11. Low-pH concretes based on CAC for underground repositories of HLRW. Resistance respect to groundwater agression

Title: 11. Low-pH concretes based on CAC for underground repositories of HLRW. Resistance respect to groundwater agression
Author(s): J.L. Garcia Calvo, A. Hidalgo, M.C. Alonso, L. Fernandez Luco
Paper category : conference
Book title: NUCPERF 2009 - Long Term Performance of Cementitious Barriers and Reinforced Concrete in Nuclear Power Plants and Waste Management
Editor(s): V. L'Hostis, R. Gens, C. Gallé
Print-ISBN: 978-2-35158-072-1
e-ISBN: 978-2-35158-087-5
Publisher: RILEM Publications SARL
Publication year: 2009
Pages: 99 - 108
Total Pages: 10
Nb references: 12
Language: English

Abstract: Engineering construction concept for high level radioactive waste (HLRW) underground repositories considers the use of a bentonite barrier in contact with cementitious materials with a pore fluid pH value < 11 (based on low-pH cements). Calcium aluminates cements (CAC) represent an interesting alternative to Ordinary Portland Cement (OPC), due to their lower pH.

The use of high content of suitable mineral admixtures to CAC cements provides a better stability to the microstructure by means of new phases such as hydrogarnet Ca3Al2(SiO4)3- x(OH)2x solid solution and gehlenite hydrate but the properties of these new binders are different and a thorough understanding of their engineering and microstructural properties is needed.

Low-pH shotcrete based on CAC plus mineral admixtures (with high silica content) have been designed for potential use in HLRW repositories for shotcreted plugs. This paper deals with the short-term functional requirements of the plugs and their resistance to long term groundwater aggression. Three types of low-pH concretes (based on CAC + high content of mineral admixtures) using the groundwater from the real site of Äspö (Sweden) have been considered.

The results show that it is possible to obtain a low-pH shotcrete plug based on CAC plus mineral admixtures suitable for use in the underground facilities of a nuclear waste repository, that has good resistance to groundwater degradation effects.

Online publication: 2009-11-16
Publication type : full_text
Public price (Euros): 0.00