The Brew Cabin

I sure hope you all can help me here in Colorado.
We have a small (20' x 10') covered flagstone porch that is in need of minor repair.
It looks like the previous owners tried to fill in some of the mortar with some kind of premixed (grey) cement. Not only does it look horrible but in the two years we have been here the cement is coming out leaving the original 50 yr old coarse pink mortar at a lower depth than the stone in most places. The flagstone is irrregularly shaped and is in good condition except for the sloppy job with the cement on some of the stone.
I would like to make the necessary repairs and also have the mortar a darker color to contrast with the lovely dark pink stone (I'm thinking a dark green to match the moss covered mortar of the same type flagstone path in front of the house and thru the garden.
Can you give me any direction on this type of repair, what to use and how to do the job so it will last?
Thanks!!

Hi Caron,

I think the best way of tackling this job would be to cut out all the existing mortar to a depth of at least 25mm (1 inch for you non-metric N.Americans!) and then re-point with a new mortar that has been coloured and strengthened to meet your needs. It would be even better if you could cut out all of the 'grey' mortar and get down to the 'pink' pre-existing mortar, so that you're laying the fresh stuff onto a reasonably sound substrate, rather than overlaying the known-to-be-iffy grey patch pointing.

I'm not familiar with what's available in N.America, but a good mix would be 4 parts building sand, 1 part cement, plus your chosen colour dye, and then a strengthener, such as SBR (Styrene Butadiene Resin ) which makes a normal mortar much harder and creates a stronger bond between the paving and the mortar itself.

There's a product I know is sold in the US that might be suitable - Dynabond (or is it Dynobond? ) Anyway, it's an epoxy-based mortar, so it will be incredibly hard-wearing and strong.

Once you've got the mortar, follow the guide given on the Pointing page to fill in the empty joints. Feed it into the joints and then smooth it off so it's 1-3mm (one-eighth inch ) lower than the surface of the flagstone.

Hope that helps

Thanks Tony for your speedy reply!!

I can remove all the patch job, but some of the original mortar is level with the flagstone (out of the high traffic areas such as nearer the house). How would I remove this (it's very hard) without damaging the flagstone? Or, can I give it a light coating on top so that all the mortar will match??

Are you familiar with an Angle Grinder? You can use one of these, with a stone-cutting disc fitted, to cut out any old mortar.

Score the old, stubborn mortar pointing with the angle grinder to a reasonable depth (25-40mm ) then use a hammer and bolster/chisel to break out anything lect behind. You'll need mask and goggle, of course, but it's not that hard a job.

Got it!! Thanks for the info on this.
Btw, great site you have here!