Masonry cement mortars (masonry cement + sand+water) are made from
proprietary mortar mixes called masonry cement. The manufacturer
combines into one bag portland cement with such materials materials as
natural cement, finely ground limestone or hydrated lime, an
air-entraining agent and gypsum to regulate the time of set. The
principal advantage of of masonry cement mortar is its convenience in
mixing, and generally good working properties. However, since the
masonry cement standard ASTM C-91 does not limit the additives, ad does
the portland cement standard, each manufacturer has the option of
varying the types and extent of additives. This makes it difficult to
predict the performance of masonry assemblies erected with masonry
cements in general, although laboratory test results from individual
manufactures for specific cements can serve as a guide. The short
answer is that it is easy to use masonry cements. If individual
components had to be blended on the job site the results would be even
harder to predict. The materials work well for new construction. I do
not recommend masonry cements for very soft old brick lime and sand
would be safer.
On Tuesday, February 4, 2003, at 04:40 PM, Hammarberg, Eric wrote:
> Folks,
>
> I am trying to find out why masonry cement (MC) is on the market when
> portland cement / lime (PCL) mortars appear, at least to me, to perform
> better and more reliably?
>
> As many of us know, MC is typically a mix of portland cement,
> pulverized
> limestone and "proprietary admixtures" which manufacturers seldom
> (never)
> will divulge. PCL is portland cement and lime, period.
>
> Can anybody shed light on this for me?
>
> Thanks,
>
> Eric Hammarberg
> Still Director of Preservation
> Associate
> Still at 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]
>
>
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