Bluestone and basalt pavers that are 20mm or 30mm thick are typically installed in sand and cement on a compacted base of crushed rock or gravel, with sand or mortar used to fill in the gaps between the pavers. Bluestone tiles that are 10mm or 12mm thick are layed like porcellian or ceramic tiles using a cement based adhesive on a prepared concrete slab. It’s important to have the pavers installed by a professional to ensure that they are level and properly secured.