The Three Biggest Threats to Surface Performance on Block Paving

Block paving is an extremely common surface in car parks across the UK and Europe. It is ideally suited for the purpose due to the ease with which it can be laid.  As its main use is in car parks, the following criteria are essential.

1. It must provide a smooth stable, long lasting surface

2. It must provide good grip for vehicles and pedestrians.

3. It must drain quickly.

4. It must look attractive.

Block paving is normally laid on a base of hard-core and sand, which can support the heavy traffic without giving way.  The blocks are spaced a little apart to allow drainage and the gaps between blocks are typically filled with sand. 

Picture Credit; http://www.cwilliampavingandlandscapes.co.uk/how-to-install-block-paving.html

Provided the surface is laid properly, surface compaction is not usually an issue. However, similar drainage issues can occur due to joints geƫting blocked by detritus, which can compact within the gaps.

The gaps between the blocks provide a perfect catchment area for detritus, which will settle in the gaps and rot down. This will prevent the surface from draining properly and will lead to puddles on the surface. The rotten detritus is also a perfect growth medium for moss and weeds, which will grow between the gaps, and eventually on the top of the blocks if left untreated.

If moss is left in between the gaps it can cause serious problems. Moss absorbs a lot of water. When the water freezes it expands which can force the blocks apart and eventually damage the surface. Some maintenance methods can also cause surface displacement. Pressure washing is a common method of cleaning block paving, but it will remove the sand between the blocks if great care is not taken, which gives them space to move.

Regular maintenance is simple and effective.   A powered sweeper and collector can be used to collect detritus before it rots down. A blower can also be used to move small debris from between the gaps.

Trees and hedges near to the block paving should be pruned  regularly in order to prevent leaves and twigs from falling onto the surface.  Grass cuttings close to a paved surface should be collected to prevent  migration of the cuttings onto the blocks.  

When the surface has been neglected, we have often found moss between the blocks and black sticky areas where puddling has  occurred.  In these cases a Kersten weed brush can be used to lift the moss and detritus from between the blocks.  The removed  debris can then be collected with a powered sweeper and collector.  

In some cases, sand will need to be taken out from between the blocks in order to brush at the required depth to remove all the soil and moss, in which case this removed sand will need to be replaced to prevent surface displacement and allow drainage. Sand can be worked into the blocks with a powered sweeper.  

Once remedial work is complete you can then return to a regular sweeping plan to prevent threats.

Like this Blog? Find out more by reading our surface maintenance handbook;