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Factors affecting the suitability of superplasticiser-amended cement for the encapsulation of radioactive waste

Isaacs, Matthew, Hinchliff, John, Felipe-Sotelo, Monica and Read, David (2017) Factors affecting the suitability of superplasticiser-amended cement for the encapsulation of radioactive waste Advances in Cement Research, 1700099. pp. 1-15.

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Abstract

Organic superplasticisers improve the flow properties of cement, offering operational advantages for the disposal of radioactive wastes. However, there are concerns that they could increase the mobility of encapsulated contaminants significantly. The effect of polycarboxylate ether superplasticisers on the solubility of Ni(II), Am(III), Pu(IV) and U(VI) in two cement-equilibrated waters (ordinary Portland cement/pulverised fuel ash (OPC/PFA) and OPC/ground granulated blast-furnace slag (GGBS)) has been assessed. The study included four commercial superplasticisers, three adjuncts (a de-foaming agent, biocide and viscosity modifier) and a bespoke, synthesised superplasticiser from which residual monomer had been removed by dialysis. The commercial products (0·5% w/w dosage) had a much greater effect on metal solubility than the dialysed equivalent, increasing solubility by 2–3 orders of magnitude. As the adjuncts alone showed no effect, the difference between the commercial and synthesised superplasticisers is attributed to small molecules, primarily residual monomers, in the commercial formulations owing to incomplete polymerisation. The distribution of radionuclides in hardened cement pastes corresponds closely to the distribution of superplasticiser, as shown by 14C-labelling in combination with digital autoradiography and accounting for the bleed observed for certain slag-rich formulations.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Chemistry
Authors :
NameEmailORCID
Isaacs, Matthewm.isaacs@surrey.ac.uk
Hinchliff, John
Felipe-Sotelo, Monicam.felipe-sotelo@surrey.ac.uk
Read, Davidd.read@surrey.ac.uk
Date : 2017
Identification Number : 10.1680/jadcr.17.00099
Copyright Disclaimer : Copyright © ICE Publishing, all rights reserved. This is an open access article under the CC-BY license. For full details see here: https://creativecommons.org/licenses/by/4.0/
Uncontrolled Keywords : Admixtures; Leaching; Solution chemistry
Depositing User : Clive Harris
Date Deposited : 13 Mar 2018 11:24
Last Modified : 13 Mar 2018 11:24
URI: http://epubs.surrey.ac.uk/id/eprint/845991

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