How to clean concrete slabs on driveway

[TellySavalashairbrush]

Had a driveway laid with large concrete slabs a few months ago. Since then I had a skip placed on them due to other building work. The skip is now gone and I’m left with really grubby looking slabs. I used a hose and washed /brushed them but they still look quite manky. Any ideas what to use to get them looking good and avoid damaging the concrete they are set in ?

Karcher

Pressure washer. Go carefully at the joints between the slabs, though.

I did consider a pressure washer but heard they can rip through concrete edging .

Power washer brought mine up lovely.

Bleach and water solution should help

Bleach could help a lot with mould/lichen etc, but it sounds like the issue here is just muck from building work. I'd use a pressure washer. Just don't use one of the "ultra high pressure" type nozzles, and don't hold the nozzle too close when working near the joints.

Sodium hypochlorite. A very strong bleach. Just be aware it will kill anything green it touches.

cheap biological washing powder..mix with water...leave for several hours then hard broom to rinse off...also good for mould and algae etc.

Some very helpful suggestions. Thanks all

We bought a karcher last week and tried it on our drive and it's made the most amazing difference!

I second Sodium hypochlorite, you can buy a 25 litre barrel for about 30 quid. Does kill all grass plants etc so be careful. Just water down and spray on with Garden sprayer

You can buyer lower pressure P-washers, they vary. Argos has a guide on which one to get. Mine is great on our slabs. I would not like the pollution levels of Sodium hypochlorite, but no solution is very env friendly. P-washers use obscene amounts of water.