Removing dried grouting haze?

[amilio]

Hi everyone,

 

I've recently grouted some paving stones, but left a significant amount of grouting haze. Is there any way of removing this haze from concrete slabs after it has dried? I was thinking on sanding it down, but I'm not sure it would work.

 

Thanks!

[nod]

Watered down brick acid on a sponge will do it But you may have to touch up the grout in places