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Effects of the Incorporation of Municipal Solid Waste Incineration Fly Ash in Cement Pastes and Mortars. Part 2: Modeling.


pdf icon Effects of the Incorporation of Municipal Solid Waste Incineration Fly Ash in Cement Pastes and Mortars. Part 2: Modeling. (1169 K)
Remond, S.; Bentz, D. P.; Pimienta, P.

Cement and Concrete Research, Vol. 32, No. 4, 565-576, April 2002.

Keywords:

cements; cement paste; mortar; solid waste; waste materials; fly ash; hydration; leaching; microstructure; diffusion; transport properties; durability

Abstract:

This work falls within the scope of a general problem regarding the assessment of concretes manufactured from waste materials. The main objective is to study the long-term evolution of these materials during the leaching process, using the cellular automata based hydration model developed at the National Institute of Standards and Technology. The work is based on the analysis of mortars and cement pastes containing an experimental waste: Municipal Solid Waste Incineration fly ash (MSWI fly ash). After having determined the mineralogical composition of the MSWI fly ash and its interactions with cement during hydration (this work has been presented in a former article), the phases comprising the fly ash have been incorporated into the hydration model. The increase in porosity of cement pastes containing MSWI fly ash during the leaching process has then been simulated. This study shows in particular that the diffusion coefficient of these pastes changes in a similar way to pure cement pastes. Finally, a simplified leaching model has been developed. This model shows in particular that the increase in the diffusion coefficient in the damaged zone increases the release of calcium. However, this release can be simulated with a constant diffusion coefficient, greater than the initial diffusion coefficient of the material.