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NF-PRO – Concrete Degradation and its Influence on the Geochemical
Conditions at the Concrete/Bentonite under Repository Conditions.
Alicia Escribano, Elena Torres, Mª Jesús Turrero, Pedro Luís Martín, Javier Peña, Paloma
Gómez
Summary
CIEMAT, Madrid, Spain
Degradation of concrete can influence the performance of the bentonite barrier, as high-pH
lixiviates could affect to the clay properties.
The experimental studies conducted by CIEMAT are designed to provide experimental evidences
on the physical, chemical and mineralogical changes during the concrete-compacted
bentonite interaction.
Concrete has been analyzed by SEM-EDS, whereas bentonite samples were studied by means
of XRD, FTIR and SEM–EDS. Chemical analysis for exchangeable cations and soluble salts
were also performed in clay samples.
1. Introduction
Deep geological disposal is the most accepted management option for long-lived and highly radioactive
wastes. In the repository, concrete will be used for the reinforcement of the access galleries
and in the final sealing of access routes.
Concrete degradation caused by external agent can affect its durability, resistance and stability
throughout time. Furthermore, concrete degradation generates a diffusive alkaline plume which can
affect the swelling and transport properties of bentonite, as well as the properties of the adjacent
host rock and groundwater flowing through.
The scope of the present study is to provide experimental data about the alteration products at the
concrete/bentonite interface and the related changes of both materials during the interaction.
2. Methodology
2.1 Materials
Bentonite
The tests have been performed with a bentonite (FEBEX) from the Cortijo deArchidona deposit
(Almería, Spain). The conditioning of the bentonite prior its use in the laboratory is detailed in [1].
Its main characteristics are detailed in Villar (2002) [2].
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