Cleaning a monoblock driveway - tips on technique and products please

[mipmop]

The driveway is one car wide and two car lengths. It's 20 years old, new to me and has moss and weeds in the gaps between blocks. The blocks, themselves could do with being cleaned too. Some sections have virtually no gap between the blocks, other bits have gaps of around 2" square due to the driveway being curved.

I tried a paving brush with wire bristles. Half of the bristles fell out before I'd completed much of the drive. I have a knife tool that's effective on weeds and moss but is slow. Any tips on how to clean the blocks themselves are appreciated. Jeyes? Bio laundry powder and a stiff brush? Also should I do that before or after re-sanding? From what I've seen online I should re-sand with kiln-dried sand for the smaller gaps up to 1cm wide, but use a different product for the wider gaps.

I'm thinking of digging out the sand and soil between the blocks then re-sanding in small sections, as it's a relatively big job and the blocks with big gaps aren't safe to drive on when the sand is removed.

Any tips are appreciated. I don't mind putting in the effort but want a good result, and obviously don't want to destabilise the blocks.

We have a similar driveway, though it's bigger (fits six cars) so it's a bigger job to maintain.

We've tried a few things, including jet washing. To be honest, that actually washes a lot of the sand and weeds out of the cracks anyway. It's a filthy job.

We let it dry, brushed it and used a very powerful leaf blower after a day or two.

We then resanded it.

Looks lovely when it's done but it's a pig of a job. You just have to keep on top of the weeds by hand, I'm afraid!

I power wash my patio which is made of blocks (pavoirs). you lose a bit of sand so some remanding is necessary but you just buy kiln dried sand and use a yard brush to brush it into the joints. The power wash cleans the bricks and blasts any weeds out of the cracks

Thanks for your advice. I hope to do a big clean now then keep on top of it so it doesn't end up this bad again. I no longer have a pressure washer so will be doing the blocks by hand.

weedkiller and sweeping is I think the answer.

If you jetwash or scrape out the sand, the blocks will become loose like old teeth and will also go uneven.

My joints are small and pretty even, and I had reasonable success by regrouting some of mine using dry mix sand and cement mortar, which you sweep to and fro and it falls into the gaps. If, after sweeping it well in, you get a couple of weeks of damp, drizzly weather, it will cure reasonably well. It is also resistant to ant digging.

If yours is very bad and you have big gaps, I would think about regrouting with mortar. You can get a tool to inject mortar into the gaps, it is like a big cake-icing gun. You may find a builder willing to do it, but it is essential that they have had experience and you can look at samples of their work.

If the blocks are loose and uneven they will need to be lifted and reset. If I was having it done from new, I would want them set on lean concrete, not sand, with mortar joints.

People in the trade tell me that Paving Expert is very good for advice.

p.s.

If you have moss, Armillatox Moss Killer is very good. I think it is still used on flat roofs, so builders merchants sell it, but there are concerns about gardeners causing pollution by pouring excessive amounts on their lawns, so it is no longer sold in garden centres. Obviously use enough to soak in, but not enough to run off into gutters.

Thanks PigletJohn. Looking at the drive again, the area with large gaps has no real edging (the outside blocks are beside grass) so maybe they've traveled over time. Some are loose when stepped on.

Can I ask if you buy a ready mixed product of sand and cement, or do you mix it yourself? The paving expert website is very good, thanks for recommending that. The polymeric joining compounds seem appropriate.

mix it yourself. You can buy a plastic "spot board" from a DIY or builders shed, to mix it up on. Also useful when digging planting holes, emptying tubs, mixing compost. Look for cement in yellow and blue plastic bags rather than paper sacks, they are damp-proof. Buy smallish ones as it will go hard in storage if you get big bags (which you will be unable to carry). Keep it off your hands, skin, eyes, clothes. Wickes is cleaner than B&Q.

Dry mix is sold, but at a fanciful price.