Before starting any repair check the crack is static and no longer growing, otherwise the damage will occur again.
CHECK THE CRACK by using a permanent marker on the ends of the crack. Measure and mark the height variation if one side of the concrete has lifted. Leave it for a month then check the marks and measurements again. If no changes have occurred then do the repair.
●1 CUT ALONG THE CRACK
To straighten and neaten the cut mark lines to follow it and use a masonry or diamond blade fitted to an angle grinder or circular saw to cut at least 15mm deep along both sides of the crack.
●2 BOLSTER OUT THE WASTE
Chip out the damaged section using a bolster with a lump hammer along the
cut lines. Remove the chipped piecesand vacuum out the remaining waste.
Paint a primer such as Bondcrete on the inside edges of the crack.
●3 FILL WITH CONCRETE
Add water to the concrete mix, blending it to a creamy consistency.
Fill the crack to above the surface, packing it tightly with a spatula.
●4 FINISH THE SURFACE
Drag a rubber floor squeegee over the crack to smooth the concrete,
feathering the edges and finishing with a steel or timber float, levelling
it out to match the surrounding surface and leaving to dry.