- Author
- Bentz, D. P. | Detwiler, R. J. | Garboczi, E. J. | Halamickova, P. | Schwartz, L. M.
- Title
- Multi-Scale Modelling of the Diffusivity of Mortar and Concrete.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Book or Conf
- Chloride Penetration Into Concrete. International RILEM Workshop. Proceedings. Paris, France. October 15-18, 1995, 85-94 pp, 1995 AND Materials Research Society. Fall Meeting. Bonding and Interfaces in Cementitious Materials. Proceedings. 1-10 pp, 1994, ['1995', '1994']
- Keywords
- cement based materials | diffusivity | interfacial transition zone | microstructure | multiscale modeling | random walk | simulation | computer models | equations
- Identifiers
- characteristics of simulated mortar microstructures; initial ratios by mass for single aggregate simulations
- Abstract
- Modelling ion diffusion in concrete is complicated by the heterogeneity which exists at a variety of length scales. The cement paste fraction of the concrete is heterogeneous at the scale of micrometers, consisting of unhydrated cement, porosity, and hydration products. The concrete itself must often be considered as a three-phase composite, consisting of aggregates, bulk cement paste, and interfacial transition zone (ITZ) cement paste. In this research, separate microstructure models for cement paste and mortar or concrete are linked to estimate the diffusivity of a mortar or concrete. Once an ITZ thickness is selected, a hard core/soft shell representation of the concrete is utilized to compute the volume fractions of ITZ and bulk pastes in the mortar. A cement hydration mocel containing a single flat plate geometry aggregate is then employed to determine the porosities of the ITZ and bulk pastes as a function of water-to-cement ratio and degree of hydration. Based on these porosities, relative diffusivities can be estimated using previously developed empirical equations. Finally, these relative diffusivities can be used in the original hard cor/soft shell representation of the mortar, where random walk algorithms are employed to estimate its diffusivity, for comparison with experimental data.