keywords

Chloride ions, crack filler, cracking, epoxy, diffusion, methacrylate, mortar, simulation.
Created August 1, 2017, Updated November 10, 2018