AP482A

AP482A - Building formwork and method of building.

Info

Publication number: AP482A
Application number: APAP/P/1994/000650A
Authority: AP
Inventors: Der Berg Dawid Johannes Van
Original assignee: Der Berg Dawid Johannes Van
Priority date: 1994-06-23
Filing date: 1994-06-23
Publication date: 1996-03-25
Also published as: AP9400650A0

Abstract

The formwork disclosed comprises a inflatable body having a base, side walls and a curving roof spanning across the walls. The body is inflated and building material is applied to the outer surface thereof. The body can be ballasted using water or sand, which is preferably pumped in andout of the body, or can be inflated within a retaining wall which serves as a foundation for the subsequently applied building material.

Description

THIS INVENTION relates to a building formwork and to a method of building.

According to one aspect of the present invention there is provided a formwork comprising an inflatable body having a base, side walls extending upwardly from the base and a roof joining the upper ends of the side walls, there being inlet means to said body through which air can be pumped to inflate the body and through which a liquid or other flowable material can be pumped to provide ballast within the inflatable body.

The formwork preferably includes a first inlet for air and a second inlet for said liquid or other flowable material. In this form said first inlet is desirably at a higher level than said second inlet.

(

The formwork can include a ballast chamber around the periphery of said formwork, said second inlet opening into said chamber.

To enable pressure in the formwork to be controlled it can include a pressure relief valve which opens to prevent the pressure within the body rising to above a predetermined value. It can further include a source of air

AP/P/ 9 4 / 00 6 5 0

-3from said source into the formwork upon the pressure in the formwork dropping below a predetermined value.

According to a further aspect of the present invention there is provided a method of building which uses a formwork constituted by an inflatable body comprising a base, side walls extending upwardly from the base and a roof joining the upper ends of the side walls, the method comprising inflating the body, providing ballast in the lower part of said body, applying building material to the outer surface of said body, removing said ballast and deflating said formwork.

Said ballast is preferably a liquid or other flowable material which is pumped into said body through an inlet in said body. Said flowable material can be water.

To avoid wastage the method can include the step of pumping the flowable material from a first body to which building material has previously been applied to a second body which is being brought to the condition in which building material can be applied thereto.

The method can include regulating the pressure in said formwork by allowing air to escape as the pressure rises and feeding air in as the pressure drops thereby to maintain the formwork's internal pressure within predetermined upper and lower limits.

AP 0 0 4 8 2

-4According to another aspect of the present invention there is provided a method of building which comprises erecting a retaining wall which forms the outer boundary of the building, placing an inflatable body in the area bounded by the retaining wall and inflating the body, the body having a base, side walls extending upwardly from the base and a roof joining the upper ends of the side walls, the inflated body extending above the upper edge of said retaining wall, and applying building material to the outer surface of said body using said retaining wall as a foundation for said material.

To provide a window and/or door the method can include the step of locating a door or window form against the outer face of said body before applying said building material, building material not being applied over said form whereby, when said form is removed, a door or window opening is left in the building.

To enhance stability, said body may be divided internally into compartments, the compartments being inflated and ballasted independently of one another.

According to a still further aspect of the present invention there is provided a formwork comprising an inflatable body having a base, side walls extending upwardly from the base and a roof joining the upper ends of the side walls, an air inlet to said body through which air can be

AP/P/ 9 4 / 0 0 6 5 0

-5pumped to inflate the body, and a plurality of anchoring loops attached to the lower portions of the outer surfaces of said side walls for attachment to anchoring means secured to a foundation.

The form can be of flexible sheet material such as synthetic plastics material eg PVC, synthetic rubber, a synthetic or natural textile material including fabrics such as canvas, or composites thereof. The flexible sheet material may be a reinforced laminate comprising two or more of said sheet materials.

The building material may be a settable building material eg a cementitious material, optionally reinforced, soil mixes, mud, aerated concrete mixes, et al. The settable building material may also include eg plastics foam materials and fibre-reinforced plastics materials. The building material may be of applied as a coating or layer, or a plurality of coatings or layers, by conventional means, including eg casting and spraying gunite-fashion.

The building material may comprise a plurality of pre-formed building elements and a settable cementitious binder, eg bricks or building blocks and mortar.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings.

ΑΡ 00482

-6Ιη the drawings:

Figure 1 is a front elevation of formwork in accordance with one embodiment of the invention;

Figure 1A is a three-dimensional view of a window-form forming part of the formwork shown in Figure 1;

Figure 2 is a rear elevation of the formwork of Figure

1;

Figure 3 is an end elevation of the formwork of Figure

Figure 4 is a plan view at IV-IV in Figure 1; Figure 5 is an end elevation from the opposite direction to Figure 3;

Figure	6	is	a	section	on	line
Figure	7	is	a	section	on	line
Figure	8	is	a	section	on	line
Figure	9	is	a	plan view of a

ί >

constructed using the formwork of the invention;

Figure 10 shows a rear view of the building of Figure

9;

Figure 11 is an end elevation of the building of Figure

9;

Figure 12 is a section on line XII-XII in Figure 9; and Figures 13 and 14 show two further possible constructions.

With reference to Figures 1 to 8 of the drawings, reference numeral 10 designates generally formwork in accordance with one embodiment of the invention. The

-Ί formwork 10 comprises an inflated body 12 of a flexible sheet material, eg a gas-impermeable reinforced rubber/PVC laminate.

The body comprises panels of said material, the 5 panels having peripheral edges which are joined air-tightly together eg by stitching and/or sealing (not shown).

ζ·'. The body 12 comprises an intermediate elongate section 20 having a base 22 of generally rectangular shape and a wall 24 extending upwardly from and spanning between the opposite edges of the base 22.

The wall 24 has an inverted U-shape defining two opposed wall-forms 24.1, 24.2 which extend upwardly from the bottom wall 22 and a roof-form 24.3 joining the upper ends of the wall-forms. The opposite ends of the intermediate s

section 20 are closed off by end walls 24.4. Beyond the end C walls 24.4 of the section 20 there are two end sections 26,

28. The end section 26 has a bottom wall or base 30 formed by an extension of the base 22 and has a wall 32, extending upwardly from the periphery of the base 30, formed by an extension of the wall 24. The wall 32 has a dome-like shape defining two opposed wall-forms 32.1, 32.2, an end wall-form

32.3 and a roof-form 32.4, the wall-forms 32.1, 32.2 being extensions of the wall-forms 24.1, 24.2 and the roof-form

32.4 being an extension of the roof-form 24.3. The opposite end section 28 has a similar base 34 and a similar wall 36

AP 00482

-8defining two similar opposed wall-forms 36.1, 36.2, a similar end wall-form 36.3 and a similar roof-form 36.4. The wallforms 36.1, 36.2 and the roof-form 36.4 are extensions of the wall-forms 24.1, 24.2 and the roof-form 24.3 in a similar fashion to the wall-forms 32.1, 32.2 and the roof-form 32.4.

The wall form 24.1 includes a closable air inlet/outlet 18.1 therethrough for connection to a pump (not shown) for inflating and deflating the formwork. A second inlet/outlet 18.2 permits ballast to be pumped in and out as will be described. The inlets each include a shut-off valve (not shown) which valves, when closed, cause the pressure in the formwork to be maintained.

Each section 26, 28 includes an air inlet/outlet 18.3 and a ballast inlet/outlet 18.4 (see Figures 3 and 5).

c

A plurality of window-forms 38, 38.1, 38.2, 38.3,

38.4, 38.5 and door-forms 40, 40.1 are shown. A threedimensional view of the window-form 38.2 is shown in Figure

1A and the other window-forms have a similar form. The doorforms 40, 40.1 have an appropriately similar form.

The air and ballast inlets/outlets 18.1, 18.2,

18.3, 18.4 are preferably but not essentially provided in parts of the formwork which are within the boundaries of the window and door forms 38 etc and 40 etc. As will be

AP/P/ 9 4 / 0 0 6 5 0

-9provided outside these boundaries will become embedded in the walls of the building which is eventually created and this can complicate the deflation procedure. However, this problem can be overcome by leaving a few bricks, or a small area of concrete out around the inlet/outlet, and filling in the resulting hole after the form has been removed.

With reference to Figures 9 to 12 of the drawings, the same reference numerals used in Figures 1 to 8, preceded by the digit 1, are used to designate building parts shaped by the corresponding parts of the inflated body 12. Reference numeral 110 designates generally a low-cost building built by a method employing the inflated body 12 as formwork. Similarly, reference numeral 112 designates an intermediate section of the building 110 having two end portions 126, 128 shaped using respectively the intermediate section 20 and the end sections 26, 28 of the inflated body

12.

In use, the body 12 is positioned on a preprepared base and is inflated with air via the inlet/outlets 18.1 and 18.3 using one or more pumps (not shown). The pressure can vary in dependence on the mass of the building material which will eventually be placed on the external face of the form. Simultaneously, ballast is pumped in through the inlets/outlets 18.2 and 18.4. The ballast is preferably water but could be a sand which is fine enough to be pumped. The mass of the ballast holds the bases 22, 30 and 34 against

AP 0 0 4 8 2

-10the pre-prepared base. The pre-prepared base can be a concrete platform but can also be levelled and compacted soil.

A building material eg steel-reinforced cement, face and/or stock bricks and mortar (eg as indicated by reference number 50, Figures 10 to 12), a reinforced synthetic plastics material, or a cement composition sprayable gunite-like fashion etc., is then applied to the outer surfaces of the body 12. Thereafter, the building material is allowed to set as necessary, and the formwork deflated by pumping out the air via the inlet/outlets 18.1 and 18.3 or by simply allowing the air to escape to atmosphere. The ballast is pumped out as the form is deflated. Preferably, particularly if the ballast is water, it is pumped to another form which is at that stage being inflated. This avoids wastage. The outer surfaces or the body 12 may be coated with eg oil prior to casting cementitious material thereon to prevent the cured concrete sticking to the body 12.

The outside walls of the building 110 can be plastered (eg as indicated by reference numeral 52, Figure 11). Similarly, the inside walls of the building 110, can be plastered, painted, or otherwise finished etc.

In the case of the window-forms 38, 38.1, 38.2, 38.3, 38.4, 38.5 and the door-forms 40, 40.1, the building

AP/P/ 9 4 / 0 0 6 5 0

BAD ORIGINAL d &

-11material is applied to the periphery of said forms. When the body 12 is deflated window openings 138, 138.1, 138.2, 138.3, 138.4, 138.5 and door openings 140, 140.1 are formed.

Internal building parts in the building 110 may 5 be formed using appropriately shaped inflated bodies in the form of units, or sub-units which can be assembled together modular fashion.

The inflated body 12, and units or sub-units of similar inflated bodies, can be free-standing or connected together eg by cross-braces, when necessary, eg when building vertical planar walls. This is illustrated in Figure 4 where a single cross brace 80 is shown spanning between the wall forms 24.1, 24.2 and suitably attached to the forms. In practice there will be a plurality of such braces along the length of the wall forms 24.1, 24.2.

( ( The end section 26 is shown braced by two cross braces 82 and a curved brace 84 all of which are secured to the walls of the formwork.

The braces illustrated prevent the wall forms

24.1, 24.2 and the sections 26 and 28 bulging outwardly under internal pressure as the formwork is inflated.

To provide additional rigidity it is possible to provide upwardly open pockets on the outside of the form.

AP O 0 4 8 2

-12This is achieved by securing panels to the outside of the form, the panels being attached along their lower edges and side edges but not along their top edges. Plywood boards are slid into these pockets from the top to resist bulging.

In Figure 13 there is shown a structure which includes a foundation 54 which can be of concrete or compacted soil. The foundation is surrounded by a wall 56 which, in plan, is of the same shape as the building to be constructed. The inflatable formwork 58 comprises a base 60, side walls 62 and a roof 64 which joins the upper ends of the side walls.

The formwork 58 is not ballasted prior to inflation. There is thus a tendency, as inflation progresses, for the bottom wall and side walls to distort as shown by the chain dotted lines LI. However as building takes place onto to the wall 56 as shown by the dashed line L2, this distortion has no effect on the building procedure. In this form the internal dimensions of the space bounded by the wall 56 must be just greater than the inflated size of the formwork. If the space is too small then the inflated form will burst the retaining wall.

Turning finally to Figure 14, the construction shown comprises a formwork 66 which includes a base 68 and side walls 70. At intervals around the lower portions of the outer surfaces of the side walls 70 there are flaps 72 to

05900/V6 /d/dV

BAD ORIGINAL A

-13which loops 74 are secured.

A foundation is shown at 76 and a base at 78.

Hooks H are embedded in the foundation 76. Before the formwork 66 is inflated, the loops 74 are attached to the 5 hooks H thereby to anchor the formwork down. This construction is only suitable for lightweight structures.

Door forms and window forms as described with reference to Figures 1 to 8 are used in the embodiments of Figures 13 and 14.

In the embodiments described above the ballast, whether it is water or sand, forms a layer over the entire extent of the bases 22, 30, 34 etc when it is pumped into the form work. It will be appreciated that the downward force necessary to resist lifting of the base when the formwork is inflated is only required around the periphery. Restriction of the ballast to the periphery of the formwork can be achieved by providing a ballast chamber 76.1 (see Figures 4 and 6) around the periphery of the base. The chamber 76.1 can be separate from the formwork and comprise a tube having the same shape as the periphery of the formwork.

Alternatively, the chamber can be an integral part of the formwork itself and secured to the inside of the walls 24, 32 etc and/or to the bases 22, 30, 34 etc.

Experimental work has shown that temperature

AP 00482

-14changes have a substantial effect on the pressure within the formwork. Daytime temperatures cause the formwork's internal pressure to rise to a level such that the formwork bulges to an undesirable extent. Overnight the pressure inside the formwork drops to a level such that it no longer properly supports the building structure. Depressions or wrinkles in the formwork result. If the structure built onto the formwork has not set then the lack of adequate support can result in fractures in and subsidence of the structure.

To counter this a pressure relief valve is provided which opens upon the pressure in the formwork exceeding atmospheric pressure by a predetermined value. A further valve is connected to an external source of air under pressure and set to open when the pressure in the formwork drops below a predetermined value. When this valve opens compressed air from said source flows into the formwork until the pressure in the formwork rises to the preset value whereupon the valve closes. These valves thus hold the

Claims

CLAIMS:

1. A formwork comprising an inflatable body having a base, side walls extending upwardly from the base and a roof joining the upper ends of the side walls, there being inlet means to said body through which air can be pumped to inflate the body and through which a liquid or other flowable material can be pumped to provide ballast within the / inflatable body.
2. A formwork as claimed in claim 1 and including a first inlet for air and a second inlet for said liquid or other flowable material.
3. A formwork as claimed in claim 2, wherein said first inlet is at a higher level than said second inlet.

c
4. A formwork as claimed in claim 2 or 3 and c

including a ballast chamber around the periphery of said formwork, said second inlet opening into said chamber.
5. A formwork as claimed in any preceding claim and including a pressure relief valve which opens to prevent the pressure within the body rising to above a predetermined value.

A formwork as claimed in any preceding claim and including a source of air under pressure and a valve which

AP 0 0 48 2

-16opens to permit air to flow from said source into the formwork upon the pressure in the formwork dropping below a predetermined value.
7. A method of building which uses a formwork constituted by an inflatable body comprising a base, side walls extending upwardly from the base and a roof joining the upper ends of the side walls, the method comprising inflating ς the body, providing ballast in the lower part of said body, applying building material to the outer surface of said body, removing said ballast and deflating said formwork.
8. A method as claimed in claim 7, wherein said ballast is a liquid or other flowable material which is pumped into said body through an inlet in said body.
9. A method as claimed in claim 8, wherein said flowable material is water.

(
10. A method as claimed in claim 8 or 9 and including the step of pumping the flowable material from a first body to which building material has previously been applied to a second body which is being brought to the condition in which building material can be applied thereto.
11. A method as claimed in any one of claims 7 to 10 and including regulating the pressure in said formwork by allowing air to escape as the pressure rises and feeding air

AP/P/ 9 4/ 0 0 6 5 0

BAD ORIGINAL

-17in as the pressure drops thereby to maintain the formwork's internal pressure within predetermined upper and lower limits.
12. A method of building which comprises erecting a retaining wall which forms the outer boundary of the building, placing an inflatable body in the area bounded by the retaining wall and inflating the body, the body having a base, side walls extending upwardly from the base and a roof joining the upper ends of the side walls, the inflated body extending above the upper edge of said retaining wall, and applying building material to the outer surface of said body using said retaining wall as a foundation for said material.
13. A method as claimed in any one of claims 7 to 12 and including the step of locating a door or window form against the outer face of said body before applying said building material, building material not being applied over said form whereby, when said form is removed, a door or window opening is left in the building.
14. A building method as claimed in any one of claims 7 to 13 in which said body is divided internally into compartments, the compartments being inflated and ballasted independently of one another.
15. A formwork comprising an inflatable body having a base, side walls extending upwardly from the base and a roof

Al·

-18joining the upper ends of the side walls, an air inlet to said body through which air can be pumped to inflate the body, and a plurality of anchoring loops attached to the lower portions of the outer surfaces of said side walls for attachment to anchoring means secured to a foundation.

AP/P/ 9 4/ 0 0 6 5 0