Modeling the decalcification of cement paste in ammonium nitrate solution

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Abstract

Ca-leaching process is extremely slow under environmental conditions. The use of ammonium nitrate (NH4NO3) solution to accelerate the leaching kinetics has become popular because of the extremely slow nature of the degradation process under environmental condition. In this study, a one-dimensional diffusion-based transport model was proposed to simulate the leaching process of saturated hardened cement paste in contact with a NH4NO3 solution. The model helps to better understand the transient state of leaching which is difficult to be observed by experimental work. This model is based on macroscopic mass balances for Ca in aqueous and solid phases which are linked together by applying solid-liquid Ca equilibrium. Besides the prediction of the leached depth, portlandite and C-S-H contents, and the amount of leached Ca, the model also enables to simulate the variation of water permeability 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 paste samples. Preliminary verification with experimental results shows a good agreement.

Details

Original languageEnglish
Title of host publication3rd internatinal conference on Service Life design for Infrastructure: Keynote speech
Place of PublicationZhuhai, China
Pages27-40
Publication statusPublished - Oct 2014
Event3rd internatinal conference on Service Life design for Infrastructure - Tongji University, Zhuhai, China
Duration: 15 Oct 201417 Oct 2014

Conference

Conference3rd internatinal conference on Service Life design for Infrastructure
CountryChina
CityZhuhai
Period2014-10-152014-10-17

Keywords

  • leaching, modelling, ammonium nitrate, permeability, diffusion, microstructure

ID: 356198