Masonry: Mortar Vs Grout

So looking at mortar versus grout, the basic difference is mortar has lime. Oops, what happened here? I need a better color. Sorry. Mortar has lime plus sand plus cement plus water. but grout does not have any lime. So that's the big difference. And what lime does is it allows the mix or the mortar to have adherence qualities, which means it can bond the CMU together. It can bond the brick together. That's what the lime does. And it has more sand than grout has sand. And of course, it's applied with a trowel. That's for the mortar. As for the grout, it has no lime and it's runnier. So it has a little bit less sand and more water. And it is poured or pumped versus mortar that is applied with a trowel. So grout is for filling voids. So inside of CMU cells or underneath a steel base plate, underneath a steel column base plate, you would use some non-shrink grout. So the main quality of grout is that its workability or its flowability is good so it fills in gaps. So back to mortar. Mortar has lime. And here are the proportions. I didn't have a graphic for this, so I went to Amerimix. They had this chart, so I cut it, pasted it, and gave them credit for it. But basically, there is five types of mortar, and two of them, the M and the S type, are high strength, 2,500 PSI, 1,800 PSI versus the type N and O are less strength, and they are used above grade versus the type M and S are used above or below grade and are structural. So for high wind zones or for structural masonry. So these guys are high strength and low workability. So they're a little bit, they don't flow as well. But they are good. The type M is good for freeze-thaw cycles. So, of course, this one, type S is less strong than a type M, but it flows a little bit better. And then these are the non-structural and used for chimneys or parapets or things like that. That's the type N. So it has medium strength and medium workability. So it can flow well. But the type O is low strength at 350 psi. It's low strength and it is used typically above grade. Now, not in this table is a type K mortar, and that one is 75 PSI, and it's basically used for historic preservation, restoration of historic structures, and pointing mortar, and that's what it's for. So it's very low strength and never used in new construction. So it's a softer mortar, and its intention, the type K, is to protect historic masonry so that it doesn't break. Typically, mortar is weaker than brick, so that if there is some kind of differential movement or a crack, then the weaker material gives, which is the mortar instead of breaking the brick, because pointing the mortar and replacing the mortar is easier than replacing the brick itself once a crack happens. So that's the story of mortar versus grout, lime versus no lime. And there is a simple way of remembering this. I've read it many times. It's like mason work is okay. Okay.