grout terrace joints with epoxy. This is similar to the joints of cement. However, these joints are waterproof, in contrast to addition of cement which can always suck up water (and may burst in winter).
I want one of these to swing and nap in by the garden. Problem is getting someone to push me for as long as I want to be pushed. Wonder if I could rope a nearby tree and just give it a yank and swing myself?