Agriculture Reference
In-Depth Information
Working from the profile tree, positioned above the arch before it had been
disassembled, all the positions of each voussoir were transferred from the strik-
ing point through the intrados marks along the turning piece or frame head
to join up to the tree. It was now possible to relay the bricks back to these lines
and their original positions. All the arches were dry-bonded, using a suitably
sized proprietary dpc for joints, to check accuracy of fit and bonding. Once
we were satisfied then the bricks were 'quenched' - soaked, but not saturated
in clean water contained within a plastic heading tank ready for laying. Each
voussoir was carefully dip-laid in a pure lime-putty and silver sand mortar and
lined-in to its correct position.
Upon completion all the joggle joints were grouted with a NHL 3 lime:silver
sand mortar containing a little boiled linseed oil in the mix. Once the exud-
ing bed joints had stiffened they were neatly trimmed flush using the sharp
blade of a plasterers small tool. The dummy joints were then carefully pointed
using an suitably sized tuck jointer guided by an appropriately positioned tim-
ber straight-edge.
To finish, once the arches were sufficiently dry, they were each lightly rubbed-
up with a hand-held 'float stone' of varying grades to suit the type of rubber.
Circle-on-circle work means that the voussoirs are not only radiating on ele-
vation but also on plan. It was therefore important to establish the radius of
both, so the arch could be drawn and each face and its bed templet could be
created and numbered to its relative position. Once again these arches were
propped up and carefully recorded, as described above, but this time so that
new bricks could be cut for each arch. This was because the original gauged
arches to the semi-circular bay had been rendered over with hard cement:
sand mortar upon heavily hatched voussoir faces, done to gain an improved
key. Regretfully it proved impossible to salvage any of these arches, despite our
very best efforts.
Due to the urgency of the work within this contract, I contacted W.T. Lambs,
and a representative, Mr Richardson, arrived at site and I handed over all the
relevant information. He also took independent dimensions of the arch and
bay. The bricks duly arrived within the time stated.
With the pre-cut voussoirs checked the work was put in hand to build them.
I had already set out the positions of each voussoir onto the curved-on-plan
timber turning piece and cut a second length of curved timber, working to the
drawing, upon which I marked the extradosial positions of the arch voussoirs.
This was placed almost directly above the face height of the arch upon which
the setting-out lines had been transferred between the profile tree and the cen-
tre (Fig. 115). As expected when dry-bonding the purpose-cut arch there was
a need for some minor adjustment due to past movement of the surrounding
brickwork on the semi-bay to be accommodated. The arch was then built and
finished in exactly as described above.
