Modelling the evolution of microstructure and transport properties of cement pastes under conditions of accelerated leaching

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Modelling the evolution of microstructure and transport properties of cement pastes under conditions of accelerated leaching. / Phung, Quoc Tri; Maes, Norbert; Jacques, Diederik; Perko, Janez; De Schutter, Geert; Ye, Guang.

In: Construction and Building Materials, Vol. 115, 15.07.2016, p. 179-192.

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@article{927d5581a59b4b8ca5a088865be59b2f,
title = "Modelling the evolution of microstructure and transport properties of cement pastes under conditions of accelerated leaching",
abstract = "Calcium leaching might be a significant degradation process in concrete and reinforced structures with an anticipated long-term service life such as nuclear waste disposal systems or large hydro structures (dams, bridges, water tanks). The leaching process is extremely slow under environmental conditions, which fosters the use of accelerated experimental approaches such as leaching in an ammonium nitrate (NH4NO3) solution. In this paper, we develop a one-dimensional diffusion-based transport model with the purpose to predict the changes in microstructure and transport properties of saturated cement pastes in contact with a NH4NO3 solution. The model helps to better understand the transient state of leaching which is difficult to observe by experimental work. The main new elements in this model are change in model configuration with extended solution domains; ability to predict the spatial profiles of diffusivity and permeability; including the effect on solubility of the spatial-temporal evolution of nitrate concentration; and including the effect of limestone addition to the cement paste of leaching kinetics. This model is based on macroscopic mass balances for Ca in aqueous and solid phases which are linked together by applying a variable solid-liquid Ca equilibrium curve. Besides the prediction of the leached depth, porosity increase, portlandite and C-S-H contents, and the amount of leached Ca, the model also enables to estimate the variation of permeability and diffusivity over the domain at different immersion periods in NH4NO3 solution. The model is verified by accelerated leaching experiments in 6 mol/l NH4NO3 solution on CEM I cement pastes with/without limestone fillers. Verification with experimental results shows a good agreement.",
keywords = "modelling, microstructure, transport properties, accelerated leaching, cement paste, limestone filler",
author = "Phung, {Quoc Tri} and Norbert Maes and Diederik Jacques and Janez Perko and {De Schutter}, Geert and Guang Ye",
note = "Score=10",
year = "2016",
month = "7",
day = "15",
doi = "10.1016/j.conbuildmat.2016.04.049",
language = "English",
volume = "115",
pages = "179--192",
journal = "Construction and Building Materials",
issn = "0950-0618",
publisher = "Elsevier",

}

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TY - JOUR

T1 - Modelling the evolution of microstructure and transport properties of cement pastes under conditions of accelerated leaching

AU - Phung, Quoc Tri

AU - Maes, Norbert

AU - Jacques, Diederik

AU - Perko, Janez

AU - De Schutter, Geert

AU - Ye, Guang

N1 - Score=10

PY - 2016/7/15

Y1 - 2016/7/15

N2 - Calcium leaching might be a significant degradation process in concrete and reinforced structures with an anticipated long-term service life such as nuclear waste disposal systems or large hydro structures (dams, bridges, water tanks). The leaching process is extremely slow under environmental conditions, which fosters the use of accelerated experimental approaches such as leaching in an ammonium nitrate (NH4NO3) solution. In this paper, we develop a one-dimensional diffusion-based transport model with the purpose to predict the changes in microstructure and transport properties of saturated cement pastes in contact with a NH4NO3 solution. The model helps to better understand the transient state of leaching which is difficult to observe by experimental work. The main new elements in this model are change in model configuration with extended solution domains; ability to predict the spatial profiles of diffusivity and permeability; including the effect on solubility of the spatial-temporal evolution of nitrate concentration; and including the effect of limestone addition to the cement paste of leaching kinetics. This model is based on macroscopic mass balances for Ca in aqueous and solid phases which are linked together by applying a variable solid-liquid Ca equilibrium curve. Besides the prediction of the leached depth, porosity increase, portlandite and C-S-H contents, and the amount of leached Ca, the model also enables to estimate the variation of permeability and diffusivity over the domain at different immersion periods in NH4NO3 solution. The model is verified by accelerated leaching experiments in 6 mol/l NH4NO3 solution on CEM I cement pastes with/without limestone fillers. Verification with experimental results shows a good agreement.

AB - Calcium leaching might be a significant degradation process in concrete and reinforced structures with an anticipated long-term service life such as nuclear waste disposal systems or large hydro structures (dams, bridges, water tanks). The leaching process is extremely slow under environmental conditions, which fosters the use of accelerated experimental approaches such as leaching in an ammonium nitrate (NH4NO3) solution. In this paper, we develop a one-dimensional diffusion-based transport model with the purpose to predict the changes in microstructure and transport properties of saturated cement pastes in contact with a NH4NO3 solution. The model helps to better understand the transient state of leaching which is difficult to observe by experimental work. The main new elements in this model are change in model configuration with extended solution domains; ability to predict the spatial profiles of diffusivity and permeability; including the effect on solubility of the spatial-temporal evolution of nitrate concentration; and including the effect of limestone addition to the cement paste of leaching kinetics. This model is based on macroscopic mass balances for Ca in aqueous and solid phases which are linked together by applying a variable solid-liquid Ca equilibrium curve. Besides the prediction of the leached depth, porosity increase, portlandite and C-S-H contents, and the amount of leached Ca, the model also enables to estimate the variation of permeability and diffusivity over the domain at different immersion periods in NH4NO3 solution. The model is verified by accelerated leaching experiments in 6 mol/l NH4NO3 solution on CEM I cement pastes with/without limestone fillers. Verification with experimental results shows a good agreement.

KW - modelling

KW - microstructure

KW - transport properties

KW - accelerated leaching

KW - cement paste

KW - limestone filler

UR - http://ecm.sckcen.be/OTCS/llisapi.dll/open/12747312

U2 - 10.1016/j.conbuildmat.2016.04.049

DO - 10.1016/j.conbuildmat.2016.04.049

M3 - Article

VL - 115

SP - 179

EP - 192

JO - Construction and Building Materials

JF - Construction and Building Materials

SN - 0950-0618

ER -

ID: 1128813