Block paving lifespan: 20 to 30 years

Block paving laid properly lasts 20–30 years and more — and what settles that is a sound, well-compacted sub-base. The upkeep is simple: keep sand in the joints, sweep it, deal with weeds without salt, and leave the rock salt in the shed over winter. Do that and the surface stays sound and stays looking right.

• The quality and compaction of the sub-base (by far the biggest factor).
• The right block thickness for the load (40/60/80mm).
• A fall that takes water off, so it never stands and never freezes in place.
• Filled joints — that is what locks the blocks into each other.

Concrete paving does not wear out from being walked on. It is made to EN 1338, where the freeze-thaw test runs 28 freeze-thaw cycles with de-icing salt and a mass loss under 1.0 kg/m². The block itself will see out decades of winters. What kills a surface is something else:

• Water with nowhere to go. It freezes in the sub-base, expands and pushes the paving up. That is why the surface wants a fall of at least 1:80 on foot traffic areas and 1:60 where a car runs — 12 to 17mm per metre. A flat area ages an order of magnitude faster.
• Empty joints. A block with no support at its sides rocks, the arrises get knocked and then they chip off. Of every maintenance job going, topping the sand back up has the best effort-to-result ratio.
• Rock salt. It breaks down the surface of the concrete and makes efflorescence worse. Grit or sharp sand gives you the same grip and does the surface no harm.
• A pressure washer held too close. It strips the sand out of the joints faster than you will notice. Wash from further back, and re-sand the joints when you are done.

The white bloom on new paving unsettles every customer. It is lime carried out of the cement inside the block to the surface. It is not a sign of bad paving or bad laying, and it has nothing to do with strength.

Rain dissolves it and washes it away over time, usually within one or two seasons. A cleaner made for efflorescence speeds that up. Do not use ordinary acid from the hardware shop blind — test it somewhere out of sight first, because it can etch the surface and shift the colour.

If the bloom is still coming back after two years, the build-up is probably still drying out from below. At that point it is not about the paving at all — it is moisture in the sub-base and drainage that is not doing its job.

Block paving has one property concrete and tarmac do not: it comes up and goes back down again with the same blocks. So it is worth being able to tell a local fault from a sub-base one.

• One or two rocking blocks. Lift them, make up the laying course, put them back and re-sand. An hour's work.
• A dip of a few centimetres. Take up the surrounding blocks, top up and compact the laying course, relay. Half a day.
• Ruts along the line the car takes. That is a sub-base that was never thick enough. A local patch lasts a year and comes back; the sub-base has to be sorted across the whole strip.
• Settlement across the whole area. An uncompacted subgrade, or fines washed out where a geotextile membrane was left out. The only fix is lifting it and rebuilding the sub-base.

When you relay, keep a few blocks back from the original delivery. Anything bought later comes from a different batch, and in a finished surface that colour difference is still visible years on.

1. Sweep, and rinse with water when it needs it.
2. Check the joints and top up the sand — most of all in the first year.
3. Take weeds and moss out mechanically or with boiling water, never with salt.
4. Let rain wash efflorescence off, or use a cleaner made for it.
5. In winter clear snow and grit for traction with sand or grit, not rock salt.

See types of block paving, jointing and the sub-base under block paving.