Civil Engineering Reference
In-Depth Information
such horizontal courses is polygonal masonry which by dei nition avoids as far as
possible all continuous horizontal bedding.
h e bonding of masonry is a subject which has a more ramii ed development in
brick masonry than in stone masonry, and accordingly will be examined in more
detail in the next chapter. However bonding is a signii cant matter in ancient stone
masonry as the following discussion indicates.
It is a simple matter to set well bonded masonry in the run of a wall, but it can
be very intricate to keep a good bond at the stopped ends, intersections and angles
of walls. h e dii culties here with stone masonry are not so acute as with brick
masonry, since stone can always be cut to required dimensions; whereas with brick
masonry the units are of predetermined size and special adjustments required can
only be met by trimming bricks into smaller units.
Bonding in stone masonry has two distinct contexts which are basically quite
dif erent in their application
Bonding
of rubble
stone
masonry
(i) Rubble Walls (particularly faced rubble walls)
(ii) Finely Dressed Stone (Ashlar) Walls
(i) Rubble Walls
Here the concern is entirely with maintaining the integrality of the structure across
the thickness of the wall—i.e. to avoid blocks falling away at the face of the wall.
Particularly is this concern in issue when the construction of the wall consists of
three separate elements: two faces and a core, e.g. ashlar faced rubble. In this con-
nection Vitruvius (II.8) animadverts bitterly against the absence of such care in
the Roman (concrete) construction of his day. To ef ect this binding together the
facing blocks should include at regular intervals “headers” tailed well into the core,
or better, if possible, running through the entire thickness of the wall (
diatonoi
).
Where walls are very massive (e.g. barrier walls) and it is not possible to provide
header blocks long enough to unite the two faces, then alternative arrangements
are made to provide the necessary transverse bonding, e.g. several blocks are set
overlapping one another to run through the thickness of the wall, thus utilising
friction to ef ect the tie. In place of this a bonding transverse “wall” (itself of two
faces and a core) can be built across the structure—obviously such a device is more
proper to “engineering” structures, where special strength and stability is required
(e.g. dams). It should be noticed also that this transverse bonding not only ties the
wall together, but it also compartmentalises the core and thus reduces its outward
pressure on the wall face (ABADY IV 1987 pp. 63-78, i gs 9, 10).
Another factor to be noted in this connection are measures taken to anchor the
bonding stones into the face of the wall. In run of the mill instances this is ef ected
by the header and stretcher bond of the face, but where maximum i xity is impor-
