Cleaning Cement from Block Paving

[thompsoc]

Hi,
In the last couple of weeks I have laid a block paving patio.
Unfortunately I misunderstood what should be used for grouting and used cement !
Result - 1 beautiful brindle block paved patio now covered in cement .
The bricks look great in the rain, but when they dry they all appear to be grey in colour.

We tried
1. Pressure hose
2. Wire brushes & pressure hose
3. Thomson's 60 Minutes cleaner.

All to very little effect

Do you have any recommendations as to what we should try next?

Chris Thompson

[84-1093879891]

You need a brick cleaning acid (Hydrochloric) - but be careful as it can permanently affect the colouring of those concrete blocks. It's sold by most BMs for around 5-10 quid, and you might need to dilute it - read the instructions carefully.

Have a read of the advice given on the Stains page before doing owt else!

[thompsoc]

Tony,
Many thanks for the advice - I got so hooked on reading the Archive stuff that it didn't occur to me that 'Stains' would merit a page of it's own!
Unfortunately I am in the US on a business trip, so won't be able to see the effects of your suggestions for a week or so - my wife has high tailed it to the BM's and returned with a can of Brick Clean & is raring to go once the rain stops.

I must say this is probably the most useful and inormative 'specialist' site I have ever come across - I will make a point of coming back from time to time to discover the latest tips & tricks.

[Kevin Whitlow]

Chris,
If you are using a pressure washer try a pin-jet nozzle for accuracy so as not to remove any mortar (which will no doubt be weaker)