Block paving staining help, not coming off

[wakewaterblue]

I have some paving in my garden pathway, made from what I believe to be, Tobermore Sienna block paving as a closest match guess. I have 2 colours of grey and a friend of mine who runs a professional cleaning company, cleaned the paving up using his jetwash setup with hypochlorite. The paving has come up amazing however there is one section which has not cleaned up at all. Before we sand and seal it, we want to try and get this mark off as this is the main area we wanted to sort! Pictures attached.

He cannot get the staining off and has asked around to people in his industry but they don't know the answer. It could be some previous sealant used, the gaps seem to be quite hard and I've even scrubbed and scrubbed in the past but nothing changed. It's just odd it's that section alone, it is slightly sheltered compared to the rest of it but I live on the coast and we get battered weather wise, but it's not out of the elements completely. An idea was to turn the blocks over to the fresh aide, however they are different on the other side, smooth and without a curved edge I believe so that isn't possible which is real shame!

 

Any ideas what I can try and use to treat it with? If it's some sort of sealant, what might cut through it? 

 

I want to try this first before buying replacements as I will need to cut them to size... I do have an angle grinder but that is a last resort for me.

 

Thanks!

[nod]

It will cost you about £25 m2 To replace the blocks For £25 I’d replace the stained blocks 

[FarmerN]

Can you lift a stained block out to experiment on?

Try different things. Brick acid, very strong hypochlorite /washing up liquid mix, different solvents ? Apply and leave to soak rather than scrub.

Care needed ! Don’t mix chemicals!

Good Luck.

[wakewaterblue]

Thank you for your replies. On further investigation the only logical conclusion is that this is some old sealant that has discoloured from UV exposure. It's a bit more sheltered in that area so perhaps it's just degraded slower or perhaps a different type of sealant was put down in that area by the builders. I may never know the answer! I bought this property from new and have never had the paving cleaned or sealed until now, so before it gets sanded and sealed, I will try to sort this. The blocks were likely put down about 14-15 years ago.

 

Hypochlorite was put on it for the jet wash clean and left on for decent time, it was like it was resistant to it and the jet wash power didn't cut through it, like a sealant would behave. 

 

I have purchased a special sealant remover for paving, so I will try that on one of the blocks first and see how it comes up and how much effort / time it takes. However, I think you are right in that it might be easier to replace the individual stained blocks! 

 

On my research, I think my paving blocks are Marshalls Argent? I know they come in a large mixed pack but I can see there is dark grey along the window edge in rectangles and the rest are the square light grey. Do places sell these blocks individually?

 

Many thanks all