A year ago I had my drive block-paved. I understand they are
'Marshalls' on hardcore plus 'membrane' plus sand. They replaced
mainly the original concrete slabs, and a small stretch of lawn.
Here's a photo:

http://i154.photobucket.com/albums....341.jpg

Overall I'm pleased with the job. But after a long enough dry spell
early this year I noticed that a score or so of the bricks seemed to
have dark patches, as if they were permanently damp. Most of these
were near the garage entrance, just in front of the drain, as shown
he

http://i154.photobucket.com/albums....cks.jpg

Note that the marks remained identical, not varying at all. (That
photo was taken about 2 months ago, yet that area looked exactly the
same yesterday morning.) So I have been assuming that the bricks were
flawed.

To cut to the quick, it's taken me until yesterday afternoon to get
the paver to replace them with new bricks. ("Next week, I promise...",
"Tomorrow...", etc, since April!) He rushed it and missed 3 that
needed replacing, but as he left me some spares I replaced those
myself afterwards.

However I now see that the sand in this area is very wet. Despite
having had a few days without rain. So could it be that that's the
main cause, not any significant flaw with these particular bricks? Are
there perhaps always some porous areas in these bricks that allow
moisture to seep through, and darken the top surface in specific
patches like this?

If so, presumably this means rainwater is not draining away
sufficiently at this small area? So how should I fix that please?
Frankly, I don't want the hassle of getting the paver back yet again,
so want to do it myself. Can I just remove a few bricks and puncture
the membrane in a couple of spots? Would I need to first remove the
wet sand and replace it with dry, or would it eventually dry out
anyway? I doubt my skill at getting it level again if I do so!

Any advice would be much appreciated please.

--
Terry, East Grinstead, UK