HITEC - technical report on Material characterisation

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21110%2F24%3A00382661" target="_blank" >RIV/68407700:21110/24:00382661 - isvavai.cz</a>

Result on the web

<a href="https://www.ejp-eurad.eu/publications/eurad-d77-technical-report-material-characterisation" target="_blank" >https://www.ejp-eurad.eu/publications/eurad-d77-technical-report-material-characterisation</a>

DOI - Digital Object Identifier

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Result language

angličtina

Original language name

HITEC - technical report on Material characterisation

Original language description

A number of different high temperature experiments were performed with bentonite clays. Both field experiments at a hard rock laboratory and laboratory scale experiments have been performed. Some experiments by heating the clay either in an open system while allowing the clay to dry or in a closed system with water available. No general significant transformation of montmorillonite was observed in the experiments. In several cases the CEC of the bentonite was affected by the heating, but with no correlation to any observed mineralogical changes. There are indications that dry heating of the bentonite had a stronger impact on the clay properties, than heating of water saturated bentonite. Swelling pressure seemed mainly unaffected by thermal treatment, while hydraulic conductivity sometimes increased somewhat. Unconfined compression test showed that a lower maximum deviator stress was seen in all materials compared to the references in the ABM5 field test. There were examples of (i) redistribution of sulphates, (ii) formation of carbonates, (iii) dissolution of quartz and cristobalite. These are observations that are not new. There were examples of compacted bentonite blocks that were physically disintegrated in parts of the experiments. The mechanism for this is not fully understood, and it is unclear if this could actually happen in a real repository as well at high temperatures. Possibly it was due to the delayed heating in relation to the water saturation of the bentonite clay. The liquid limit and swell index of dry treated bentonite are lower than corresponding reference material. The decrease of both parameters is observed as a function of the heating time. None of the analyses performed could detect any specific high temperature reaction. During the test period the experiments did not alter the bentonite in a way that it lost its important properties as a buffer material.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

20101 - Civil engineering

Project

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Continuities

R - Projekt Ramcoveho programu EK

Publication year

2024

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů