Garden wall repair

neilmcl

My front garden wall's piers are topped off with brick on edge and due to a combination of moss growth and snow/ice getting in over the years the mortar is failing on some of them. I'm tempted to do the repair myself and was wondering what's the best mortar mix to use in this instance, particularly to prevent it happening again. Should I consier using a sharp sand in the mix. Also, I'm not sure whether a lime or cement based mortar was used as it looks very light, although I suppose this could be the sand that was used. Here's a pic of one of the worst piers.

stuart45

4/1 sand/OPC would be a common mix for something like that. Sharp sand is a bit harder to work with for brickwork. One of the problem with a brick on edge is that a lot of bricklayers don't fill the joints properly.
If you DIY start in the center first. If you start at the edge you tend to push the end brick out a bit. Try and slope the bricks a bit so the moisture runs off.

Belenus

Consider buying some flat coping stones to place on top. They can look nice.

That would both cover up the dodgy mortar on the top and protect it from getting worse.

You might still have to redo some of the mortar on the sides 

stuart45

Pier caps are a good idea, but he will probably have to match another pier, and then possibly want to lay some matching coping on the wall.
Does protect the wall a lot better though.

neilmcl

Belenus said:

Consider buying some flat coping stones to place on top. They can look nice.

That would both cover up the dodgy mortar on the top and protect it from getting worse.

You might still have to redo some of the mortar on the sides 

I wanted a more traditional, rustic look, particularly with the choice of brick so didn't want pier caps, plus out of 7 piers only 3 need looking at and it might cause more damage trying to remove the other pier edging bricks.

FreeBear

Looks like the mortar used snowcrete (a white cement), perhaps with a bit of hydrated lime mixed in. If it is indeed a lime mortar instead, it should be fairly soft & friable. Drop a sample in to a bit of vinegar - If it fizzes, then it could well be a lime mortar.