I’m making a patio out of irregular limestone flagstones, bedded in masonry cement (9:2:1 ratio of sand, portland and lime… is that Type-N or Type-S?) I still need to grout the cracks, or to be more accurate, I need to build up the gaps between the rocks (since the rocks are irregular, these gaps range up to 3″ across.)
I’m wondering what ratio of materials to use for the grout. I seem to recall that grout is usually a 1:1 ratio of sand and cement. Considering the softness of the limestone, it seems like a good idea to add some lime. Does this make sense to y’all, and does anyone have a suggestion for the ratio?
Thanks,
John
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I'm not an expert on this topic by any means but really wonder why you feel you need to concoct your own mixtures. What I'm suggesting is that most people buy a masons mix and then the only variable is the amount of sand... I gotta think there is more in those mortar mixes than just cement and lime, and I'd be more trusting of a manufacturing plant to get an even mixture at the correct ratio.
Thanks, I'll look into it.
I mixed my own mortar mainly to save a few bucks. Money's a little tight right now, so I decided to spend time instead by making a second trip to get sand. The mix is a standard ratio, so there's no surprises there.
Ordinarily, the joints would be tooled after the rock was set. Since the stones were irregular, I found it easier to mix a little more water into the cement and jiggle them down to level. Sure, the extra water might weaken the mortar, but I think that this gave better adhesion and helped prevent voids under the rock. I didn't have time each day to wait and come back to work the joints, so I decided to just leave gaps and "grout" them out later.