Forum: Block Paving
Topic: Driveway not drying uniformly
started by: angeldotkom

Posted by angeldotkom on 13 Nov. 2017,22:00
Hi everyone - I recently got my driveway block paved and it doesn't seem to be drying uniformly - even after 2 sunny days, there are what look like wet patches all over the driveway. So the entire drive looks patchworky and awful. Could this be because there could be bits of sand on the blocks which are stopping the blocks from drying uniformly? Thanks!
Posted by Tony McC on 26 Nov. 2017,10:37
There are a few possible causes for this 'phenomenon'.

1 - shade

2 - blocks of varying porosity

3 - poor drainage of bedding layer

4 - poor drainage of sub-base

5 - incorrect jointing this time of year, and assuming it doesn't start to settle or deteriorate, I'd be very tempted to leave it until the Spring and see how it looks in, say, April. If it still has the same damp spots then, it might be worth investigating further.

Just to be on the safe side, I'd suggest puting your concerns in writing to the contractor, stating that you will review the situation in Spring and would appreciate their attendance at that time, if necessary.

Posted by angeldotkom on 01 Dec. 2017,11:27
Thanks for your advice. I have raised my concerns with the contractor and will revisit in Spring.

Posted by kwdConstruction on 07 Feb. 2018,14:24
Tony's advice is spot-on. When I see this it's mainly due to varying porosity of blocks and is more noticeable when newly installed, over time it lessens. Another reason can be bagged aggregates being much wetter than others providing a patchy-in-terms-of-dampness screed that's perfectly sound (as long as it's not absolutely soaked and making the blocks pump). That'd take a few months to sort itself out at this time of year. Hopefully it's nothing more serious than either of those - it's not likely to be.

From an installer's POV, the best way to avoid the whole drive looking patchy is to, as we all should anyway, install from a number of packs instead of consecutive packs. It's not always possible on smaller jobs and when your delivery driver has dropped your packs vertically stacked. Instead of large patches you have interspersed individual units remaining wet-looking, these will also "dry off" more readily being surrounded by drier units as they can draw the moisture. Still not ideal from a customer's perspective, but just one of those things.

After the fact, a simple way to lessen the effect is to use a very good quality jointing sand stabiliser such as the multicrete one I prefer. I had to do this on a small job where the packs of block looked identical but were of different batches and dried very differently. This not only ties that jointing sand together and avoids its removal, it also puts a sheen on the blocks that can last a year or more, and a side-effect of this is a much more uniform drying out.

EDIT - sorry, didn't realise this post was from a couple of months ago :blush:

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