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Service Life Modeling of Reinforced High Volume Fly ash (HVFA) Concrete Structures Containing Cracks

Published

Author(s)

Scott Z. Jones, Dale P. Bentz, Kenneth A. Snyder, Nicos Martys, Daniel S. Hussey, David L. Jacobson

Abstract

Chloride ions, resulting from the application of de-icing salts travel through the concrete matrix by diffusion in a connected pore network. Cracks in concrete facilitate chloride movement by allowing ions to bypass the concrete matrix and travel directly to reinforcing bars, reducing the protective capacity of the alkaline environment and the time to corrosion initiation. A service life model that incorporates diffusivity and chloride binding capacity measurements as well as capturing the effects of cracking, will improve service life predictions. In this study, 5 concrete mixtures, two of which are high volume fly ash (HVFA) mixtures are investigated. The diffusivity is measured by electrical resistivity and the chloride binding capacity is measured by submerging ground mortar in a solution of NaCl. Neutron tomography of epoxy and methacrylate-filled cracks provides insights into the ability of concrete crack fillers to seal cracks. These results are incorporated into a service life model where the chloride ion concentration in a reinforced concrete slab is computed given a chloride ion exposure condition. The output of the model is the service life, defined to be the time required for the chloride concentration to reach a threshold level. Experimental and simulation results show that HVFA concretes have longer service lives due to decreased diffusivity and increased chloride binding. Crack fillers are able to fill moderate sized cracks and prevent chloride ion ingress, increasing the service life of the structure
Conference Dates
May 11-13, 2015
Conference Location
Miami, FL
Conference Title
2015 International Concrete Sustainability Conference

Keywords

Service Life, High Volume Fly Ash Concrete, Cracks, Chloride Ingress, Corrosion
Created May 1, 2015, Updated February 19, 2017