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Re: Masonry Cement

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Domenic,

I will not permit the use of either "masonry cement" (ASTM C 91) or "mortar 
cement" (UBC Std 21-14) as both are proprietary products whose ingredients 
are known only to the producer.  Neither specification requires that either 
have *any* portland cement as an ingredient.  In fact, neither specification 
requires any specific ingredient in the product.

Prepackaged mortar conforming to ASTM C 270 is all of the dry ingredients 
preproportioned and packaged and is the same as (or better than) job mixed 
mortar (# of shovels of sand to # of bags of portland cement to # of bags of 
lime) and only has to have water added.  Prepackaged mortar conforming to 
ASTM C 270 should not be confused with "masonry cement" (ASTM C 91) or 
"mortar cement" (UBC Std 21-14).

Masonry constructed with "masonry cement" or "mortar cement" has been 
reported to be less resistant to moisture than portland cement-lime-sand 
mortar.

Hope this helps.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Domenic DeAngelo wrote:

>>Section 2104.4.6 of the Massachusetts State Building Code (6th Edition)
states "Material Requirement: Neither Type N mortar  nor masonry cement
shall be used as part of the lateral force resisting system."

The masonry subcontractor on a job wants to use  pre-proportioned blend of
masonry cement that meets the requirements of C-150 for the Portland cement
and C-207 for the hydrated lime. The mix (with mason's sand) produces a
masonry mortar that conforms to ASTM C-270 Type S.

Two questions:

Does anyone know why "masonry cement" was put into Section 2104.4.6?

Can the contractor use the pre-packaged mix?

Thanks in advance,

Domenic W. DeAngelo P.E.<<

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