Run off from patio

[NUMBSPAR]

Hi All

First time I’ve posted on this site, I’m looking for some advice to remove this build up from the blue engineering bricks it appears to be run off from the patio this has developed over the past 18 months it is solid to the touch, so far I’ve tried hot steam pressure washer (no effect) and hydrochloric acid 17% strength, the acid fizzed but had no effect either. Any advice would be appreciated .

 

[JohnD]

Might be lime run off from the paving slabs, what are they made of? Are they laid with an overhang drip?

Water will not wash it off.

Try brushing it off dry if it ever gets powdery.

 

[NUMBSPAR]

hi John
It is definitely run off, they are laid with a overhang however the damage is where the gaps in the flags are grouted, it is too hard brush off and I’ve tried a hot water power wash 120c but it doesn’t budge

 

[freddiemercurystwin]

What was the grout used?

 

[NUMBSPAR]

It was the brush in type

 

[ETAF]

our garden walls were cleaned up when they did the block patio with a pressure washer (but a petrol high powered unit) - My karcher doesnt touch it
the difference is like chalk and cheese - really got all the muck of the bricks from years and years of buildup

brilliant result - i'll try and find photo of old v new
Had to repoint some of it

 

[Mike13]

If it fizzed with the brick acid, then you need to continue with that, use a stainless steel wire brush to agitate the surface, and it will eventually clear.

 

[NUMBSPAR]

Hi Mike
I was concerned I’d do more damage to the mortar joints before the actual soiling is removed

 

[Mike13]

use an old paintbrush to put it only on the brick faces, when depleted it will not attack the mortar much at all.