Repair mortar is a ready-made, cement-based mix designed for repairs to concrete: ceilings, beams, columns, balconies. Compared with ordinary plasterRender (plaster)A layer of mortar (sand, cement or lime, and water) spread over brick or concrete to give a wall a straight, sound surface ready for paint or tiles., it grips old concrete more strongly and shrinks less as it dries, so a crackCrackA split or gap in render, concrete, a wall, a coating or wood. Fine cracks are usually only on the surface; ones that grow, keep reopening or run diagonally need attention. is less likely to open around the patch.
It is used mainly when rebarRebar corrosionRust on the steel bars inside concrete. Rusting steel swells, cracks the concrete around it and makes it fall away in pieces, leaving the bars exposed. corrosion has broken the concrete. The area is opened up back to sound material, the bars are cleaned and given an anti-corrosionAnti-corrosion coatingA protective coat brushed onto steel reinforcement, once the rust has been cleaned off, so the bars don't keep rusting before they are covered with new material. coating, and then the missing section is rebuilt with repair mortar so that it covers the bars on every side. FillerFillerA fine paste or powder that fills holes, fine cracks and dents so a wall, ceiling or piece of wood is smooth before it is painted. and paint go on top.
There are different types, for thin or thick layers, for indoors or outdoors. The choice depends on how deep the damage is and where it is. And as with any concrete repair, it only lasts if the water that caused the damage has been stopped.
Related terms
Rebar corrosionRebar corrosionRust on the steel bars inside concrete. Rusting steel swells, cracks the concrete around it and makes it fall away in pieces, leaving the bars exposed.Anti-corrosion coatingAnti-corrosion coatingA protective coat brushed onto steel reinforcement, once the rust has been cleaned off, so the bars don't keep rusting before they are covered with new material.Render (plaster)Render (plaster)A layer of mortar (sand, cement or lime, and water) spread over brick or concrete to give a wall a straight, sound surface ready for paint or tiles.CrackCrackA split or gap in render, concrete, a wall, a coating or wood. Fine cracks are usually only on the surface; ones that grow, keep reopening or run diagonally need attention.
