Sandy mortar

[Rick Cantrell]

35 year old house with brick siding.
The mortar is very soft and can be easily scraped out with a key.
The surface of the mortar is white, but scrape the white off and the mortar is dark. The dark mortar is just as soft as the white mortar on the surface.
On the window ledges, near the ground where water splashes on the wall, and a few other areas, the mortar is almost completely gone.
In one area all the mortar is gone and I can see the foundation.
In most places the mortar is fine.
I have seen this before but always on 100 year old brick.
I suspect bad mix of mortar, but would like your opinions.
Thanks
YouTube - VID 20110305 142302 (http://www.youtube.com/watch?v=F4-YRkDtseM)

[Vince Santos]

Looks like typical water damaged caused by lack of weep holes to me.

[James Duffin]

When I was in high school the bricklaying teacher mixed the mortar mix with more sand than normal so the bricks could be cleaned up easily and reused. This sandy mix did not hold up too well to water. This is what it sounds like you have at your house....sand enriched mortar.

[Rick Cantrell]

Looks like typical water damaged caused by lack of weep holes to me.

Not typical on a 35 year old house that I've seen.
also the video was showing mortar at 3 ft up. Only 1-2 ft over the mortar was fine.


When I was in high school the bricklaying teacher mixed the mortar mix with more sand than normal so the bricks could be cleaned up easily and reused. This sandy mix did not hold up too well to water. This is what it sounds like you have at your house....sand enriched mortar.

I also took brick mason class. We used sand and lime.
We called it practice mortar.
Is a possibility that too much sand was used.

Thank you both for your answers.

[Fred Herndon]

Rick,
I have run into the same thing with a few houses built in the 1940s here and was told by an old brick mason that they sometimes used left over fly ash from burning coal in the mix. Of course, when it gets wet sufur compounds from combustion mix with water and form sufuric acid. Which, of course, eats out the lime leaving you with pretty much what the video showed. That would account for the color, softness and erosion near the ground (where it gets wettest).

[Timothy M. Barr]

Fifty plus years of brick laying, experince say
Mason used the wrong mixture or wrong type on cement
Recommend tuck pointing before brick start to shift

[DANIEL SNYDER]

Besides the wrong mix with excess sand, there could be too much lime. the fact that the surface is white leads me to belive that there is efflorescence which is pulling the lime out of the mortar. Besides having proper drainage behind the brick, the brick itself may be absorbing too much water which would make the problem worse.
As the water pulls out the lime from the mix, the mortar weakens. The mortar may not be the proper strength as well. The most common types of mortar are M, S and N. They correspond to compressive strengths of M=2500 PSI, S=1800 PSI, and N=750 PSI.

Lastly, modern bricks, post WWII, are hard bricks and can damage the mortar as the wall moves during thermal expansion.

[Wayne Carlisle]

Rick,
I have run into the same thing with a few houses built in the 1940s here and was told by an old brick mason that they sometimes used left over fly ash from burning coal in the mix. Of course, when it gets wet sufur compounds from combustion mix with water and form sufuric acid. Which, of course, eats out the lime leaving you with pretty much what the video showed. That would account for the color, softness and erosion near the ground (where it gets wettest).

If there was fly ash in there I don't think that would cause this type of problem. Fly ash makes concrete stronger.

[Mitchell Toelle]

Wayne C.,

You are right of course...at least over a long period of time...and depending on the quality (size) of the fly ash. If unclean, larger fly ash particals are present when added to the mix, this can actually weaken the mix.

To the original poster....generally if there was not enough portland (if that is what they used and depending on the type) added to the mix you will end up with a sandy product that is not bound enough. If the portland to sand mix was proper and the mix was over watered when placed (unlikely because it would then be unworkable or unuseable) then your mix will be weak and will deteriorate sooner.

BTW...another reason for adding fly ash, especially if we are talking about concrete mix for flat work or slabs, is to combat or counteract higher sulfates in the soils (only useful where a moisture barrier is not used).

[Glenn Duxbury]

Hi, ALL &

Am thinking - maybe that fellow took the same masonary class and has always been using the mix he learned (never deviated) ?

Otherwise = what Timothy stated...


CHEERS !

[Garry Sorrells]

Called into the psychic connection. Possible thought. The brick were laid in freezing weather and calcium or other additive was used to counteract freezing in addition to a wrong mix ratio or just a bad batch of cement.

35 yrs ago mason tenders were mixing using bagged cement and loose sand. Not many were using bagged mortar mix on large jobs. Saved a few dollars on job.