Efflorescence can come from anywhere in the masonry envelope, of course -
mortar, CMU, etc. The bloom which is not unusual on new masonry work should
peak at around 18-24 months and then begin to weather away from there. If it
continues to get worse beyond that, it may be an indication that you have bulk
water infiltration somewhere and the water is continually making its way out
through the mortar, dropping the salts as it evaporates there.
If you are using lime/cement, rather than masonry cement, (as your question
suggests) spot to spot variations in color can be related to workmanship
during mortar installation. Inadequate/inconsistent pre-dampening, or tooling
too soon or too late are a couple of things that can cause these color
variations. As for efflorescence in the cracks, you may be looking at
autogeneous healing of the lime.
As for iron contamination in the CMU, we have seen this before. I was told by
one CMU manufacturer that this can be related to poor equipment maintenance
and/or sloppy procedure in the plant, resulting in iron contamination of their
sandpile.
Edison Coatings, Inc.
M. P. Edison
President
3 Northwest Drive
Plainville, CT 06062
Phone: (860) 747-2220 or (800)697-8055
Fax: (860)747-2280 or (800) 697-8044
Internet: www.edisoncoatings.com
E-Mail: [log in to unmask]
> Got a question re: efflorescence. I am looking at a 3 year old bldg
> (built with a polished-face CMU, that looks almost like terrazzo) with
> some efflorescence in the (colored) mortar joints; there are two
> different-colored mortars used with the two different-colored blocks.
> My prior experience has left me with the observation that 1) some
> degree of efflorescence is pretty much unavoidable; 2) some may be
> incurable, or at least until the lime is all leached out; 3) some may
> be due to concentrations of lime in mortar which was not adequately
> mixed/dispersed (why else would it show up in this particular joint
> and and not 3' away?). In a few cases, the efflorescence shows up in
> hairline cracks within the block, which makes me think that in these
> areas at least, the efflorescence is the result of the setting mortar
> (assuming the block were grouted solid) rather than the colored
> pointing mortar. Given this last bit, is it likely that the
> efflorescence is a byproduct of the setting mortar which only leaches
> through the colored pointing mortar?
>
>
> Ralph
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> ZƧv^w(}hr 쨺 ا m-
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