Mortar Identification

**David D. Whitt** · 03-05-2010, 06:45 AM

I am trying to identify this type of material used in the mortar joints. It appears to be SAND. I took my screwdriver and removed some and it flaked off without any problem. Why I ask is that I see what looks like a pea or smaller type aggregate in the joints.
Photo 1 and 2 are the same picture different angles.
Photo 3 is off of the chimney
Picture 4 window. Several windows have this same problem.
Picture 5 self explanatory.

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**Jerry Peck** · 03-05-2010, 04:24 PM

I would be VERY CAUTIOUS in identifying it as a certain type of mortar ... in fact ... *I* would not do so.

Just me, maybe, but I would report what you saw: 'what looked like mortar was mostly sand in places with some other matter in the mortar'

Just describe it, don't try to say what type it is.

**Scott Patterson** · 03-05-2010, 04:50 PM

Originally Posted by Jerry Peck

I would be VERY CAUTIOUS in identifying it as a certain type of mortar ... in fact ... *I* would not do so.

Just me, maybe, but I would report what you saw: 'what looked like mortar was mostly sand in places with some other matter in the mortar'

Just describe it, don't try to say what type it is.

I agree wholeheartedly with Jerry, just report what you found and don't try and determine the type of mortar.

**David D. Whitt** · 03-06-2010, 10:26 AM

Jerry/Scott
I agree with you..

I reported that the mortar joints needed to be re-pointed and was missing in several places on the building along with dislodged brick. Recommend repair by a licensed mason.

I was curious for myself, not to tell the client.

Thank you very much for replying.

A.D. Miller · 03-07-2010, 03:46 PM

DW: Each time I recommend re-pointing or pointing up mortar I include a copy of this:

**John Goad** · 03-07-2010, 04:00 PM

AD, I had a new construction inspection one time where there were some mortar joints that needed pointing up, I received an irate phone call from the contractor wanting to know what difference did it make which way the mortar joints were pointing. Ya gotta luv it.

**David D. Whitt** · 03-07-2010, 08:12 PM

Originally Posted by A.D. Miller

DW: Each time I recommend re-pointing or pointing up mortar I include a copy of this:

Thanks AD, great information.

**Michael Thomas** · 03-08-2010, 04:51 AM

By the way, interesting IMO link in the references at the bottom of the page that A. D. linked to: how to properly (per the BIA) to remove plant growth from brick:

http://www.gobrick.com/pdfs/Ivy%20on...TOKEN=98213001

**Bob Harper** · 03-08-2010, 07:03 AM

I agree I'm not sure why a HI would need to determine the analysis of the mortar per se. However, when reading that Tech Note that AD provided, you really need to click on the link about preservation and lime mortar. If a building was constructed using lime mortar then that is what it should be repointed with. In the East, most any structures built before 1925 should be considered lime mortar until proven otherwise. Portland cement mortars are very hard, which can lead to spalling of brick and stone and moisture retention problems. Lime mortar is soft, undergoes autogenous healing (recarbonation from atmospheric CO2) and porous so it breathes moisture vapor.

There are several good historic mortar preservation companies out there that do a mortar analysis and matching. If you are doing a historic preservation, the formal matching can cost several thousand dollars just for the analysis. However, some, such as the Va Lime Works will do a cursory match for very little. Regardless, these companies will sell you the matching lime mortar and recommend matching aggregate for local purchase.

This appears to be local creek sand. It was usually dug locally, given a quick rinse if you were lucky then mixed. A lot of impurities in it, which often lead to early joint failures. Beach sand is the worst. Really eats up steel and fails almost predictably. The Calif. coast is crumbling because of its rampant use.
HTH,
Bob

Ken Bates · 03-08-2010, 04:44 PM

Hopefully you are stating that these joints are too large and that they are the worst type to use, worse than raked joints. (although aesthetically nice)

Lime mortar will often fizzle in acetic acid (vinegar).

chris mcintyre · 03-08-2010, 06:09 PM

Originally Posted by Ken Bates

Hopefully you are stating that these joints are too large and that they are the worst type to use, worse than raked joints.

If these are not raked joints, then what are they called?

**Jerry Peck** · 03-08-2010, 07:14 PM

Originally Posted by Bob Harper

Beach sand is the worst. Really eats up steel and fails almost predictably. The Calif. coast is crumbling because of its rampant use.

South Florida has the same problem with older structures too, but that practice by the mid-1930s to mid-1940s, and then even using washed beach sand stopped by the mid-1950s because they found out that washing beach sand still left a lot of salt in the sand. Most spalling problems prior to the mid-to-late-1950s was the use of beach sand, after that it is due to the severe salt environment down there near the coast (any where along the coast has the same problem, still affects modern structures, and the use of epoxy-coated steel only made the problem worse - but localized the problem - in that any and all chips in the epoxy coating caused all the galvanic action to take place at those chipped areas instead of spreading the effects out along the entire piece of steel, meaning that one spot would get eaten through and the rest of the steel would be "okay" ... if you consider rusted through in sections rebar to be "okay" even though it lost it useful strength by no longer being continuous).

**Matthew Klein** · 03-13-2010, 04:40 PM

Are you going to mention anything about the algae growing on the block, indicating that it has seen more than its share of moisture which likely contributed to, if not caused, the mortar failure?