Hi. Any recommendations for cleaning outside concrete that has gone black/grey. It gets very slippery when its wet & getting it ready for marketing. Would like to just waterblast but not recommended for concrete. Its quite a large area so what would be the easiest most effective solution.
gpg58,
Jul 4, 8:53pm
Never done anything but water-blast myself? (Other than spray with a mold killer first).
flier3,
Jul 5, 4:50am
well, I have been known to get down on hands and knees and attack a huge area of concrete path and driveway with a scrubbing brush, Janola and water! If that's any help?
cagivachick1,
Jul 5, 6:32am
if you are selling just waterblast it
happychappy50,
Jul 5, 7:34am
I use a strong solution of bleach & water,spray it & leave for a few days,bleach kills the spores & water blast off or leave it till it rains,lasts several months.Happens every winter as our courtyard is on the southern side of the house where it receives no sun.
mrfxit,
Jul 5, 8:29am
ONLY Lightly waterblast concrete driveways. Strong pressure will lift the very fine sand surface on top & leave it very rough. Great while it's clean but attracts more dirt really fast.
gag5,
Jul 5, 12:34pm
happychappy - what kind of ratio do you use? Half & half? & just your regular supermarket bleach?
gag5,
Jul 5, 12:36pm
yes, We learnt this lesson by doing this very thing! Now the concrete is very rough & gets black quickly. Think we will try the strong bleach left on & then try hosing.
sky44,
Oct 23, 9:12am
Make a slurry of lime ( not the garden type) apply with broom and leave then hose off
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