In message , Harman Sanghera writes
I have a patio area in the back garden, and also a lot of paving stones in
>the front. I have to pressure washer these area regularly due to having a
>lot of trees nearby. Some of the joints in the paving stones have come
>"apart", i.e. there is no mortar (or whatever was used) in the joints. How
>can I replace the joint compound and what with? I want it to be able to
>withstand pressure washing which I have to do at least once a year.
I assume that there is a reasonable gap between the slabs? - about 10 mm. (If the slabs are butt jointed like you find on pavements with concrete slabs then you can't do the following)
They need to be repointed with mortar, scrape out the old stuff and repoint. I would do this with a wet mortar mix.. You can do it with a dry mix brushed into the joints, but on already laid slabs with dry joints I don't think it works as well.
Have a look at: