Agriculture Reference
In-Depth Information
sliding and rubbing action, against the previous and dampened voussoir to gain
a good bond and the 1 mm joint required (Fig. 148).
Figure 148
Re-building the arch
by placing the voussoirs
to the lines ranging
from the profile tree
and those set out on the
centre, 1998. (Courtesy
of Richard Keech)
After each voussoir was laid the line was moved onto the next pins, ready for
the following voussoir to be laid. This was repeated until the centre 'key bricks'
were reached. For the final key voussoirs the dipping mortar had to be applied
to both bed faces of the voussoir and they were then carefully slid down tightly
into place. A traditional thin-bladed bricklayer's jointing tool, the thickness of
the arch joints, was then used to fully compact the bed joints either side of the
key voussoirs. This was also used to lay-in the mortar into the 'dummy joints',
guided by an appropriately positioned timber pointing rule.
The next stage was re-building the standard brickwork over the arch. A mor-
tar mix to match the original was specified based on a blend of fine and course
sands and hydraulic lime. The bricks were dampened and laid to line, gauge
and bond of the surrounding original brickwork. For the long extradosial cut
up to the arch a neat and even joint width was obtained by setting out accur-
ately and using a bench-mounted disc cutter, a fairly quick process only involv-
ing two courses. The extrados of the arch in reality cut into four courses of
facework, but the top two ran in line with the central projecting key block, so
no cutting was required for them; other than cutting to length. The Platt band
was built directly over the crown of the arch. This consisted of three projecting
courses of London Stocks that ran straight over the arch and this was a sim-
ple job of 'lining-in', to established bond, between the existing brickwork on
either side. The final lining-in of the remaining brickwork was completed.
Once the face brickwork was completed. The specified joint finish was car-
ried out on stiffened mortar to produce a finish, to match the aged appear-
ance of the original surrounding brickwork. Once all had set sufficiently the
