As with most projects, the base coat or preparation is vitally important to creating a high quality finish that will last for many years to come. With block paving, the quality of the sub-base is not only important, it is in fact critical.
Firstly the area is excavated to a typical minimum depth of 200mm. The ground should then be covered by a geotextile terram weedbarrier. This is then covered with a minimum 150mm layer of mot type 1 crushed granite hardcore which must be firmly compacted into place.
with block paving, it is important to establish a solid and fixed border to frame your paving. This serves two primary purposes.
Firstly, during the construction process the edging will help you establish your falls for drainage etc and provide a good edge to work from when screeding in the grit layer upon which the infill blocks will be laid.
Secondly it securely holds everything in place and prevents the blocks from moving over time due to the passage of vehicles over the surface of the blocks. This is notable in particular if your driveway is sloping and your vehicles constantly turn around the same spot. Over a period of time this action can force the blocks apart if not held securely with a decent solid framework.
When compacted, the laying course sand should be 25-40mm deep. The key to successful screeding is creating a smooth, even and flowing surface on which to lay the bricks. The surface profile of the screeded laying course more or less matches that of the finished pavement, so attention to detail is essential.The plan calls for a 45° pattern, so a stater couse of blocks square to the building is established. 90° patterns are best started at a corner or main edge of the building.
|laying of all full blocks continues, with the operatives working from the already laid paving, not from the screeded laying course. The bricks (blocks) are randomised prior to laying by selecting them from at least three open packs. this helps prevent blotching or banding of colours and allows the paving to show off the full range of hues to best effect|
Once all the full blocks are laid, they need to be checked for alignment by using a string line stretched along the diagonal courses and adjusting as necessary, using the alignment bar tool . Clay pavers often require significant re-alignment as the imperfect rectangles are prone to drifting off-line during the laying process. Concrete blocks, being moulded as perfect rectangles, usually suffer less drift and so require less re-alignment, but they should always be checked prior to cutting-in.
Once the alignment has been checked and verified, the edges can be cut in. Clay pavers are noticeably harder to cut than their concrete counterparts and so use a bench-mounted saw rather than rely on a block splitter This is a matter of personal choice as it is perfectly acceptable to use a splitter for clay pavers and it would be the first choice tool for most concrete pavers.use a hose pipe providing dust suppression on the saw cutter.
Finishing TouchesFix Recess Trays and gully covers, if necessary.
Check paving for compliance.
Jointing and compactionThe final task is jointing. This is done once all the cutting-in has been completed, and the compliance checks carried out.
Kiln-dried jointing sand is spread over the block surface and swept into the joints using a soft brush.The paving is now compacted using a vibrating plate compactor (wacker plate). 4 to 6 passes are made over each section of paving, alternating passes at 90° to the previous pass. With clay pavers and some of the more decorative concrete blocks, a neoprene cushioning mat is attached to the base of the plate compactor to prevent spalling damage to the edges of the bricks.
CompletionExcess jointing sand can be swept off the surface and it is now ready to be used.
The jointing sand may settle over the first few weeks and should be topped up as soon as this becomes apparent. Many block pavements, of both clay and concrete pavers, may exhibitefflorescence in their early life but this should disappear within 12 months.