Reusing laying substrate

[SGKitchener]

11 months ago, we laid a drive using charcoal brickwork.
Recently spots of rust have appeared which is pyrites in the aggregate.
We will be lifting some, if not all, of the bricks back out and replacing with new.
So the question is: Does the sand substrate need to be dragged back up and thrown or can it be reused and lay the new bricks back on it as it is still quite clean?
TIA

[lutonlagerlout]

if its the odd block here and there you can leave it

but if you have large section i would remove,relay and rescreed

the reason being its been wacked down hard and if you try and wack it again you run the risk of breaking blocks
LLL

[SGKitchener]

Thanks LLL. That makes sense.

So, just to confirm, we can reuse the sand that is currently down, we don't need to use new?

Thanks

[lutonlagerlout]

not really
as you remove blocks the sand becomes contaminated with moss and kiln dried sand

if you are careful you could re use

LLL