one metre of paving, or 10 courses. Stand back and look
along the joints - are they straight and true? Stretch a string
line over the surface to check how the joints align and use the
alignment bar to lever them one way or the other as necessary
to get them into the correct alignment, and tap the leading edge
with the paving hammer to ensure the joints are reasonably
tight. Remember to check from at least two directions at right
angles to each other. Walk around the paving to check and check
again. It's much easier to fix a misalignment while it's only
affecting a couple of square metres than to allow it to "creep" and
end up distorting 20 or 30 square metres.
Note that clay pavers, with their inherent imperfections can
sometimes be quite difficult to align, but persevere; you have to
live with this pattern for a long time!
Level accuracy
consolidation means checking levels and surface.On a 'flat' or 'even' pavement, the relevant Standard sets a limit
of 10mm dip beneath a 3m straightedge, indicates something has
gone seriously wrong.
consolidation, refers to the use of a vibrating plate to level
the blocks once they are laid. It should be carried out once
you have finished putting in any cuts or replacement blocks.
The plate compactor vibrates the paving units, driving them
downwards and settling them into the laying course.The plate
spans several blocks at once, and so any slight variation in block
thickness is "ironed-out" as the plate passes over the blocks
The aim is to compact or consolidate the blocks into the layingcourse which is simultaneously compacted to, more or less, the
point of refusal, which is the point at which no further compaction
is possible.
Consider a typical selection of 60mm blocks. The manufacturing
standard allows for a ±3mm tolerance, which means there could
be a 6mm lip between two adjacent blocks laid onto an even screeded
laying course. In actuality, most British and Irish manufacturers
achieve a tolerance closer to ±1mm, but even this would, potentially,
allow for a 2mm lip between adjacent blocks.
| Using a plate compactor for extended periods runs the risk of HAVS which can be disabling for those affected. Try to ensure the plate compactor being used is adequately dampened to minimise the danger.  | |
| It is essential that the surface of the pavement is cleared of any debris, rubble, bits of block, the crusts off butties, and anything else that could adversely affect compaction before starting up the plate compactor. If, for example, a small pebble or a piece of block was left on the surface, and the plate was to run over it, there's a real risk that this would force down the block underneath to a level that is too low. | |
minimum of TWO passes over each and every part of the pavement.
These two passes should be at 90° to each other, so, in effect, one pass
would be up-down, while the second would be side-to-side. In practice,
we prefer a minimum of FOUR passes:
- up-down
- side-side
- diagonal top-right bottom-left
- diagonal top-left bottom-right
this indicates that no further consolidation of the paving layer
is possible and that the point known as "Compaction To Refusal"
has been reached. Shouldthis happen, STOP the plate
immediately or move away to areas that are not causing the plate
to bounce. Continuing to consolidate when the plate is bouncing will
only result in damage to the blocks, or even to the plate itself.
Once compaction has been completed. Any blocks that have broken
or become badly damaged during the compaction process should
be removedand replaced. Levels and alignment should also be
checked, and any corrections made before moving on.
selected jointing sand which then generates a phenomenal amount
of frictional interlock between the adjacent blocks. This frictional
interlock "grips" the blocks and helps transfer loads from individual
blocks to each of its neighbours, which then transfer the received load
to each of their neighbours and so on and so forth. This is how the
blocks that have not been completely compacted to refusal, as
described above, are able remain at the required surface level
Dry jointing can only be done in dry conditions . If the blocks are the
damp, or if the heavens open, the sealing sand will not flow freely as
required, and you may have wasted your time and money.
most builders' and civils merchants. This is a selected sand, very clean,
and of certain grain sizes that work to increase the 'friction' between
each brick or block
Building sand, play sand, soft sand, grit sand or any other form of sand
is NOT acceptable: it will fail and result in a rutted pavement. Don't spoil
the ship for a ha'porth of tar! The correct jointing sand costs around £4
for a 25kg bag, and this quantity should seal 8 - 15 m² of block paving
depending on unit thickness and type.The sealing sand is simply brushed
over the surface repeatedly, and allowed to trickle down into the joints
between the paving units.
Once the joints are as full as possible, all of the excess sand should be
swept off the paving, or into a corner where it can be salvaged for re-use.
The vibrating plate compactor should make a couple of passes over the
paving, ideally in different directions, to vibrate and settle the sealing sand,
and complete any partial compaction of the
paving units.At this point it's worth emphasising that any excess jointing sand
must be swept off you go over it with the plate one more time. This is
important because the plate compactor has a tendency to crush the sand
grains into the surface of the blocks, which leaves marks/stains that are
all but impossible to shift. Sweep off any surplus - it's not necessary to remove
every last loose grain of sand, but as much as practicable should be removed
before using the plate compactor to settle the sand into the joints.
After settling the jointing sand, some joints will appear empty or only partially
filled. These should be topped up immediately, but there is no need to repeat
the compaction. Finally, sweep off any extra sand
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