If you need to reach 750 psi at 14 days then I suggest you go with a type
'N'. If you can wait for it to reach a strength higher than 620 psi, I
suspect that the mix you have would do it. (How long? I don't know though.)
What do you "limeys" have to say?
Please note my direct phone and fax numbers have changed again
Eric Hammarberg
Associate Director of Preservation
Associate
LZA Technology
641 Avenue of the Americas
New York, NY 10011-2014
Telephone: 917.661.8160 (Direct)
Mobile: 917.439.3537
Fax: 917.661.8161 (Direct)
email: [log in to unmask]
-----Original Message-----
From: Ilene R. Tyler [mailto:[log in to unmask]]
Sent: Monday, August 05, 2002 12:04 PM
To: [log in to unmask]
Subject: Mortar mix for Hill Auditorium
I have a technical question for youz (gender-neutral) guys:
We specified a mortar mix of 1/4 part white Portland cement, 2 parts
hydrated lime, and 7 parts sand to match the historic mortar. The brick
are really hard, testing out at 14,500psi, so mortar strength is not the
problem, unless it is too weak. Initial tests of our mix are just that,
too weak, starting at 620 psi, and not increasing at 14 days. Something
might be wrong with the mix. This is all using too much time, and the
contractor is anxious to start his repointing and rebuilding at repair
areas, and we keep saying we need the mortar mix to test initially at
750 psi, with indications that it will increase at 14 and 28 days,
before his work can proceed.
Should we give up and switch to 1:1 1/4: 7 to make it more like a
standard Type N mix, or should we hold out for the hybrid historic
mortar, when strength is not the problem? Our testing consultant would
like us to stay with the high lime mix, but I'm feeling time pressure to
revert to the standard.
I know I won't get a straight answer, but I might find a reply on this
email list that I had not, even in my wildest dreams, imagined possible.
Surprise me... Thanks.
Ilene R. Tyler, FAIA
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