Old bathroom and laundry floors often lose their
surface if this has been applied as a separate layer.
To repair, first remove all loose or cracked
concrete. If the area of damage is large and the remaining area small, it might
be wise to lift the whole surface layer, at least so far as it will come off
with a cold chisel and moderate hammer: blows. Clean off all debris. The surface
should be dressed with a suitable surface preparation, like Bondcrete, to ensure
good adhesion.
Mix concrete in the proportions 1 cement: 4 sand;
making the mix reasonably plastic. Trowel in the mix and bring level with a
screed board. Use the existing surface as a level if satisfactory areas are
sufficient, otherwise test with a spirit-level and a straight-edge, screeding
off excess with a screed board, which can be a straight piece of 100 mm x 25 mm
dressed softwood.
Leave the concrete for about twenty minutes, then
use a steel trowel in long, smooth sweeping strokes to bring water to the
surface and give a smooth finish. Some workmen like to sprinkle a little dry
cement evenly on the surface before steel trowelling, though this will give a
finish that can be slippery when wet.
Allow the new surface to cure thoroughly before
use.
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