Just had a new buff-coloured patio fitted by a friend.
Last thing he said I had to do was to sweep a dry sand/cement mixture over
the patio to fill the gaps.
So I mixed two bags of kiln-dried sand with 1/2 size bag of cement and did
this. Seemed to fill the gaps OK but now some of the patio slabs seems to
have a 'grey' tinge left by the cement.
How do I remove this ? (I've tried both sweeping and hosing).
The only way to get cement off once it has set is to dissolve it off (other
than chipping it off which spoils the surface. You can get cement remover
from builders' merchants. It's actual hydrochloric acid. Don't drink it or
dip your finger in it.
If theres thick layers of cement try chipping as much off with a chisel etc,
then try the pressure washer as much as reasonably possible. If that dosent
work you will have to use acid, but be carefull as this may take some of the
colour of the slabs in question if you use alot of it!
If you have a piece of left-over patio slab, use it as a scourer and scrub
the stained areas with plenty of water. This will take off the surface layer
without introducing any new colouration. I'm assuming that your slabs are
coloured right through. Of course you should test this on a small
unobtrusive area first.
Did you make sure that the slabs were *perfectly* dry and the cement/sand
was very well mixed. The mixture does sometimes leave a greyish colour(but
not as bad as you describe) that is short lived and comes of with a quick
Try patio cleaner (Thomsons ?). When we had our conservatory built the
builders left one of two areas of cement stains on our patio, generally from
the holes in the tarpaulin they covered the lawn and patio with. Using the
cleaner and a stiff brush bought it up a treat.
Now as for the floor leveling compound their trainee poured, he dropped odd
drops everywhere on the patio (and up the house outside walls) and they are
still there. They are removed using brick acid, but the acid also attacks
the patio so took bloomin ages just dripping on the set blobs of leveling
compound.to remove the ones I tried !!!!
To follow the leveling compound story on a bit, after a week drying, large
areas lifted up in the conservatory base and cracks appeared. Anyway the
trainee lad that did it 1. Didn't sweep the concrete base before pouring
leaving the leveling to set over piles of dust. 2 Didn't PVA to it so it
didn't even stick on the non dusty areas. Anyway the builders came back and
lifted the compound up in huge sheets except for where he had poured it our
where it had actually bonded to the floor.
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