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51317--9531-Reinforced Concrete Corrosion Damage Forecast with Potential Dependent Threshold: Sensitivity to System Parameters

The phenomenon of a potential-dependent chloride threshold (PDT) along with the corrosion macrocell coupling between active and passive steel assembly components allows to combine a corrosion initiation-propagation model to forecast the durability of reinforced concrete structures in marine service.

Product Number: 51317--9531-SG
ISBN: 9531 2017 CP
Author: Andrea Sanchez
Publication Date: 2017
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The potential of passive steel embedded in concrete is a key parameter on the value of the chloride corrosion threshold. The phenomenon of a potential-dependent chloride threshold (PDT) together with corrosion macrocell coupling between active and passive steel assembly components needs consideration in corrosion forecast models for reinforced concrete structures in marine service. Initial deterministic corrosion initiation-propagation models incorporating PDT projected much lower damage development in an aged system than when using the traditional potential-independent chloride threshold (PIT) assumption. In contrast for early stages of corrosion damage the relative effect tended to be in the opposite direction. These diverse outcomes are explained by the interplay between delayed corrosion initiation and concentration of corrosion when it is localized. An expansion of that PDT forecast model case is presented here using advanced model formulations with emphasis on establishing the model output sensitivity to the choice of model input parameters. The concrete parameters varied were: oxygen diffusivity resistivity chloride diffusivity and combinations representing their linked variation and random variability of selected properties. Parameter values comparable to those encountered in the field are used plus some extreme conditions especially at the low resistivity end. Results are compared with those projected by the traditional PIT approach for implication on the development of next generation forecasting models.

Keywords: chloride corrosion threshold, potential, modeling, forecast, reinforced concrete, service life

 

The potential of passive steel embedded in concrete is a key parameter on the value of the chloride corrosion threshold. The phenomenon of a potential-dependent chloride threshold (PDT) together with corrosion macrocell coupling between active and passive steel assembly components needs consideration in corrosion forecast models for reinforced concrete structures in marine service. Initial deterministic corrosion initiation-propagation models incorporating PDT projected much lower damage development in an aged system than when using the traditional potential-independent chloride threshold (PIT) assumption. In contrast for early stages of corrosion damage the relative effect tended to be in the opposite direction. These diverse outcomes are explained by the interplay between delayed corrosion initiation and concentration of corrosion when it is localized. An expansion of that PDT forecast model case is presented here using advanced model formulations with emphasis on establishing the model output sensitivity to the choice of model input parameters. The concrete parameters varied were: oxygen diffusivity resistivity chloride diffusivity and combinations representing their linked variation and random variability of selected properties. Parameter values comparable to those encountered in the field are used plus some extreme conditions especially at the low resistivity end. Results are compared with those projected by the traditional PIT approach for implication on the development of next generation forecasting models.

Keywords: chloride corrosion threshold, potential, modeling, forecast, reinforced concrete, service life

 

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