FR3118080A1 - Construction method comprising the production of at least one non-prestressed concrete and wooden slab, and concrete and wooden slab - Google Patents

Abstract

The invention relates to a construction method, comprising the production of at least one prefabricated slab (1') at least partly in the factory according to the following chronological steps: - laying of metal stiffeners (2) on wedges (6), placed beforehand on a prefabrication table (T);- casting a concrete slab (3), by making the stiffeners (2) emerge above the concrete;- preparing wooden slabs (p1-p3);- laying blocks of wood between the stiffeners (2) emerging from the concrete slab (3), leaving a space between the adjacent blocks of wood (p1-p3); - drying of the semi-finished slab (1') not prestressing; - delivery of the semi-finished slab (1') on site; - casting on site of a concrete compression slab (30) on the semi-finished slab (1') and simultaneous casting of ribs (n1-n6) between the blocks of wood (p1-p3), by embedding the stiffeners (2) completely to form a floor. Figure for abstract: Fig 12

Description

Construction method comprising the production of at least one non-prestressed concrete and wooden slab, and concrete and wooden slab

The present invention relates to the technical field of building construction, and more particularly to reinforced concrete construction from partially or totally prefabricated construction elements, and more particularly from concrete and wooden slabs for making floors.

PRIOR ART

It is known from the state of the art several ways of treating a concrete floor. The two most common solutions are:
- casting in place, i.e. on a construction site, using formwork,
- the use of pre-slabs generally manufactured in the factory, outside the site.

Cast-in-place has the disadvantage of the time and labor required for its implementation. In particular, a significant time is essential for the drying of the concrete before the construction of an upper floor can be started.

Factory-made slabs, also called pre-slabs, overcome the drawbacks of cast-in-place. There are in particular hollow core slabs or lightened slabs, commonly called elegy slabs, which have an unattractive appearance. In addition, these hollow or elegy slabs do not allow easy integration of reservations for water pipes, ventilation pipes, electrical cables, etc. As a result, the use of hollow core or elegy slabs is generally limited to industrial buildings or car parks. Thus, there is a need to adapt floor slabs for use in housing and offices.

Ecological requirements are becoming increasingly important in construction. Thus, CO ₂ emissions during construction must be limited. However, the cement needed to manufacture concrete remains a major source of CO ₂ emissions. It is therefore conceivable that the reduction in the use of cement is desired. In addition, the introduction of biosourced materials, such as insulating panels made from plant fibers, in the slabs allows an additional reduction in the CO ₂ footprint of the finished floor.

The publication DE102004059590 describes a method for constructing an elegant ceiling, comprising hollow bodies aimed at lightening the construction. The hollow bodies have an inverted U shape or a wavy shape. Hollow bodies can be made of metal, plastic, wood, chipboard or corrugated cardboard. The hollow bodies leave voids in the slab, which is not entirely satisfactory in terms of mechanical strength, and acoustic and thermal performance. When workers walk on the site, they risk deforming the hollow bodies before they are covered by a compression slab.

Publication GB1401439 describes a method of constructing an elegy slab, comprising lightweight blocks aimed at lightening the construction. The blocks located at the ends of the slab are provided with a lower height than the blocks located between the ends. Lightweight blocks can be polystyrene. Polystyrene is not entirely satisfactory in terms of mechanical resistance and ecological footprint. Light blocks can be replaced by hollow bodies made of wood wool, metal or cardboard. As in the previous example, hollow bodies are not satisfactory. In addition, metal is not entirely satisfactory in terms of cost, ecological footprint, and acoustic and thermal performance. Wood wool and cardboard are not entirely satisfactory in terms of mechanical resistance, and acoustic and thermal performance.

Publication WO2019/086791 belongs to the applicant and describes a process for manufacturing a slab, with casting of a concrete slab, then placing metal stiffeners in the still fresh concrete slab. However, significant effort is required to penetrate the stiffeners into the fresh concrete. In addition, the positioning of the stiffeners in the fresh concrete slab makes it necessary to respect a tight timing, before drying and hardening of the slab, to prevent the ribs from being cast on a slab whose drying is too advanced. This constraint is all the more evident when the concrete used is a so-called low-carbon concrete, whose drying time is particularly short, around twenty minutes. In this case, a risk also lies in the handling of the concrete, which risks drying out in the skip, making it impossible to pour it. In addition, the “blind” positioning of the stiffeners in the fresh concrete slab may lack precision. Consequently, this manufacturing process is restrictive because it requires to be implemented in automated factories, equipped with carousel systems, which make it possible to guarantee a fast execution time, that is to say less than the time concrete setting. This objective cannot be achieved when the manufacturing process is manual or semi-automatic.

One of the aims of the invention is therefore to propose an improved construction method, the method comprising the production of at least one concrete and wooden slab, this slab being able to be prefabricated in whole or in part in the factory, in order to suitable for both automated manufacturing and manual manufacturing to expand the panel of users. The slab resulting from the process must be aesthetic, resistant, easy to install, ecological to produce, and have good acoustic and thermal performance.

Another objective of the invention is to drastically reduce the carbon footprint of the concrete slab by adding enough biosourced material to it, without harming its technical performance.

Another objective of the invention is to facilitate the integration of reservations for conduits and cables, and thus allow the method according to the invention to be used in the construction of buildings, in particular housing.

To this end, a first variant of the invention relates to a construction method comprising the production of at least one prefabricated slab at least partly in the factory according to the following chronological steps:
installation of metal stiffeners on wedges, previously placed on a prefabrication table;
pouring a concrete slab, by making the stiffeners emerge above the concrete;
preparation of wooden loaves;
lays blocks of wood between the stiffeners emerging from the concrete slab, leaving a space between the adjacent blocks of wood, the blocks of wood being placed in the still fresh concrete to obtain a semi-finished slab;
drying of the semi-finished, non-prestressed slab, made up of the concrete slab, stiffeners, wedges and blocks of wood;
- delivery of the semi-finished slab, not prestressed, on site;
- casting on site of a concrete compression slab on the semi-finished slab and simultaneous casting of concrete ribs between the blocks of wood, by completely embedding the stiffeners to form a floor.

For this purpose also, a second variant of the invention relates to a construction method, comprising the production of at least one slab according to the following chronological steps:
installation of metal stiffeners on wedges, previously placed on a prefabrication table;
pouring a concrete slab, by making the stiffeners emerge above the concrete;
preparation of wooden loaves;
lays blocks of wood between the stiffeners emerging from the concrete slab, leaving a space between the adjacent blocks of wood, the blocks of wood being placed in the still fresh concrete;
casting of concrete ribs between the wooden blocks, by embedding the stiffeners at least in part, the casting of the ribs being carried out on the still fresh concrete slab to obtain a finished slab;
drying of the non-prestressed slab made up of the concrete slab, stiffeners, wedges, blocks of wood and concrete ribs;
- delivery of the finished slab, not prestressed, on site; and
- casting a concrete compression slab on the finished slab to form a floor.

In practice, the process comprising the laying of stiffeners then the casting of a concrete slab is simpler to carry out and makes it possible to position the stiffeners with greater precision, in comparison with a process comprising the casting of the slab then the incorporation of stiffeners in the thickness of the still fresh concrete slab, as described in the applicant's publication WO2019/086791. In the latter case, the installation of the stiffeners requires significant effort, tight timing, and may lack precision.

The first variant of the process has the advantage of being able to be implemented in any type of automated and non-automated factory, since the casting of the ribs is deferred and carried out on site, simultaneously with the casting of the compression slab. This technique does not extend the working time on site. However, the semi-finished slab having lower technical performance than a finished slab, must be supported on site before pouring the compression slab.

The second variant of the method is for its part particularly well suited to implementation on a carousel in an automated factory. Indeed, the laying of the stiffeners, the casting of the concrete slab, the laying of the wooden blocks, and the casting of the ribs can be carried out on the same prefabrication table, mobile between different stations of a carousel.

Wood blocks are denser, more insulating and more resistant (to mechanical stress, fire and humidity), compared to wood wool, polystyrene or cardboard. In addition, they constitute solid blocks which fill the voids between the ribs, unlike the existing elegy slabs.

According to other advantageous characteristics of the invention, taken in isolation or in combination, and depending on the variant of the invention considered:
- The laying of the wooden slabs is carried out on the still fresh concrete slab. This reinforces the adhesion between the wooden slabs and the slab.
- The casting of the concrete ribs between the wooden blocks, by embedding the stiffeners at least in part, is carried out on the still fresh concrete slab in the second variant of the invention. This ensures cohesion between the ribs and the slab.
- The preparation of the wooden blocks includes a cutting operation. In particular, this cutting aims for the blocks of wood to have dimensions adapted to the predefined spacing between stiffeners and to the predefined width of the ribs.
- The wood block cutting operation is carried out by water jet. Alternatively, the cutting operation can be carried out by other known techniques.
- The preparation of the wooden slabs includes a milling operation to form housings for receiving sheaths, in particular electrical sheaths. The blocks of wood can be provided with housings having different paths and different depths depending on the number of ducts to be integrated. The same housing can have variable depths to accommodate three ducts, then two, then only one, depending on the routing plan of the ducts.
- The preparation of the blocks of wood includes an operation for marking the housings for receiving the sheaths, to identify each of the sheaths. This facilitates the positioning of the ducts in the factory or on the construction site.
- The preparation of the wooden slabs includes an operation of marking information representative of their position within the slab, and sheaths intended to be integrated into the wooden slabs. This facilitates the laying of the wooden blocks in the correct position on the slab, and the subsequent installation of the ducts.
- Marking operations can be carried out by painting, engraving, labeling, or any other technique.
- The preparation of the wooden blocks can be carried out on a single machine designed to carry out cutting, milling and marking operations.
- The stiffeners are placed on wedges, which are then embedded in the concrete slab.
- Additional elements are positioned on, in or between the stiffeners before casting the slab, for example spacer vents, reservation tubes, electric pots, or lifting devices.
- The spacer vents have a dual function of positioning the adjacent blocks of wood and circulating air through the slab.
- The blocks of wood have a density of between 80 and 200 kg/m ³ .
- Wood slabs have a thermal conductivity between 0.038 and 0.044 W/(mK).
- The wood blocks are made of wood fibres.
- The wood is natural, for example fir and/or spruce, from responsible and local forestry operations.
- The wood slabs are cut from single-layer wood fiber insulation panels.
The slab is dried in an oven.
The drying of the slab is carried out on a heating table. The heating table can be the prefabrication table, or another table.
The drying of the slab is carried out by exposure to ambient temperature, without heating means requiring an energy supply, and therefore in a natural way.
- The method comprises, prior to the laying of the stiffeners, a step of identifying areas of interference between, on the one hand, the ribs, and on the other hand, reservations provided in the slab. The metal stiffeners associated with the ribs outside the interference zones are placed with a reference gap between them. The metal stiffeners associated with the ribs in the interference zones are laid offset with the reference gap, to avoid said interference.
- The reference gap between the metal stiffeners is of the order of 60 cm, while the offset is of the order of 10 cm on one side or the other.
- The method comprises the following additional step: laying a metal reinforcement on the finished or semi-finished slab delivered to the site and before the casting of said compression slab above the reinforcement and the finished or semi-finished slab finished.
- The metal frame is a welded mesh.
- During the casting step of the concrete ribs between the wooden blocks, in the second variant of the invention, the stiffeners are only partially embedded in the concrete and emerge at the top of the ribs.
- The concrete slab is between 4 and 8 cm thick.
- The concrete slab has an average thickness of 6 cm.
- The slab has a width of up to 3.80 m.

The invention also relates to a semi-finished concrete and wooden slab, in accordance with the first variant of the method, which comprises:
- wedges;
- metal stiffeners placed on the wedges;
- a concrete slab embedding the wedges and the stiffeners at least in part; and
- wooden slabs placed between the stiffeners emerging from the concrete slab, with a space between the adjacent wooden slabs.

The invention finally relates to a finished concrete and wood slab, in accordance with the second variant of the method, which comprises, in addition to the semi-finished slab:
- concrete ribs cast between the wooden slabs, at least partially embedding the stiffeners.

Thanks to the invention, the finished or semi-finished slab can support the weight of the concrete poured on site (compression slab), give the floor complex (concrete of the slab, blocks of wood, concrete of the ribs, concrete of the compression slab with good acoustic and thermal performance, and have a very favorable balance in terms of CO ₂ emissions.

Workers can walk on the finished or semi-finished slab on site, without the risk of deforming it, before casting the compression slab with or without the ribs. Blocks of wood can support the weight of workers without deforming, which would not be the case with hollow elements or light materials. This facilitates the installation of networks (electrical, fluids, etc.).

DESCRIPTION OF FIGURES

Other characteristics and advantages of the invention will emerge clearly from the description which is made of it below, by way of indication and in no way limiting, with reference to the appended figures, in which:

is a sectional view of a finished slab obtained by the method according to a variant of the invention;

is a schematic representation in perspective of the slab with the stiffeners of part of the slab of the , before laying the wooden slabs;

is a layout plan comprising zones of interference between ribs and reservations, said interference being able to be avoided by the use of a slab according to the invention;

is a plane similar to the , but with the ribs moved to avoid interference in a slab according to the invention;

is a layout drawing representing an area in which a slab can be used with a reference gap between ribs;

is a layout plan showing an area in which the offset of the ribs does not make it possible to avoid reservations;

is a cut analogous to , for another slab obtained by the process according to the invention;

is a schematic representation in perspective of a slab and the ribs partially embedding the stiffeners, without showing the wooden slabs of the slab of the ;

is a representation in perspective of another slab obtained by the process according to the invention, surmounted by a trellis and a compression slab;

is a top view of the slab of the , without the trellis and the compression slab;

is a partial cross-section of the slab of the ,

is a sectional view of a semi-finished slab obtained by the process according to another variant of the invention; and

is a perspective representation of the slab of the , surmounted by a truss, a compression slab and ribs cast simultaneously with the compression slab.

For the purpose of simplification, the same elements bear the same reference numerals in the different figures.

Claims (12)

Construction method, comprising the production of at least one prefabricated slab (1') at least partly in the factory according to the following chronological steps:
laying of metal stiffeners (2) on shims (6), previously placed on a prefabrication table (T);
casting a slab (3) of concrete, causing the stiffeners (2) to emerge above the concrete;
preparation of wood loaves (p1-p3); and
laying wooden blocks (p1-p3) between the stiffeners (2) emerging from the concrete slab (3), leaving a space between the adjacent wooden blocks (p1-p3), the wooden blocks (p1-p3 ) being laid in the still fresh concrete to obtain a semi-finished slab (1');
drying of the semi-finished, non-prestressed slab (1'), consisting of the concrete slab (3), stiffeners (2), wedges (6) and wooden slabs (p1-p3);
- delivery of the semi-finished, non-prestressed slab (1') on site;
- casting on site of a concrete compression slab (30) on the semi-finished slab (1') and simultaneous casting of ribs (n1-n6) of concrete between the wooden slabs (p1-p3), by drowning the stiffeners (2) in their entirety to form a floor.
Construction method, comprising the production of at least one prefabricated slab (1) at least partly in the factory according to the following chronological steps:
laying of metal stiffeners (2) on shims (6), previously placed on a prefabrication table (T);
casting a slab (3) of concrete, causing the stiffeners (2) to emerge above the concrete;
preparation of wood loaves (p1-p3);
laying wooden blocks (p1-p3) between the stiffeners (2) emerging from the concrete slab (3), leaving a space between the adjacent wooden blocks (p1-p3), the wooden blocks (p1-p3 ) being laid in the still fresh concrete;
casting of ribs (n1-n6) of concrete between the blocks of wood (p1-p3), by embedding the stiffeners (2) at least in part, the casting of the ribs (n1-n6) being carried out on the slab (3) still fresh concrete to obtain a finished slab (1);
drying of the finished slab (1), not prestressed, consisting of the concrete slab (3), stiffeners (2), wedges (6), wooden blocks (p1-p3) and ribs (n1-n6 ) concrete;
- delivery of the finished slab (1), not prestressed, on site; and
- casting a compression slab (30) of concrete on the finished slab (1) to form a floor. Construction method according to Claim 2, characterized in that the laying of stiffeners (2), the casting of the concrete slab (3), the laying of the wooden blocks (p1-p3) and the casting of the ribs (n1- n6) are made on the same prefabrication table (T), mobile between different stations of a carousel. Construction method according to any one of the preceding claims, characterized in that the preparation of the blocks of wood (p1-p3) comprises a cutting operation. Construction method according to any one of the preceding claims, characterized in that the preparation of the blocks of wood (p1-p3) comprises a milling operation to form housings for receiving sheaths. Construction method according to any one of the preceding claims, characterized in that the preparation of the blocks of wood (p1-p3) includes an operation of marking the housings for receiving the sheaths, to identify each of the sheaths. Construction method according to any one of the preceding claims, characterized in that the preparation of the blocks of wood (p1-p3) comprises an operation of marking information representative of their position within the slab (1, 1') . Construction method according to any one of the preceding claims, characterized in that additional elements are positioned on, in or between the stiffeners (2) before the slab (3) is cast, for example spacer vents (4), reservation tubes, electric pots, or lifting devices. Construction method according to any one of the preceding claims, characterized in that it comprises, prior to the laying of the stiffeners (2):
- a step for identifying interference zones (ZI) between, on the one hand, the ribs (n1-n16) and, on the other hand, reservations (r1-r11) provided in the slab (1, 1 ');
and in that :
- the metal stiffeners (2) associated with the ribs (n2-n4, n8-n11) outside interference zones (ZI) are placed with a reference gap between them; and
- the metal stiffeners (2) associated with the ribs (n1, n5) in the interference zones (ZI) are placed offset with the reference gap to avoid said interference. Construction method according to Claim 10, characterized in that the reference distance between the metal stiffeners (2) is 60 cm, while the offset is 10 cm on one side or the other. Semi-finished concrete and wood slab (1'), characterized in that it is obtained according to the construction method defined in any one of claims 1 and 3 to 10, and in that it comprises:
- wedges (6);
- metal stiffeners (2) placed on the wedges (6);
- a slab (3) of concrete embedding the wedges (6) and the stiffeners (2) at least in part; and
- wooden blocks (p1-p3) arranged between the stiffeners (2) emerging from the concrete slab (3), with a space between the adjacent wooden blocks (p1-p3). Slab (1) finished in concrete and wood, characterized in that it is obtained according to the construction method defined in any one of claims 2 to 10, and in that it comprises:
- wedges (6);
- metal stiffeners (2) placed on the wedges (6);
- a slab (3) of concrete embedding the wedges (6) and the stiffeners (2) at least in part;
- blocks of wood (p1-p3) arranged between the stiffeners (2) emerging from the slab (3) of concrete, with a space between the blocks of wood (p1-p3) adjacent; and
- ribs (n1-n6) of concrete cast between the wooden slabs (p1-p3) drowning the stiffeners (2) at least in part.