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The Effect of Leaching on the Pore Structure of Cement-Based Grouts for Use in Nuclear Fuel Waste Disposal

Published online by Cambridge University Press:  28 February 2011

M. Onofrei ,
M. N. Gray ,
D. Breton  and
G. Ballivy
M. Onofrei
Affiliation:
AECL Research, Whiteshell Laboratories, Pinawa, Manitoba, Canada ROE 1L0
M. N. Gray
Affiliation:
AECL Research, Whiteshell Laboratories, Pinawa, Manitoba, Canada ROE 1L0
D. Breton
Affiliation:
Sherbrooke University, Sherbrooke, Quebec, Canada J1K 2R1
G. Ballivy
Affiliation:
Sherbrooke University, Sherbrooke, Quebec, Canada J1K 2R1
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Abstract

Research on the longevity of cement-based grout materials for sealing a deep geological disposal vault is an important aspect of the Canadian and other nuclear waste management programs. These studies include assessments of the chemical durability of cement grouts, and the effects of leaching and phase transformation on the long-term hydraulic and diffusion characteristics of grouts.

This paper presents the results of laboratory studies carried out to assess the effects of leaching of cement phases on the pore structure of hardened grouts. Measurements of mercury intrusion and scanning electron microscopy with energy dispersive x-ray analysis, have been used to investigate the changes in pore structure of both a reference grout (90% Type 50 cement, 10% silica fume, water-to-cementitious materials ratio between 0.4 and 0.7) and ALOFIX-MC (a fine cement product of Japan), as a function of leaching time.

The work discussed here reveals that the porosity of hardened grout does change during leaching, but within limits that depend on grout composition and initial porosity. The results confirm that the materials have the potential to self-seal and maintain their performance for longer periods than those currently predicted by longevity models.

Our studies of the porosity and permeability of grouts suggest that pore size distribution rather than total porosity is the more important parameter in determining longevity.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 212: Symposium P – Scientific Basis for Nuclear Waste Management XIV , 1990 , 417
Copyright
Copyright © Materials Research Society 1991

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References

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