[Clayart] Ivor's proposal [GroupMail]

L TURNER magnolia.mud.list at gmail.com
Tue Mar 25 21:01:48 EDT 2014


you said:
"My original point was that the spatial ratio of solids to water in terms
of numbers can differ significantly when compared to the ratios of mass
(weight).. I did hope that a few of your audience would take the Glenn
Nelson examples and convert them to volumetric measure."

Using your density estimates for clay and water, my conversions of the
"water of plasticity" table in Nelson's textbook, <5th edition> from (grams
water/100 grams dry solids) to volume fraction solids in the wet clay are
as follows: <xxx/xxx match the two values in Nelson's table>
washed kaolin  0.44 / 0.45
sedimentary kaolin 0.55 / 0.41
ball clays  0.59 / 0.42
plastic fire clays 0.73 / 0.51
stagger clays  0.66 / 0.57
stoneware clays  0.65 / 0.52
brick clays  0.73 / 0.49

These values are not inconsistent with the maximum solids loading for
pumpable slurries, in that when slurries become non-pumpable they resemble
a sticky but plastic material.

There are several aspects of Nelson's data that seem ambiguous to me.
I.   Do the two numbers provided for each entry represent the statistical
spread if the optimum plasticity that Nelson observed? Or, do the numbers
represent the beginning and end of the region where clay/water mixture is
considered to be plastic? Nelson does not say, or he said it in a place
that is not easily found.

II.  What was Nelson's criteria for Plasticity?  Was he using the crude
'coil around his finger' criteria, or was he using an point on the shear
stress/strain curve?

III. Nelson provides tables of oxide analyses for some of the clays in the
'water of pa
plasticity table' but nothing on the distributions of particle size or
mineralogical makeup, nor identifies the organic compounds contained in the
dry clay. Neither is it clear that the clays listed in one table are the
same as in another.

Without reasonable clarity on these issues I consider the data to simply,
and effectively, illustrate that moist clay bodies are not all the same.
The data tell us very little beyond that unless we make assumptions about
particle size, mineralogical and organic makeup.  If we make the
assumptions, then the conclusions depend more on the assumptions than on
the experimental evidence.  Said another way, the experimental data are


The Woodlands, TX

On Mon, Mar 24, 2014 at 10:25 PM, ivor and olive lewis <
iandol at westnet.com.au> wrote:

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