AU619306B2 - Concrete products - Google Patents

Description

019306 COMMONWEALTH OF AUSTRALIA Patents Act 1952

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00 00 0* 0 0 Na&nl- of Applicant Address of Applicant Actual Inventor Address for Service ARTHUR WILLIAM THOMAS CROTTY Lot 93, Staydar Crescent, Meadowbank, Loganlea, Queensland, 4131, Australia ARTHUXR WILLIAM THOMAS CROTTY GRANT ADAMS COMPANY, Patent Trade Mark Attorneys, 333 Adelaide Street, BRISBANE. QUEENSLAND. 4000

AUSTRALIA.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: 1'CQ*P2RETE PRODUCTS" The following sti.atement is a full description of the invention inclUding the best method of performing it known to the applicant.

2 THIS INVENTION relates to concrete products, and in particular to concrete products such as swimming pools and marine pontoons, that utilise a steel f ree reinforced concrete where contacted by water.

There are concrete products that are designed to hold water (such as swimming -pools) and to be sited in water (such as pontoons) As with all concrete products, reinforcement is desirable, and the type of reinforcement is critical. The usual reinf orcing steels might be used, but the product's engineering must take account of water penetration of the product, and consequent corrosion of the reinforcement. Steels contacted by water rust, and that process is associated with expansion which, if it occurs within a concrete product, internally stresses the product, often leading tits destruction. Various techniques are devised to V. overcome such problems, but the existence of defects may defeat them with sometimes disasterous results.

V It is an object of the present inventIon to I 20 provide a means of establishing products for use in association with water, as in swimming pools and pontoons, which products are not subject to the same V problems as has occurred with the prior art.

*The present invention achieves its objects in *25 a concrete product which in use is contacted by water and extends above and below a water level which concrete product comprises: a first portion that is normally disposed, kin in use, above the water level; and a second portion that is normally disposed, in use, below the water level; the first and second portions being integrally adjoined to each other; -the secon~d portion being reinforced substantially only with non-corrosive fibre ,%ZA46 kk reinforcement; and the first portion being substantially reinforced with corrosive reinforcements with or without a non-corrosive fibre reinforcement.

The fibre reinforced concrete of the present invention is preferably of the type set OLit in Australian Patent Application No. 61621/86 and is preferably formulated to suit a sprayed, application technique.

The invention will now be described with reference to preferred embodiments which are shown in the accompanying drawings in which:- FIG. 1 is a sectional view through a part of a swimming pool which is constructed in accordance with the present invention;

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I FIG. 2 is an end elevation of a pontoon which is constructed in accordance with the present invention; ij FIG. 3 is a sectional view of the pontoon of FIG. 2; FIG. 4 is a plan view of the pontoon of FIGS.

2 and 3; FIGS. 5 and 6 are side elevations and sectional views of the pontoon of FIGS. 2 to 4; FIGS. 7A to 7D are details of pontoons in accordance with the present invention; FIGS. 8 and 9 are side and plan views of a connecting ramp as may be used in a marina, or in connection with a jetty that is constructed using the pontoons of the present invention; oo 15 FIG. 10 shows a plan view of a section of a I*I marina in accordance with the present invention.

In FIG. 1 is shown a section through the side wall 11 of a swimming pool formed integrally with a base 11 and coping 12. The upper edge of the pool may be extended horizontally at 15, and a reinforcement 14 may be incorporated therein. A facing treatment 15 may be used to finish the rim of the pool. The reinforcement 14 extends down the wall 10 only so 'Car as point 16 which is above tha intended water line of the pool.

•o 25 This way, no reinforcement of a corrosive nature exists in the concrete pool bIelow the waterline to put the pool at risk of that reinforcement being contacted with water and corroded. The concrete of the pool is preferably of the type set out in prior Patent Application AU61621/86 wherein a fibre reinforcement is employed. The pool may, if desired, be lined with any suitable liner or decorative finish.

In the above set out pool, a steel reinforced rim provides an edge beam that adds to the pool's structural integrity. The pool may be formed in ground, with a sprayed concrete used to establish the integral wall floor and edge beam. It is possible to build into such pools any of the ancillary spas, etc. The shell of the pool may be precast, it may be formed in situ using formwork, or it may be sprayed. The actual design of the ring beam will be dependent on ground conditions, pool size, etc. The use of a pool i.ner provides a double safeguard. Ground movements can cause cracking in any pool so that a pool liner may be desirable.

The pontoon 18 of FIG. 2 comprises a top or deck 19 and bottom section 20, which bottom section is submerged when the pontoon is floated with a water i level around the indented waist 21. FIG. 3 shows a i section through the pontoon of FIG. 2 with a core 22 i having a concrete shell 23 thereabout, which shell may 15 be provided with steel reinforcement 24 within its cap I 25. A foam core 22 might be used for its buoyancy and ease of forming into the requisite shape. The core acts S: as a former for a sprayed concrete coating process. A process of production may involve laying up a base 26 of concrete, resting a core 22 thereon and spraying the sides to coat them. A layer may be applied to the top, reinforcement laid up, and the reinforcement coated over to bury it. The reinforcement is bent down at the sides of the pontoon, but extends downwardly only so far, 25 stopping short of the water line.

1 As is described with reference to FIGS.4, and 6, the pontoon may have internally threaded anchor fittings 27 along the upper edge 29, set into the I pontoon, and conduits 28 passed therethrough from side to side. Conduit 28 provides a means whereby lengthwise timber railing 30 (see FIG. 3) may be applied along the sides, and/or pontoons may be interconnected, and a gap 31 may be established therebeneath to serve as a place to locate service lines. FIG. 4 is a plan view showing where a plurality of anchor fittings, such as 27, rIay be arrayed along the abutment face 29, and a plurality of

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conduits, such as 28, may be regularly spaced over the top 19 of the pontoon.

The core 22 may be chamfered at its edges, such as at 32 (see FIG. and the waist of the pontoon may be rebated at the waterline 21. The rebate assists wave action to reduce the build up of floating debris.

The concrete applied about the core may be of the type set out in 61621/86 using a 40 or 60mm fibre mesh incorporated at between 1.5kg to 5.0kg per cubic metre of 30 Mpa concrete. The upper reinforcement steel may be a 100 x 150 x 5mm galvanised mesh. The conduit 28 may be established by a PVC pipe inset into top 19 to pass a 16mm galvanised through bolt which may pass S 1 through railing 30 to fix it with galvanised nuts and 15 washers within a recess so as to establish a flat finish.

i FIGS. 5 and 6 show the pontoon on its long side, FIG. 6 being a sectional view. Conduits, such as 28, are recessed into core 22 into rebates, such as 34, i 20 cut into its upper surface. By use of a shaped core 22, any degree of overhang 35 may be provided, the overhang being useful to prevent wave action slopping water over onto top 19 of the pontoon. Alao, when pontoons are interconnected on their long sides, water flow is 25 allowed between them. When the pontoons are stacked end to end, the rebate at the water line 21 allows the same thing. An extensive marina may be built up with a high degree of free flow therethrough without any damming of floating debris and stagnant water as usually occurs with what is presently utilised. FIGS. 7A to 7C show different styles of rebate FIG. 7C shows how a post 36 may be bolted to wooden railing 30 using brackets 37 and 38 (see FIG. 7D). Bracket 37 overlaps the top of rail and bracket 38 secures the lower end of post 36 to the railing side.

6 FIGS. 8 and 9 show a gangway 39 from the side (FIG. 8) and above (FIG. 9) which may be supported upon suitable roller wheels at each side on brackets such as and 41. Welded, galvanised, stock steel may be used as the f ramning with a ply deck.

FIG. 10 shows four pontoons 42 to 45 joined end to end (42 to 44) and side to side (44 and extended between two piles 46 and 47 which locate the structure. End sections 48 and 49 comprise a decking and 51 which are holed to pass the piles therethrough with rollers, or other suitable bearings, therebetween.

In the figure, four rollers are indicated, one being numbered 52. A 50mm clearance around the pile is adequate to allow the structure to rise and fall with 15 the tide. A connecting pontoon walkway is shown at 53, which may be joined to -the pontoon sides, as at 42, and additional braces 54 and 55 may be provided. The structure may be surrounded by a railing which can comprise pairs of overlapped timbers which overlap the 20 joint-9 between pontoons to establish a stable surface, Timber length 56 spans the pontoons 42 and 43 and butts against fuy. -her length 57 spanning pontoons 43 and 44.

Outer timber 5F3 and 59 further overlap the joints between pontoons and also the end to end meeting of the first layer of timber. A gap of 20mm may be maintained between the pontoons. The anchor fitti,"qs and conduits may be used in the connecting up process.

The~ above described pontoons comprs aIte prs a*see reinforced upper surf ace and a lower steel free section at and below the water line so that corrosion is not a problem. Gaps are established, in use, therebetween so that wave action will wash away any debris; there is no staignant water, aiid less tidal pressures.

Building pontoons is simple; the floor is put in pl.ace; the styrenie foam inf ill is placed thereon; and the inf ill's sides are spray coated (this overcomes the 111 prior art mould process where a foam plug must be held against its buoyancy in the wet concrete). The present technique enables any number of different shapes, with a large range of overhangs possible, to enable designs to suit particular wave actions, user requirements etc.

A synthetic fibre reinforcement which may be used in the present invention is preferably formed from a polypropylene or propylene copolymer tape which is fibrillated by uniaxial stretching and cutting to produce, when expanded, a net of fibrils.

In producing the synthetic fibre reinforcement a length of tape is fibrillated by a plurality of cuts j to produce a web of interconnected fibres. The base of the product may be a polypropylene tape or a tape formed 15 from a propylene copolymer. This is an oriented material formed by a uniaxial stretching during fabrication. The base tape may be typically formed with the following properties; 1.53 grams per metre; density 0.91; tensile strength 400 mpa; modulus of elasticity i 20 8000 mpa; and an elongation at break of 10:1 to 15:1.

The base tape is chopped to particular lengths depending on the particular application, and typically i 12, 40 and 60 mm lengths are employed.

As a cement reinforcement, it has been found 2 through testing that from 1.5 kgm per cubic metre of fibre is useful for many applications, with 2kgm per cubic metre and more being preferable for higher load i bearing applications.

For general concrete needs a 60 mm length j 30 fibre product will be found to be useful, with 4 mm fibres being applicable to lighter aggregate mixes.

In normal use, the fibre is kept dry until mixing. When ordering ready mixed concrete, the slump provided in the concrete agitator at site shoulu be around 100 sluop; fly ash is to be typically no more than a maximum of The strength of the concrete

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should not be less than a minimum of 20 mpa for most applications. The fibre is added on site. It should be introduced to an agitator by separated handfuls. At no time should the whole quantity be poured at once into an agitator. The action of the aggregate in the concrete is believed to result in an expanding of the product into a mesh of filaments which provide a three dimensional bonding of the matrix, so holding the concrete together. A typical mixing period is a minimum of three minutes, and a maximum of ten minutes. Between to 10 minutes is preferable.

Whilst the above has been described with reference to a preferred embodiment, it will be apparent that many modifications and variations, as would occur to a man skilled in the art, may be made thereto that are within the scope and spirit of the invention as hereinbefore set forth.

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Claims (9)

1. A concrete product which in use is contacted by water and extends above and below a water level which Sconcrete product comprises: a first portion that is normally disposed, in use, above the water level; 'hnd i ia second portion that is normally disposed, in use, below the water level; iI the first and second portions being integrally adjoined to each other; the second portion being reinforced r| substantially only with non-corrosive fibre reinforcement; and the first portion being substantially 15 reinforced with corrosive reinforcements with or without a non-corrosive fibre reinforcement,

2. A concrete product as claimed, in Claim 1 wherein: the product is a swimming pool wherein said *j 20 fir jt portion encircles the pool with steel reinforcement to establish a strengthening edge beam.

3. A concrete product as claimed in Claim 1 e.t: wherein: the concrete product is a pontoon comprising 25 said first portion incorporating interconnection means whereby a plurality of said pontoons may be i interconnected and said second portion being a buoyant fibre reinforced concrete shell. 1

4. A concrete product as claimed in Claim 3 wherein: the buoyant concrete shell is formed around a light weight plug by a concrete spray coating process after laying the plug on a preformed fibre reinforced concrete bottom plate.

5. A concrete product as claimed in either of 11 Claims 3 or 4 wherein: the first portion meets the second portion at an edge with a rebated waist thereunder, the second portion having an extent in directions parallel to the water level that is less than the corresponding extent of the first portion.

6. A concrete product as claimed in any one of Claims 3 to 5 wherein: the first portion includes a deck with a vertically faced perimeter, which vertically faced perimeter includes the interconnection means, these means comprising threaded anchor fittings and/or Sconduits traversing the deck.

7. A concrete product as claimed in Claim 6 15 wherein: the plug is a rectangular block of foamed plastic wherein the top surface over which the deck is formed is grooved and plastic conduits are laid in the grooves prior to application of the concrete shell to 20 establish the conduits by which said pontoons may be S joined.

8. A concrete product as claimed in any one of i the preceding claims wherein: the means of joining said pontoons includes :4 25 timber planks affixed to the pontoons by the interconnection means.

9. A concrete product substantially as hereinbefore described with reference to the accompanying drawings. DATED this twenty-third day of September 1991. ARTHUR WILLIAM THOMAS CROTTY, by his Patent Attorneys, GRANT ADAMS COMPANY. D i