Note: Descriptions are shown in the official language in which they were submitted.
IMPROVEMENTS IN OR RELATING TO MOULDS FOR
CASTING CONCRETE OR OTHER CEMENTITIOUS COMPONEN'rS
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to moulds for casting concrete
or other cementitious components. The invention is
particularly although no~ exclusively applicable to
moulds for casting arcuate concrete tunnel lining
segments.
2. Background prior art
In the casting of concrete tunnel lining segments it
is co~mon to get more than one cast ~rom a mould each
working day. In some cases, principly where steel
moulds are used (but also concrete) the manufacturer
may get one cast say every four to ~ive hours by
using a steam chamber to assist in the curing of tha
cast conrete. The moulds are put into the chamber or
the chamber put over the moulds. The chamber is then
filled with steam at a temperature high enough to
- give the concrete sufficient strength for removing
from the mould in the required time.
Whilst this method works quite welI and gives the
desired results, it is nevertheless expensive in
terms of energy used, requires extra handling by
transferring the moulds into and out of the steam
chamber or the steam chamber to and from the moulds;
it can be w~t and messy through steam condensing and
consequently requires provision for drainage; the
steam plant itself can be relatively axpensive and
~7~
requires maintenance.
SUM~ARY OF THE INVE TION
This invention provides a mould for casting
concrete or other cementitious components, the mould
having a mould surface and electric heating means
embodied in the mould adjac~!nt the surface to heat
the surface and thereby a component being cast in the
mould to accelerate curing of the component.
By casting electric heating elements into the moulds,
the temperature of the wet concrete can be raised to
achiPve a more rapid curing of the concrete and
thereby similar time for stripping of the cast
concrete components from the mould as with the use of
st~am. The advantages over the use of steam are that
there is a relatively inexpensive energy consumption, I
no extra handling arises as the mould remains static. ~ -;
Working conditions remain relatively clean as there
is no possibility of steam condensation affecting the
working area. The cost of wiring and associated
control equipment is substantially less than the cost
of steam plant and the steam chamber.
The invention also provides a mould for casting a
concrete or other cementitious component having a
device acting on the mould for applying vibration to
the mould to consolidate the concrete or other
cementatious mix in th~ mould, a chamber enclosing
the vibration applying device and engaging the mould
around the location where the device acts on the
mould and a means for creating ~ vacuum within the
chamber to minimize transmission of noise from the
vibrating device.
3 _
By enclosing the vibration device in a chamber and
creating a vacuum by means of a vacuum pump, a major
source of noise transmitted by the device is removed.
5 sRIEF DESCRIPTION OF THE DRAWINGS
~he following is a description of a specific
embodiment of the invention, reference being made to
the accompanying drawings in which:
Figure 1 is a side elevation view of a mould for
creating arcuate concrete tunnel lining segments:
Figure 2 is a plan view of the mould illustrated in
Figure l; and
Figure 3 is a plan view o~ a prGduction area showing
typical mould layout.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring firstly to Figures 1 and 2 of the drawings,
there is shown the base 10 of a mould for forming
arcuate concrete tunnel lining segements having a
mould cavity indicated at 11 formed in its upper
surface and extending between ends 12 of the base.
The cavity has an upwardly facing convexly curved
mould surface 13 extending between the ends 12 to
: define the inner surface o~ the segment to be cast
and the inner sides of the ends 12 are formed with
mould surfaces 14 to define the circumferential ends
o~ the segment to be cast.
.
An electrical heating element 15 is cast into the
body of the base 10 and extends thr~ugh a number of
closely spaced turns in a zig-zag pattern parallel to
2 0 ~
- 4 -
and just below the mould surface 13 throughout the
length of the mould surface. Equally the heating
element could follow a zig-zag path across the widkh
of the mould. The ends of the heating element 15
terminate in a junction box 16 built into a side wall
of the base 10 adjacent the center of the base (or at
any other convenient location on the base) and ara
connected by leads 17 to a control box and power
source (not shown~. A the~nostat unit 18 is mounted
lo on the junction box 16 to project into the thicXness
of the base and is connected by leads ls to a
thermostat control for the power source to the leads.
Thus mould surface 13 can be heated during casting of
a concrete segment in the mould to raise the
temperature o~ th~ segment and thereby accelerake the
curing o~ the segment in the mould.
Figure 3 illustrates the layout of a production area
in which a number of rows of moulds lo are mount2d
parallel with one another along the length of the
workshop area with four moulds in each row. The
moulds in each row are connected to a common control
box along one side of the production area and the
control boxes 20 are all interlinked to a common
power supply.
It will be appreciated that in the moulding operation
standard side walls are applied to the mould to
define the circumferentially extending sides of the
segment to be moulded and the outer convex surface of
the segment is ~inishsd by hand trowelling in
conventional manner. In addition the outer surface
of th~ mould can be closed by arcuate cover plates 25
as illustrated in Figure 1. Each cover plat2 is of
hollow construction comprising inner and outer plates
,. : ' ; :: .. :, ': . ' . ' . , ', .. ., ' ,, ,, . . , ! - , . ... . .
~ 3
26, 27 spaced hy frame members 28 and a port 29 is
formed in the outer surface for a connection to a
vacuum supply. The inner plates 26 of the covers are
formed with a multiplicity of apertures through which
vacuum can be drawn to assi'3t in extracting air from
the surface of the concrete to improve the ~inal
surface finish of the segment.
To assist in consolidating the concrete in the mould
and the extraction of air f;rom the concrete vibration
devices 30 are clamped to the mould sides on both
sides of the mould to vibrate the mould and thereby
consolidate the concrete. In accordance with the
present invention, vacuum boxes 31 are fitted to the
mould over the vibrators to engage the mould around
the vibrators each box having a conduit 32 leading to
a vacuum pump to draw vaccum within the box. By
extracting the air from the box during the vibration
operation, the transmission of noise from the
vibriators is minimized.
