Obligatory first-time-mortar-concerns post

[ThisOldGarageNJ]

A couple of things. Lime is a plasticizer, not an accelerant. It does not increase the set time, it decreases it. Portland is used in lime plasters to gauge them, i.e. give them a faster set FYI.

So what your saying TS is that the portland regulates the lime, rather than the other way around.

The forum post have always been not to use too much lime as it will cause your mortar to "go off" quickly...

After reading Kebs post, What suggestions do you offer ?? Remember we are all here to help....

Cheers
Mark

Cheers
Mark

[kebwi]

Just for the record, we all use weird handles here...my name is Keith, just in case you didn't pick up on it. kebwi is a mangling of initials from my full name. keb is kindy catchy though, I don't mind. I find the handles distancing. It's too bad the forum interface doesn't encourage real-name-usage more easily, by including it somewhere that is easy to see.

One odd thing is, I remain a little unclear on the distinction between mortar and concrete. Other than the aggregate size, I don't see a difference.

Well, I'll keep plugging away, maybe trying less lime (I'm already at 1/13th, 6:4:2:1). I actually haven't felt that I had any trouble with the mortar setting too quickly...to the extent that I know what setting is when I see it. I have found my mortar to be fully workable for the twenty to thirty minutes that it takes me to use up a small batch.

Cheers!

[ThisOldGarageNJ]

Hey Keith, Keb....
I checked out your website,, you have some very cool stuff going on there... The Main reason I used heat stop 50 is that it removed a lot of variables for me.. The homebrew mortar here has been sucessfully used by so many,, I wish someone here with more experience with it can chime in and offer more suggestions for you..

One odd thing is, I remain a little unclear on the distinction between mortar and concrete. Other than the aggregate size, I don't see a difference.

Mortar is a cement/sand/water (and usually lime) mixture designed for laying up masonry units like cement block, stone or brick. Mortar is "sticky" so it adheres to the block, stone or brick. Concrete is designed to stand alone

Mortar and concrete are random composite materials, with the fine and coarse aggregate acting as the inclusions and the cement paste acting as the matrix. The only real difference between mortar and concrete is in the size of the aggregates used. Typically, the maximum aggregate diameter in a mortar is 1- 3 millimeters, while the maximum aggregate diameter in a commercial concrete is around 30 millimeters.

I think you hit the nail right on the head with your definition

Cheers
Mark..

p.s. Maybe Keb can be your altar-ego

[Tscarborough]

Keith, in your thread "parge recipe", I explained the differences between concrete, mortar, and stucco.

Lime mortar, that is mortar made with just lime and sand, will not take a set for hours (and this only because of the moisture absorbed by the masonry units), and will not cure for days to weeks. The reaction it relies upon to set is with carbon dioxide in the air to form calcium carbonate. Thus, lime mortar is not hydraulic.

Portland cement relies upon the water in the mix to hydrate. Thus it is hydraulic, i.e. the reaction is internal and does not rely on external ingredients (like carbon dioxide).

Adding lime to a mortar will increase the set time, but the most important reasons have to do with bond strength and workability.

[kebwi]

Originally Posted by ThisOldGarageNJ

Mortar is a cement/sand/water (and usually lime) mixture designed for laying up masonry units like cement block, stone or brick. Mortar is "sticky" so it adheres to the block, stone or brick. Concrete is designed to stand alone

Mortar and concrete are random composite materials, with the fine and coarse aggregate acting as the inclusions and the cement paste acting as the matrix. The only real difference between mortar and concrete is in the size of the aggregates used. Typically, the maximum aggregate diameter in a mortar is 1- 3 millimeters, while the maximum aggregate diameter in a commercial concrete is around 30 millimeters.

Weeeellll, when I said I didn't understand the difference, I fully understood that concrete is that "stand-alone stuff" in driveways patios and that mortar is "brick-glue". What I meant was that, aside from aggregate size, I couldn't see the difference in components or approximate ratios within the margin of variety, so it seemed difficult for one to "be different" or to applied toward different goals than the other...since they are basically the same stuff aside from the aggregate.

Just as an example, you say that mortar is usually sticky...but they're the same stuff! That confuses me. I think I am picking up that it is lime that makes mortar sticky...so maybe you're saying mortar has more lime than concrete...but that seems completely at odds with what I've read about parging. I realize parge isn't the same as mortar, but it has to be sticky to hold to a vertical wall while at the same time most parge recipes have no lime at all...so, more confusion...but it's my problem. Really, don't worry about it. I'm obsessive, I admit it.

That's all I meant. Let's consider this dead-horse beat to a pulp. Thank you for entertaining the discussion, but I don't want to bother you.

Originally Posted by ThisOldGarageNJ

p.s. Maybe Keb can be your altar-ego

Wow, my alter-ego has an alter-ego.

[kebwi]

Originally Posted by Tscarborough

Keith, in your thread "parge recipe", I explained the differences between concrete, mortar, and stucco.

Yeah, thanks. I need to ponder this a bit. I'm not trying to be argumentative. Let me dwell on it and reread the posts some. I may be falling behind, or drowning in information. Thanks for the detailed input.

[ThisOldGarageNJ]

drowning in information

That is ust one of the many problems of the internet........