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[SEAOC] Re: [SEAOC] Type M vs Type S mortar

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You wrote:

>Aside from strength what are the relative benefits of the two types of
>mortar?

We have found that type M, while giving higher compressive strength often
gives lower bond strength to the block. While not imporant in most
applications, in heavy wind loads, where some codes allow use of
unreinformced masnory in minor tensions, bond strenth, which allows
flextural stresses to develop in the wall can be very benificial.

Since the allowable flextural stress is usually quoted as a percent of f'm,
it would seem that the M would give higher allowable flextural stresses.
Since the bond is often lowered, it in fact does not, based on our testing.
So we often find ourselves specifing S mortar where the compresive stresses,
and placment considerations will allow. This is of course, a savings to the
contractor.

John Pepper, P.E.
John Pepper
The Pepper Engineering Group, Inc.
20895 East Dixie Highway
Aventura, FL 33180

pepper(--nospam--at)netrunner.net

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