[Ged]

hi folks

does anyone know if pressure washing can cause the appearance of efflorescence on block paving. the reason i ask is that i completed a job yesterday and noticed that the dry paving was affected in places. the client said he hadn't noticed it before and i hadn't 'cos the surface was v. dirty before cleaning and you can't see efflorescence when the paving is wet. i advised him to acid wash the paving to get rid of it.


Regards

Ged

[REVIVE-A-DRIVE]

hi ged
as from the resiblock course,the efflorence can be in the block work just below the surface,when u clean/seal, it can bring up to the surface.

[exoclean]

Hi Ged,

Effloresense(calcium carbonate) is a naturally occurring phenomena found usually in concrete products but has been known to appear on clay pavers as well. You could acid wash it but you run the risk of discolouration if your acid solution is too strong. Any use of acid should be applied with caution. Pressure washing sometimes accelerates the chemical reaction that causes effloresense and in most cases it is unavoidable. Sometimes doing nothing and allowing it to gradually disappear is an option or the old fashioned but safe method of clean water, stiff brush and loads of elbow grease will remove the bulk of it.

If you are going to seal the drive, the effloresense must be removed, as all you will be doing is sealing it in permanately. Also, allow it dry properly, applying a sealer on wet or damp pavers will cause them to go milky white.

Good Luck

Paul

[keith b]

Ged.

Go to www.pavingexpert.com and hunt around for the topic on efflorescence!

good luck

keith b

P.S. try and get a clause written in to your contract that you are not liable for the appearence of efflorescence and that it is a natural occuring factor!

[mark bowditch]

Hi ged
Have a look at this link http://www.paving.org.uk/interpave/downloads/downloads.html
Go to bottoms of page
All precast concrete paving
Cleaning maintenance sealing  and down load the pdf file
Hope this helps
Have got my p/w now starting next year
Good luck
Mark bow