The Brew Cabin

The foot of my block paved driveway is on a slope and the joints are wider than elsewhere in the driveway and as a result I lose jointing sand in heavy rain. I recently had driveway power washed and sealed - fresh jointing sand was added after sealing and if anything the problem is worse. Have you any tips/sugggestions as to how I might keep sand in place.

Thanks,

Alex

Hi Alex,

Is there some reason why the joints are wider at the threshold of your driveway? They should all be the same size, really - around 3mm.

Anyway, there's a couple of ways to keep the jointing sand in place. The simplest is to use a "Joint Stabilising Fluid", such as Keybond by Marshalls. This is, basically, a PVA glue that is diluted with clean water and allowed to soak into the joints whereupon it sets and binds the sand grains together.

The other option is to use a paving sealant (see Sealants page). This does more or less the same job of binding the sand grains together, but also creates a seal over the entire pavement.

Whereas the keybond-type products seal only the joints and have no discernable affect on the appearance of the paving itself, the acrylic or urethane sealants give the blockwork a sort of 'varnished' appearance that, to be honest, isn't to everone's taste.

From personal experience, the urethane sealants do the best job, but, if you don't want the semi-glossy look, try the keybond and see how it fares over the first season. We find that, for the best protection, the Joint Stabilising Fluids need re-applying every couple of years, but they are only a fraction of the cost of a quality acrylic/urethane sealant.

It should be noted that with clay pavers, the 'varnishing' effect of sealants is far less noticeable than it is with concrete blocks and, because the joint widths are so variable (6-10mm wide in extreme circs), it's well worth considering the use of a decent Sealant on this type of paving.

HTH

Tony,

Thanks for the very prompt and helpful response to my "loose sand" query - I'll certainly give Keybond a try.

You ask if there's any reason why the joints are wider - I'm not sure why. There is some subsidence in that area - is it likely that this is causing the joints to widen or will it be the wider joints causing the subsidence? In either event, would it make sense to deal with the subsidence before resorting to Keybond?

Regards,

Alex

Bit of a chicken and egg problem that one, Alex. The settlement could cause the joints to open up, but open joints make it easier for water to invade the bedding and sub-base which could cause settlement. Whatever, it needs looking at before you spend good money on the Keybond or a sealant.

Take up a few of the blocks (see Maintenenace and Repair page) and check the bedding/sub-base before relaying the blocks to the correct level. Once you've got the blocks back to the correct level,and the joints re-sanded, then you can apply the Keybond.