Garden Slabs

[Jambo Forever]

I have recently laid about 20 600x600 slabs in my back garden. I was told to brush in a sand/cement mix 5:1 to compact the edges.

Now that this has dried iv noticed some damp stains on the slabs, probably caused by cement drying on the slabs.

 

Does anyone have any idea to remove these stains to retain the original colour of the slabs?

 

Cheers.