Structural element for constructions

Abstract

A structural element for constructions comprising a structure (2) made of concrete and/or geopolymer and/or alkali activated material and at least one strip (3) made of a fibre-resin composite. Such strip surrounds at least part of said structure (2), compressing it. The strip also at least partly surmounts an external surface (20) of said structure (2).

Claims

1. A structural element for constructions comprising a structure (2) made of concrete and/or geopolymer and/or alkali activated material; characterised in that it comprises at least one tensioned strip (3) made of a fibre-resin composite which: surrounds said structure (2), compressing said structure; at least partly surmounts an external surface (20) of said structure (2); said strip comprises a plurality of superposed layers (30) made of a fibre-resin composite which surround the structure (2); a more external layer being connected to a more internal layer without external means for maintaining a tension of said strip (30).

2. The element according to claim 1, characterised in that said strip (3) comprises two flaps (21) which surmount one another and which adhere by gluing.

3. The element according to claim 1, characterised in that the fibre comprises a plurality of filaments; the filaments extending flanked to one another, not intertwined to form a warp and a weft.

4. The element according to claim 1, characterised in that said layers (30) are superposed on one another, the more external layer being glued to the more internal layer without external means for maintaining a tension of said strip (30).

5. The element according to claim 1, characterised in that the fibre-resin composite defines a barrier having a low permeability to water.

6. The element according to claim 1, characterised in that it comprises one or more sheets (4) of an organic polymer interposed between two superposed zones of said strip for improving impermeabilization to water.

7. The element according to claim 1, characterised in that said fibre is a glass fibre or a carbon fibre or a basalt fibre.

Description

(1) Further characteristics and advantages of the present invention will become more apparent from the indicative and thus non-limiting description of a preferred, but not exclusive, embodiment of a structural element, as illustrated in the accompanying drawings, in which:

(2) FIG. 1 is a perspective view of a structural element according to the present invention;

(3) FIG. 2 is a cross-section view of the structural element of FIG. 1;

(4) FIG. 3 is a section view of a further structural element;

(5) FIGS. 4 and 5 show details of structural elements according to the present invention.

(6) A structural element for constructions is denoted in the attached figures by reference number 1.

(7) The element 1 comprises a structure 2 made of concrete and/or geopolymer and/or alkali activated material. These materials are well known in the technical field and are therefore not described further herein. In particular, alkali activated material can refer to any bonding system derived from the reaction of an alkaline metallic source (solid or in powder form) with a solid silicate powder. As shown by way of example in the appended figures, the structure 2 might comprise/be a beam. It is possible for the structure 2 to comprise an internal core, for example made of metal.

(8) The structure 2 comprises at least one strip 3 made of a fibre-resin composite.

(9) In the preferred solution the fibre is a glass fibre or a carbon fibre or a basalt fibre. The fibres are advantageously inert against corrosion and chemical attacks, so that the durability of the elements is enormously increased.

(10) The resin can for example be a polyester, vinyl ester, epoxy, polyurethane resin.

(11) The fibre comprises a plurality of filaments. The filaments advantageously extend flanked to one another. The filaments are preferably not intertwined to form a warp and a weft. The resin enables an optimal distribution of the load among the filaments.

(12) The strip 3 surrounds at least part of said structure 2, compressing it. The strip 3 winds about itself, following a closed line. The strip 3 can advantageously involve the lower part of the structure 2.

(13) Further, the strip 3 at least partly surmounts an external surface 20 of said structure 2. The term surmount and the term superpose throughout the present description are intended to mean that one element at least partly covers another element, not that it is above the other element. Compression is therefore made externally of the structure 2 and consequently a large portion of the material constituting it cooperates with the load.

(14) The strip 3 comprises two flaps 21 which surmount one another and which adhere by gluing. The gluing can be determined by application of additional glue. Alternatively it can also derive only from the interaction between the two superposed flaps 21 of fibre-resin composite material. The two flaps 21 might also possibly adhere only by friction. Elements external to the blocking strip 3 of the two flaps 21 are advantageously absent. The strip comprises a plurality of superposed layers 30 made of fibre-resin composite which surround the structure 2.

(15) The layers 30 are superposed on one another, a more external layer being glued to the more internal layer without external means for maintaining a tension of said strip 30.

(16) The fibre-resin composite defines a barrier having a low permeability to water. This is important as it enables protecting those areas which experience micro-cracking and consequent corrosion of the steel armatures and which can be attacked by water contaminated by corrosive elements (chlorine present in the salts used for prevention of ice-forming, brackish water, etc.).

(17) Where an even more significant impermeabilisation is required, the structural element 1 can comprise one or more sheets 4 of an organic polymer interposed between two superposed zones of said strip 3 for improving impermeabilisation to water.

(18) As shown by way of example in FIG. 3, three distinct strips 3 are used, which surround corresponding parts of the concrete structure 2. FIG. 3 advantageously illustrates a cladding 5 located on the structure 2.

(19) A further object of the present invention is a method for improving a structural resistance of a structure 2 made of concrete and/or geopolymer and/or alkali activated material (also known as AAM).

(20) The method comprises a step of applying a strip 3 made of a fibre-resin composite to the structure 2. As indicated in the foregoing, the fibre is preferably a glass fibre or a carbon fibre or a basalt fibre.

(21) The fibre advantageously comprises a plurality of filaments. The step of applying the strip 3 includes surrounding at least part of the structure 2 with the strip 3. This also includes superposing said strip 3 at least in part on an external surface 20 of the structure 2. The step of applying the strip 3 advantageously includes extending the strip 3 by means of a suitable mechanical arm.

(22) The step of applying the strip 3 to the structure 2 takes place after the curing of the structure 2 has terminated. The step of applying the strip 3 therefore includes a post-compression of the structure 2 (meaning the structure 2 first cures and is then compressed from outside).

(23) The strip 3 keeps the part of the structure 2 it surrounds compressed.

(24) The step of surrounding at least part of the structure 2 advantageously comprises superposing at least two end flaps of the strip 3 (the flaps can be retained by gluing or simply by friction). The strip 3 can possibly define a plurality of layers 30 which annularly envelop the structure 2.

(25) In a first solution, the step of surrounding said structure 2 with said strip 3 comprises a step of compressing said structure 2. Thus the step of compression is performed at the same time as the application of the strip 3. In this case the strip 3 is thus applied tensioned.

(26) In an alternative solution the structure 2 is mechanically compressed before application of the strip 3. Subsequently the strip 4 is applied, which in this case might be done by applying it at a lower or nil tension (it is therefore applied less tensioned than in the preceding solution even though the structure 2 will in any case be compressed).

(27) The present invention provides important advantages.

(28) The compression on the outside is such that almost all the material of the structure 2 cooperates with the load. Further lightened concretes can be used as the high-specific pressure zones that are generate along the tension rod-concrete contacts are eliminated. Further, the strip 3 is resistant to corrosion and chemical attacks, differently to the internal metal tension rods of the prior art. The strip further has an impermeabilisation function. The production process in the prefabrication sites is largely simplified as the post-tensioning and production steps of the structural element 1 are simpler.

(29) The invention as it is conceived is susceptible to numerous modifications and variants, all falling within the scope of the inventive concept characterising it. Further, all the details can be replaced with other technically-equivalent elements. In practice, all the materials used, as well as the dimensions, can be any according to requirements.