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Re: [SEAOC] Stucco

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Terry Weatherby said:

>...A testing lab found the REAL reason for the
>problem was because the original installer had "skimped" on the cement in
>the plaster mix; ...

Thanbks for responding.

I have strong reasons to believe that's not the problem I'm dealing with, but
the question of stucco mix tolerances makes me wonder whether a mix
containing more cement/lime is better or a mix containing less cement/lime is
better.

Why?  My understanding of the curing of concrete paste (cement and water
only) is that shrinkage occurs.  Since stucco is essentially a grout (cement,
water, sand, and lime), increasing the amount of cement or lime should cause
it to shrink more, leading to more net tensile stress in the stucco, leading
to more shrinkage cracks.  Offhand, it would seem that a leaner mixture is
more beneficial.  Does this logic make sense from a practical viewpoint?

Before someone starts arguing that the tension is taken up by the wire lath,
let me say now that the situation I have in mind is that the stucco was
placed with no wire lath or metal plaster base, a situation is permitted by
ASTM C926.

...