The guy who built our boundary wall didn't attach the capping stones , he just plonked them on the top and presumed that gravity alone would be sufficient.

Well normally thats OK - until (as they will do when they're 8 )  grandchildren walk along the top and then ...... FFS

So I need to fix the capping stones properly.

 

That means I need a sharp sand mix.  I  haven't got any sharp sand left. But loads of builder's sand.

I've got some 10mm limestone to spare.

 

Is it OK to whack some of that 10mm into the mix to sharpen the mortar up? 

I will of course butter the bottom of the capping stones.

 

Yours - Disgusted of Lancaster

Edited April 29Apr 29 by ToughButterCup

I would just use the builders sand on its own. It'll be easier to level the capping stones as you lay them.

I think anything you add needs to be finer than 10mm. Maybe supplement your builders sand with a small bag or two of sharp sand. If you have any SBR that'll strengthen the mortar and also make a good slurry for buttering the coping.

I replaced some paving/capping last year using foaming polyurethane adhesive. Worked great. Soudial or something like that it was called.

 

 

Edited April 29Apr 29 by Temp

This is what I used. It foams up a bit so had to take care not to use too much that it came out of the joint.