Replies

1. 
   canuk | Mar 01, 2006 02:23am | #1

   No aggregate=no strength. Are you sure he's not using any sand?

2. 
   zak | Mar 01, 2006 02:29am | #2

   I think you might mean type S mortar, not type S cement (which I've never heard of). type S should be ok, although it's more cement than you need for interior stonework, and thus more difficult to clean off the rocks. I usually use type N for exterior stonework, unless I'm mixing my own.

   You might want to look at this, too: http://www.taunton.com/finehomebuilding/pages/h00032.asp

   zak

   edited to make hyperlink work (I hope)

   
   

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   Edited 2/28/2006 6:29 pm by zak

3. 
   jayzog | Mar 01, 2006 03:44am | #3

   Type S is a mix of approximatly 1 portland & ¼-½ lime& 2¼-3 times the cement volume in sand.

   There is ready mix type S available, that already has the correct proportions,which may work, but for stone work, normally the mortor is portland & sand-no lime.

4. 
   csnow | Mar 01, 2006 04:48am | #4

   Type S mortar has lime in it.

   It's a pretty good compromise between compressive and tensile strength, and it is pretty workable.  I use it for most exterior masonry work, unless I have soft brick, and I need a softer mortar.

   For interior work Type S is fine, but is overkill.  I would use a softer mortar (more lime in it) because it is easier to work.

1. 
   john_carroll | Mar 01, 2006 05:26pm | #5

   There is a lot of confusion about mortar, even among professional masons. First of all, mortar is a generic term. It can be any of dozens of mixtures used to hold masonry units, stone, tile or glass blocks together.

   In the masonry industry there have been two competing kinds of mortar for decades. These are portland cement/lime mortars and masonry cement mortars. Portland cement/lime mortars are usually, but not always, blended on site. Masonry cement mortars are also portland cement based. But the admixtures are proprietary ingredients and they are always preblended in the bag. The manufacturers of masonry cement mortars don't disclose the exact ingredients of the admixtures. They may or may not include lime, pulverized clay, and latex. The mortars sold at HD and Lowes are masonry cement mortars. When I use portland cement/ lime mortars, I get the ingredients in two separate bags at my masonry supply store and proportion them on site.

   Both kinds of mortar meet ASTM standards and the competition between the manufacturing groups is roughly equivalent to the competion between the makers of plywood and OSB. Both kinds of mortars can be made into the four Types; namely Tpyes O, N, S and M. These Types reflect the compressive strength of the mortar, which is determined by the proportion of portland cement in the mix.

   Portland cement/lime mortars, however, seem to perform better in terms of water infiltration into the wall. For this reason, they are usually specified for commercial work. Masonry cement mortars are cheaper and easier to use and, thus, are more common on residential sites. The main advocate of portland cement lime mortars is the National Lime Association http://www.lime.org. The main advocate for masonry cement mortars is the Portland Cement Association. I think their address is http://www.cement.org.

   If all this is not confusing enough, the makers of masonry cement mortars have come up with yet another class of mortar, called "mortar cement mortar." This preblended mortar is designed to combine the performance of portland cement lime mortars with the convenience of masonry cement mortars. This mortar can also be made into the different Types noted above.

   To get back to the original question, all these mortars should be mixed with sand. The proportions are 2 1/2 to 3 parts sand to 1 part cementious material. 

   Edited 3/2/2006 8:30 am ET by Mudslinger