Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
-`` 1069719
This invention relates generally to chimneys or
stacks for flue gases, and has to do particularly with a
method for constructing a chimney of this kind.
Many prior art chimney constructions include an
inner, refractory lining of cylindrical or other suitable
section, closely surrounded by an outer concrete wall.
Typically, both the liner and the outer wall are composed
of precast interfitting segments in stacked relationship,
and the main strength of the chimney is invariably associa-
ted with the segments composing the outer wall. The indivi-
dual precast segments of the outer wall, in the prior art,
are typically provided with both circumferential reinforcing
steel (to allow the wall to resist hoop stresses) and also
means for receiving longitudinal reinforcing bars (rebars).
The latter are typically provided in the form of open-ended
pipes extending longitudinally of the outer wall segments,
in such a way that when the segments are stacked one on top
of the other these pipes can be aligned, and can thus receive
elongated reinforcing bars which can extend from the top to
the bottom of the chimney.
This necessity for providing both circumferential
and longitudinal reinforcement within the outer wall segments
results in considerable expense in the precasting of these
segments, and involves tricky manoeuvres in ensuring that
the adjacently stacked outer wall segments are properly
aligned so that the longitudinal reinforcing bars can be
inserted.
It is with the foregoing disadvantages of the
prior art method in mind that the present invention has been
developed.
106~'719
Accordingly, this invention provides a method of
constructing a composite chimney having a unitary cross-sec~ion
through the wall thereof, comprising the steps of:
providing an inner precast lining composed of
annular segments in interfitting stacked relationship,
forming a plurality of reinforced annular segments
by placing a plurality of circumferential steel hoops in
each of a plurality of concrete annular segments to reinforce
each of said segments against circumferential stressing,
providing a precast concrete outer wall composed of
said annular reinforced segments in interfitting relationship
surrounding said lining and spaced outwardly therefrom in
non-contacting relationship therewith to define an interstitial
gap,
providing linked longitudinal and circumferential
reinforcing steel bars within said interstitial gap,
and pouring in situ concrete into said interstitial
gap and aIlowing it to harden to integrally connect said
outer wall thereby forming a multilayer chimney which is
composed of at least three layers and is solid and continuous
: through the thickness thereof about the circumference
thereof with said reinforcing bars providing longitudinal and
circumferential reinforcement to said concrete.
An example of the method of this invention is illus-
- trated in the accompanying drawings, in which like numerals
denote like parts throughout the several views, and in which:
Figure 1 is a perspective view of a typical chimney
installation;
Figure 2 is a perspective view of a portion of the
chimney of Figure 1, in a partially completed condition;
Figure 3 is a horizontal section through a com-
pleted portion of the chimney of Figure l;
-3-
7~9
Figure 4 is a vertical section through a completed
portion of the chimney of Figure l; and
Figure 5 is a horizontal section through a completed
chimney of different sectional configuration from that
illustrated in Figure 3.
Essentially, the method of this invention involves
the provision of an inner precast lining composed of
interfitting segments, the latter to be situation within and
spaced inwardly from the inner surface of a precast concrete
outer wall also composed of interfitting segments. Within
the interstitial gap existing between the lining and the
outer wall the longitudinal reinforcing steel bars are
-3a-
~,...
10~9719
supported and maintained while in situ concrete is poured
into the interstitial gap and around the longitudinal re-
inforcing steel bars. When the in situ concrete hardens,
there is in effect a three-part sandwich having the original
precast concrete outer wall segments on the outside, the
segments of the precast lining on the inside, and
between them a hardened concrete layer in which the longitudi-
nal reinforcilly steel bars are embedded.
In Flyure 1, a chimney 10 is associated with a
building 12 which may be a manufacturing plant, commercial
building, or the like.
In Eiyure 2, the chimney 10 is seen to consist of
an outer wall 14 which includes precast concrete segments 16
in stacked relationship, within which a series of stacked,
interfitting segments 18 of a precast refractory lining are
disposed. As can be seen in Figure 2, there is left an inter- -~
stitial gap 20 between the outer wall 14 and the segments 18
of the lining.
Situated within and extending vertically longitudin-
ally of the yap 20 are a plurality of longitudinal reinforcing
steel bars 22, these being tied together with heavy wire 24
in kno~n manner. A chute 26 for in situ concrete is provided
to allow mixed concrete to be poured into the interstitial
gap 20 around the longitudinal reinforcing bars 220 When
the in situ concrete within the interstitial gap 20 hardens,
the longitudinal reinforcing bars 22 will be embedded in the
hardened concrete.
In Figure 3, the hardened in situ concrete is shown
by the numeral 270
As can be seen in Figures 2 and 4, the segments 18
of the lininy interfit at ogee joints 30 which are stepped
--4--
1069719
down toward the inside of the chimney, while the segments
16 of the outer wall interfit at ogee joints 32 which are
stepped down toward the outside of the chimney. This arrange-
ment ensures that water running down the outside of the
chimney will not penetrate into the structure of the wall,
and also that water droplets running down inside the lining
will likewise be prevented from entering the structure of
the wall at the joints. Preferably, the interfitting
adjacent segments both of the lining and of the outer wall
are cemented together with mortar, with the mortar for the
lining being of a refractory composition.
As can be seen in Figure 4, the segments 16 of the
precast outer wall contain internal reinforcing in the form
of circumferential reinforcing steel hoops 33. The steel
hoops 33 are provided to permit the outer wall to contain
hoop stresses, and it will be appreciated that by providing
the segments 16 only with the circumferential reinforcement
and not with means to allow longitudinal reinforcement,
there will be no need to align the outer wall segments 16 at
the time of assembly.
Figure 5 shows an alternative horizontal sectional
construction of a chimney, which differs from that shown
in Figure 3 primarily in the outer fluting of the outer wall
14' and in the specific section of the refractory lining
segments 18'. Again, however, the longitudinal reinforcing
steel bars 22' are provided within the interstitial gap
existing between the lining segments 18' and the outer wall
14', which is seen in Figure 5 to be filled with hardened in
situ concrete 36.
It will be appreciated that many other appropriate
:'
--5--
069719
sectional configurations could be devised to utilize the
advantage of the method of this invention.
While the lining segments are described as being
of refractory material in this disclosure, it is to be
understood that fibreglass material or other similar
compositions could also be utilized.
--6--
