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Re: Slurry

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Dan,

Slurries generally need to have a high water-cement ratio to be flowable.
That is likely to result in significant shrinkage -- I don't have a
quantitative number.

A simple test for shrinkage is to use an 8x8x8 concrete block with cell
vertical.  Grout or slurry is poured into the cell of the block and screeded
level with the top of the block.  The materials will shrink away from the
walls of the cell as they cure, showing a perimeter crack.  Also, the grout
surface will drop.  I've used this test, not to come up with a percent
shrinkage, but to visually compare different recipes for shrinkage.

Something that I've found using this test that didn't mention in my post to
Sharon, and should have mentioned, is that a shrinkage control admixture
such as Sika Grout Aid, or PMP Grout Additive, is very effective in
controlling shrinkage.  It even works well with soil/cement slurries, for
which I've found that the amount recommended by the manufacturer [1 lb/ 100
lbs. cement] is generally not enough, 50% more is about right, 100% more and
the grout rises like a muffin in the oven.

Nels Roselund
Structural Engineer
South San Gabriel, CA
njineer(--nospam--at)att.net


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