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-   -   Ramifications of Using an Incorrect Mortar Mix (http://www.diychatroom.com/f19/ramifications-using-incorrect-mortar-mix-9680/)

makke 07-06-2007 11:34 AM

Ramifications of Using an Incorrect Mortar Mix
 
We believe that our contractor may have used 100% portland cement to set our clay patio bricks instead of the cement/sand/lime or cement/sand mixtures as recommended pretty much everywhere I've looked. What are the likely ramifications of using 100% cement?

Thank you.

Brik 07-06-2007 02:43 PM

I have heard of this but have no experience. How does it look? How does it feel under foot? What is the base under the bricks? Are they really clay bricks or are they pavers?

makke 07-06-2007 04:02 PM

"How does it look?"
It looks fine to my untrained eye.
"How does it feel under foot?"
Feels solid, they are set in mortar, after all.
"What is the base?"
A concrete slab on top of gravel.
"Are they really clay bricks?"
Yes, they are really clay bricks. We chose them specifically because we don't like the artificial look of paver systems.

SecretSquirrel 07-08-2007 09:54 AM

I would expect 100% Portland to be very brittle and to separate from the pavers over time due to expansion and contraction from temperature fluctuations.

Quote:

We believe that our contractor may have used 100% portland cement
Is there some doubt as to what he REALLY used? Why don't you call him and ask him directly?

concretemasonry 07-08-2007 05:38 PM

Where did you get the rumor? Were there any bags of materials left around after he left?

Just ask what he used.

It would be much more expensive and troublesome to use Portland cement and water without sand or lime if he could even work with the mixture.

Have you considered that he may have used a pre-proportioned mix that was bagged?

Tscarborough 07-08-2007 06:24 PM

Portland cement mixed with water is unworkable and would be cracked and dusty within a day or two.

makke 07-08-2007 07:07 PM

Thank you for the comments. We are not sure exactly what was used because at the time we thought they knew what they were doing and, as a result, we did not pay a lot of attention. When the patio dried, however, all of the bricks were discolored. So, we started doing our own research.

Turns out that they installed the bricks like tile, with grout placed into the gaps and wiped with a damp sponge. The discoloration is from the mortar being smeared around and absorbed by the porous bricks. The proper technique is to butter two sides, place the brick, and wipe away access with a trowel. The tile technique is also likely to leave voids within the mortar that will initiate cracks due to freeze/thaw cycles.

Anyway, to make the long story short, once we figured out that they used a totally incorrect technique, it became obvious that they did not know what they were doing. Therefore, we started questioning other things. I remember seeing bags that said "Portland Cement" and I don't recall seeing them mixing in any sand. However, it is certainly possible that the bags were indeed a proper pre-bagged mix.

The contractor is on vacation for two weeks. We will ask him when he gets back. However, before we did that, we wanted to understand the possible consequences. Your comments are very helpful -- thank you.

Tscarborough 07-08-2007 07:34 PM

Actually, the proper method is to set the brick into a mortar bed, then use a grout bag to fill the joints. You do not grout it like tile.


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