Claystone is being investigated in many countries as a potential host rock for the final disposal of high-level radioactive waste (HLW). Two types of clay, ductile clay (e.g. the Opalinus Clay in Switzerland and Callovo- Oxfordian Clay in France), and plastic clay (e.g. the Boom Clay in Belgium) are being studied intensively in underground laboratories by the international research community. As a geotechnical barrier, bentonite and sand/bentonite mixtures are regarded as favourable materials in most multi-barrier concepts because of their low hydraulic conductivity and high sorption properties. Since both claystone and bentonite are initially water-saturated or partially saturated, the heat emitted by HLW can induce significant changes in the hydro-mechanical properties of such materials.
What's the difference between ductile clay and plastic clay?
Elasticity/plasticity refers to deformation that springs back. Like rubber - if you compress it and then release it, it will return to its original shape.
Ductility refers to deformation that doesn't spring back, but also doesn't break/crack. Like clay - if you compress it and them release it, it will not return to its original shape .
Dear Ma Zhaoyang, please see this link about plastic clay
http://www.ima-europe.eu/about-industrial-minerals/industrial-minerals-ima-europe/plastic-clays
I think the concept of plastic or ductile behavior should be same for all different types of rocks including clay-stone; Thus, I will mention a general definition of them based on solid mechanics. Plasticity refers to a behavior in which irreversible deformation occur in the rock during loading and successive cycles of loading and unloading would trace out different curves. The ductile behavior is an ability of some types of rocks to support an increasing load as it deforms. It shows the capacity of rock for substantial changes in shape without grass fracturing.
Ductile clay? Is this a new fashion? Ductility is a property assigned to (amorphous) metals or alloys which is irrelevant to water content or overconsolidation history. Clay is a clastic geological material and pending on water content, consolidation history and its mineralogical suite can behave in a plastic or brittle manner under stress. I thing that some people are divising terms without deep understanding of the language they are using...
Perfect explanation, Georgios. Is anybody who considers e.g. a "ductile limit" for cohesive soils? No, there is only a plastic one.
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