CONNECTOR FOR REINFORCEMENT WITHIN A FORMWORK
Described is a building structure comprising a basic horizontal element, substantially flat and forming a treadable surface, comprising a plurality of stirrup bodies rising from the surface and aligned for identifying at least one habitable room, a plurality of wall elements each comprising a pair of panels parallel to each other and spaced at a predetermined distance so as to form a hollow space between them for receiving a construction material and an upper horizontal element connected to the upper ends of the wall elements for delimiting the top of the habitable room. The hollow space is filled with a volume of clayey soil having a percentage of between 19% and 26% of inert material and delimited by lower connection means anchored to the stirrup bodies and upper connection means anchored to the upper horizontal element; the volume of clayey soil compacted such as to have a compression strength of at least 22 kg/cm2 and a shear strength of at least 4 kg/cm2.
This invention relates to a reinforcement mesh for load-bearing building panels, a load-bearing building panel (preferably comprising the mesh), a building structure with load-bearing partitions and a method for making a load-bearing building panel.
The invention applies to the building sector and, more specifically, to the construction of low-cost building structures with load-bearing partitions in difficult areas.
BACKGROUND ARTNumerous solutions are known in the prior art for the construction of multi-storey residential buildings with load-bearing partitions by the installation of load-bearing panels provided with metal reinforcement (generally made of steel) embedded in a volume of construction material, such as concrete, mortar or the like.
Depending on the structural needs and the climatic-territorial characteristics of the construction area, it is possible to use so-called “single” panels, that is, which act as internal support for the outer casting (of concrete), or “double” panels, that is, which act as disposable formwork for the inner casting.
The reinforcement, that is, the metal mesh connected to the panel and embedded in the concrete, also possesses variable strength characteristics depending on the design specifications, generally determined by the current regulations.
The reinforcement is basically mesh formed by horizontal and vertical bars (or chains) (more specifically, two vertical bars and five horizontal bars) connected together at a plurality of nodes by special joining elements.
More specifically, the bars comprise a deformed bar for reinforced concrete with a diameter of approximately 6 millimetres.
The current regulations require that, if there are two adjoining horizontal chains, these must overlap for a length of at least 80 centimetres.
Disadvantageously, this means that, since the lengths of the walls on which the panels will be mounted are not known beforehand, the horizontal chains are mounted in situ so as to limit the overlappings.
This makes the construction of the walls particularly laborious.
Moreover, with regard to the formwork structures (double panel), their prefabrication is currently divided into three different steps, substantially repeated on the same machine.
In effect,
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- in a first step, a first steel mesh is anchored to a first panel;
- in a second step, a second steel mesh is anchored to a second panel;
- in a third (and last) step, the first and the second panel are positioned in front of each other and connected by a joint.
Disadvantageously, this process prevents the formwork from being mounted in situ and makes the transport of the formwork difficult.
In effect, since the formwork is internally hollow (due to the hollow space which divides the two panels) the volume occupied by the formwork is extremely large (especially relative to its weight), forcing the builder to use very bulky means of transport for transporting a very limited weight, with a considerable waste of resources.
Moreover, the need to use concrete (as construction material) and polystyrene (for making the panels) makes the construction of the buildings particularly expensive, both in terms of the cost of the plant for processing the polystyrene and the transport difficulties in the absence of adequate infrastructure routes.
AIM OF THE INVENTIONThe aim of this invention is to provide a reinforcement mesh for load-bearing building panels, a load-bearing building panel, a building structure with load-bearing partitions and a method for making a load-bearing building panel which overcome the abovementioned disadvantages of the prior art.
More specifically, the aim of this invention is to provide a reinforcement mesh for load-bearing building panels, a load-bearing building panel which is easy to assemble and transport.
Moreover, the aim of this invention is to also obtain a building panel and a building structure which is of excellent quality and inexpensive to make.
These aims are fully achieved by the steel mesh for load-bearing building panels, by the load-bearing building panel, by the building structure and by the method for constructing a building panel, according to one or more of the claims.
These and other features of the invention will become more apparent from the following description of a preferred, non-limiting embodiment of it, with reference to the accompanying drawings, in which:
With reference to
The mesh 1 comprises a plurality of metal bars 2, 3 (preferably made of construction steel) warped with one another so as to define a grid of first 2 and second bars 3 intersecting each other.
Thus, the first bars 2 are at right angles to the second bars 3 and each second bar 3 is connected to all the first bars 2 at respective coupling nodes 4 (wherein the bars are jointed by a hook made of harmonic steel).
The mesh 1 comprises at a least a pair of first bars 2 and a plurality of second bars 3.
Both the first 2 and the second bars 3 are parallel to each other and spaced at a predetermined spacing.
In other words, the first bars 2 are parallel to, and at a certain distance from, each other.
Similarly, the second bars 3 are parallel to, and at a certain distance from, each other.
In use, the mesh is applied on the face of a panel 10 (which will be described in more detail below) preferably by arc-welding.
After installation, the first bars 2 are, again in use, orientated vertically, whilst the second bars 3 are oriented horizontally.
Thus, the first bars 2 define (in combination with the corresponding first bars 2 of a panel 10 above or below) the vertical chains of the partition.
Similarly, the second bars 3 define (in combination with the corresponding second bars 3 of an adjacent panel panel 10) the horizontal chains of the partition.
In this regard, it should be noted that each second bar 3 extends along a respective main direction between a first 3a and a second end 3b, each provided with a through socket 5.
In other words, each second bar 3 has two terminal portions having a through annular element 6.
More specifically, each end 3a, 3b is formed by a terminal portion 7 bent back on itself, for forming the socket 5, and in part placed on the body of the second bar 3 for reinforcing it.
In other words, the terminal portions 7 of a single second bar 3 are folded back on themselves (by special folding means) for forming the socket 5 they close on the section nearest the socket itself with an overlapping of a predetermined length (in the embodiment illustrated 10 centimetres).
Preferably, a distance between the centres of the sockets 5 of each horizontal bar corresponds substantially with the width of the panel 10 on which the mesh 1 is mounted.
Moreover, each through socket 5 is substantially coaxial with the through sockets 5 of the corresponding ends 3a, 3b of the other second bars (of a same mesh 1) so as to define a joining line “A”.
The joining line “A” may be passed by a third bar 6 for the connection, during assembly, of two meshes 1 adjacent to each other.
In other words, the sockets 5 of the second ends 3b of the second bars 3 (of a single panel 10) are aligned with each other along the above-mentioned joining line “A”, which is vertical in use.
Similarly, the sockets 5 of the first ends 3a of the second bars 3 (of a single panel 10) are aligned with each other along the above-mentioned joining line “A”, which is vertical in use.
Thus, during assembly, the meshes of two adjacent panels 10 are positioned in such a way that the sockets 5 of the second ends 3b of the second bars 3 of a mesh 1 are aligned with the sockets 5 of the first ends 3a of the second bars 3 of the other mesh 1.
As already indicated, this alignment allows the introduction inside the sockets 5 of a third bar 6 for connection and stiffening the building structure.
The third bar 6 preferably has a diameter (or, more generally, a cross-section) greater than that of the first and second bars 2, 3.
Still more preferably, the third bar 6 has a cross-section such that its shear strength is greater than the tensile/compressive strength of the first 2 and/or second bars 3.
In the embodiment illustrated, the first 2 and the second bars 3 are formed by deformed steel bars having a diameter of approximately 6 millimetres.
In accordance with this, the third bars 6 are formed by steel bars having a diameter of approximately 8 millimetres.
Advantageously, the presence of the sockets 5 allows prefabrication of the panels 10 already reinforced, thereby reducing the complexity of the work in situ.
Moreover, the possibility of connecting together the second bars 3 of each mesh 1 using the third bar 6 allows the number of vertical chains for each panel 10 to be increased, thereby increasing the strength of the partition.
The first main function of the panel 10 is as a central support for receiving construction material (mortar class C25/30, concrete preferably class C25/30 or compacted soil) on its outer faces in the “single panel” type or inside a hollow space between two panels, which act as disposable formwork, in the “double panel” type.
Moreover, the panel 10 also has the function of thermal protection for the walls, and its heat transmission must necessarily have a value less than, therefore better, than those set by the current regulations in the construction sector.
The panel 10, in the version illustrated, has a width of 1120 millimetres and a thickness of 100 millimetres. However, the dimensions of the panel can change considerably depending on the use and purposes of the building.
It should be noted that each panel 10 has at least one first face 10a provided with a plurality of longitudinal (vertical) protrusions 11 (so as to form a succession of grooves 12 in which the construction material (concrete or mortar) introduces itself for gripping the panel 10.
These protrusions 11 are preferably in the shape of trapezoidal corrugations (in the embodiment illustrated having thicknesses of approximately 16 millimetres).
Moreover, the panel 10 comprises a second face 10b, opposite the first face 10a, provided with a roughness such as to form a succession of small grooves and apexes (preferably micro-corrugations) for favouring a better adherence of the plaster.
Preferably, a lightweight mesh 18 is embedded inside the panel 10, having the function of stabilising the panel, providing a greater strength to the panel and a lesser probability of sliding between the two faces.
More precisely, the panel is made in two halves made in succession (or separately) connected together downstream of the interposing of the lightweight mesh 18.
In all its construction applications the panel 10 constitutes the wall of the buildings vertically joining one floor to the next.
This already has a defined height and a relative numbering during design and production, thus allowing an operator to position it unequivocally during the assembly of a wall.
Thus, the panels 10 arrive on site ready for assembly in accordance with an assembly diagram.
The construction steps start with the assembly of the panels 10 by their tying together, which is facilitated by the overlapping of a small mesh (not illustrated). This is followed by the alignment, vertical positioning, cross-bracing, if necessary, and casting.
For making the load-bearing partition, it is possible to use the panels 10 as a central core of the wall (single panel solution) or as disposable formwork forming a hollow space for receiving the casting (double panel solution).
In the first case (
The two panels 10 assembled in this way form a single panel element 13 provided with a pair of faces 13a opposite to each other and each having a plurality of longitudinal protrusions 11 parallel to each other and spaced at a predetermined distance so as to form a succession of apexes and grooves.
This panel element 13 can also be obtained by making a single panel provided with corrugations on both faces.
The choice of one or the other will depend on the climatic characteristics of the construction zones.
The panel element 13 acts as internal support to the external casting.
A lightweight mesh (fixed by a mechanical or pneumatic staple gun and not illustrated for reasons of clarity) is mounted on both the first faces 10a of the panels 10 (or both the faces of the single panel).
It should be noted that this mesh has the same height as the panel 10, but it is wider so as to favour in the two sides a better attachment with the adjacent panel 10.
The function of this very lightweight mesh is to ensure and improve the cohesion of the cast concrete or mortar. It can be made of, depending on the choices of the designer:
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- galvanised metal (mesh size 50×50 and wire diameter 1.7 mm.),
- glass fibre,
- nylon fibre,
- treated vegetable fibre or the like.
The panel element 13 also comprises a pair of meshes 1, each superposed on a respective face 13a of the panel element 13 and connected together at respective nodes 4.
More specifically, each mesh 1 is superposed on the respective grid.
The meshes 1 substantially mirror each other, so the intersection points of the bars 2, 3 are coincident in the two faces 13a of the panel element 13.
The two meshes 1 are connected together by joining elements 14 which cross the panel element 13 between the two faces 13a.
Preferably, the two meshes 1 are connected at respective nodes 4.
Alternatively, they could in any event be connected in different points.
Consequently, the meshes 1 remain clamped to the two faces 13a of the panel element 13 and consequently also secure the two lightweight grids below. From the structural design point of view, the meshes 1 and the relative mortar (or concrete) perform the static load-bearing function of the building.
The first bars 2, or vertical bars, of the meshes 1 are bound to the castings of the gradeplane and of the stringcourses, whilst the second bars 3, or horizontal bars, must have a continuity in the wall until reaching the vertical corner bars of the building which are naturally embedded in a concrete column.
The main function of the mesh is that already described above, but it also adopts another, no less important, function which is that of preventing the two layers 16 of concrete (preferably approximately 40 mm thick) of the panel element 13 from sliding relative to each other, in the event of extreme stress.
The function which the joining elements 14 perform (8-10 for each panel and positioned two by two horizontally) is also important as they keep the two layers of wall made of reinforced concrete as parallel as possible to each other due to the effects of the stresses on the panel.
The concrete used for the configuration just described comprises an aggregate with a diameter not greater than 5 mm and its strength class is C25/30.
This construction system allows three-storey buildings to be constructed in category 1 earthquake zones.
It should be noted that, if necessary, it is possible (for the designer) to increase or reduce the reinforced concrete steel.
In the formwork (
In other words, it comprises the same panels 10 used in the “single panel” type, but spaced and with the corrugations oriented in the opposite direction, that is, facing the inside.
In this configuration, the two panels 10 form a “disposable” formwork 20, since it is an integral part of the wall and not re-usable.
Preferably, the hollow space 21 has a variable thickness of between 12 and 22 centimetres, more preferably between 15 and 20 centimetres.
This provides a disposable formwork for constructing a wall made of reinforced concrete (class C25/30) which, for the purposes of the design, is considered to be lightly reinforced.
Preferably, for reasons which will be made clearer as this description continues, the panels 10 used for the formwork 20 are provided with a plurality of recesses 17 (or rather, conical flarings) on the second face 10b.
The recesses 17 are specially created in a half-part of the panel 10.
The panels 10, positioned opposite and spaced from each other, are connected by special through connectors 22 (preferably in number between 8 and 10).
Each connector 22 comprises an elongate bar 23 extending along its own main axis “B” between two end portions 23a, 23b and configured for crossing the formwork 20 from one panel 10 to the other transversally to it.
The connector 22 also comprises a pair of contact elements 24 rigidly connected to the bar 23, at an intermediate portion 23c of the bar.
The contact elements 24 are located at a distance substantially corresponding to the distance between the meshes 1 of the two panels 10 so as to act as a spacer between the two.
In other words, the two contact elements 24 are located at a distance such as to keep the two panels 10 spaced from each other.
Preferably, the contact elements 24 are formed by two washers or bars welded on the bar 23 which abut and press the meshes 1 inside the formwork 20.
The welded bars are basically portions of welded bars (similar to the first and second bars 2, 3 described above) folded into a “U” or cross shape and welded.
The contact elements 24 preferably act on the meshes 1 at the nodes 4.
Advantageously, the presence of the lightweight mesh 18 distributes the action of the contact elements 24 along the entire surface of the panel 10.
Moreover, the connector 22 comprises adjustable pressing means 25 associated with the end portions 23a, 23b of the bar 23 for pressing each panel 10 and the relative mesh 1 against the respective contact element 24.
In other words, the connector 22 is substantially subdivided into three aligned portions.
An intermediate portion (interposed between the contact elements 24) acts as a spacer between the two panels 10 (and the two meshes 1), whilst the two end portions 23a, 23b act as fastening portions, keeping the panels 10 anchored to the respective meshes.
Preferably, both the end portions 23a, 23b of the bar 23 are provided with a thread 26 engageable with a suitable pressing nut 27.
The threads 26 and the respective nuts 27 thereby form the adjustable pressing means 25.
Alternatively, the pressing means could be formed by a snap-on or pressure coupling between a pressing body (similar to the nut 27) and the bar 23.
Preferably, the threads 26 (and thus the end portions 23a, 23b of the bar 23) cross the panel 10 at the recesses 17 (or conical flarings) mentioned previously.
In other words, the ends of the connector 22 have long threads which lead to the outside of the panels 10 at the recesses (specially created in a half-part of panel 10). Preferably, the depth of this recess 17 coincides with a gripping grid (not illustrated) inserted at the centre of the panel 10.
In use, the nut 27 of the pressing means is located inside the conical flaring, which is successively filled with concrete (or the like) to prevent the connector 22 from forming a “thermal bridge” between the outside and inside of the building.
A sufficient quantity of free thread 26 remains at the end portions 23a, 23b of the connector 22 to allow the anchoring to it of the structural steelwork necessary for containing the thrust of the concrete casting (and also any scaffolding).
In this regard, the connector 22 comprises a pair of tubular bodies 28, threaded internally, and each screwable with the thread 26 of a respective end portion 23a, 23b of the bar 23.
Each tubular body 28 is thus crossed by a threaded through cavity.
Alternatively, as in the case of pressing means, the coupling could be obtained by a snap-on or pressure mechanism.
The tubular bodies 28 comprise an abutment shoulder 28a protruding radially.
A space is thus formed between the abutment shoulder 28a and the second face 10b of the panel 10 variable according to the coupling between tubular body 28 and bar 23 (in particular, according to the threading of the tubular body 28 on the thread 26).
The abutment shoulder 28a is preferably formed by a body welded to the tubular body 28.
Alternatively, a thread outside the tubular body 28 can be provided to allow the screwing of a nut (provided with washer) so as to allow a better adjustment of the space between the abutment shoulder (in that case defined by the nut-washer pairing) and the panel 10.
Advantageously, a thrust bearing element 29 necessary to contain a thrust generated by concrete casting inside the hollow space 21 can be positioned (and locked) in that space.
It should be noted that, due to the distribution of the pressures during the casting, the most highly stressed connectors 22 are the lower ones and consequently the distribution of the connectors along the vertical must take into account this factor, providing a greater concentration lower down.
Moreover, after completing the casting, the presence of the free thread 26 allows the anchoring of scaffolding to the panel, both with a load-bearing function and with the function of a support for the walkway.
In order to plaster the wall it is sufficient to apply on the walls small glass fibre meshes, which are available on the market and used in the plastering of the cladding.
The structures of this type allow the construction of fifteen-storey buildings in category 1 earthquake zones.
In this type it is also possible to provide a quantity of additional reinforcement both in the standard details and for any static design requirements. In any event, it is unlikely that this quantity would exceed 2 kilograms for every square metre of wall.
This invention also relates to a building structure 30 with load-bearing partitions, that is, substantially free of columns, wherein the walls have the task of supporting the entire structure, overcoming both vertical (compression) and horizontal (shear) loads.
The building structure 30 comprises a horizontal element 31, substantially flat and forming a treadable surface C.
The basic horizontal element comprises a foundation 31a, preferably made as a pad and having a thickness of approximately 50 centimetres.
Above the foundation 31a, the structure 30 comprises a screed 31b and a flooring 31c superposed on the screed 31b.
The thickness of the screed 31b is variable on the basis of the type of room (for example, it may range from 4 to 8 cm inside a building). Its purpose is to make the underlying substrate of concrete flat; secondly, it is used to receive service pipes and cables. If the overlying flooring 31c (ceramic, stone or wood) is laid by gluing, the adhesive is spread above the screed 31b.
The horizontal element 31 (in particular the foundation 31a) is provided with a plurality of stirrup bodies 32 rising from the surface “C” and aligned for identifying at least one habitable room 40.
It should be noted that the term “habitable room 40” means in this text each of the rooms inside a building, used for habitation or office or the like, divided from each other by walls. It is in communication with the other parts of the building by doors and with the outside by windows and/or glass doors.
In other words, these stirrup bodies 32 (preferably steel anchors 32a) are embedded in the foundation 31a and protrude from the surface “C” to allow the anchoring of a plurality of vertical modular walls.
The anchors 32a are aligned (and spaced) between each other so as to identify the perimeter of the rooms defined by the walls.
Each wall is defined by a plurality of wall elements 33 alongside each other and having lower ends 33a and upper ends 33b opposite to each other.
The lower ends 33a are connected to the stirrup bodies 32 to laterally delimit the aforementioned habitable room 40.
The upper ends 33b are, on the other hand, connected to an upper horizontal element (or slab) 34 delimiting at the top the aforementioned habitable room 40.
It should be noted that the wall elements 33 each comprise a pair of panels 10 parallel to each other and spaced at a predetermined distance so as to form a hollow space 36 between them for receiving a construction material.
For example, the panels 10 have the dimensions mentioned previously in the text.
In other words, the wall element 33 is of the “double panel” type, that is, it is a disposable formwork 35.
In this version no provision is made for meshes made of bars inside the hollow space 36 between the panels 10, but only the external grids of the lightweight type made of fibreglass (or the like) solely for the plastering requirements.
However, each panel 10 comprises at least two horizontal reinforcement bars 41 located on the respective second face 10b (that is, the outer face of the formwork 35).
The horizontal bars 41 are preferably similar to the second bars 3 of the mesh 1 described previously.
In other words, the horizontal bars 41 are provided with connecting sockets 5 at the ends.
In the preferred embodiment, the panels 10 have a plurality of grooves 42, horizontal in use, for receiving the above-mentioned horizontal bars 41.
During assembly, the grooves 42 are filled with concrete (or the like) so as to increase the contact surface (that is, for release of the stresses) between the horizontal bar 41 and the panel 10.
The formwork 35 also comprises a plurality of unction bodies 37 between the two panels 10.
Preferably, each formwork 35 comprises a number of junction bodies 37 between 6 and 12, more preferably between 8 and 10.
In the embodiment illustrated, there are eight junction bodies 37 for each formwork 35.
Preferably, each junction body 37 comprises a threaded bar equipped with bolts for keeping the two panels 10 anchored to each other.
According to the invention, the hollow space 36 is filled with a volume clayey soil 38 having a percentage of between 15% and 30% of inert material (gravel and sand).
Preferably, the percentage of inert material is between 19% and 26% of the total, more preferably between 20% and 25%.
The volume of soil 38 is delimited by lower connection means 39a anchored to the stirrup bodies 32 and upper connection means 39b anchored to the upper horizontal element 34.
The soil 38 is preferably compacted according to the known method “PISÈ”.
Alternatively, ready-made soil bricks (10×10×40 cm, 10×15×30 cm) could be used.
The compaction of the volume of soil 38 must be such as to give to the volume of soil a compression strength of at least 20 kg/cm2 (preferably at least 22 kg/cm2, more preferably 25 kg/cm2) and a shear strength of at least 3 kg/cm2 (preferably at least 4 kg/cm2, more preferably 5 kg/cm2).
In any event, the volume of soil 38 must consider the strength of the clay, that is, 25 kg/cm2 under compression and 5 kg/cm2 under shear.
Advantageously, this allows the characteristics of the volume of soil 38 to be known even though the soil itself has non-homogeneous characteristics.
Advantageously, since the panels 10 are already cured when they are installed for use, they can also firstly absorb the quantity of humidity which the soil 38 releases, changing from the plastic state to that of the constant final humidity.
Preferably, the lower 39a and upper connection means 39b are defined by a layer of concrete (or the like, mortar, etc. . . . ) wherein the junction bodies of end 37a of the formwork 35 are embedded.
Advantageously, this makes the structure of the wall monolithic, constraining it at the ends.
In order to always keep each wall element 33 in its axes, horizontal and vertical, even if subjected to horizontal stresses (seismic), the structure 30 according to this invention provides for the use of efficient and appropriate construction technique methods.
Firstly, the horizontal bars 41 of each panel 10 are connected to the corresponding horizontal bars 41 of the adjacent panel 10, so as to form a single belt 43 for each face of the wall, so bi-annular, for stiffening the structure.
In other words, the structure 30 comprises an outer belt and one (or more) inner belts for containing the wall elements 33.
Moreover, each horizontal bar 41 is rigidly connected with a corresponding horizontal bar 41 of the other panel 10 of a same wall element 33.
In other words, the formwork 35 is crossed by a plurality of connecting means 44, each having a first end 44a connected to a horizontal bar 41 outside the structure and a second end 44b connected to a horizontal bar 41 inside the structure.
Advantageously, in this way the belts 43 are connected and clamped together, preventing a relative sliding between the two and especially preventing the inclination of the wall if it is subject to shear forces.
In the preferred embodiment, the connecting means 44 comprise a main elongated body 45 provided at its ends with a pair of hooks 46 designed to engage with (accommodate) the horizontal bars 41.
More precisely, a first hook 46a is made as a single part with the bar 45, whilst a second hook 46b is removably connected (and in an adjustable manner) to the bar 45.
In the preferred embodiment, this connection is made by means of a screw coupling (that is, by a thread and a nut).
More precisely, the nut is used for tightening the second hook 46b, obtained by machining a flat metal plate from bent steelwork.
Preferably, at the corner portions of the structure 30, the structure 30 also has one (or more) vertical reinforcement bars 47 embedded in the construction material (soil 38 and concrete or the like).
Advantageously, these vertical bars (or chains) 47 force the stringcourses to remain horizontal.
In other words, the vertical bars 47 act as stiffening elements which prevent the walls from inclining relative to the horizontal.
If another reinforcement of the 30 is necessary, cross braces may be used (not illustrated).
These cross braces are basically steel bars or steel cables or treated timber beams.
The cross braces are housed inside the formwork 35, alongside and bordering the outer panel 10, starting from a vertex of the panel 10 and reaching the opposite vertex.
These are embedded on each storey in the reinforced concrete of the gradeplane and slab stringcourse and in the roof edge.
Advantageously, the structure 30 allows parallelism to be obtained between the reinforced concrete stringcourses even under the effect of a horizontal seismic action. In effect, these cannot significantly change their level which remains “unchangeable” as it is assured by the compaction of the soil 38 (measured by laboratory tests), by the horizontal belts 43 which clamp the panels, by the vertical bars 47 and, if the designer considers it necessary, by the above-mentioned cross braces.
Therefore, all these solution collaborate together to create optimum structural conditions for the structure 30.
An important function is also performed by the slab 34, which, whilst satisfying the needs of inexpensiveness and simplicity, does not fail to meet the structural requirements.
The slab 34 comprises a plurality of beams 48 positioned alongside each and extending between two wall elements 33 which are opposite (and facing) each other.
In a first embodiment, the beams 48 are made of laminated wood (obtained, for example, from waste timber).
In the embodiment illustrated, these beams 48 have a cross-section of 140×200 mm and are positioned with a spacing of 56 cm.
The beams 48 are anchored, at their ends, to the layers of reinforced concrete located at the upper ends 33b of the wall elements 33.
This anchoring is obtained by metal fasteners (hooks 52) embedded in the concrete and preferably connected to the end junction bodies 37 of each formwork 35.
An internally hollow weight reduction body 49 (or hollow block) is interposed between each pair of successive beams 48. It should be noted that the weight reduction body 49 is interposed substantially to size between the two beams.
Preferably, the hollow block is made from the same ingredients as the panels, but with considerably greater density characteristics.
Moreover, the weight reduction body 49 has a shape such as to overlie at least partly the beams 48.
In other words, the weight reduction body has a supporting portion 49a overlying the beams 48.
Thus, the weight reduction body 49 is substantially T-shaped. More precisely, the weight reduction body 49 is Π-shaped (like the Greek letter Pi).
The slab 34 also comprises a plurality of finishing elements 50 designed to wrap the beams making the structure of the slab 34 monolithic. In the embodiment illustrated, the finishing elements 50 comprise a plank 50a made of “parquet” (with a thickness of 1 cm) superposed on the supporting portion 49a of the weight reduction body.
Moreover, the finishing elements 50 comprise a false ceiling 50b (made from 8 mm thick plywood) connected at the bottom of the beams 48.
Preferably, the weight reduction body 49 (and the finishing elements 50) is connected to the beams by anchoring means 51 for forming a single body which is able to increase the horizontal load strength of the structure.
The anchoring means 51 are preferably nails, screws or the like, in order to maintain the inexpensiveness of every detail of the structure.
Advantageously, a monolithic slab 34 ensures that the horizontal plane is maintained, even if it is stressed by horizontal forces, and prevents the arching of the beams 48.
A more costly variant of the slab (not illustrated) keeps the same beam cross-section, again made with the planks, but with the function of disposable formwork for a beam made of reinforced concrete (or the like) and joined by a floor-level casting using a lightweight metal mesh.
Also in this variant, the weight reduction body 49 remains the one just described.
Alternatively, a slab can be provided (not illustrated) consisting of a prefabricated element preferably comprising biological material with a density of the material much greater than that of the panel 10. It comprises a base panel with a rectangular cross-section (1120×60 mm).
The latter is superposed by four weight reduction elements, preferably all equal, and having an upturned U-shape with a hollow interior and a trapezoidal cross-section.
The assembly of the product in the shape recreates the solution of the slab with hollow blocks allowing the creation of a space for housing two small beams.
The external plaster can be made with sand and hydraulic lime and the internal plaster can be made with the new techniques which use clay.
Therefore, all these reinforcement solutions and measures are, in their entirety, particularly advantageous in the construction of buildings which must withstand horizontal seismic actions, thereby giving an adequate structural response.
This allows the construction of two-storey buildings also in category 1 earthquake zones and with maximum internal spans between the walls of approximately 5 metres.
They possess an excellent housing quality whilst with a great inexpensiveness.
The greatest advantage from this particular housing system may be had in all those parts of the world which are forced to import materials with lengthy waiting times and extremely high costs.
In effect, a building according to this invention with an area of 100 square metres, considered without foundations, requires approximately 60 bags of cement (for 10 cubic metres of concrete) and approximately 350 kg of various reinforcement, plus the hydraulic lime for the external plastering.
It should also be noted that, considering the shear strength only of the soil (that is, 5 kg/cm2) and a cross-section with a fill of 0.30, the vertical walls of the building will have a total thickness on the ground of 0.50 cm.
Thus, a metre of wall (50×100 cm) provides 25,000 kg of shear strength.
This invention also relates to a process for making a load-bearing building panel 10.
The process comprises preparing a predetermined quantity of fibrous (and inert) material to substantially occupy the volume of the panel 10 and a tank full of a water-vinegar solution, wherein the vinegar corresponds to a quantity of between 55% and 70% of the solution.
Preferably, the solution is 60% vinegar (minimum 6% acidity) and 40% water.
Advantageously, the presence of the vinegar prevents the micro-organisms from attacking the walls, thus overcoming the problems introduced by the use of the salt.
It should be noted that the fibrous material is preferably chosen from the following list:
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- straw;
- coconut mesocarp;
- fibrous extracts of palm leaves (obtained by beating the leaves);
- bamboo cane (especially bamboo fibre, that is, a regenerated cellulose fibre, extracted from the bamboo pulp).
Advantageously, in this way it is possible to make the panel also in those zones in which straw is not readily available, such as, for example, in many African countries.
Hereinafter, reference will be made explicitly to straw, but without limiting the scope of the invention. In effect, all the features of this method referred to the straw can be applied in the same way to the above-mentioned fibrous materials. Thus, the straw is cut into strips of predetermined length (preferably approximately 10 cm) and immersed in the tank for a preset length of time.
Meanwhile (or successively), the solution in the tank is heated to a temperature close to boiling point (between 80° C. and 95° C.), preferably approximately 90° C.
In a first embodiment, wherein the panel 10 is made solely from straw and lime, the straw remains in the tank for approximately 48 hours.
In a second embodiment, described below, the straw remains in the tank for approximately 24 hours.
After that period of time, the straw is poured into a mixer (concrete mixer).
Meanwhile, the method comprises preparing a predetermined quantity of hydraulic lime or plaster and pouring the hydraulic lime or plaster into the mixer with the straw for amalgamating them, thereby obtaining a mix ready for pouring into the formwork.
In the first embodiment, approximately 160 kg/m3 hydraulic lime or plaster introduced into the concrete mixer.
In the second embodiment, the panel 10 is made with a combination of straw and lime (or plaster) with a binding element.
Preferably, the binding element is defined by the paper.
However, alternatively, especially where the paper is not readily available (for example, in those places where a separate collection of waste is not performed), the binding element may be defined by beer processing waste (for example, beer spent grain). The paper or the beer spent grain is used as a binding mixture.
With regard to the paper, it should be noted that the cellulose paste is obtained from selected paper waste.
The final specific weight of the dry panel is variable between 190 and 240 230 kg/m3, as a function of the composition.
The quantity of fibrous inert material (for example, straw) used is between 45 and 55 kg/m3, preferably 50 kg/m3.
The quantity of binding material mixed is variable between 60 and 130 kg/m3 as a function of the material.
For example:
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- the quantity of cellulose (paper) used is between 110 and 130 kg/m3, preferably equal to 120 kg/m3,
- the quantity of beer waste (spent grain) used is between 55 and 75 kg/m3, preferably 65 kg/m3.
Similarly, the quantity of plaster (or hydraulic lime) mixed differs depending on whether the panel is composed of paper or beer spent grain.
For example, if the panel comprises paper, the quantity of plaster (or the hydraulic lime) mixed is between 50 and 70 kg/m3, preferably approximately 60 kg/m3.
If the panel comprises spent grain, the quantity of plaster (or the hydraulic lime) mixed is between 65 and 85 kg/m3, preferably approximately 75 kg/m3.
Hereinafter, reference will be made explicitly to paper, but without limiting the scope of the invention. In effect, all the features of this method referred to the paper (except for those exclusively relevant to the paper) can in the same way be applied to the beer processing waste material (spent grain).
Thus, the method provides for preparing a predetermined quantity of paper (or spent grain) and another tank filled with a water-vinegar solution, similar to the one described above.
Once the paper has been immersed in the tank (or even before), the solution is heated until reaching a temperature close to boiling point [between 80° C. and 95° C.].
After a preset length of time, the paper is drained and chopped using a blender in order to obtain a binding fluid.
After that, the chopped paper or the drained spent grain (that is, the binding fluid) is introduced into the mixer for amalgamating it with the hydraulic lime or plaster and the fibrous material (for example, the straw), thereby obtaining a mix ready for pouring into the formwork.
Both the embodiments thus provide for pouring the mix into the formworks for making the panel 10.
A formwork is this prepared having a profile corresponding to the panel 10 to be obtained.
In the second embodiment, the formwork is also fixed to a vibration table.
A first layer of mix is then poured inside the formwork.
In the second embodiment, a first distribution of the mix is performed by activating the vibration table.
In both the embodiments, a mesh for the aggregation of the mix is positioned above the first layer.
After that, a second layer of mix is poured inside the formwork, above the mesh, and the formwork is closed.
In the second embodiment, a second distribution of the mix is performed by activating the vibration table.
After it is made, the panel 10 is sent to a first accelerated drying step in an environment ventilated with hot air.
After a predetermined time interval (one day) the panel is placed in an environment at ambient temperature, but protected and with natural air circulation where it will cure (possibly for a month) during autumn and winter periods. With the type of mix described, panels 10 are also made for making partition walls in houses.
After drying, the panel can be sent for the preparation of the frame (that is, the assembly of the grid and the mesh 1).
Advantageously, this process not only allows panels 10 to be made which are structurally of a high quality at a low cost, but also allows high performing panels from a thermal point of view to be made.
In effect, a wall made using the panels obtained in this way has particularly low transmittance values. For example, the following data, obtained experimentally, is provided:
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- a “single panel” wall, with a panel thickness of 20 cm, made with the paper-straw-lime method has a transmittance of 0.28;
- a “double panel” wall, with a 15 cm hollow space filled with clayey soil, with a thickness of the panels of 10 cm each, made with the paper-straw-lime method has a transmittance of 0.24;
- a “single panel” wall, with a panel thickness of 14 cm, made with the straw-lime method has a transmittance of 0.44;
- a “double panel” wall, with a 15 cm hollow space filled with clayey soil, with a thickness of the panels of 7 cm each, made with the straw-lime method has a transmittance of 0.35.
As can be seen, these values are extremely low, often less than those required for energy certification in mountain areas.
The above-mentioned process may generally also be used for making slabs, counterframes for doors and windows, hollow blocks for slabs, panels for sliding wardrobes, cores for internal and external doors and even coffins and the like.
In these cases, a mix of cellulose and straw is used with the same proportions mentioned previously, but with an increase in the quantity of hydraulic lime or plaster to 90-100 kg/m3.
The mesh to be used in the formwork would also be larger, for example, it could be a woven steel mesh with 1.7 mm wires and 30×30 mm size.
The formwork would naturally change given the different profiles. Its specific weight is approximately 260-270 kg/m3.
The invention achieves the above mentioned aims and has important advantages.
In effect, thanks to the provisions of this invention, products can be made which are more within the reach of persons without significant capital means, all without lowering the quality specified by the standards.
The presence of a socket in the horizontal chains of the panels allows the entire panel element to be completely prefabricated, leaving only the assembly of the structure to the operators at the construction site.
Moreover, this considerably increases the strength of the wall, reducing the possibility of sliding between the layers.
As well as being easy to make, even with recycled bars, the connector for disposable formwork allows the passage of the panels in the preparation machine to be reduced.
In effect, a single passage is sufficient for connecting together both the panels forming the hollow space.
The assembly simplicity and the use of this connector also allows the panels to be transported individually, performing the assembly in situ.
The building structure made of soil, using a series of measures relative to the connection between the horizontal chains and the constraint of the end of the formwork, allows a structure to be obtained at a low cost which is extremely resistant to horizontal forces.
The making of the slab “wrapped” and monolithic makes the slab (and the beams) extremely resistant to the bending imparted by seismic shocks.
Moreover, the possibility of making “biological” panels using materials available locally (soil, paper, straw), with a minimum need for lime or plaster, makes their production extremely economical and prevents enormous investments for the builder with regard to their construction.
The panels prepared, constructed and made in this way are biologically protected by natural components against the attack of micro-organisms. The need to use only natural additives in this respect should be stressed.
The mass production processes studied are simple and require the use of simple mechanised equipment (vibration tables, tanks etc.).
Lastly, but of no less importance, it should be stressed that all the above-mentioned measures join together the economic aspect with that of the high quality of housing, in compliance with the European regulations (Eurocodes 2 and 8), allowing high quality houses to be obtained even with low quality materials and little industrialisation, so as to improve the quality of life of the most disadvantaged populations.
Claims
1. A connector for disposable formwork equipped with a pair of panels parallel to each other and spaced at a predetermined distance so as to form a hollow space between them for receiving construction material, each of the panels being provided with a reinforcement mesh at the inner face of the hollow space;
- the connector wherein it comprises: an elongate bar extending along its own main axis between two end portions and configured for crossing the formwork from one panel to the other transversally to it; a pair of contact elements rigidly connected to the bar, at an intermediate portion of the bar, and located at a distance substantially corresponding to the distance between the meshes of the two panels so as to act as a spacer between the two; adjustable pressing means associated with the end portions of the bar for pressing each panel and the relative mesh against the respective contact element.
2. The connector according to claim 1, wherein both the end portions of the bar are provided with a thread engageable with a suitable pressing nut; the threads and the nuts forming the adjustable pressing means.
3. The connector according to claim 2, wherein it comprises a pair of tubular bodies, threaded internally, and each screwable with the thread of a respective end portion of the bar; each tubular body comprising an abutment shoulder protruding radially for forming a space between the abutment shoulder and the panel in which a thrust bearing element may be positioned, necessary to withstand a thrust generated by a concrete cast during casting inside the hollow space.
4. A disposable formwork, comprising:
- a pair of panels parallel to each other and spaced at a predetermined distance so as to form a hollow space between them for receiving construction material, each of the panels being provided with a reinforcement mesh at the inner face of the hollow space;
- a plurality of connectors according to claim 1 interposed between the two panels.
5. A reinforcement mesh for load-bearing building panels, comprising: wherein each second bar extends along a respective main direction between a first and a second end, each provided with a through socket; each through socket being substantially coaxial with the through sockets of the corresponding ends of the other second bars so as to form a joining line which may be passed by a third bar for connecting, during the assembly step, two adjoining meshes.
- at least a pair of first bars;
- a plurality of second bars, which are parallel to and at a certain distance from each other, oriented at right angles to the first bars; each second bar being connected to both the first bars at respective coupling nodes;
6. The reinforcement mesh according to claim 5, wherein, in the second bars, each end is formed by a terminal portion bent back on itself, for forming the socket, and in part placed on the body of the second bar for reinforcing it.
7. A panel element, for building structures with load-bearing partitions, comprising a pair of faces opposite to each other and each having a plurality of longitudinal protrusions parallel to each other and spaced at a predetermined distance so as to form a succession of apexes and grooves; the panel comprising a pair of reinforcement meshes according to claim 5, each superposed on a respective face of the panel element and connected together at respective nodes using joining elements which cross the panel element.
8. A building structure comprising: wherein the hollow space is filled with a volume of clayey soil having a percentage of between 19% and 26% of inert material and delimited by lower connection means anchored to the stirrup bodies and upper connection means anchored to the upper horizontal element; the volume of clayey soil compacted such as to have a compression strength of at least 22 kg/cm2 and a shear strength of at least 4 kg/cm2.
- a basic horizontal element, substantially flat and forming a treadable surface, comprising a plurality of stirrup bodies rising from the surface and aligned for identifying at least one habitable room;
- a plurality of modular walls each provided with a plurality of wall elements alongside each other and having lower ends connected to the stirrup bodies for laterally delimiting the habitable room; the wall elements each comprising a pair of panels parallel to each other and spaced at a predetermined distance so as to form a hollow space between them for receiving construction material;
- an upper horizontal element connected to the upper ends of the wall elements for delimiting the top of the habitable room;
9. The structure according to claim 8, wherein each panel comprises at least two horizontal reinforcement bars each rigidly connected with a corresponding horizontal reinforcement bar of the other panel of a same wall element and connected to a horizontal bar of a panel adjacent to it so as to form an inner belt and an outer belt of the structure for stiffening the structure.
10. The structure according to claim 8, wherein the upper horizontal element comprises:
- a plurality of beams positioned alongside each and extending between two opposite wall elements;
- an internally hollow weight reduction body interposed substantially to size between two adjacent beams and at least in part overlapping the beams; the weight reduction body being connected to the beams by anchoring means for forming a single body which is able to increase the horizontal load strength of the structure.
11. The structure according to claim 9, wherein it comprises a plurality of vertical reinforcement bars embedded in the construction material and located at the angular zones of the structure for preventing inclination of the walls following a shear action.
12. A process for making a load-bearing building panel wherein it comprises the following steps:
- preparing a predetermined quantity of fibrous material to substantially occupy the volume of the panel;
- preparing a tank full of a water-vinegar solution, wherein the vinegar corresponds to a quantity of between 55% and 70% of the solution;
- cutting the fibrous material into strips of predetermined length;
- immersing the strips of fibrous material in the tank for a preset length of time;
- preparing a predetermined quantity of hydraulic lime or plaster;
- pouring the hydraulic lime or plaster and the fibrous material into a mixer for amalgamating them, thereby obtaining a mix ready for pouring into the formwork.
13. The process according to claim 12, wherein the fibrous material is selected between one or more of the following:
- straw;
- coconut mesocarp;
- fibrous extracts of palm leaves;
- bamboo cane.
14. The process according to claim 12, wherein it comprises the following steps:
- preparing a predetermined quantity of a binder element;
- preparing another tank full of a water-vinegar solution, wherein the vinegar corresponds to a quantity of between 55% and 70% of the solution;
- immersing the quantity of binder element in the first tank;
- heating the solution until a temperature close to boiling point is reached;
- draining the binding element after a preset length of time to obtain a binding mixture;
- pouring the binding mixture into the mixer for amalgamating it with the hydraulic lime or plaster and the fibrous material, thereby obtaining a mix ready for pouring into the formwork.
15. The process according to claim 14, wherein the binding element is paper; the step of draining the binding element being followed by a step of chopping the paper using a blender in order to obtain a binding mixture.
16. The process according to claim 14, wherein the binding element is obtained from the recovery of beer processing waste.
Type: Application
Filed: Sep 12, 2012
Publication Date: Jul 31, 2014
Inventor: Nicola Angelo Vitullo (Rimini)
Application Number: 14/240,217
International Classification: E04G 11/08 (20060101); E04B 1/41 (20060101); E04C 5/07 (20060101); E04B 2/84 (20060101);
