The method we typically use is called "stitch repair", which involves grinding down the entire length of the crack, and then adding cross sections every 200mm accross the length of the crack, afterwich a renforcing metal "strip" or "stitch" is placed into these cross sections. Once these stitches are inplace we fill the entire crack with a 2 part epoxy resin, then a thin layer of sand is applied to the surface.
Following the crack repair, if required we trowel on a 2 part DPM (damp proof membrane) system, followed by a thin layer of smooth sceed to completely seal the surface ready for our
Microcement to be applied.