I have in last few days laid 60x60cm grey natural paving slabs in garden to make a path. The slabs were laid right against each other just about with a gap of 1mm or so sometimes, and also on a bed of mortar mixed 1:5 cement/sharp sand.
A friend who is more DIY aware than myself said to help firm up the slabs afterwards to sprinkle sand or cement in between slabs to help firm them up, I had ran out of sand completely when finished but had cement left over, he said sprinkling a little should be fine as it would help secure the slabs.
My concern is was this right to do? I noticed a few hours after doing this that some of the slabs have developed, not cracks as such, but marks which are a few cm long and couple mm thick which do look strange.
Can anyone advise? Thanks.