This invention relates to structural elements formed from castable material. In particular, the invention relates to reinforcement of polymer concrete structural elements using fibre-reinforced plastics. However, it should be appreciated that other castable material such as standard concrete may be used to form the structural element.
Polymer concrete is made by polymerising a polymeric material with filler material such as aggregate (e.g. gravel, sand etc.). Polymer concrete has generally good durability and chemical resistance and is therefore used in various applications such as in pipes, tunnel supports, bridge decks and electrolytic containers. The compressive and tensile strength of polymer concrete is generally significantly higher than that of standard concrete. As a result polymer concrete structures are generally smaller and significantly lighter than equivalent structures made out of standard concrete.
However, polymer concrete still requires reinforcement as with standard concrete. This normally involves the use of traditional reinforcement bars that are placed with the concrete during the forming process. In corrosive environment traditional steel reinforcement is subject to corrosion and therefore has been increasingly replaced with fibre composite reinforcement.
The superior physical properties of fibre composites are well recognised. They combine high strength with low weight and have generally good durability and resistance to salts, acids and other corrosive materials, depending on the resin formulation. Based on these material characteristics, fibre composite reinforcement has a range of advantages over traditional steel reinforcement which is heavy and subject to corrosion. Fibre composite reinforcement for concrete and polymer concrete structures is available but generally has a form similar to traditional steel reinforcement. That is, different diameter, round bars and ligatures (stirrups).
This type of fibre composite reinforcement does not result in any significant material or weight saving over standard steel reinforcement. Furthermore, this standard fibre composite reinforcement is expensive and rather inflexible. The straight bars are extremely difficult to shape to include cogs or hooks at the ends to improve the anchorage. The ligatures are supplied as a prefabricated item and cannot be re-shaped or adjusted for different size or shape beams.
Reinforcement bars and ligatures were developed to be made of steel and used in standard concrete. As has been shown many times before, structural concepts developed for traditional materials are not necessarily the most efficient solution in fibre composites.
It is an object of the invention to overcome or alleviate one or more of the disadvantages of the above disadvantages or provide the consumer with a useful or commercial choice.
It is a preferred object of this invention to enable structural elements made from concrete with continuous fibre composite reinforcement to be produced that have improved load-carrying characteristics.
It is a further preferred object of the invention to allow structural elements made of concrete and continuous fibre composite reinforcement to be produced cost effectively.
It is a still further preferred object of the invention to allow structural elements made of concrete and continuous fibre composites reinforcement to be produced with a significantly reduced weight.
In one form, although not necessarily the only or broadest form, the invention resides in a structural element formed from castable material, said structural element comprising:
a plurality of fibre reinforced plastic, tubular members;
a plurality of fibre reinforced plastic, spacer members, said spacer members extending between said plurality of tubular members;
a plurality of fibre reinforced plastic, interconnecting members, said interconnecting members positioned in a different orientation to said spacing members; and
castable material surrounding said members;
wherein the interconnecting members and spacer members intersect with each other.
The members may be produced from any suitable glass, carbon or aramid fibre and/or plastics material dependant upon the desired properties of the structural element. A surface area of the members that contact the castable material may be abraded to increase adhesion between the castable material and the members. Alternatively, the members may be coated with sand and/or gravel interface to increase adhesion.
The tubular members may be pultruded fibre reinforced plastic. Preferably, the tubular members are substantially square in transverse cross-section. The tubular members may be hollow to save maximum weight.
In another form, the tubular members may be filled with standard concrete, polymer concrete or a filled resin system to increase their load carrying capacity.
In yet another form, the tubular members may be filled with standard concrete, polymer concrete or a filled resin system and a metal or fibre composite reinforcing bar to further increase their load carrying capacity.
The spacer members and interconnecting members are usually constructed from the same fibre reinforced plastic. Preferably, the spacer member and interconnecting members are normally stronger than the transverse strength of the tubular members.
The interconnecting members may pass through the spacer members or the spacer members may pass through the interconnecting members or a combination of both.
Slots may be located in either or both of the interconnecting members and/or spacer members to allow the interconnecting members and spacer members to intersect.
The interconnecting members and spacer members may be locked to each other after they intersect. Notches may be provides in the interconnecting members and/or spacer members to engage with the slot on the other of the interconnecting member or spacer member to lock the interconnecting members and spacer members together.
Preferably the interconnecting members are oriented so that they are substantially perpendicular to the spacer members.
The castable material is usually concrete. Preferably, the concrete is polymer concrete or a filled resin system.
In another form, the invention resides in a method of producing a structural element formed from castable material, said method including the steps of:
producing a mould that has a portion of an outer shape of the structural element to be produced;
placing fibre reinforced plastic, tubular members; fibre reinforced plastic, spacer members; and fibre reinforced plastic, interconnecting members; within the mould such that said spacer members extending between said plurality of tubular members and said interconnecting members are positioned in a different orientation to said spacing members; so the spacing members and interconnecting members intersect;
locating castable material between and over said members;
allowing said castable material to set to form said structural element.
The members may be abraded prior to the members being introduced into the mould. Alternatively, the members may be coated with sand and/or gravel interface to increase adhesion.
In one embodiment, the members may be located within the mould and castable material poured over the members.
In another embodiment, the members may be located within the mould after sufficient castable material to complete the structural element has been delivered into the mould.
In still another embodiment, a portion of castable material may be introduced into the mould and some of the members introduced into the mould. More castable material may then be introduced into the mould and more members may be introduced into the mould. This may be continued until the structural element has been completed.
Embodiments of the invention, by way of example only, will be described with reference to the accompany drawings in which:
The tubular members 120 are square in transverse cross-section and are pultruded from polyester resin and glass fibre. The spacer members 130 and interconnecting members 140 are flat sheets that are produced from vinyl ester and carbon fibre.
Referring also to FIGS. 2 to 4, the arrangement of the tubular members 120, space members 130 and interconnecting members 140 are shown in more detail. The tubular members 120 extend the length of the marine beam 101 with the spacer members 130 located between adjacent tubular members 140. Slots are located within the spacer members 130 so that the interconnecting members 140 can be placed through the spacer members 130.
It should be appreciated that the interconnecting members 140 are spaced along predetermined lengths of the marine beam 101. The spacing of the interconnecting members 140 along the spacer members 130 may be varied according to the structural requirements. That is, if increased lateral strength is required, the distances between adjacent interconnecting members 140 can be reduced.
The advantage of a construction of the marine beam 101 is that fibre dominated behaviour is exhibited in three dimensions. That is, increased strength is provided both longitudinally, laterally and transversely. Specifically, the tubular members 120 provide both longitudinal, lateral and transverse strength to the marine beam. The spacer members 130 provide additional longitudinal and transverse strength. Further, the spacer members 130 also provide a tie for an upper and lower part of the marine beam 101 through which the tubular members 120 do not extend. This prevents the delamination of a top 102 and base 103 of the marine beam from the tubular member. The interconnecting members 140 provide additional transverse strength and also prevents lateral delamination of the tubular members 120 and spacer members 130.
A level of polymer concrete 110 is then delivered into the mould shown in
It should be appreciated that the tubular members 120, spacer members 130 and interconnecting members 140 may be formed as shown in
The use of the tubular members 120 provides for a lighter structure and also reduces material costs. Another advantage is that the tubular member provides a space for electrical conduits. Still another advantage is that the size of the tubular member can be varied to produce structural elements of different densities.
It should be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit or the scope of the invention.
Number | Date | Country | Kind |
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2002951633 | Sep 2002 | AU | national |
2002952659 | Nov 2002 | AU | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/AU03/01269 | 9/25/2003 | WO | 3/23/2005 |