|
(11) | EP 1 790 792 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||||||
| (54) | Building artefact |
| (57) The building artefact comprises a mixture (2) of inert material and of bonding material
and a plurality of plastic material fibres (3) embedded in the mixture (2). The main
feature of such artefact (1) consists in the fact that the fibres (3) present at least
two subsequent sections (5 and 6) which converge in a convergence point (4). |
[0002] As it is known, building artefacts are formed by a mixture of inert materials and bonding material, such as for example concrete. It is also known that in order to increase tensile strength, a structure defined by bars or rods formally formed by iron or an iron-based alloy is positioned within the aforesaid mixture. If on one hand an increase of the tensile strength is obtained by reinforcing the artefact with an iron structure, on the other hand some problems or drawbacks are introduced. A first drawback is due to the considerable costs of iron procurement and of complex structure assembly, by specialised personnel. A second drawback is due to the fact that concrete is a porous material and therefore water, salinity or other atmospheric elements which attack the artefact may extend within the latter and attack the iron structure with all the disadvantages which derive therefrom on the mechanical strength of the artefact itself. Furthermore, the iron structure is inserted within the artefact in well-defined positions and this determines a lack of homogeneity of the mechanical features of the artefact between the zones in which the reinforcement is present and the zones from which the reinforcement is absent, the latter zones being subject to crumbling. In order to avoid the aggression of the iron structure and the crumbling it is used to fill the pores of the artefact with resins which however in turn introduce other drawbacks, such as manufacturing costs and the toxicity of such resins. In order to overcome the aforementioned drawbacks, some companies have adopted, sometimes in combination with the metallic reinforcement, the introduction in the aforesaid mixture of plastic material fibres. Such fibres present either a straight longitudinal conformation or a slightly undulated longitudinal conformation. The main drawback of the aforesaid fibres consists in the poor grip which occurs between the fibres and the artefact mixture. As a consequence, the fibres cannot perform their supporting action towards the concrete matrix, because they tend to slip off the latter before being able to perform an appreciable mechanical action.
[0003] It is the object of the present invention to make a building artefact which is free from the aforementioned drawbacks.
[0004] According to the present invention, a building artefact is made of the type comprising a mixture of inert material and of bonding material and a plurality of plastic material fibres embedded in said mixture, characterised in that said fibres present at least two subsequent segments which converge in a convergence point.
[0005] The present invention will now be described with reference to the accompanying drawing which shows a partial section of a building artefact indicated as a whole by numeral 1.
[0006] Artefact 1 consists of a mixture 2 of inert materials and of bonding material, such as for example concrete. Within mixture 2, during its preparation step, a plurality of fibres 3 formed by plastic material is introduced. Fibres 3 preferably present an elliptical section and a rough surface. Fibres 3 are constituted by a sequence of straight segments in which each single segment converges with the previous and next segment in a corresponding convergence point 4 forming a sharp edge to the greatest possible extent. Specifically, fibre 3 presents a plurality of segments 5 alternated with segments 6. Segments 5 present a longer length than that of next and previous segment 6 and define with these an acute angle. Furthermore, all segments 5 are reciprocally parallel, and all segments 6 are reciprocally parallel.
[0007] In use, according to the mechanical features one intends to confer to artefact 1, the number of fibres 3 to be embedded in mixture 2 during the preparation of the latter and the length and the diameter of such fibres 3 is calculated. Subsequently, mixture 2 is cast in a mould (not shown) and after curing such mixture defines artefact 1 ready for use.
[0008] From the description above, the advantages obtained by implementing the present invention are apparent and numerous.
[0009] Specifically, a building artefact is made within which a plurality of fibres formed by plastic material is present whose design is appropriately made for the purpose of significantly increasing the grip with the concrete matrix and consequently obtaining the maximum mechanical benefit from the property of the fibres. The action of the latter determines a significant reduction of cracking, an increase of ductility and tensile strength. Most of these benefits are ascribed to the convergence angles between the fibre segments, which determine the meshing of the mixture with the fibres. Indeed, the filling of the subintended zones by the matrix occurs at such convergence points between adjacent segments. Similarly, the action of a sharp edge is known to induce a concentration of the stresses in the matrix, which favours the penetration of the fibre therein and inhibits slipping off. Furthermore, the particular shape of the fibre and the roughness defined on its surface leads as a consequence to a significant increase of grip between fibre and mixture. All these features have been assessed in laboratory tests performed at the University of Modena and Reggio dell'Emilia where some of the inventors above designated work.
[0010] It is finally apparent that changes and variants can be made to artefact 1 described and shown hereof without departing from the protective scope of the present invention.
[0011] Specifically, the section of fibre 3 may differ from that described, and specifically such section may be polygonal. Furthermore, between reciprocally adjacent pairs of segments 5 and 6 there may be introduced a third joining segment with a different angle with respect to segments 5 and 6. It must be underlined that fibres 3 or at least a certain number of the latter may be reciprocally braided or however a connection between such fibres 3 may be contemplated so as to determine a well-defined position of at least a plurality of fibres 3 at a zone of artefact 1.
1. A building artefact of the type comprising a mixture (2) of inert material and of
bonding material and a plurality of plastic material fibres (3) embedded in said mixture
(2), characterised in that said fibres (3) present at least two subsequent segments (5 and 6) which converge
in a convergence point (4).
2. An artefact according to claim 1 characterised in that said segments (5 and 6) are straight.
3. An artefact according to claim 1 and/or 2 characterised in that said convergence point (4) is a sharp edge.
4. An artefact according to at least one of the preceding claims characterised in that the subintended angle between said subsequent segments (5 and 6) is acute.
5. An artefact according to at least one of the preceding claims characterised in that the pair of said subsequent segments is defined by a first segment (5) and by a second
segment (6) of length shorter than that of said first segment (5).
6. An artefact according to claim 5 characterised in that each of said fibres (3) presents a plurality of said first segments (5) alternated
with said second segments (6).
7. An artefact according to claim 5 characterised in that each of said subsequent pairs is connected by means of a third segment.
8. An artefact according to claim 6 characterised in that said first segments (5) of the same said fibre (3) are reciprocally parallel and
characterised in that said second segments (6) of the same said fibre (3) are reciprocally parallel.
9. An artefact according to any of the preceding claims characterised in that the section of said fibre (3) is elliptical.
10. An artefact according to any of the claims from 1 to 8 characterised in that the section of said fibre (3) is polygonal.
11. An artefact according to any of the preceding claims characterised in that the surface of said fibre (3) is rough.
12. An artefact according to any of the preceding claims characterised in that said fibres (3) are reciprocally connected.
13. An artefact according to any of the preceding claims characterised in that said bonding material is a concrete-based material.