WO2023235927A1

WO2023235927A1 - Construction of annular concrete tanks on-site

Info

Publication number: WO2023235927A1
Application number: PCT/AU2023/050502
Authority: WO
Inventors: Antonio John Lazzarotto
Original assignee: Antonio John Lazzarotto
Priority date: 2022-06-07
Filing date: 2023-06-07
Publication date: 2023-12-14

Abstract

Apparatus for constructing an annular wall, the apparatus comprising inner and outer forms having respective substantially upright form surfaces defining a mold cavity therebetween corresponding to a segment of the wall to be constructed. The forms are attached to a support assembly rotatable about a fixed pivot anchor located substantially at a central axis of the wall such that the support is rotatable about the axis in a substantially horizontal plane. The arrangement is such that, in use, the forms are positioned at a selected first angular location relative to the central axis and a concrete composition is filled into mold cavity to create a first wall segment, after which the form is moved by rotation about the pivot axis to an adjacent location whereat the concrete composition is filled into the mold cavity to create a second wall segment adjoining the first.

Description

CONSTRUCTION OF ANNULAR CONCRETE TANKS ON-SITE

Field of the Invention

[0001] The invention relates to large storage vessels, such as water tanks, and their construction. In particular, disclosed herein is an apparatus, system and method for the on-site construction of annular tank structures from concrete.

Prior Application

[0002] The present application claims priority from Australian Provisional Application No. 2022901549 titled “CONSTRUCTION OF ANNULAR WALLS AND ROOF FOR CONCRETE TANKS” as filed on 7 June 2022, the content of which is hereby incorporated by reference in its entirety.

Background

[0003] The construction of large concrete water tanks involves a number of challenges. One construction method involves pre-fabricating the tank structure in sections (i.e. panels) at an off-site facility. The preformed concrete sections are then transported to the site at which the tank will be located and assembled into the form of the tank by interconnecting the panels and sealing the joints so as to be watertight. The construction of a tank in this manner is relatively time-consuming, even though part of the fabrication takes place off-site, and transportation of the large pre-cast segments to remote sites can be difficult.

[0004] Another construction technique requires an internal framework (large scaffolding) to be erected on-site, wherein the outer surface of the framework is then sprayed with concrete matrix to produce a tank walls. A still further technique requires concentric inner and outer annular shells to be constructed, in between which concrete is poured to form a unitary circular wall. For large-scale applications, it will be apparent that constructing an internal framework or concentric inner and outer shells prior to application of the matrix, and maintaining the structural integrity of the construction during and after the concrete has been applied, is difficult. For the most part, this approach necessitates construction of the full circular internal framework or concentric shells prior to commencing spraying or pouring of the concrete. [0005] In this context, there is a need for an improved technique and apparatus able to quickly and conveniently erect annular walls or segments thereof that overcomes one or more of the problems described above or that least provides the public with a useful choice.

Summary of the Invention

[0006] This invention may be used in construction of almost any size circular concrete tank, which may be used for water storage for instance.

[0007] In accordance with the present invention there is provided an apparatus for constructing a circular storage vessel on a preformed base, the apparatus comprising a molding form support structure with an adjustable length pivot arm that in use couples the support structure to a pivot anchor fixed to the base, inner and outer mold forms attachable to the support structure, the inner and outer mold forms defining, in use, a mold cavity corresponding to an annular wall segment, wherein the support structure has first and second sets of wheels capable of supporting the support structure on the base, the first and second sets of wheels being selectively engageable to enable respective orthogonal movements of the support structure relative to the pivot anchor.

[0008] In embodiments, the first and second sets of wheels are mounted to the support structure by way of respective actuators capable of selectively raising and lowering the wheels relative to the support structure.

[0009] In accordance with the present invention there is also provided a method of constructing a circular storage vessel, comprising: constructing a base having a circular wall interface and a central pivot; positioning a wall segment mold cavity over a first segment of the circular wall interface; constructing a first wall segment; moving the mold cavity circumferentially around the wall interface to position the mold cavity over a second segment of the circular wall interface; constructing a second wall segment adjoining the first wall segment; sequentially forming further adjoining wall segments to form an annular wall.

[0010] In one aspect of the present invention, there is provided an apparatus adapted for constructing an annular wall, the apparatus comprising an inner form and an outer form, which supports the steel reinforcing and concrete mix is pumped into these forms. These forms are supported with frame and telescopic link mounted on pivot located on the central axis of the annular wall such that the forms can rotate about the axis in substantially horizontal plane. The forms are positioned at a selected first angular location relative to the pivot and concrete mix is pumped into the forms to construct the first segment. Once the first segment cures, the frame along with both the forms are moved to an adjacent location and again concrete mix is pumped into the forms to construct the adjacent segment. This process is continued till the entire annular wall is constructed.

[0011] According to another aspect of the present invention, there is provided a process of constructing an annular wall using the above-described device. The method comprise of the following steps: constructing the first annular wall segment by pumping the concrete mix into the form and allowing the concrete to harden fully; and moving the forms to an adjacent location and pumping the concrete mix into the form at the adjacent location to form an adjacent wall segment.

[0012] According to a further aspect of the present invention, there is provided a frame arrangement for use in the construction of a reinforced wall, the arrangement comprising: Substantially upright frame positioned at spaced locations along a side of the wall to be constructed.

[0013] A first layer of reinforcement is secured to the inner form such that the layer is parallel to the side of the wall and extends along the wall. Vertically spaced elongate truss members secured at one lengthwise edge to the supports such that the truss members extend laterally along the wall and such that they each lie in a substantially horizontal plane.

[0014] A second layer of reinforcement secured to the free lengthwise edge of each of the truss members such that the second layer is generally parallel to, but sideways spaced from, the first layer of reinforcement.

[0015] Using the present invention an annular tank can be constructed without requiring extensive scaffolding or other framework to define a complete form surface. Furthermore, the rotation of the form around the pivot enables the wall to be constructed continuously or in a stepwise, or semi-continuous manner, thereby avoiding a difficulty encountered in the prior, which the alignment of individual adjacent preformed wall segments requires sophisticated surveying and precision scaffolding / framework.

[0016] In a preferred form of the invention, the annular wall is cylindrical, in which case the central axis constitutes the axis of curvature of the wall, and means are provided for adjusting the orientation of the form relative to the frame support assembly such that the axis of curvature of the form may be inclined relative to the axis of curvature of the wall and/or the axis of curvature of the form may be moved such that it is slightly offset relative to the pivot.

[0017] In some applications, after a wall segment has been formed and has set, or has commenced to set, upon the form surface it may be necessary to physically remove the inner form by a radially inward movement and outer form by radially outward movement prior to rotation of the frame and form to an adjacent location. It is therefore desirable that the frame support assembly further comprises means for raising and lowering the frame support assembly to facilitate the insertion of means for preventing the apparatus from rotating when the concrete mix is applied.

[0018] Adjacent wall segments may be post-tensioned, for instance, by disposing circumferentially extending conduits adjacent to the inner face of outer form and then pumping the concrete mix into the forms. After the annular wall has been cast, cables or other tensioning means disposed within the conduits can be tightened to post-tension the wall. Alternatively, external tensioning means can be disposed around the circumference of the hardened wall. Additionally, or alternatively, vertically extending conduits can also be disposed such that they extend vertically through the wall to receive vertically, extending tensioning means to assist in stressing of the wall. If it is desired to form the wall in a non- continuous manner, the individual hardened wall segments can be locked by the circumferential tensioning means after a sealant has been interposed between adjacent wall segments.

[0019] In general the material used to cast the annular wall will comprise a concrete such as mixed on site or pre-mix. Other construction materials appropriate for moulding/casting onto the form surface such as organic polymers will also be known to those skilled in the art.

[0020] The lateral extent (degrees of arc) of the form surface is not particularly limited - for a cylindrical tank, a circumferential length of the order of 8.5 meters is convenient when constructing walls of 10 to 15 meters radius and 6.5 meters high.

[0021] With both the apparatus and process of the invention, the inner and outer form may define an accurate cross-section such that the internal and external surface of completed annular wall is smooth circular surface. However, the invention is not limited to this and other configurations of the form surface are also appropriate. For instance a flat form surface will produce a polygonal shape wall. It will be apparent, for instance, that the device could be used to produce conical walls by providing an inwardly directed sloping form surface. It is also envisaged that the method and apparatus are also adaptable to the construction of structures such as channels.

[0022] It will be appreciated that the broad forms of the invention and their respective features can be used in conjunction and/or independently, and reference to separate broad forms is not intended to be limiting. Furthermore, it will be appreciated that features of the method can be performed using the system or apparatus and that features of the system or apparatus can be implemented using the method.

Brief description of the drawings

[0023] Further aspects, features and advantages of the invention and/or its embodiments may be apparent from the following detailed description, presented by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0024] Figure 1 is a side elevation view of a concrete water tank structure;

[0025] Figure 2 is an upper perspective view of the base and wall of the water tank structure;

[0026] Figure 3 is an upper perspective view of a base slab for constructing a water tank in accordance with an embodiment of the invention;

[0027] Figure 4 shows a section through a portion of the base slab of Figure 3, illustrating a base-wall interface;

[0028] Figure 5 illustrates a portion of the base slab of Figure 3 including installation of a central pivot anchor;

[0029] Figure 6 shows the base slab with a wall formwork support structure mounted thereon and attached to the pivot anchor;

[0030] Figure 7 shows details of the wall formwork support structure;

[0031] Figure 8 shows the wall formwork support structure mounted on the base slab;

[0032] Figure 9 shows the wall formwork support structure with internal formwork mounted thereon; [0033] Figures 10 and 11 illustrate installation of concrete reinforcing in relation to the internal formwork;

[0034] Figures 12 and 13 show the wall formwork support structure with external formwork mounted thereon;

[0035] Figure 14 shows detail of the wall formwork support structure with internal and external formwork mounted thereon;

[0036] Figure 15 shows the wall formwork support structure with internal and external formwork containing concrete poured to form a first segment of the water tank wall;

[0037] Figure 16 shows the wall formwork support structure being positioned to form a second segment of the water tank wall

Detailed description

[0038] Embodiments of the present invention provide an apparatus, system and method for constructing large-scale annular storage vessels such as water tanks and the like. An example of a water tank 10 constructed according to an embodiment of the invention is shown in side elevation in Figure 1, and is seen in Figure 2 in perspective view without the optional roof structure. The tank 10 comprises a circular base slab 2 formed with a wall interface 4 near the outer edge of the slab. An annular wall 6 extends vertically upwards from the wall interface of the base slab. The wall 6 has an exterior face 7 and an interior face 8, and is also constructed from concrete as described hereinbelow. In this case the water tank 10 also has a roof structure 9 supported around its periphery by the top edge of the wall 6 and by a central support column (not seen). Here the roof structure 9 is also constructed from reinforced concrete, although the roof is not necessarily required for structural integrity of the tank and may optionally be made from different materials or the tank left open at the top.

[0039] As seen in Figure 4, the circular base slab 2 is constructed so as to be thicker around the periphery thereof, underneath the wall interface 4, so as to provide addition strength and support for the wall 6. The wall interface is in the form of a circular channel 40 within which are arranged vertically protruding steel reinforcing bars 42 spaced around the circumference of the base slab. The reinforcing bars 42 of the wall interface are arranged in two concentric circles between which is provided a ring of extruded PVC waterstop 46 in the centre of the channel 40, partially embedded in the concrete of the base slab 2. Side faces of the channel 40 are lined with flex mastic filler tape 48 which, together with the PVC waterstop, assist in ensuring the interface between the wall 6 and base 2 is watertight.

[0040] Construction of the annular wall 6 in accordance with embodiments of the invention first involves installing a central pivot anchor 50 (Figure 5) in the centre of the base slab 2. This provides a central anchor about which a wall forming apparatus 100 can pivot (rotate) while the wall 6 is being constructed on the base slab 2, as described herein.

[0041] The wall forming apparatus 100 has a formwork support structure 120 that is, in use, supported on the base slab 2 adjacent the wall interface 4. The formwork support structure 120 is supported on a first set of wheels that allow it to move around the circumference of the base slab, guided by a coupling arm 110 extending radially from the central pivot anchor 50 (Figure 6). The coupling arm 110 includes a hydraulic actuator 112 which can be used to adjust the radial position of the formwork support structure 120 by movement on a second set of wheels.

[0042] The formwork support structure 120 is made primarily from structural steel and comprises a base 122 from which a plurality of upright members 124 extend upwardly to a top platform 126. The top platform may be equipped with a hoist 160, as seen in Figures 10 and 14, which can be used to lift and position personnel (162) and/or materials during use of the wall forming apparatus 100. The base 122 is supported on first and second sets of wheels that can be used to manoeuvre and position the formwork support structure radially and circumferentially.

[0043] The first set of wheels 140 have their axes of rotation aligned for circumferential movement of the support structure 120 about the axis of the central pivot anchor 50. Each of the first set of wheels 140 are mounted on a respective hydraulic actuator 142 for raising and lowering the wheels 140 relative to the base 122. In the illustrated embodiment the first set of wheels comprises five wheels 140 each with their own hydraulic actuator 142. Three of the wheels 140 are mounted to the base 122 toward the radially outer extent thereof, adjacent the wall interface 4 when the support structure 120 is positioned for use, and a further two wheels 140 are mounted to the base radially inboard toward the centre of the apparatus.

[0044] The second set of wheels 150 have their axes of rotation aligned for radial movement of the support structure 120 relative to the central pivot anchor 50. Each of the second set of wheels 150 are mounted on a respective hydraulic actuator 152 for raising and lowering the wheels 150 relative to the base 122. In the illustrated embodiment the second set of wheels comprises six wheels 150 each with their own hydraulic actuator 152.

[0045] The hydraulic actuators 142, 152 act between the base 122 and respective first and second sets of wheels 140, 150. If the first set of wheels 140 are raised by use of the actuators 142 and the second set of wheels 150 are lowered by use of actuators 152 then the support structure 120 will be supported by the second set of wheels 150 and the apparatus is in condition for circumferential displacement. One the other hand, if the first set of wheels 140 are lowered by use of the actuators 142 and the second set of wheels 150 are raised by use of actuators 152 then the support structure 120 will be supported by the first set of wheels 140 and the apparatus is in condition for radial displacement. When both the first and second sets of wheels are in contact with the surface of the base slab 2, the support structure is then held in place as nether sets of wheels can rotate.

[0046] The actuators 142, 152 are preferably operable individually to raise and lower their respective wheels 140, 150. This can be used to raise/lower the wheels asymmetrically to control a tilt angle of the support structure 120. For instance, the radially outer wheels can be lowered relative to the radially inner wheels to tilt the top of the support structure radially inward, and vice versa. This permits construction of a wall 6 that is not strictly annular but rather having a frustoconical form (i.e. the wall has a different radius at the top than at the bottom).

[0047] In order to use the apparatus 100 to construct a wall on the base slab 2, first an inner formwork structure 202 is fitted to the radially outer upright members 124 of the support structure 120 (Figure 9). This may be done with use of the hoist 160 for example. The inner formwork structure 202 has a generally smooth outer surface that extends vertically from the surface of the base slab to the height of the support structure. Horizontally, the inner formwork structure 202 has a curvature that matches the curvature of the inner face of the circular channel 40 of the wall interface 4. Circumferentially, the inner formwork structure 202 subtends an angle that is a fraction of the total. With the inner formwork structure 202 fitted, the support structure 120 is radially positioned, by use of the second set of wheels 150 and the hydraulic actuator 112 of the coupling arm 110, so that the bottom edge of the inner formwork 202 aligns with the inner face of the wall interface channel 40. [0048] With the inner formwork structure 202 in position aligned with the inner edge of the wall interface 4 of the base slab 2, the apparatus is then fitted with concrete reinforcing structure (Figure 10). The concrete reinforcing structure in this case comprises one or more layers of rebar mesh 230 and a plurality of vertically spaced, circumferentially arranged post-tensioning conduits 240. Preferably two layers of rebar mesh are provided, aligned with and fastened to the respective two rows of reinforcing bars 42 projecting from the channel 40 (Figure 11). The reinforcing structure may be temporarily fastened to and held in place against the inner formwork structure in conventional manner.

[0049] Once the concrete reinforcing structure is in place, an outer formwork structure 204 is mounted on the support structure 120. The outer formwork structure 204 can be supported from the top of the support structure by means of slidably adjustable support beams 128 mounted on the top platform 126 as seem in Figure 12 for example. The position of the outer formwork structure 204 relative to the inner formwork structure can thus be adjusted, by sliding movement of the support beams, until a radially inner face of the outer formwork 204 aligns with the radially outer face of the wall interface channel 40. When positioned, the facing surfaces of the inner and outer formwork structures 202, 204 are substantially parallel/concentric with one another, forming a uniform space therebetween containing the concrete reinforcing structure. In order to maintain this uniform spacing the inner and outer formwork structures may be secured together by a plurality of fasteners (’bolts') 212 that span the gap and are secured at each end to respective horizontal ribs 210 on opposing sides of the inner and outer formwork structures. The fasteners 212 are arranged in a two-dimensional matrix pattern, across the vertical and horizontal extent of the wall formwork structures 202, 204.

[0050] When the inner and outer formwork structures 202, 204 are mounted to the support structure 120, secured to one another and positioned as described above, the formwork structures together form the faces of a concrete mold that contains the reinforcing structure and is located directly above the wall interface channel 40. Edge forms are provided, although not shown in the drawings, to seal the vertical edges of the concrete mold cavity between the inner and outer formwork structures. The edge forms are constructed to allow the ends of the rebar mesh and the ends of the post-tensioning conduits to protrude therefrom for connection to an adjacent segment of the wall during construction (described below). Each edge form is also arranged to hold in place a length of extruded PVC waters top material 146 so that one edge of the waterstop strip protrudes into the concrete wall mold cavity and is embedded in the edge of the concrete wall section when set (Figure 14).

[0051] The outer formwork structure 204 has a plurality of concrete pour access ports 220 positioned at different heights. When the time comes to fill the wall mold cavity, concrete is first pumped in through the lowermost access port until the poured concrete level in the mold reaches that height. Those access ports are then closed and sealed with a cover 221 (Figure 13), and concrete is poured into the mold from the next highest access port(s), and so on until the concrete reaches the top of the formwork.

[0052] Once the concrete in the mold cavity has set sufficiently for the wall segment 300 to stand on its own (Figures 14 and 15) the apparatus 100 can be shifted rotationally about the central pivot anchor in preparation for forming an adjacent and adjoining wall segment. To do this, the heads of fasteners 221 are removed so that the inner and outer formwork structures 202, 204 can be released from the moulded concrete wall section. This may be accomplished by: moving the outer formwork structure 204 outward, away from the outer surface of the completed wall segment, using the slidably adjustable support beams 128; moving the inner formwork structure 202 inward, away from the inner surface of the completed wall segment, by moving the support structure 120 using the second set of wheels and hydraulic actuator 112; and rotating the apparatus 100 about the central pivot anchor, using the first set of wheels, to position the formwork cavity to mold a wall segment adjacent and adjoining the previous one (Figure 16).

[0053] The rebar mesh 230 and conduits 240 for each new wall segment are attached to the corresponding portions of the reinforcing structure protruding from the edge of the already formed adjacent wall section, before the mold is closed for concrete pour. Following the first, stand-alone wall segment, only a single edge form is required for each subsequent wall segment since the opposite edge of the mold cavity will be sealed by the edge of the adjacent wall segment already formed.

[0054] The final wall segment that completes the annular wall will not require any edge forms since there will then be a completed wall segment on each side. Moreover, the final wall segment may be constructed with a greater concrete wall thickness so as to accommodate and allow for adequate post-tensioning of the annual wall structure. To that end, the horizontal conduits 240 are threaded with respective post-tensioning tendons (cables), the ends of which terminate at the final wall segment where tension is applied to strengthen the completed concrete wall structure.

[0055] The wall forming process disclosed herein allows the complete cylindrical tank to be formed continuously in one piece and avoids problem encountered with the prior art in which individual wall segments must be locked together and sealed to waterproof the tank. The interface between the wall and the base slab, comprising a channel with rubber mastic composition on its side faces and a ring shaped waterstop, provides excellent sealing between the wall and the base. Moreover, the vertical edge interface between each adjacent wall segment is also formed with a length of waterstop strip embedded in the concrete to prevent liquid leaks where the segments join.

[0056] Further, it is envisaged that more than one wall forming apparatus 100 can be used to further reduce the overall construction time of the tank. In this case each apparatus would rotate about a common pivot post such that, for example, each apparatus initially forms adjacent wall segments after which each apparatus is rotated in opposite directions about the common pivot, each forming sequential wall segments, and again come together again to form the last of the wall segments, thereby completing the tank.

[0057] Once the construction of the annular wall on the base slab has been completed, the structure is able to hold and store water, whether or not a top cover or roof is to be used. If a top cover is desired, it may be constructed from concrete and/or other materials in a variety of different manners, including by way of a similar technique as employed for the wall construction. Such practice is described, for example in the specification of the Inventor's aforementioned provisional patent application, although the present invention should not be considered as limited or restricted in that way.

[0058] Although the invention has been described using an example of a circular water tank many modifications may be made thereto without departing from the spirit and scope of the invention, which includes every novel feature and combination of novel features herein disclosed.

[0059] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.

[0060] In the foregoing description of preferred embodiments, specific terminology has been resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as “front” and “rear”, “inner” and “outer”, “above” and “below” and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms.

[0061] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0062] Throughout this specification and the claims which follow, unless the context requires otherwise, the word ‘comprise’, and variations such as ‘comprises’ and ‘comprising’, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims

1. Apparatus for constructing a circular storage vessel on a preformed base, the apparatus comprising a molding form support structure with an adjustable length pivot arm that in use couples the support structure to a pivot anchor fixed to the base, inner and outer mold forms attachable to the support structure, the inner and outer mold forms defining, in use, a mold cavity corresponding to an annular wall segment, wherein the support structure has first and second sets of wheels capable of supporting the support structure on the base, the first and second sets of wheels being selectively engageable to enable respective orthogonal movements of the support structure relative to the pivot anchor.

2. Apparatus according to claim 1 , wherein the first and second sets of wheels are mounted to the support structure by way of respective actuators capable of selectively raising and lowering the wheels relative to the support structure.

3. Apparatus for constructing an annular wall, the apparatus comprising inner and outer forms having respective substantially upright form surfaces defining a mold cavity therebetween corresponding to a segment of the wall to be constructed, the forms being attached to a support assembly rotatable about a fixed pivot anchor located substantially at a central axis of the wall such that the support is rotatable about the axis in a substantially horizontal plane, the arrangement being such that, in use, the forms are positioned at a selected first angular location relative to the central axis and a concrete composition is filled into mold cavity to create a first wall segment, after which the form is moved by rotation about the pivot axis to an adjacent location whereat the concrete composition is filled into the mold cavity to create a second wall segment adjoining the first.

4. Apparatus according to claim 3, wherein the support assembly has a first set of wheels that can be selectively raised and lowered.

5. Apparatus according to claim 4, wherein the support assembly has a second set of wheels that can be selectively raised and lowered.

6. Apparatus according to claim 5, further comprising means for adjusting the orientation of the form surfaces relative to the central axis such that an axis of curvature of the form surfaces may be inclined relative to the axis of curvature of the wall.

7. Apparatus according to claim 6, wherein the means for adjusting the orientation of the form surfaces relative to the central axis comprises actuators for raising and lowering the first and/or second wheels, operable to adjust an inclination angle of the support assembly.

8. Apparatus according to any one of claims 1 to 7, wherein the frame support assembly is telescopic and the support assembly includes first driving means for moving the forms radially in a plane substantially normal to the axis of curvature of the wall.

9. Apparatus according to any one of claims 1 to 8, wherein the support assembly is mounted on a base arrangement on which the pivot anchor is located, the base arrangement having a circumferentially extending channel for receiving a bottom portion of the wall.

10. A method of constructing an annular wall using the apparatus of any one of claims 1 to 9, the method comprising: forming a first wall segment by applying a hardenable composition into the mold cavity and allowing the composition to harden, at least partially; moving the mold cavity to an adjacent location; and applying the hardenable composition into the mold cavity at the adjacent location to form an adjacent wall segment.

11. A method of constructing an annular wall as claimed in claim 10, wherein the mold cavity is moved and the adjacent wall segment is formed while the first wall segment is hardening, thereby causing the adjacent wall segments to be integrally formed.

12. A method of constructing a circular storage vessel, comprising: constructing a base having a circular wall interface and a central pivot; positioning a wall segment mold cavity over a first segment of the circular wall interface; constructing a first wall segment; moving the mold cavity circumferentially around the wall interface to position the mold cavity over a second segment of the circular wall interface; constructing a second wall segment adjoining the first wall segment; sequentially forming further adjoining wall segments to form an annular wall.

13. A method according to claim 12, wherein each wall segment includes embedded reinforcing structure that joins to reinforcing structures of adjoining wall segments.

14. A method according to claim 13, wherein the wall interface of the base includes reinforcing structure that joins to the reinforcing structure embedded in each of the wall segments.

15. A circular storage vessel constructed according to the method of any one of claims 12 to 14.