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Thread: capillary action in clay?

  1. #1 capillary action in clay? 
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    capillary action is the force that seemingly pulls liquids into a very thin tube (like a glass capillary).
    clay has a capillary action, but no tube.
    How does this work?


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  3. #2  
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    At a microscopic level clay, I think in particular kaolinite (could be wrong there) has a layered structure, like sheets with little interstices between the layers. Often there is a net charge between these layers caused by ions of some variety, it is well known that clays have a very high porosity, so it follows that water is stored in these interstices. Note that clay also has a very low permeability, it soaks up plenty of water but water cannot flow through it with ease.


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  4. #3  
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    Billiards is correct. In a little more detail, clays are generally made up of two types of layers. One layer consists of interconnected silica tetrahedra (one silicon surrounded by four oxygens), the other of aluminium octahedra (one aluminium surrounded by six oxygens). When the sheets form, the oxygens are shared by adjacent silicons or aluminiums.
    These sheets then link up in various ways, depending upon the particular clay minreal.

    The silicon can be substituted for by aluminium in the tetrahedra, and the aluminium by various ions, including potassium. These substitutions produce the charge imbalance referred to by Billiards. Because water is bi-polar, having a negative end and a positive end, it is attracted to the clay surfaces, attempting to satisfy this charge imbalance.

    Recently deposited clays can have porosities as high as 90%, as the clay particles are arranged in a ''house of cards' structure. During the first one hundred feet of subsidence the weight of overlying sediments collapses this structure. The porosity falls significantly, but is still in the region of 50%, but with a very low permeability, as noted by billiards, because of the hydrophillic properties of the clay surfaces.
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  5. #4  
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    thanks for the replies.

    OK, so no tubes, but more like plates on a microscopic level.

    @Ophiolite
    eh, that is very very detailed. I'm just an amateur wondering how this works.


    (getting slightly off-topic)
    Which are the conditions the clay will let go of the water?
    Could it be when the gaps between the layers get wider?
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  6. #5  
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    Quote Originally Posted by carsten888
    @Ophiolite
    eh, that is very very detailed. I'm just an amateur wondering how this works.
    You tapped into a topic that is relevant to my work, so I just went onto autopilot.
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  7. #6  
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    @Ophiolite
    ehr, curious what work that would be.

    (getting slightly off-topic)
    Which are the conditions the clay will let go of the water?
    Could it be when the gaps between the layers get wider?
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  8. #7  
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    Quote Originally Posted by carsten888
    @Ophiolite
    ehr, curious what work that would be.
    Just to give you some mental exercise, can you identify my avatar?
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  9. #8  
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    I can, I know eactly what business you're in, are you based in Aberdeen?

    Actually, I'm graduating next year with a degree in geophysics, not sure what I want to go into, but was wondering about the *ahemmm* business. Is it good pay, what about the quality of life, any regrets etc..?

    I would love to hear about it from an insider. Cheers
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  10. #9  
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    i dunno.
    looks like a piece of tai sclupture to me, but I'm sure thats not what it is.

    (slightly more on topic)
    still wondering about what conditions it takes for clay to loose its capillary action...
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