This Week: Repairing Monoblock Paving

Nov 18 2007 Donny

Diy Donny

Everyone seems to have monoblock these days - but your smart new driveway can leave you with a sinking feeling.

The weight of your car can push the blocks into the drive and they can crack if a heavy item is dropped on to them.

Lifting and replacing them might sound a simple job but it needs a lot of care.

Monoblock is basically a system of concrete blocks individually laid on a bed of sand, butted tightly together and kept in place with an edging or kerb.

It is fairly common for blocks to sink into a driveway due to the sub-base not being laid deep enough.

The biggest problem to overcome when repairing a damaged block is removing it without damaging or disturbing surrounding blocks.

TOOLS YOU'LL NEED

Club hammer

Cold chisel

Brick trowel

Straight section of timber

Drill (hammer action)

Large masonry drill bit

MATERIALS

Matching block paving

Sharp sand

Kiln-dried sand

Here's how it's done..

1 Use a masonry drill bit to drill holes into the broken block. This allows it to be taken out without affecting other blocks.

2 Once the holes have been drilled use a cold chisel to break up the block, removing broken sections as you go. You will find it gets easier to break up as the block becomes dislodged.

3 After the block has been broken up remove all the loose rubble from the hole. Add sharp sand into the hole to build a decent sub-base before the new tile is added.

4 Get a straight section of timber and use the end of it to firm up and compact the sharp sand in the hole. Add a small amount of loose kiln-dried sand for the bedding in of the new block.

5 Once the kiln-dried sand is in place, get the new block and place it into the hole. The new block should sit around 10mm above the surrounding blocks because it is on top of the kiln-dried sand.

6 Place the timber over the new block to protect it and tap the timber with a club hammer. This will force the block level with the surrounding blocks.

7 Brush fine kiln-dried sand between the joints of the new block. This will prevent it from moving and hold it firmly in place.

TOP TIP - the kiln-dried sand can only be applied on a dry day.