WO2017083903A1

WO2017083903A1 - Improvements in slab on ground formwork design and installation

Info

Publication number: WO2017083903A1
Application number: PCT/AU2016/000385
Authority: WO
Inventors: Malcolm Alexander GOLLEDGE; Lyndon James GOLLEDGE
Original assignee: Bfre Pty Ltd As Trustee
Priority date: 2015-11-21
Filing date: 2016-11-21
Publication date: 2017-05-26
Also published as: AU2016355914A1

Abstract

A formwork support fin peg (14) comprises an elongated steel peg body (11) having a pointed lower end (11a), two triangular fins (12) made from steel plate welded to opposing sides of the body (11) about halfway along its length, and the body (11) having an upper section comprising a plurality of spaced holes (13) drilled though the peg at nominal 40 mm centres (spacings). The fins (12) act as depth markers as well as maintaining rotational orientation of the fin peg relative to the slab to be formed. An adjustable rebate bracket (27) is then installed over the top of the peg (14). The adjustable rebate bracket (27) comprises a support arm (28) having a socket (33) at one end, and a vertical plate (29) with predrilled holes 30 at another end which is welded to support arm 28 at 90 degrees. A rebate board (31) can be screw fixed (32) to the vertical plate (29).

Description

Improvements in Slab on Ground Formwork Design and Installation

Field of the Invention

[1] The present invention relates to an improved building method and in particular to improvements in set outs and installation of concrete slab on ground in Low Rise Residential and Commercial Buildings.

[2] This application claims priority from Applicant's Australian provisional application numbers 2015904808, 2016902025 and 2016902854, the entire specifications and disclosures of which are incorporated herein by reference

Background of the Invention

[3] Concrete slab on ground come in two basic forms, waffelpod slabs and raft slabs. Wafflepod slabs comprise the assembly of polystyrene pods approximately 1 100 mm x 1 100 mm square in a grid pattern and separated from each other by a uniform spacing of nominally 100 mm so that a grid of concrete beams is formed when the Wafflepod is combined with concrete and reinforcement steel. The height of the pod enables a cost effective way to increase the concrete slab above ground level, thus removing the need to bring in fill material to create the same objective. It is a very cost effective means to form up and pour slabs and is by far the most popular method of slab construction in Australia.

[4] In raft slab construction, instead of polystyrene pods, fill is brought to the site to raise the height of the concrete floor above natural ground level. Edge beams and internal beams are cut into the fill by an excavator and bucket and then a plastic membrane, trench mesh and mesh are installed in the usual way. The grid of beams in raft slabs are generally larger than those in waflepod slab, and are nominally on a 4000mm grid. Concrete is placed and finished in the normal way on both slab systems after the edge boards and supports are installed.

[5] Due to the variable ground conditions, concrete or steel screw piers are installed around and under the perimeter of the slab edge and under the internal beams. The location of the piers are marked out after the site has been benched to the desired level and surveyors have been to place marker pegs off set from the slab corners. Benching the site is a term used to define the process whereby the base of the slab construction begins, and is level. In the case of a wafflepod slab, the bench height plus the depth of the waffle pod and the concrete slab thickness on top of the wafflepod acquires the finished floor level. In raft slabs, the height of the benched site (which has now been filled) plus the levelling screed, normally 50 mm and the slab thickness, normally 1 10 mm gives the finished floor level.

[6] Survey pegs, called offsets, are then installed to assist the concreter to locate the slab on the site. The surveyor offsets are placed away from the edges of the slab so they are not dislodged when machinery moves around the slab area, and this means that to locate the slab edges, profiles, comprising two vertical posts and a horizontal timber rail fixed to them, are installed facing the end and side of the slab where the offsets are installed. This means, generally, 8 sets of profiles are constructed, 2 at each main corner of the slab. String lines are run between the profiles which are parallel to each side of the slab and by reference to the offset dimension in the surveyors set out plan, the sides of the slab, location of internal beams and piers can be determined.

[7] From these string lines, the pier, trench and slab edge boards locations are determined and normally the string lines are set up and re used for checking dimensions of the formwork and can consume a lot of time and as such, labour costs in doing so. The piers are marked out prior to the drilling machine comes to the site, in and averaged sized slab, it may take up to 4 hrs for two workers to locate and mark the pier locations by measuring from the string lines. So it is usual for the pier locations to be marked out the day before the piers are drilled and filled, hence there is inefficiency in labour due to the travelling from the site to another, travel costs, and a second lot of set up costs, which means the 4 hrs left in the day is not used effectively on another job. The location of piers using tape measure and string lines is inefficient and time wasting and a lot of times inaccurate, due to the need to translate and compute offset measurements to architecture plans and then to engineering plans. It is not uncommon for piers to be in the wrong location, and sometimes outside of the perimeter of the slab edge altogether. It is desirable to remove the need for the profiles and string lines to locate the piers saving labour and materials.

[8] Once the piers are installed, the process of building the formwork around the edge of the slab begins. The bottom board, the inside of which defines the outside edge of the building, is installed first. Hardwood pegs are driven in to the ground using a heavy sledge hammer, the first board is nailed to the inside of it at the appropriate height and timber bracing is installed at the back of the peg to brace it against concrete loads from the formwork, and keep it vertical. The process of hammering in pegs, fixing edge boards to it and bracing continues around the perimeter of the slab generally at a maximum spacing of 1800 mm centres. The work is hard and at times dangerous, as sometimes there are mishits and other times pegs splinter and tear apart under hammer impact increasing the risk of injury to workers doing the work or in proximity to where the work is being done. The pegs are also difficult to drive in due to the variable sharpness of the points and the hardness of the ground, The wedging effect caused by the point of the pegs being driven into the ground by heavy hammer impacts can also dislodge and fracture the soil making it necessary to drive the peg in further to anchor it properly and to employ bracing to hold it in place. And because it is difficult to hammer a square peg to stop rotation, have it remain exactly in position and remain vertical and its face parallel to the board it fixes to, it is normal to knock them sideways or pack out between the board and the pegs to maintain accuracy in dimensions and edge board straightness, thus increasing labour cost and increasing installation time. The timber pegs are frequently damaged beyond repair and so need replacing regularly, although they are relatively cheap to buy, it remains a cost nevertheless. It is desirable to remove the need to use a sledge hammer to install these pegs and employ a new peg design that can be located and installed in a more economical labour saving and safe way, they can be installed accurately and vertical and done so without fracturing the soil and hence can remain vertical and stable and do not require bracing, saving labour and material.

[9] The internal drainage is next to be installed and so at this time the concreting contractor leaves the site and if they have no other work to go to lose income.

[10] The plumbers use the lower edge boards to determine the location of the drainage risers through the floor. The risers are the vertical section of the drains which join to the toilet, floor waste, showers, basins, baths and sinks. The trenches are cut into the ground, the drains are laid in them and parged with sand or fine gravel and then backfilled. At this time, if the concreters have made an error in the location of the edge board then it is likely the plumbers will make an error in their set out as well. It is not uncommon for slabs to be poured with the drainage risers in the wrong location from miss-reading the plans, incorrect measurement or from inaccuracies in the edge boards. When this happens there is a lot of expense in the repair as the slab is cut up, new drains laid and the slab reinstated. It is thus desirable to provide an alternate location system for the drainage risers in the slab, thus making it unlikely that any errors can occur in their location, saving time and money.

[1 1 ] After the internal drainage is installed, plastic membrane and perimeter trench mesh and other reinforcement steel and mesh is installed in the normal way, along with wafflepods (if a waffle pod slab) and afterwards chaired up to give the required concrete cover. Metal rebate brackets are then installed on the bottom boards and the rebate boards are nailed in position, which leaves the top of the rebate boards approximately level with the top surface of the slab when it is poured. The rebate is a term used to describe a step formed in the side of the slab which is the thickness of the cladding and an air gap called a cavity. In brick veneer construction the rebate width is a brick width of 1 10 mm plus a cavity width of 50 mm, giving a total rebate width of 160 mm. The rebate depth is normally a multiple of brick heights, so a one brick rebate is 86 mm and the more common rebate, a two brick rebate is 172 mm deep below the finished floor level. Generally the rebate is 172 deep and 160 wide in raft slab and 160 mm deep and 150 mm wide in wafflepod slab. Steel rebate brackets are employed in holding up and positioning the rebate boards. These brackets are fitted over the bottom slab edge board and due to the height set on this board, and its vertical orientation, and the tolerance in the fit of the bracket and the thickness of the board it fits to, the rebate bracket generally needs to be lifted by installing another peg to its side, and braced back to the peg supporting the bottom edge board. At other times, deeper boards are used so the top of them may be higher than the slab height, so when pouring the slab a laser level needs to be used to set the level, rather than taking it from the top of the edge boards. This takes considerable more labour time and deploys a lot more material in the process.

[12] The formwork is sometimes checked by a surveyor prior to the pour, because it is very common for the concreters to make mistakes in locating the boards due to the complexity in the shape of the house design in the first place, but also in the difficulty of taking measurements from string lines and offsets. When errors occur it can result in brickwork overhanging the slab rebate edge, wall frames overhanging into the rebates, and slabs being too short of long, requiring extensive remedial work. It is thus also desirable to provide a means for locating pilot holes to be drilled in the ground to accurately locate the pegs supporting the edge boards, without the need to use stringlines and profiles, saving labour in measurement checking during the installation of the formworks and also the cost of a surveyor to visit the site and check the accuracy of the formwork placement and height prior to the pour.

[13] Where alfrescos or porches are part of the house design, they are normally set down from the finished floor level by one brick, to achieve this a step down board is installed on the edges of the area which bounds the main slab, and is tied and most times braced into position using timber pegs to hold it to the right height. When the slab is being poured, these pegs and boards are removed before the concrete sets, and the peg holes left in the slab are filled and the edges trowelled and finished. If left too late, it is very difficult to remove the timber pegs and oft times are broken off under the concrete height and left in place. It is thus also desirable to provide a peg support system for the step down board that can be easily removed after the slab is poured requiring little repair, saving labour and time.

[14] Internal and external drop edge beams are used on sites with slope and allow in most cases a level slab to be formed and the \outside edge of the slab to extend to the natural ground level in the case of external drop edge beams, and to accommodate a change in slab level in the case on an internal drop edge beam. The former is built using planks and a lot of external bracing, and involves a lot of labour in the construction and in its demolition and de nailing and stacking on the truck for removal, since there is normally no means of material movement by mechanical means on site.

[15] The forming up of internal drop edge beams is also very material and labour intensive and requires a lot of attention to detail, and normally involves stripping the formwork du ring the pour as the bracing is placed at the lower ground level. The process is complicated and in most times requires accelerator in the concrete for fast setting, as the lower portion of the beam is poured first, so when the concrete is still plastic, the upper level can be poured thus reducing the loads on the formwork from wet concrete pressures.

[16] It is thus also desirable to provide a more cost effective method and means to form up drop edge beams by reducing the material required and labour to install and remove the formwork.

[17] When all the edge boards and reinforcement steel is installed, concrete is brought on site and is placed. The typical installation process requires the concrete to be loosely placed then vibrated. Levelling pads using a laser level are placed at uniform spacings so that a screed board can form levelling pathways between them. A number of these levelling pathways equi-spaced and parallel to each other form the basis for levelling the slab by sliding a screed boards between them and pulling it along in a sliding zig zag pattern, perpendicular to the levelling pathways.

[18] There can be significant inaccuracies in the slab levels due to this process, in the first place setting the levelling pads using the laser level, screeding between these levels and then screeding between the pathways formed by the process. Powered vibrating screeds have been introduced into this market which can quicken this process, however, due to the amount of spot levelling required, and the fact that the top of the rebate boards are not level, they have had very little success. The out of level in the slab can cause problems in wall frame installation which may require cutting them back or packing the bottom of the panels, or in more extreme cases, further work on the slab using levelling compounds, which are usually expensive to buy. It is thus also desirable to provide a system of levelling so that lasers are not required during the slab installation process, and a powered vibrating screed can be employed to reduce labour and on - site concrete placement time.

[19] After the slab is trowelled finished the edge boards are stripped by firstly knocking the braces and pegs out using the sledge hammer, The rebate board is leveraged of the side of the slab by pulling it upwards sometimes damaging the top edges. The rebate bottom board is removed and the rebate brackets which were saddled to it, removed. The indent from the rebate bracket is left in the side of the slab and is visible when the slab edge is left exposed. It is thus also desirable to provide a formwork system that allows the construction to be systematically and easily dismantled without damage to the slab edge and leaving no indent in the exposed slab edge form the rebate bracket.

[20] The boards, braces and pegs are de nailed and cleaned, and in the same day loaded onto a truck ready to be installed on the next job. It is also desirable to provide a formwork system that significantly reduces nailing and subsequent de nailing saving labour and damage to the re-useable boards and decreasing risk of injury to workers from the exposed nails in the timbers, during the formwork deconstruction process.

[21 ] In conventional rail installations supporting a vibrating screed, the top of the rail is installed so that it is level with the top of the concrete slab. This allows the Vibrating screed to rest on top of the rail while levelling the concrete. There are a number of problems associated with this method, namely, the rail is immersed in wet concrete when the screeding is completed in that section, and the removal of the rail means that a groove needs now to be filled in with concrete and the rail needs to be cleaned before installing into the next section to be placed when it needs to be married up to support brackets. There is a limitation in the depth of the rail that can be deployed in these situations as there is a maximum clearance between the top of concrete and the concrete cover on the reinforcement bars or mesh, in most cases this is 25 mm. The small depth of embedment in the rail combined with the variability in reinforcement bar and mesh installation means that the rails may be difficult to install accurately and require more supports along its length to keep it straight.

[22] Powered vibrating screeds have been introduced into this market which can quicken this process, however, due to the amount of spot levelling required, and the fact that the top of the rebate boards are not level, they have had very little success. The out of level in the slab can cause problems in wall frame installation which may require cutting them back or packing the bottom of the panels, or in more extreme cases, further work on the slab using levelling compounds, which are usually expensive to buy. Conventionally, vibrating screeds have a blade made from extruded aluminium and can come in a variety of lengths. The blades are normally a right angle shape with a little scalloping in the vertical contact face that allows the concrete to roll against it when the blade is being pulled across the concrete.

[23] If there is insufficient concrete in front of the blade face then holes or pockets will result in the concrete surface at the back of the screed, which may necessitate the re-screeding of the section when the holes are filled, causing times delays and inefficiencies in the process.

[24] If there is too large a buildup of concrete in front of the blade, causing a bow wave, then the screed unit will become more difficult to pull, and will begin to lift from the levelling pathways each side, as the screed tries to adjust the bow wave height to suit its constraints.

[25] This causes the slab to be screeded out of level, and repeating the screed process to bring the slab back to level causes loss in level in the levelling pathways either side. This is the main reason why vibrating screeds have not been successfully deployed in concrete placement due to the difficulty in maintaining a level concrete surface. So it is desirable to provide a levelling screed blade that automatically controls a bow wave height on the leading edge of the screed and maintains its level while it is being operated. [26] The workers who are generally deployed to rake the concrete in front of the screed blade to prevent the build up of the bow wave have a difficult job, since there is very little indication of the finish concrete height as they are pulling the concrete in front of the screed as it is moving. So it is usual to remove too little causing the bow wave build up, and too much, causing pockets or holes in the concrete surface at the back of the screed, so it is also desirable to use the screed blade as a height control on the concrete raking process as well as to remove the excess concrete from the blade top surface rather than from in front of it.

[27] The present invention seeks to overcome or substantially ameliorate at least some of the deficiencies of the prior art, or to at least provide an alternative.

[28] It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms part of the common general knowledge in the art, in Australia or any other country.

Summary of the Invention

[29] According to a first aspect, the present invention provides a formwork support peg comprising an elongated peg body having a pointed lower end, at least one fin welded to the body at a mid-length portion thereof, wherein the peg is adapted to be driven to the ground until the fin is embedded.

[30] Preferably, the peg comprises two fins attached to opposite sides of the body.

[31 ] Preferably, the body comprises an upper section having a plurality of spaced holes.

[32] Preferably, the holes comprise two aligned vertical series of holes drilled at 90 degrees relative orientation to each other.

[33] In another aspect, the present invention provides a formwork support peg comprising an elongated peg body having a pointed lower body section, the lower body section comprising a thread formation, wherein the body comprises an upper section having a plurality of spaced holes.

[34] Preferably, the body comprises a rotation formation at a top end thereof, such as a nut.

[35] Preferably, the overall diameter of the thread formation is not larger than the largest diameter of the peg body.

[36] Preferably, the peg further comprises a rail support bracket mounted to a top end of the peg.

[37] In another aspect, the present invention provides an assembly comprising the peg of any one of the above and an adjustable rebate bracket attachable to the peg. [38] Preferably, the adjustable rebate bracket comprises a support arm having a mounting means at one end for mounting to the peg and an attachment means at another end to which a rebate board can be attached.

[39] Preferably, the mounting means comprises a socket which receives the peg therethrough.

[40] Preferably, the socket comprises a U-shaped bracket having its open end welded to the support arm.

[41 ] Preferably, the socket comprises an adjusting screw mounted to a back web thereof.

[42] Preferably, the support arm has a sharp edge at the open end of the U-shaped bracket.

[43] Preferably, the attachment means comprises a vertical plate with predrilled holes.

[44] Preferably, the assembly further comprises a brace for attachment to the peg, the brace having a distal end adapted to be anchored to the ground.

[45] Preferably, the brace comprises a pointed spade at the distal end which is curved as an arc, the arc radius corresponding to the length of the brace.

[46] In another aspect, the present invention provides an adjustable rebate bracket attachable to a peg, the adjustable rebate bracket comprising a support arm having a mounting means at one end for mounting to the peg and an attachment means at another end to which a rebate board can be attached.

[47] Preferably, the mounting means comprises a socket which receives the peg therethrough.

[48] Preferably, the socket comprises a U-shaped bracket having its open end welded to the support arm.

[49] Preferably, the socket comprises an adjusting screw mounted to a back web thereof.

[50] Preferably, the support arm has a sharp edge at the open end of the U-shaped bracket.

[51 ] Preferably, the attachment means comprises a vertical plate with predrilled holes.

[52] Preferably, the assembly further comprises a brace for attachment to the peg, the brace having a distal end adapted to be anchored to the ground.

[53] Preferably, the brace comprises a pointed spade at the distal end which is curved as an arc, the arc radius corresponding to the length of the brace.

[54] In another aspect, the present invention provides a screed tool comprising an elongated blade having a lower edge, the tool having a raised horn at at least one end, the raised horn being spaced form the lower edge. [55] In one embodiment, the screed tool comprises a raised horn at both ends of the blade.

[56] In another embodiment, the horns are adjustable in depth.

[57] The present invention also provides a screeding assembly comprising:

[58] an adjustable height rail support;

[59] a support rail; and

[60] a screed tool according to the above.

[61 ] Preferably, the adjustable height rail support comprises a U-shaped bracket mounted to a base, wherein the distance of the bracket from the base is adjustable.

[62] The present invention also provides a method of screeding using the screeding assembly of the above, the method comprising:

[63] placing the adjustable height rail support into position with the base of the bracket to be level with the slab height

[64] placing one end of the support rail onto the bracket and the other end of the support rail onto an edge rebate board.

[65] The present invention also provides a screed comprising an elongated body having a base, a rear vertical side and a front leading side which is lower in height than the rear side.

[66] In one embodiment, the leading side is 25 to 30 mm in height.

[67] In another embodiment, the base and the sides define an upper trough.

[68] In another embodiment, the screed comprises raised horns at ends thereof.

[69] In another embodiment, the rear side comprises a vibrating power unit mounted thereat

[70] Other preferred aspects of the present invention are described.

[71 ] A laser level is used to adjust the rebate board around the perimeter of the slab, so that at the end of this process, the top of all the rebate boards and step down boards are level with the top of the house slab and at this time the slab is ready to install the concrete placement means.

[72] The adjustable rail support brackets with its base and adjustable U shape on top are then placed at particular locations within the slab on top of the pods and adjusted to height using the laser level. A series of equi- spaced and parallel arrangements of the brackets are strategically installed across the slab.

[73] A support rail made from extruded tube or pipe is then installed by simply resting one end on top of the rebate board and the other end on the adjustable rail support bracket. Another rail may be installed parallel to this one in the adjacent section to be screeded next. The support rail can alternatively be cold formed seam welded tube, e.g RHS, SHS, CHS, and can be made from any material such as plastic, steel, aluminium or wood.

[74] The concrete is pumped into the area, vibrated and raked out to remove the humps and excesses.

[75] The manual or powered vibrating screed with its ends modified to rest on top of the rail (where required) is then placed into position to begin the process of levelling the concrete

[76] After the first section is placed and is screeded using on one side, the top of the rebate edge board and on the other, the rail located on the adjustable bracket, the rail and bracket support may be removed. The rail is re located to the next set of rail support brackets, and the screeding process re starts when this next section of slab is filled with concrete. The adjustable support brackets 5 are reusable and not permanently buried in the concrete.

[77] The vibrating screed at this point, uses the already screeded slab portion on one side of it to rest upon, and the rail support in its new location as support on the other side. Alternatively, the first rail system may be moved into the screeded portion by 200 mm and the screed may be support on it as well as the next rail parallel to it at a distance which allows the cranked ends of the screed to be supported. This method employs a positive support for each end of the screed at all times.

[78] This process is continued until there is no more need for a screed rail in that row, and the final screed used the screeded concrete on one side, or a rail left in place and on the other, the top of the rebate board

[79] House plans and engineering designs and surveyor house set out plans are sourced in electronic format. A new file is formatted which shows pier, plumbing, formwork peg and stepdown peg locations with reference to the surveyor set out. The file is uploaded into a Total station, which is automated surveying equipment, and in the first instance, is taken to the prepared and benched slab site, calibrated to the surveyor offsets, and the pier locations progressively marked out, and positively located using a wire pin and flag system.

[80] The location of the plumbing riser are marked in a similar way or 2 pegs are installed a set distance, from which the plumber can triangulate measurements from.

[81 ] The piers are bored and filled with concrete to the required level, and then eitherfooting trenches are excavated in the case of a raft slab, and pilot holes for formwork pegs and step down pegs are marked out afterwards using the total station for the raft slab and a waffle pod slab design. Using the peg locations, which are nominally 1800 mm centres and at each of the slab corners, from the house cad file design in the total station, a hole template made from steel plate is positioned over the mark and a vertical hole is drilled into the soil to the required depth. Depending on the soil type a screw peg or a fin peg is installed. A screw peg is positioned in the pilot hole and the peg is screwed into position using an electric impact drill, and installed with the holes in the side of the peg being at right angles to the slab edge. The peg has thread formed to a tapered shaft section, and outside diameter of the thread is no larger than the diameter of the main section of the peg, as this allows the peg to be unscrewed through the rebate bracket without obstruction, as well as from the concrete when used in support of step down boards. The taper on the screw peg allows it to wedge itself into the pilot hole and provide enough grip to resist sideways forces and thus not require bracing. Alternatively, the fin peg is installed into the pilot hole using a drill on impact mode only, or with a dolly, a tool which is generally made of steel and can slide over the peg and impacts the peg into position by up and down movements of the dolly, (a larger version is used to install star pickets in rural fencing.) The fin is positioned parallel to the edge of the slab because it allows greater bearing capacity of the peg at the ground level in softer soils. The screw peg is installed into firm to hard soils, the fin peg is installed into firm to soft soils, since the fins increases the bearing capacity of the peg at the top of the hole, where the fins are located on the peg and will provide the lateral resistance of the formboards due to wet concrete. The pegs are installed along the outside edge of the stepdown boards at the required centres ready to receive the step down boards.

[82] The lower edge boards are installed consecutively and progressively from a corner peg and to the slab side, around the perimeter of the slab, so that the top of the board is level with the top of the bottom of the rebate. The boards are fixed to the pegs by using hex head screws and in conjunction with the pre drilled holes in the peg. The Plastic moisture barriers are installed on the ground and the installation of the pods and trench mesh and mesh begins in the case of a waffle pod slab, and the cages and mesh is installed in the case of raft slabs. Other reinforcement fitments may be required , but once this installation is completed, the adjustable rebate bracket is placed over the formwork peg and placed so that its long side is perpendicular to the slab. The rebate boards are located onto the outside of the vertical projection of the rebate bracket and all the boards are installed around the slab perimeter. Particular attention is required in the construction process at step down transitions such as at porches, alfresco and garage slabs, however this detail is the similar for all slabs, and simply manages the closure or otherwise of the rebates. The step down boards are then located to the main slab side of the pegs and the top of the board level with the top of the slab and the board is screwed fixed into position.

[83] A laser level is set up for this purpose, and is used to progressively manage the rebate bracket adjustment to the rebate board height around the perimeter of the slab, so that at the end of this process, the top of all the rebate boards and step down boards are level with the top of the house slab.

[84] When external drop edge beams are required a simple support process is deployed by closing the spacing of the concrete piers or screw piers, and installing a steel tube vertically into the concrete at the back of the screw pier, or leaving the top of the screw pier proud of the soil by a height which is the distance from the base of the footing to the underside of the slab at the upper level. The Tube is set back from the face of the drop edge beam by the thickness of the drop edge beam itself, which is nominally 150 mm. The reinforcement bar for the drop edge is installed. The adjustable rebate bracket is installed onto the formwork support peg and the first drop edge form board is place on top of it and screwed into position. The rebate bracket is made level with the base of the rebate. A pre holed steel angle is placed in a vertical position on the outside of the first board and opposite the tube and it is screwed onto and through the board and into the metal tube. The metal angels are installed along the drop edge and opposite the tube upright. The holes in the angles coincide with the width of the board, so another screw installed directly on top of the first board and into the tube behind. As each board is installed on top thereon, another long screw is installed through the predrilled hole in the steel angle and into the tube behind, so that there is a little crack the thickness of the screw is left between each board as it is installed. This process is repeated until the top of the slab is reached. When the height of the slab is reached the top board is simply fixed to the angle and the top of the angle tied to the mesh of the slab. The tube embedded into the pier is structural and can withstand the lateral pressure of the concrete as the drop edge is filled, however it is prudent to part fill the drop edge in increments of half a metre so that the burst out pressures don't get excessive. When a screw pier is used, the shaft of the screw pier is left proud of the footing and a process similar to the one for the tube is employed to form up the drop edge, except wire is used to tie the angle to the steel pier shaft instead of screws. For internal drop edge beams the same process is deployed to form up the beam.

[85] Levelling pegs are then placed at particular locations within the slab and set to a height using the laser level. A series of equi-spaced and parallel arrangements of the levelling pegs are strategically located in line and across the slab and when fitted with a rail, is used to support a vibrating or manual screed.

[86] After the first section of the concrete floor is placed and is screeded using on one side, the top of the rebate edge board and on the other, the rail located on the levelling pegs, the rail and levelling pegs supporting it are removed. The rail is re located to the next set of levelling pegs, and the screeding process re starts when this next section of slab is filled with concrete. The vibrating screed at this point, uses the already screeded slab portion on one side of it to rest upon, and the rail support in its new location as support on the other side. [87] This process is continued until there is no more need for a screed rail in that row, and the final screed used the screeded concrete on one side and on the other, the top of the rebate board

[88] Other aspects of the invention are also disclosed. Brief Description of the Drawings

[89] Notwithstanding any other forms which may fall within the scope of the present invention, preferred embodiments of the present invention will now be described, by way of examples only, with reference to the accompanying drawings in which:

[90] Figure 1 Fig. 1 is a typical slab layout plan showing the locations of piers, slab edges, rebates and stepdowns as well as location of the formwork support pegs around the slab perimeter as well as their location in the rebates. Indicative levelling peg location are shown as well as dotted lines for the placement of the screed support rails and arrows showing the direction of concrete screeding using a vibrating screed.

[91 ] Fig. 2(a) is an elevation view of a formwork support fin peg according to a preferred embodiment of the present invention, 2(b) shows a fin peg with an alternative fin shape.

[92] Fig. 3 is an isometric view of the fin peg.

[93] Fig. 4 is an isometric view of a pilot hole drilled into the ground to locate a fin or screw peg.

[94] Fig. 5 is an isometric view of an installed fin peg showing the fins slightly proud of the ground.

[95] Fig. 6 is an elevation of a screw peg according to a preferred embodiment of the present invention.

[96] Fig. 7 is a dolly for installing a fin peg.

[97] Fig. 8 is an isometric view of a dolly showing a Bulls eye level installed on top of it.

[98] Fig. 9 is a plan view A showing a bulls eye level centrally located so that the dolly can be held vertical during the initial installation of the peg.

[99] Fig. 10 is an adjustable rebate bracket which can be installed over a fin or screw peg, and is used to hold, and level the top of a rebate board

[100] Fig. 1 1 is a section thorough a typical concrete slab edge showing an installed fin peg, adjustable rebate bracket, rebate board and lower formwork board.

[101 ] Fig. 12 is a typical section through a step down transition from a house slab to a garage or porch slab using a screw peg and a rebate board. 102] Fig. 13 is an isometric view of a screw or fin peg brace.

103] Fig. 14 is a side view of a brace

104] Fig. 15 is an isometric view of a part of an external drop edge beam.

105] Fig. 16 is a section through an external drop edge beam with a brace installed.

106] Fig. 17 is a part elevation of a levelling screw peg with an adjustable U bracket on top.

107] Fig. 18 is a typical side view section of an installed levelling screw peg with U bracket and a screed support rail installed, resting on the U bracket one end and another end onto the op of the rebate board.

108] Fig. 19 is a plan view of a section of placed concrete being screeded using a vibrating screed with top of rebate board one side being used to support one end of the screed and the screed support rail the other end.

109] Fig. 20 is a plan view of a corner section of a waffle pod slab ready to place concrete.

1 10] Fig. 21 is a plan view of an adjustable rail support bracket.

1 1 1 ] Fig. 22 is an elevation of the adjustable rail support bracket

1 12] Fig. 23is an end elevation of the rail support bracket

1 13] Fig. 24 is an oblique projection of the rail support bracket

1 14] Fig. 25 is a view A or side elevation of a waffle pod slab portion shown in Fig. 20.

1 15] Fig. 26 is a manual screed with end horns either formed into the ends or attached to hem.

1 16] Fig. 27 is an extruded aluminium blade used in conjunction with a powered vibrating screed with horns cut into the vertical portion of each end of the blade or otherwise fabricated and attached to each end.

1 17] Fig. 28 is a section of the powered vibrating screed blade of Figure 8.

1 18] Fig. 29 is an isometric view of a vibrating screed and blade with horns for use with rails

1 19] Fig. 30 is a section of the screed blade showing bow wave height and concrete overflow into the base of the screed

120] Fig. 31 is an isometric drawing of part of the screed blade showing a rake being used on its leading edge

121 ] Fig. 32 is a screed blade section with a rake blade being used to level the bow wave and undercut the concrete in front of the screed blade leading edge [122] Fig. 33 is a screed blade section showing a rake being used to clean the concrete from the base of the screed blade

[123] Fig. 34 is an alternative edgeboard design

[124] Fig. 35 shows two edgeboards of Figure 34 with overlapped adjacent edges

[125] Fig. 36 is an assembly similar to Figure 1 1 using the edgeboard of Figure 34.

Description of Embodiments

[126] It should be noted in the following description that like or the same reference numerals in different embodiments denote the same or similar features.

[127] The information from the architects, engineering a survey set out plans are formatted into a slab plan as shown in Fig 1 , which shows piers, pier locating at footing intersections 2 and 3, footings 4, rebate and slab edge 5, stepdown 6, screed levelling peg 7, and screed support rail location 9 and direction of screed 10 and formwork support peg locations 8 around the slab perimeter and is uploaded into a Total station.

[128] Figs. 2 and 3 show a formwork support fin peg 14 according to a preferred embodiment of the present invention. The fin peg 14 comprises an elongated steel peg body 1 1 having a pointed lower end 1 1 a, two triangular fins 12 made from steel plate welded to opposing sides of the body 1 1 about halfway along its length, and the body 1 1 having an upper section comprising a plurality of spaced holes 13 drilled though the peg at nominal 40 mm centres (spacings). The holes 13 comprise two aligned vertical series 13a and 13b drilled at 90 degrees relative orientation to each other (when viewed from the top) as shown in Figure 3. The body 1 1 is nominally 22 mm in diameter, however other sizes in tube or solid bar can be used depending on site conditions.

[129] A pilot hole 15 (see fig 4) is drilled at the location where a fin peg 14 is to be installed depending on ground conditions. Figure 5 shows a fin peg 14 installed into the pilot hole 15 and driven into position until the fins 12 of the fin peg 14 are embedded into the soil, but slightly proud of the ground. The fins 12 act as depth markers as well as maintaining rotational orientation of the fin peg relative to the slab to be formed.

[130] For stiffer soil conditions a screw peg 16 is used as shown in Figure 6. The screw peg 16 similarly comprises an elongated steel peg body 1 1. The body 1 1 has a hex nut 17 welded to the top, and a steel thread formation 18 welded to a tapered lower body section 21 . The thread formation 18 extends from a smaller (pointed) lower end 19 of the tapered section 21 to a wider upper end 20 thereof. The overall thread diameter at the upper end 20 is no larger than the largest diameter of the peg 16 which allows the peg 16 to be unscrewed from locations without the thread fowling against formboards or its supports. A pilot hole 15 is also used being of a size that allows the screw peg 16 to wedge into the hole and pulling the peg hard against the soil at the peg shoulder 21 for increased bearing capacity. The screw peg 16 in the example is made from 48 mm diameter tube.

[131 ] Figures 7 and 8 show a steel dolly 22 which is used to drive the fin peg 14 into the pilot hole 15. The dolly 22 comprises a hollow body with handles 23 at its top section. The dolly 22 is open towards its bottom end which fits over the fin peg 14 as a sleeve. The dolly 22 is moved up and down repeatedly in use and its closed upper end and mass impacts the top of the fin peg 14. A bulls eye level 24 (see Figure 9) can be installed on the top of the dolly 22 and used to gauge a vertical orientation of the dolly 1 1 prior to impacting the peg 14.

[132] Referring to Figure 1 1 , once all the pegs 14 are installed, edge form boards 25 can be screw fixed 26 thereto using the lower holes 13. An adjustable rebate bracket 27 (see fig 10) is then installed over the top of the peg 14.

[133] The adjustable rebate bracket 27 comprises a support arm 28 having a socket 33 at one end, and a vertical plate 29 with predrilled holes 30 at another end which is welded to support arm 28 at 90 degrees. A rebate board 31 can be screw fixed 32 to the vertical plate 29. The socket 33 is formed by a steel U bracket 33a having a lower portion of its open end welded to the support arm 28 and which has an adjusting screw 35 mounted centrally and located on the upper portion of the back web of the U bracket 33a. The support arm 28 has an acute angle cut to an end edge 34 thereof attached to the open end of the U-bracket 33a. The angled sharp edge 34 forms a point loading and engaging onto the support peg 14.

[134] The adjustable rebate bracket 27 is installed by inserting the mounted peg 14 through the socket 33. The adjusting screw 35 can be rotated clockwise which raises the bracket 27 along the peg 14 thus raising the rebate board 31 , and anti-clockwise to lower the rebate board 31 . This allows the top of the board 31 to be made level with the top of the slab 36 (to be poured). The adjustable rebate bracket 27 rotates around the sharp edge 34 of the support arm 28, which is in contact with the fin peg 14, and the end of the adjusting screw 35 is in contact with the back portion of the fin peg 14 at a height above the level of the sharp edge 34.

[135] Referring to Figure 12, the step down boards 36 are located and fixed using screws 32 to a screw peg 16 as they can be removed after the slab is poured when still plastic, and the screws 32 removed, without further damaging the concrete and with the step down board 36 in place. The step down board 36 is removed afterwards and the peg hole filled and the slab underneath the step down board finished.

[136] Referring to Figure 13, a brace 37 is shown which is made from elongated steel square hollow section and has two flanges 38 with aligned holes 39 at one end. Pins 40 (see fig 17) are installed through the flanges 38 and into peg holes 13. A pointed spade 41 made from steel plate is welded to the other end of the brace 37 and when the brace 37 is installed, the pointed spade end is pushed into the ground using body weight, or hammered in with a mallet. The spade 41 is curved as an arc, as can be seen in the side view thereof, the arc radius corresponding to the length of the brace 37.

[137] Figures 15 and 16 shows a drop edge beam structure 50 which comprises a structural post 42 (preferably a steel square hollow tube which is embedded vertically into concrete pier 1 ) set back a distance equalling the thickness of the vertical portion of formed edge. The fin peg 14, lower formboard 25, adjustable rebate bracket 28 and bracing 37 if required are installed in the usual way. Reinforcement steel 43 is installed and the bottom rebate board 45 is installed to the plate 29 of the rebate bracket 28. A steel angle (bar) 44 with spaced holes

47 is positioned at a nominated spacing along the drop edge beam opposite the structural post 42 and is screw fixed 46 through the bottom of the first rebate board 45 and into the face of the structural post 42. The spaced holes 47 of the angle bar 44 are pre drilled therealong at the spacings equivalent to the depth of the rebate boards 45 to be mounted as described below.

[138] Another screw 46 is fixed through the angle bar 44 at the first hole 47 and into the structural post 42. The distance between the inside of the rebate board 45 and the inside face of the structural column is adjusted using the screws 46 to a nominated thickness of the concrete edge to be formed. The screw 46 is positioned on top of the first rebate board 45. After all the screws are installed in the angle bars 44 positioned along the formed edge, another rebate board 45 is placed in position, resting on the shanks of the screws 46 providing a small gap between the rebate boards 45. Another screw 46 is installed on top of the installed rebate board 46 to each angle bar 44 and the process repeats itself until the slab level 36. Concrete is poured in layers of 500 mm height when filling up the drop edge beam.

[139] Figure 17 shows a levelling screw peg 16 installed within the slab area in locations 7 (see Figure 1 ) and has an adjustable U-shaped bracket 47 screwed into the nut 17. The bottom

48 of the u bracket is set to the height of the slab 36 and screed support rail 49 (see Figure 18) is placed in the U-bracket 47 and onto the rebate board 45 at the other end. A vibrating screed 50 (see Figure 19) with both ends adapted to rest and slide on the screed support rail 49, and also on top of the rebate board 45. When screeding of the section is completed the screed support rail 49 is relocated to another section, and the levelling peg 16 that supports the rail 49 is removed.

[140] The preferred embodiment in one aspect provides an adjustable bracket that can be fitted to a formwork peg, rather than the lower edge board, and the rebate boards are fitted to it and they can be raised and lowered so that the top of the rebate boards coincide with the top of the slab, which means the slab levels can be determined by the formwork rather than by the concreters using laser levels when pouring the slab

[141 ] The preferred embodiment provides a more cost effective and user friendly installation process, whereby location of piers, beams trenches and edge boards are located independent of string lines, so that not only string lines are not required, neither are profiles needed to be supplied or installed, sledge hammers are not required to drive in pegs, and the pegs are designed to locate accurately and are more easily installed without excessive soil fracturing. Plumbing risers are located accurately from markers independent of the edge boards and as such, the plumbers can install the internal drains before the concreter starts working on site installing the slab edgeboards, a slab levelling system thus making the concreter labour more efficient and effective with a very small chance of error. In summary, the preferred embodiment is about, negating the use of sledge hammers and tape measures during the formwork installation process, and negating the need for a laser level during the concrete placement process, thus in all cases making the site safer and the labour more effective in the formwork construction and slab installation process.

[142] The preferred embodiment provides an improved method for marking out slab piers, edges and trenches and a more efficient method of installing pegs and edge boards and braces, internal plumbing, internal levelling pegs and internal and external drop edge beams in concrete slabs, and in particular, provides one or more of the following:

a. Provide an installation method that doesn't require the use of sledge hammers b. An installation method that employs surveyor equipment, namely a Total station to locate piers.

c. Provide an installation system based upon the total station and formwork support pegs that removes the need for workers to use a tape measure during the construction of formwork.

d. An installation method that employs a Total station to accurately locate pilot holes which are used for the installation of formwork support pegs.

e. Provide a method that drills pilot holes into the earth which are vertical and to a nominal depth.

f. Provide a formwork peg made of steel.

g. Provide a formwork support peg in one form that can be screwed into the pilot hole. h. Provide a formwork support peg that has a tapered shaft and thread formed around extending from the bottom of the peg, and stops where the overall diameter of the threaded section is equal to or less than the shaft diameter of the top of the peg.

i. Provide a formwork support peg that can be unscrewed from its embedment without the thread disrupting or engaging the formwork timber edge or concrete, or adjustable rebate bracket

j. Provide a formwork support peg that wedges itself into the soil as it is being screwed.

k. Provide a formwork peg in another form that has fins welded to each side of it.

I. Provide a finned formwork peg that can be located and pushed into a pilot hole. m. Provide formwork pegs in each case that are rigid when installed and as such don't require bracing.

n. Provide a formwork peg installation process so that they can be installed vertically.

o. Provide a formwork peg that has holes made through it, and regularly spaced along it in one plane or in orthogonal planes.

p. Provide a formwork peg design that can support and engage a rebate bracket. q. Provide a rebate bracket that is set to a rebate depth.

r. Provide a rebate bracket that is adjustable in the vertical direction.

s. Provide an adjustable rebate bracket which can support a rebate board.

t. Provide an adjustable rebate bracket which can move a rebate board up or down so that the top of the board can be adjusted and made level with the top of the slab.

u. Provide an adjustable rebate bracket that can maintain the top of the rebate board in a fixed position so that a laser level is no longer needed to level the slab along its edge during the pour.

v. Provide a rebate board support system that allows the top of the board to be at the slab height all around the slab.

w. Provide a rebate board support system that allows it be reliably used to screed from when placing the concrete.

x. Provide a re - useable brace means made of steel. y. Provide a brace means that can be used to support the formwork pegs if required

z. Provide a brace means that can be installed over and onto the formwork support peg.

aa. Provide a brace means that can be easily fixed to formwork support peg using a steel pin fixed into its end and through the existing hole in the peg.

bb. Provide a brace means that can be easily installed into the ground by a foot or mallet.

cc. Provide a means by which the formwork can be dismantled easily by removing screws.

dd. Provide a means of disassembly of the formwork system where damage to the slab edges is minimised.

ee. Provide a means whereby nailing and nail removal is minimised during the formwork construction and deconstruction process.

ff. Provide a means of construction an external drop edge beam that does not require bracing.

gg. Provide a means of constructing an internal drop edge beam that does not require external bracing.

hh. Provide a means of constructing both external and internal drop edge beams that saves materials and labour.

ii. Provide a levelling peg so that a slab height can be set within the slab.

jj. Provide a levelling rail that can be installed on top of and between the levelling pegs.

kk. Provide a levelling rail and corresponding levelling pegs that run parallel to the slab rebate boards so they can be used as guides for a powered vibrating screed.

II. Provide a levelling rail and peg system that can be removed and reused. mm. Provide tools and methods that at least improve the formwork and concrete installation process for concrete slabs in terms of greater accuracy, labour and material saving.

[143] Whilst preferred embodiments of the present invention have been described, it will be apparent to skilled persons that modifications can be made to the embodiments described. [144] For example, the pegs can be made from hard plastics material instead of steel. Also, the fin peg can include different shaped fins, such as square shaped, or the peg can include one fin only.

[145] The adjustable bracket can also be used in the existing formwork systems either on the bottom board (as they currently are as a fixture) or over the timber post.

[146] Referring to Figures 20 and 25, a waffle pod slab is shown with the top of rebate board 201 set to the height level 208 of the slab to be poured. The height of the rebate board 201 is adjusted via bracket 203 on peg 202 as disclosed above and in AU 2015904808. The reinforcement mesh 207 is chaired up and installed on waffle pods 204. The rail support 205 is installed onto waffle pod 204 at the desired distance from the rebate board 201 so that the rail 206 can rest on the rail support 205 as well as on top of the rebate board 201 at its other end as shown in fig 25.

[147] The adjustable height rail support 205 is comprised a U-shaped bracket 214 fixed onto a threaded stem portion 215, the stem portion 215 being screwed into a nut portion 216 fixed to a base plate 217. Rotation of the U-shaped bracket 214 relative to the base plate 217 thus adjusts the height. The U-shaped bracket 214 has a base 218, the top of the base 218 being adjusted to level with the slab height 208 so the rail 206 can be supported by the rail support 205 at the correct height. The lower edge of the rail 206 will thus be level with the slab height 208.

[148] As shown in Figures 26 and 27, the manual screed 210 or vibrating screed 213 comprises an elongated blade 220 having horns 21 1 at ends thereof, the horns 211 being raised relative to the lower edge 218 of the blade 220.

[149] The depth D 209 of the rail 206 is used to determine (will be equal to) the depth D of the horn 21 1 on each end of the manual screed 210 in fig 26. The horns 21 1 can be fabricated and fixed to a standard screed 210. The horns 21 1 can be cut into the aluminium extrusion of the powered vibrating screed blade 213 or can be fabricated and fixed onto each end of the current blade design fig 27.

[150] The horns 21 1 can also be made to be adjustable in depth.

[151 ] The horns 21 1 rests on top of the rail 206 such that the lower edge 218 of the blade 220 will be level with the slab height 208.

[152] The lower edge 218 of the blade 220 can also rest on top of the rebate board 201 in use.

[153] The adjustable height rail support 205 is installed within the slab area in locations and has an adjustable U head bracket screwed into the nut. The bottom of the u bracket is set to the height of the slab and the screed support rail 206 is placed in the U bracket and onto the rebate board at the other end. A vibrating screed with ends adapted to rest and slide on the screed support rail, or on top of the rebate board. When screeding of the section is completed, the screed support rail is re-located to another section and rail support, and the rail support that supported the rail is removed.

[154] A laser level is used to adjust the rebate board around the perimeter of the slab, so that at the end of this process, the top of all the rebate boards and step down boards are level with the top of the house slab and at this time the slab is ready to install the concrete placement means.

[155] The adjustable rail supports with its base and adjustable U-shape brackets on top are then placed at particular locations within the slab on top of the pods and adjusted to height using the laser level. A series of equi-spaced and parallel arrangements of the brackets are strategically installed across the slab.

[156] The support rail 206 is made from extruded tube or pipe, and is installed by simply resting one end on top of the rebate board 201 and the other end on the adjustable rail support bracket 205. Another rail 206 may be installed parallel to the first rail 206 in the adjacent section to be screeded next.

[157] The concrete is pumped into the area, vibrated and raked out to remove the humps and excesses.

[158] The manual or powered vibrating screeds 210 or 213, with ends having raised horns to rest on top of the rail 206 is then placed into position to begin the process of levelling the concrete. The other end of the screed 210 or 213 can rest of the rebate board 201 at its lower edge 18.

[159] After the first section is placed and is screeded using on one side, the top of the rebate edge board 201 and on the other, the rail 206 located on the adjustable support bracket 205, the rail 206 and support bracket 205 may be removed. The rail 206 is relocated to the next set of rail support brackets 205, and the screeding process restarts when this next section of slab is filled with concrete. The vibrating screed 213 at this point, uses the already screeded slab portion on one end of it to rest upon, and the rail support 206 in its new location as support on the other end. Alternatively, the first rail system may be moved into the screeded portion by 200 mm and the screed may be supported on the first rail as well as the next rail parallel to the first rail at a distance which allows the raised ends of the screed to be supported. This method employs a positive support for each end of the screed at all times. [160] This process is continued until there is no more need for a screed rail in that row, and the final screed uses the screeded concrete on one end or a rail left in place, and on the other, the top of the rebate board.

[161 ] The present embodiments thus provide positive support for the powered vibrating or manual screeds using a rail and adjustable brackets either mounted on the ground or with an adjustable U bracket mounted on the formwork or top of the pods.

[162] The rail support that has a lower edge level with the top of the slab rather than its top, so that its installation does not interfere with the reinforcement bar and mesh placement. That is, the reinforcement bar and mesh can extend below the rail support. The rail support remains relatively clean and because of there being no constraint on its depth, can span much greater distances requiring far less supports and far less labour to install.

[163] The present embodiment also provides a vibrating screed blade design and a manual screed design that allows the blade to be supported above the wet concrete on the rail support, by its vertical face as well as on top of the rebate boards with the horizontal face. As shown in Figure 9, for an L-shaped cross-section screed, the horns 1 1 are formed with the vertical face whilst the horizontal face will engage the rebate boards 1 as needed.

[164] The preferred embodiments provide a more cost effective concrete placement installation process, by employing a higher strength longer spanning rail support system which can be supported by an adjustable bracket mounted on top of the pod system, as well as improving the design of the power vibrating or manual screed system to suit it. This can significantly improve the flatness of the concrete slab by implementing physical processes that reduce the need for trade skill in concrete placement.

[165] The invention can also be used for suspended concrete slabs and not just "waffle & raft" ground slabs.

[166] The preferred embodiments provide an improved method for concrete placement so that a slab can be installed with a very flat and level top surface, in particular:

a. Provide a rail system for supporting manual or powered vibrating screeds that is installed so its bottom face is level with the top of the slab.

b. provide a rail system that can be installed by resting one end on top of a rebate board and the other on a rail support adjustable bracket.

c. Provide a rail system that can be installed on an adjustable support bracket at each end d. Provide a rail support adjustable bracket that can be mounted on the top surface of the waffle pod void former and has a U shaped rail support on top. e. Provide a rail support adjustable bracket that can be reused.

f. Provide a screed blade design which is adapted to rest on the top surface of the rail system and can be used manually to screed concrete. g. Provide a screed blade design which is adapted to rest on the top surface of the rail system and can be used in conjunction with a powered vibrating screed.

[167] Figs 29 to 33 shows a vibrating screed 310 according to another aspect of the present invention. The screed blade 310 comprises an elongated body which is generally unequal sided U-shaped in cross section and having raised horns 305 at ends thereof. The screed blade 310 comprises a base 313 and one rear vertical side 302 of the U-shape being the normal height of the screed blade to structurally support itself and its vibrating motor assembly 303 which is bolted to its side. The othervertical leading side 301 of the U shape is the leading edge of the screed blade 310 and is lower in height than the rear side 302, the leading side 301 being nominally 25 to 30 mm. The base 313 and sides 301 and 302 define an upper trough 309.

[168] In use, the concrete is pumped into the formed slab area in sections, vibrated and raked out to remove the humps and excesses. The manual or powered vibrating screed incorporating the modified screed blade design is placed into position between equi-spaced levelling pathways in the wet concrete, or on levelling rails to begin the process of levelling the concrete.

[169] The screed 310 is pulled in the direction of the arrow with the leading side 301 being the leading edge. The screed leading edge 301 is nominally 25 to 30 mm high although other heights may be used, is used to control the concrete bow wave height 306 in fig 30 and allow excess concrete 307 to overflow into screed blade trough 309 and leaving a level concrete screed 31 1 at the rear.

[170] The vertical side 302 of the screed blade in Fig 30 maintains the structural rigidity of the screed blade and supports and is bolted to the vibrating power unit 303 with handles 304. A rake 308 in fig 31 is deployed along the top of the screed blade leading edge 301 and removes the excess concrete 307 in a controlled way from the front of the moving screed. Fig 32 shows the same rake 308 at angle 310 against the screed section. Fig 33 shows a screed section with rake 308 removing excess concrete 307 from the trough 309 which is contained in the screed U section shape. [171 ] The screed blade is an unequal sided U shape, one vertical side of the U being the normal height of the screed blade to structurally support itself and its vibrating motor assembly which is bolted to its side. The other vertical side of the U shape is the leading edge of the screed blade and is lower in height than the rear, nominally 25 to 30 mm, although this height may vary up or down to suit the wet concrete constraints such as slump and aggregate size in the slab. The leading edge screed height limits the height of the bow wave, allowing excess concrete to flow into the bottom of the U screed as the screed is moved along. The leading edge acts like a pressure valve, and as such stops the build up of concrete in front of the blade which, if not removed, would lift the screed out of level. The excess concrete collected in the base of the screed is removed by raking as the screed is pulled along the concrete surface.

[172] Concrete is continuously removed from the concrete surface in front of the screed, by conventionally pulling the wet concrete in front of and in the same direction as the screed, or by angling the rake blade into the concrete while resting the other end of the blade on top of and at right angles to the leading edge of the screed and pulling the excess concrete sideways and then away from the screed.

[173] The section of the slab is screeded and either another levelling pathway or levelling rails are deployed to begin another run, and the process is repeated until the concrete placement is complete.

[174] This invention provides an improved method for concrete placement so that a slab can be installed with a very flat and level top surface, in particular:

a. Provide a method of placing and levelling concrete

b. Provide a screed blade design which is adapted to rest on the top surface of levelling pathways or alternate rail system and can be used manually or in conjunction with a vibrating motorised attachment to screed concrete.

c. Provide a screed blade design which controls the height of concrete build up at its front of the blade leading edge.

d. A screed blade that has a trough incorporated within it where excess concrete gathers and can be removed by raking.

e. A screed blade leading edge design that can be employed as a height guide for raking concrete in front of it to the desired level

f. An improved screed design that enables effective and efficient levelling of wet concrete in slabs [175] Figures 34 to 36 show an alternative edgeboard design 401 for use with the assembly shown in Figure 1 1 . The edgeboard 401 is a C-section metal board having a front vertical web 402, upper and lower horizontal webs 403, a lower rear vertical web 404, and an upper rear vertical web 405. These webs define a hollow cavity 406.

[176] The lower rear vertical web 404 is longer that the upper rear vertical web 405. The reason for this is that the longer web 404 on the bottom of the C-section increases the strength of the bottom of the board 401 so as to better the resistance to the higher loading from the concrete pressure pushing against in as the concrete depth increases.

[177] The hollow edgeboard 401 section allows the insertion of wooden boards into the ends thereof if needed. A timber board can be inserted into the C-section edge boards to overcome a short fall in length as well as forming an angled corner on the edge of the slab (e.g. 135° - a wooden board will connect two C-section edgeboards 401 ). The metal edgeboard section is designed so as it could fit the standard timber size available, which means that the applicant does not have to cut the metal edge boards 401 , in the event they have to make up for a shortfall in length - the applicant can use an extension piece cut from timber and slide it into the C-section.

[178] One end of the edgeboard 401 has a cut out in the lower horizontal web 403 and the lower rear vertical web 404. This allows one edgeboard 401 to be overlapped with another edgeboard 401 as shown in Figure 35.

[179] The edgeboard is mounted to the adjustable rebate bracket 27 (see fig 35 and 36) via a mounting block 401 inserted into the hollow cavity 406 thereof. .

[180] Whilst preferred embodiments of the present invention have been described, it will be apparent to skilled persons that modifications can be made to the embodiments described.

Claims

Claims The claims defining the invention are as follows:

1 . A formwork support peg comprising an elongated peg body having a pointed lower end, at least one fin welded to the body at a mid-length portion thereof, wherein the peg is adapted to be driven to the ground until the fin is embedded.

2. The peg of claim 1 wherein the peg comprises two fins attached to opposite sides of the body.

3. The peg of claim 1 wherein the body comprises an upper section having a plurality of spaced holes.

4. The peg of claim 3 wherein the holes comprise two aligned vertical series of holes drilled at 90 degrees relative orientation to each other.

5. A formwork support peg comprising an elongated peg body having a pointed lower body section, the lower body section comprising a thread formation, wherein the body comprises an upper section having a plurality of spaced holes.

6. The peg of claim 5 wherein the body comprises a rotation formation at a top end thereof.

7. The peg of claim 5 wherein the overall diameter of the thread formation is not larger than the largest diameter of the peg body.

8. The peg of claim 5 further comprising a rail support bracket mounted to a top end of the peg.

9. An assembly comprising the peg of any one of claims 1 to 8 and an adjustable rebate bracket attachable to the peg.

10. The assembly of claim 9 wherein the adjustable rebate bracket comprises a support arm having a mounting means at one end for mounting to the peg and an attachment means at another end to which a rebate board can be attached.

1 1 . The assembly of claim 10 wherein the mounting means comprises a socket which receives the peg therethrough.

12. The assembly of claim 1 1 wherein the socket comprises a U-shaped bracket having its open end welded to the support arm.

13. The assembly of claim 12 wherein the socket comprises an adjusting screw mounted to a back web thereof.

14. The assembly of claim 12 wherein the support arm has a sharp edge at the open end of the U-shaped bracket.

15. The assembly of claim 10 wherein the attachment means comprises a vertical plate with predrilled holes.

16. The assembly of claim 10 further comprising a brace for attachment to the peg, the brace having a distal end adapted to be anchored to the ground.

17. The assembly of claim 16 wherein the brace comprises a pointed spade at the distal end which is curved as an arc, the arc radius corresponding to the length of the brace.

18. An adjustable rebate bracket attachable to a peg, the adjustable rebate bracket comprising a support arm having a mounting means at one end for mounting to the peg and an attachment means at another end to which a rebate board can be attached.

19. The assembly of claim 18 wherein the mounting means comprises a socket which receives the peg therethrough.

20. The assembly of claim 19 wherein the socket comprises a U-shaped bracket having its open end welded to the support arm.

21 . The assembly of claim 19 wherein the socket comprises an adjusting screw mounted to a back web thereof.

22. The assembly of claim 19 wherein the support arm has a sharp edge at the open end of the U-shaped bracket.

23. The assembly of claim 18 wherein the attachment means comprises a vertical plate with predrilled holes.

24. The assembly of claim 18 further comprising a brace for attachment to the peg, the brace having a distal end adapted to be anchored to the ground.

25. The assembly of claim 24 wherein the brace comprises a pointed spade at the distal end which is curved as an arc, the arc radius corresponding to the length of the brace.

26. A screed tool comprising an elongated blade having a lower edge, the tool having a raised horn at at least one end, the raised horn being spaced form the lower edge.

27. The screed tool of claim 26 comprising a raised horn at both ends of the blade.

28. The screed tool of claim 26 wherein the horns are adjustable in depth.

29. A screeding assembly comprising:

an adjustable height rail support; a support rail; and

a screed tool according to claim 26.

30. The screeding assembly of claim 29 wherein the adjustable height rail support comprises a U-shaped bracket mounted to a base, wherein the distance of the bracket from the base is adjustable.

31 . A method of screeding using the screeding assembly of claim 30, the method comprising:

placing the adjustable height rail support into position with the base of the bracket to be level with the slab height

placing one end of the support rail onto the bracket and the other end of the support rail onto an edge rebate board.

32. A screed comprising an elongated body having a base, a rear vertical side and a front leading side which is lower in height than the rear side.

33. The screed of claim 32 wherein the leading side is 25 to 30 mm in height.

34. The screed of claim 32 wherein the base and the sides define an upper trough.

35. The screed of claim 32 wherein the screed comprises raised horns at ends thereof.

36. The screed of claim 32 wherein the rear side comprises a vibrating power unit mounted thereto