Pratanu Ghosh

Prediction of Equivalent Steady-State Chloride Diffusion Coefficients

This paper presents an approach for determining the chloride migration rate of hardened concrete by applying fundamental electrochemistry for different cementitious mixtures using the measurements from the chloride-ion penetration test (CIPT) data following ASTM C1202 specifications. The steady-state condition is verified by comparing the numerical values of chloride migration rates during 5, 30, and 360 minutes of testing. Three different theoretical approaches—Nernst-Plank, Nernst-Einstein, and the Zhang-Gjorv method—were applied to obtain the equivalent steady-state diffusion coefficients for different cementitious materials. These results are compared with the diffusion coefficients obtained from Berke’s empirical equation using CIPT data. These methods for the computation of diffusion coefficients include both the joule effect and temperature dependency and eliminate the need for other extended migration tests to obtain the steady-state conditions. Overall, this research presents a reliable method of determining the chloride migration rate for diffusion coefficient prediction.

Evaluation of Chloride Influence on the Cracking in Reinforced Concrete Using Korozeeneck Software

Evaluation of Chloride Influence on the Cracking in Reinforced Concrete Using Korozeeneck Software Korozeeneck software allows for deterministic as well as stochastic modelling of chloride-induced degradation of reinforced concrete structures. To perform stochastic modelling it is necessary to use the Monte reliability framework. The Korozeeneck software ensures the modelling of both phases (initiation as well as propagation). It helps to estimate the time until initiation of corrosion in the steel reinforced concrete structures. Also, the time until unacceptable cracking caused by uniform corrosion can be assessed. The Paper consists of a description of the analytical model used in the Korozeeneck software as well as of the example of a deterministic application. Modelování Vlivu Chloridů Na Vznik Trhlin v Železobetonu Programem Korozeeneck Program Korozeeneck umožňuje provádět deterministické a stochastické modelování degradace železobetonové konstrukce. Ke stochastické aplikaci je nutné použít spolehlivostní nástavbu Monte. Korozeeneck modeluje jak iniciační, tak propagační fázi koroze. Umožňuje odhadnout dobu do vzniku koroze ocelové výztuže v železobetonové konstrukci, a také dobu do vzniku rovnoměrnou korozí vyvolaných trhlin. Příspěvek obsahuje jak popis analytického modelu užitého v programu Korozeeneck, tak příklad deterministické aplikace.

SBRA Model for Corrosion Initiation of Concrete Structures

This paper presents a finite element based probabilistic corrosion initiation model using Simulation Based Reliability Assessment (SBRA). The model is focused on the effect of diffusions and ingress of chloride ions in bridge decks with excessive cracks to investigate the performance of different corrosion resistant steel reinforcements. The objective of this research is based on the formulation of probabilistic corrosion initiation model with the inclusion of distribution of High Performance Concrete (HPC) diffusion coefficients computed from fundamental electrochemistry and the variation of surface chloride concentration from the field data of Virginia bridge decks as well as other random variable parameters. This study shows the variability and sensitivity on estimation of the time to onset of corrosion using Monte Carlo technique. In addition, the estimation of corrosion free service life for the preliminary design of concrete structures in harsh chloride environments will be indicated.

Variation of Diffusion Coefficient for Selected Binary and Ternary Concrete Mixtures Considering Concrete Aging Effect

The paper deals with the variation of resistance of selected High Performance Concrete (HPC) materials against chloride ion penetration. The resistance of chloride penetration is described by means of the diffusion coefficient and it is derived from emerging non-destructive tests. It is computed from the measurements of surface electrical resistivity (see e.g. AASTHTO TP-95 specification) data. The effect of concrete aging on the diffusion coefficient is taken into account as the concrete properties are time dependent and it is significantly important for High Performance Concrete (HPC) materials.