CAMILLERI, Paul (c/- Ahearn Fox Patent & Trade Mark Attorneys, Level 4 141 Queen Stree, Brisbane QLD 4000, AU)
| THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A method of constructing a building, including: driving a plurality of screw piles into the soil on which a building is to be constructed to a predetermined founding depth and in a predetermined array; casting a plurality of concrete floor panels remote from the soil on which the building is to be constructed, the floor panels being adapted to be joined together at predetermined edges to form the floor of the building to be constructed and to rest on selected ones of said plurality of screw piles respectively; and placing said concrete floor panels on the selected screw piles respectively such that they adjoin at said predetermined edges to form the floor of the building and such that at least a substantial part of each panel is spaced above the soil by a predetermined distance determined by reference to the swell potential of the soil. 2. A method according to Claim 1, wherein the site is levelled prior to driving the screw piles into the soil. 3. A method according to Claim 2, wherein the site is also levelled after the piles have been driven. 4. A method according to any one of the preceding claims including placing a load bearing cap on each screw pile and setting the upper faces of all screw pile caps to the same level. 5. A method according to any one of the preceding claims wherein the screw piles are cut off to the same level after being driven into the soil prior to the caps being fitted and the caps are fitted so as to bear directly against the upper ends of the respective piles. 6. A method according to Claim 1, wherein each floor panel is constructed with an integrally formed perimeter beam and a suspended portion, the perimeter beam extending along at least one side and being adapted to seat on the selected screw piles, and the suspended portion extending from the perimeter beam. 7. A method according to Claim 6, wherein the perimeter beam extends along at least two opposite sides and the suspended portion spans between the opposite portions of the perimeter beam. 8. A method according to Claim 1, wherein the bottom face of the perimeter beam is lower than the bottom face of the suspended portion whereby in use, the suspended portion spans the soil between adjacent rows of piles. 9. A method according to Claim 1, wherein the floor panels are constructed such that the suspended portion is at least 100mm above the soil surface for M category soils, 150mm for H category soils and 200rnm for E category soils. 10. A method according to any one of Claims 6 to 9, wherein each floor panel is cast with a width of about 3.6m. 11. A method according to Claim 1, wherein the length of each panel is about 12m. 12. A method according to Claim 1, wherein selected floor panels are fitted with plumbing fixtures such as floor wastes, bathtub wastes, vanity basin wastes, shower waste and toilet wastes and discharge pipes and wherein such fixtures are accommodated substantially in the void between the lower surface of the suspended portion and the lower surface of the perimeter beam. 13. A method of constructing a concrete floor panel of the type having a deck and a beam depending from said deck and formed integrally therewith, the method including forming the concrete floor panel in an upside down disposition, allowing the floor panel to at least partially cure and then turning the panel over. 14. A method of constructing a concrete floor panel of the type having a deck and a beam depending from said deck and formed integrally therewith, the method including: providing a horizontal forming surface for forming thereon the floor panel in an upside down disposition; mounting outer edge formers on said horizontal forming surface for forming the perimeter edges of the floor panel, the horizontal forming surface and the upper edge of at least one outer edge former defining the thickness of the deck, and the horizontal forming surface and the upper edge of another outer edge former defining the thickness of the beam; placing reinforcing material between said outer formers in a predetermined position for reinforcing the concrete therebetween; supporting an inner edge former above the horizontal forming surface and spaced from said other outer edge former, the upper edge of said inner edge former being in the same plane as the upper edge of said other outer edge former, and the lower edge of said inner edge former lying in the same plane as the upper edge of said at least one outer edge former and together with the upper surface of the horizontal forming surface defining the thickness of the deck; filling the space between said at least one outer edge former and said inner edge former with concrete to the level of the upper edge of said at least one edge former and the space between said other outer edge former and said inner edge former to the level of their upper edges to form the lower face of the deck and the lower face of the beam of an uncured concrete floor panel respectively; placing the uncured floor panel in a curing chamber and allowing the concrete wall panel to cure; and turning the cured concrete floor panel over. 15. A method of constructing a concrete floor panel of the type having a deck and a perimeter beam depending therefrom and formed integrally therewith, the method including: providing a horizontal forming surface for forming thereon the floor panel in an upside down disposition; mounting outer edge formers on said horizontal forming surface for forming the perimeter edges of the floor panel, the horizontal forming surface and the upper edges of said edge formers defining the depth of the beam relative to the upper surface of the deck; placing reinforcing material between said edge formers in a predetermined position for reinforcing the concrete between the edge formers; supporting inner edge formers above the horizontal forming surface and spaced from respective ones of said outer edge formers, the upper edges of said internal edge formers being in the same plane as the upper edges of said outer edge formers, and the lower edge of said inner edge formers together with the horizontal forming surface defining the depth of the deck; filling the space between opposed inner formers to their lower edges and the space between respective adjacent spaced apart outer and inner edge formers to the level of their upper edges to form the lower face of the deck and the lower face of the concrete beam of an uncured concrete floor panel respectively; placing the uncured concrete floor panel in a curing chamber and allowing the concrete to cure; and then turning the cured concrete floor panel over. 16. A method according to claim 14 or Claim 15, wherein said inner edge formers are supported from above the horizontal forming surface and are selectively retractable away from their positions above the horizontal forming surface. 17. A method according to any one of Claims 13 to 16 including placing the concrete panel on a tilting device after curing, the device being arranged to turn the floor panel over to its in use disposition. 18. A building including a concrete floor constructed according to the method previously described. 19. A method of constructing a building as hereinbefore described with reference to the accompanying drawings. 20. A method of constructing a concrete floor panel as hereinbefore described with reference to the accompanying drawings . 21. A factory for manufacturing concrete floor panels arranged as hereinbefore described with reference to the accompanying drawings . |
This invention relates to methods of constructing buildings and components therefor and in particular, methods of constructing dwelling houses and small commercial and industrial buildings.
The floors of many dwelling houses and small buildings are commonly constructed by the "slab-on-ground" method in which the ≤ite is levelled, edge formwork is constructed on the levelled site to form the perimeter of the slab and then the concrete is poured within the formwork. A perimeter beam and/or underfloor cross beams may be formed integrally with the floor slab depending on size, soil conditions and other parameters.
One problem with on-ground concrete slabs is that they are subject to soil movement and in particular a phenomenon known as "soil heave" which is due at least in part to expansion of soil particles when they become wet. Soil heave results in the surface of the soil rising and applying uplifting forces to the slab resting thereon. The uplifting forces can be high enough to lift the concrete slab which can cause cracking of the slab and the walls which rest on the slab. Soils which have a high clay content are highly reactive to moisture levels and thus can apply high uplifting forces thereby causing significant damage to the slab and the walls constructed thereon.
The present applicant has used a method of construction which involves loosening the soil on which the slab is to be ^ constructed so as to raise its surface level and then screwing steel piles into the ground through the loosened soil to a suitable founding depth in a predetermined array and then pouring the slab on the raised soil so that it is supported by the screw piles when cured. The soil is loosened to a depth sufficient to raise the surface of the soil to a level which is equal to or greater than the level to which the surface would rise if the soil was to become wet, that is, such that the loosened soil can accommodate the swell potential of the soil- While the "loosened soil method" described has been found to substantially overcome the problem of soil heave it still requires significant on-site works in site preparation and slab construction which are subject to weather constraints. Thus, the present invention is aimed at providing a method of construction which provides at least some of the advantages of the loosened soil method of slab-on-ground construction but in a manner which has benefits at least in terms of overall construction costs.
With the foregoing in view, the invention in one aspect resides broadly in a method of constructing a building, including: driving a plurality of screw piles into the soil on which a building is to be constructed to a predetermined founding depth and in a predetermined array; casting a plurality of concrete floor panels remote from the soil on which the building is to be constructed, the floor panels being adapted to be joined together at predetermined edges to form the floor of the building to be constructed and to rest on selected ones of said plurality of screw piles respectively; and placing said concrete floor panels on the selected screw piles respectively such that they adjoin at said predetermined edges to form the floor of the building and such that at least a substantial part of each panel is spaced above the soil by a predetermined distance determined by reference to the swell potential of the soil .
Preferably, the site is levelled prior to driving the screw piles into the soil and again after the piles have been driven if desirable to properly space the floor panels above the soil.
Preferably, the method includes placing a load bearing cap on each screw pile and setting the upper faces of all screw pile caps for each panel to the same level. It is also preferred that the screw piles be cut off to the same level after being driven into the soil prior to the caps being fitted so that the caps may bear directly against the upper ends of their piles respectively.
It is also preferred that the screw piles be cut off at ground level prior to the caps being fitted if the caps are to be encased in concrete. However, if the caps are not to be encased, the piles are preferably cut off at a predetermined height above ground level to allow for clearance under the perimeter beams or to provide greater clearance between the suspended portion and the soil thereunder.
Preferably, each floor panel is constructed with an integrally formed perimeter beam along at least one side which is adapted to seat on the selected screw piles (or the caps when fitted) for that beam and a suspended portion spanning between the opposite portions of the perimeter beam or in the case where thre is no opposite portion spanning between the one side portion of the beam and the perimeter beam of the adjoin panel. Suitably, the bottom face of the perimeter beam is lower than the bottom face of the suspended portion whereby in use, the suspended portion spans the soil between the rows of piles. In a preferred form, the floor panels are constructed such that the suspended portion is at least 100mm above the soil surface for M category soils, 150mm for H category soils and 200mm for E category soils.
Preferably, each floor panel is cast with a width of about 3.6m or less so as to be reasonably transportable by truck from a manufacturing facility to the relevant building site. It is also preferred that the length of each panel be about 12m or less so that transport can be carried out by a common length semi-trailer but greater width and length panels can be manufactured if desired.
Preferably, selected floor panels are fitted with plumbing fixtures such as floor wastes, bathtub wastes, vanity basin wastes, shower waste and toilet wastes and discharge pipes which are accommodated substantially in the void between the lower surface of the suspended portion and the lower surface of the perimeter beam. In cases where the void is not of sufficient height to accommodate the discharge pipes, they can be hung from the underside of the slab and rest in a complementary trench suitably formed in the underlying soil.
In another aspect the invention resides broadly in a building including a concrete floor constructed according to the method previously described.
In another aspect, the invention resides broadly in a method of constructing a concrete floor panel of the type having a deck and a beam depending from said deck and formed integrally therewith, the method including forming the concrete floor panel in an upside down disposition, allowing the floor panel to at least partially cure and then turning the panel over.
In yet another aspect, the invention resides broadly in a method of constructing a concrete floor panel of the type having a deck and a beam depending from said deck and formed integrally therewith, the method including: providing a horizontal forming surface for forming thereon the floor panel in an upside down disposition; mounting outer edge formers on said horizontal forming surface for forming the perimeter edges of the floor panel, the horizontal forming surface and the upper edge of at least one outer edge former defining the thickness of the deck, and the horizontal forming surface and the upper edge of another outer edge former defining the thickness of the beam; placing reinforcing material between said outer formers in a predetermined position for reinforcing the concrete therebetween; supporting an inner edge former above the horizontal forming surface and spaced from said other outer edge former, the upper edge of said inner edge former being in the same plane as the upper edge of said other outer edge former, and the lower edge of said inner edge former lying in the same plane as the upper edge of said at least one outer edge former and together with the upper surface of the horizontal forming surface defining the thickness of the deck; filling the space between said at least one outer edge former and said inner edge former with concrete to the level of the upper edge of said at least one edge former and the space between said other outer edge former and said inner edge former to the level of their upper edges to form the lower face of the deck and the lower face of the beam of an uncured concrete floor panel respectively; placing the uncured floor panel in a curing chamber and allowing the concrete wall panel to cure; and turning the cured concrete floor panel over.
In still yet another aspect, the invention resides broadly in a method of constructing a concrete floor panel of the type having a deck and a perimeter beam depending therefrom and formed integrally therewith, the method including: providing a horizontal forming surface for forming thereon the floor panel in an upside down disposition; mounting outer edge formers on said horizontal forming surface for forming the perimeter edges of the floor panel, the horizontal forming surface and the upper edges of said edge formers defining the depth of the beam relative to the upper surface of the deck; placing reinforcing material between said edge formers in a predetermined position for reinforcing the concrete between the edge formers; supporting inner edge formers above the horizontal forming surface and spaced from respective ones of said outer edge formers, the upper edges of said internal edge formers being in the same plane as the upper edges of said outer edge formers, and the lower edge of said inner edge formers together with the horizontal forming surface defining the depth of the deck; filling the space between opposed inner formers to their lower edges and the space between respective adjacent spaced apart outer and inner edge formers to the level of their upper edges to form the lower face of the deck and the lower face of the concrete beam of an uncured concrete floor panel respectively; placing the uncured concrete floor panel in a curing chamber and allowing the concrete to cure; and then turning the cured concrete floor panel over.
Preferably, said inner edge formers are supported from above the horizontal forming surface and are selectively retractable away from their positions above the horizontal forming surface.
Preferably, the concrete floor panel is placed on a tilting device after curing, the device being arranged to turn the floor panel over so that it can then be stored in its in use disposition and subsequently loaded by forklift, transported in that disposition and unloaded by forklift on site and carried to its final resting place on predetermined screw piles also by forklift.
In order that the invention may be more clearly understood and put into practical effect, reference will now be made to the accompanying drawings wherein:
Fig. 1 is a plan of a concrete floor for a dwelling house constructed according to the present invention;
Fig. 2 is a cross-sectional elevation of one of the floor panels of the concrete floor of Fig. 1 along line 2 - 2;
Fig. 3 is an isometric view of a different concrete floor for a dwelling house with the floor panels shown separated and in line for assembly;
Fig. 4 is a lateral cross-sectional elevation of the leftmost one of the floor panels shown in Fig. 3 along line 4 - 4 after erection;
Fig. 5 is a longitudinal cross-sectional elevation of the leftmost one of the floor panels shown in Fig. 3 along line 5 - 5 after erection;
Fig. 6 is a lateral cross-sectional elevation of the rightmost one of the floor panels shown in Fig. 3 along line 6 - β after erection with an external wall erected thereon;
Fig. 7 is a lateral cross-sectional elevation of the edge portions of two adjoining intermediate ones of the floor panels shown in Fig. 3;
Fig. 8 is a longitudinal cross-sectional elevation of the a rear edge portion of an intermediate one of the floor panels shown in Fig. 3 which forms part of the bathroom floor;
Fig. 9 is a plan of a concrete floor for a different dwelling house constructed according to the present invention with a forklift shown overlaid to depict the method of erecting the floor panels on the screw piles;
Fig. 10a is a schematic floor plan layout of a factory designed for manufacturing floor panels according to the invention;
Fig. 10b is a flow chart of the basic operations being carried out in the factory of Fig. 10a;
Fig. 11 is an isometric view of a forming bed at a workstation of the factory of Fig. 10 with outer wall formwork arranged thereon for manufacturing the floor panels shown in Fig. 3 according to the invention;
Fig. 12 is an isometric view of the forming bed shown in Fig. 11 with steel reinforcing mesh laid withing the formwork;
Fig. 13 is an isometric view of the forming bed shown in Fig. 11 with inner and outer formwork thereon;
Fig. 14 is an isometric view of the forming bed shown in Fig. 11 after the concrete has been poured in the formwork; and
Fig. 15 is an isometric view of the concrete floor panel formed on the forming bed shown in Fig. 11 after the formwork has been removed.
The concrete floor 10 illustrated in Fig. 1 is made up of seven separate floor panels 11 to 17 of generally rectangular form in top view which are joined one to another along their long side edges as required. The panels are all constructed of reinforced concrete in accordance with known principles and has the necessary steel reinforcing fabric and bar as well as cables if required to achieve normal floor strength and deflection requirements.
Each floor panel includes a perimeter beam 21 extending fully around the perimeter of the panel, the perimeter beam being integrally formed with a suspended floor portion 22 as can be seen by way of example in panel 11 as shown in section in Fig. 2. As also can be seen in Fig. 2, the portion of the perimeter beam along outside edges 11a, lib and Hd have a setdown 23 formed therein for supporting a brick wall 24 thereon, the level of the setdown being below the upper face of the floor shown as floor level 26. A timber frame wall 25 rests on the upper face 26 of the floor panel spaced from the brick wall in the usual manner of brick veneer house construction.
Edge Hc of the beam has an elongate recess 27 for receiving therein a complementary elongate protuberance or tongue 28 formed on the adjoining edge 13a of the perimeter beam of adjacent panel 12. Thus, it will be appreciated that portions of the perimeter beam of different panels are different depending on whether they are outside edge portions or adjoining edge portions. It will also be appreciated that the bottom face 21a of the perimeter beam is a generally flat rectangular face which is adapted to rest level on any number of selected level topped screw piles as will be described more fully later. Advantageously, the bottom face 22a of the suspended floor portion is substantially higher than the bottom face 21a of the perimeter beam and suitably results in use in the formation of a void 30 between the suspended portion and the ground surface 20.
Each floor panel is supported on a plurality of spaced apart cylindrical screw piers 31, each screw pier being capped at its upper end by a pile cap 32 which has a sleeve portion 33 and a support plate portion 34. In order to fit the caps, the pile stems are cut off level with each other at about ground level or at a selected height above ground level and then the sleeve portion is slid onto the upper end portion of its respective pier stem and is secured thereto by bolts 36 and 37 which pass through the sleeve and the pile stem. Suitably, the underside of the support plate engages the upper end of the stem so that download is applied directly to the stem. In some cases it is preferred that steel encased concrete/load bearing grout caps be fitted to the tops of the piers. In such cases a substantially conical shaped steel former is secured to the top portion of the respective pier and then filled with concrete which is then levelled off at the top of the former. However, in other cases a wholly steel or cast iron cap is used.
After the floor is fully fitted, a waterproof barrier, suitably formed of plastics material may be run along the outside edge of the perimeter beam to prevent ingress of rainwater under the floor, the barrier being secured to the perimeter beam adjacent its upper edge and to the ground at its lower edge. If desired light weight concrete panels or reinforced fibre cement products may be used if desired.
Advantageously, the present invention allows the site to be prepared by straightforward levelling whereupon the screw piers 31 can be driven into the ground in the design positions marked out. Once the screw piers have been driven, they are cut off level and then the caps are fitted and secured. The floor panels which have been previously made in a factory off site (as will be described later) are then transported to the site and lifted into place by a suitable crane or more suitably by a purpose fitted fork lift with the perimeter beams resting on the pier caps as shown in the drawings. Suitably, termite barrier protection is provided at the joints between panels.
The floor 110 illustrated in Fig. 3 is similar to the floor 10 illustrated in Fig. 1 and the panels incorporated in floor 110 are similar to the panels incorporated in floor 10. Accordingly the same reference numbers are used to refer to corresponding integers or components where possible except prefaced by a "1". In floor 110, the floor panels 111 to 119b engage with each other in a different manner from the panels in floor 10. In that respect, the right hand edge portion 129 of left hand side panel 111 rests on the set down 123 of the adjacent panel 112 and all the intermediate panels rest on the adjacent panel in like manner while the right hand side panel has a perimeter beam and set down extending full around. Such form allows for easier and more accurate positioning and interlocating of the adjacent floor panels. Notably, the screw piles supporting floor 110 extend above the ground surface such that the perimeter beam or edge beam as the case may be is spaced above the ground by a predetermined distance selected according to the swell potential of the soil, and the weight of the floor panels such that wetting of the underlying soil cannot lift any floor panel even by engagement under the perimeter beam.
In the case of floor 110, a retaining panel 141 extends from the upper face 123a of the set down to a line just below ground surface 120 as can be seen in Fig. 6 and is affixed to the outside edge face of the perimeter beam to form a retaining wall against which soil 142 can be back filled.
Advantageously, selected ones of the floor panels are provided with drainage pipes 143 already fitted thereto when they arrive on site so that a plumber can easily connect the house to the sewage system 144 and similarly fit toilets, basins, sinks and showers to drainage pipes on site.
As can be seen in Fig. 9, a house slab 210 of similar form to those previously described can be erected by first levelling the site then installing the screw piles 231 as described, cutting the screw piles off at the same level, fitting the screw pile caps and then placing the respective floor panels on the corresponding screw piles by a fork lift 246 or similar vehicle to form a complete house floor or slab with sufficient void space under the slab to accommodate soil heave. The floor panels previously described are preferably made in a factory or manufacturing facility of the type illustrated in Fig. 10a and shown in flowchart format in Fig. 10b. In factory 350, a forming table 351 enters the production line and is cleaned and oiled at station A ready for the formwork to be placed thereon for the upside down forming of a slab of predetermined size to suit a selected house floor. The forming table then moves to station B where it is marked out ready for the formwork and the formwork is then mounted on the table as illustrated in Fig. 11 with outer edge form 352, outer end form 353, outer side form 354 and outer edge form 355. Forms 356 and 357 are fitted to form the setdown 23 as will be appreciated from Fig. 11. The forming table then moves to station D where reinforcing bar 358 is fitted within the outer forms. After the reinforcing bar is fitted, the inner edge forms 359 and 360 are fitted. Typically those forms depend from a swinging arm which is rigidly mounted to the edge of the forming table for pivoting movement relative thereto so as to swing into place in the position shown in at 359 and 360 in Fig. 13. However, temporary fixed forms can be used if desired. The forming table then moves to station F where the concrete is poured into the form and vibrated and then to station G where the concrete is trowelled and then the table is lifted into the curing rack shown at station H. Each curing rack is constructed to accommodate eight panels although a queuing rack of any suitable size could be manufactured. Once the floor panel has suitably cured, the forming table is lifted to station J where the forms are removed and the floor panel and the forming table is turned over at tilting station K in order to place the floor panel in its in-use disposition and then the forming table is lifted from the floor panel. If desired, the floor panel can be lifted from the forming table while horizontal and still in its upside down disposition and then placed on the tilting device which would then turn the floor panel over ready for loading onto a truck. After the slab leaves the tilting station, it is lifted to station L where plumbing fittings are installed as required. Suitably, the penetrations can be formed during casting via forming blocks 371 or they can be cut by a drilling machine after curing. It will be appreciated that the manufacturing facility is capable of manufacturing floor panels of relatively exacting dimensions with an excellent finish on the top side, that finish being formed by the forming table.
While the foregoing description has been given by way of illustrative example of the invention, it will be understood that the invention may be embodied in many other forms and all such forms are deemed to fall within the broad scope and ambit of the invention as defined by the appended claims .
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