Sam Stockley
Hi James, What you need is a "Jointing Compound". It is a resin based sand that fills the joints and sets rock hard! It comes in different colours to match all types of paving. You simply brush it into the gaps and let it harden, the added bonus is that it doesn't mark/stain the slabs as a traditional mortar would. I suggest Easy Joint, Geo-Fix or Pavetuff. Make sure you read the individual instructions as all products differ slightly. Best of luck.
