Replacing individual blocks in paving is possible, although the success of the repair does depend on some extent to the problem that you are trying to solve. If a block has cracked because the substrate below is not even, for example, then replacing the block without levelling the substrate will simply mean that the new block will break again.
But the process of removing and replacing the block is in itself quite simple, if a little tricky. The block (or blocks) that needs to come up have to be levered out without damaging the surrounding blocks, then a new one inserted in place. The key is getting the first block out, after that the rest should follow easily.
Removing the First Block
If the blocks are held in by mortar then that bond needs to be broken, with gentle application of a slender cold chisel and mallet. Then use a blunt, flat lever (the side or heel of a trowel should be ok) and lever one side of the block up a few millimetres. Keeping that lever in place, use another to lever up the other side. Repeat the process, alternating sides until enough of the block is clear of the driveway surface to grip it and lift it out.
There are block extractors available that will make the job a lot easier. They are essentially a set of adjustable jaws with a lever system that grabs either side of the block and grips it so that it can be lifted straight out. But unless you can hire one they are probably too expensive to bother with for a one off repair.
If you have a cracked or damaged block it makes sense to pick on that one to start with. In this case you can dispense with the painstaking easing out of the block and just break it up. Do this with a cold chisel and a mallet, holding the chisel at around 35 degrees to the horizontal, and strike in from the edge to the centre of the damaged block. This should minimise damage to any surrounding paving that you want to reuse.
Taking Up More Blocks
If you need to remove more than one block then the surrounding ones should come out if they are levered from underneath. One handy tip: if you have to lift a number of blocks start with a block that had to be cut to make it fit in the first place. The rougher cut edge will give more grip for the lever to hold on to and it should come up more easily.
Talking of reusing blocks, take care to stack blocks carefully if they are to be re-laid. If you don’t have any suitable material to protect the tops (old carpet would do fine) while they are stacked up, consider stacking them on their sides. Then any scratches or scrapes when stacking or un-stacking will occur on a face that won’t be seen.
Replacing the Blocks
Once the area is clear of blocks any remedial work can be carried out then the paving re-laid. Chip off any mortar, or brush off loose sand, from the sides of the blocks. Replacing the blocks is no different to laying them in the first place (see our article How To Lay Paving in this section), although you should leave the bedding layer about a quarter of an inch higher to leave room for compaction.
Once all the blocks are in place level the area using a long straight piece of timber and a mallet. Then compact with a mechanical compactor or a pavior’s mall, a very large mallet. Use fresh mortar or, if the blocks are loose-laid, brush new sand into the edges.
That’s it, although you should go over the area again in a month or so to check that it’s still level, refill loose sand and re-compact if necessary.
