EP2930287B1 - Method for constructing a non-structural flooring - Google Patents

Description

The present invention is in the field of construction and building, more particularly in the realization of a tessellation based on concrete.

The present invention will find a preferential application, but in no way limiting, in the realization of a non-structural reinforced slab.

A structural pavement is used to receive on the upper face and support a structure, such as a building. For reasons of mechanical strength, such a structural pavement incorporates a metal reinforcement, generally uniformly distributed over the height of said pavement and giving it its structural character.

A non-structural pavement does not receive any structure, the building located above being supported directly by the base or the foundations located under and also supporting said non-structural pavement. Such non-structural pavement is generally free of reinforcement.

Such a non-structural pavement is generally provided in the industrial-type floor construction, for example in the case of a logistics platform or a hangar. These structures require a high quality of realization due in particular to the importance of the loads that the pavement is intended to receive. In particular, such a pavement must withstand the traffic of lifting gear depending on the type of machine, their speed of movement, their support on the ground, etc. These constraints are accentuated in that this type of industrial structure extends over large areas with small thickness.

However, a pavement made only of concrete has a disadvantage related to the removal of concrete once the tiled floor, during its solidification. This removal may lead to cracking of the pavement. To overcome this problem, so-called "shrink" joints are usually considered. Depending on the total surface area of the pavement, these removal joints are therefore made at substantially regular intervals and close to each other, then delimiting a pavement. from about 25 to 36 m ² . To do this, it is possible to cause a so-called straight crack during a step of sawing said tiling, this step for channeling the crack. It has also been planned to fill these withdrawal joints with a synthetic material, such as an elastomer.

The presence of seals poses other disadvantages always related to shrinkage. Firstly, the linear shrinkage causes the opening of the seal which renders ineffective the filling to the elastomer due to the rupture of the filling product or the detachment of the edge of the lips relative to its elastic limit.

Then, the differential shrinkage results in an uplift of the edges of the shrinkage joints because of the differences in hygrometry between the surface and the underside of the pavement. This uplift is often maximum at intersections of joints. We can then observe a phenomenon of bending and strumming which is accentuated over time by a very localized settlement of the platform and the underside of the pavement, especially through the formation of a cavity or void under them. joints.

In these two cases, the concrete deteriorates by sponging of the lips of the joints or by breaking of the concrete in the raised angles. In addition, this degradation is accentuated by the passage of gear as previously mentioned.

It is therefore necessary to regularly maintain the withdrawal joints and the materials that may fill it, which implies additional costs subsequent to the construction and thus difficult to estimate in advance.

To reduce these disadvantages, the concrete constituting such a non-structural pavement are added metal fibers to improve the mechanical properties of the concrete to traction and therefore to the withdrawal. However, this type of pavement is not entirely satisfactory and it is always necessary to provide withdrawal joints.

To improve the mechanical characteristics of a non-structural slab, it has been planned to add a reinforcement, like a structural slab, but having another functionality to resume the aforementioned withdrawals and limit the joints in spacing them further. Such a structure also makes it possible to increase the load that such a non-structural pavement is capable of supporting.

The state of the art described in the document DE 92 10 992 U1 an attempt to solve these problems through the insertion of an armature in the lower and median part of the slab to be cast. This particular arrangement of the frame is accompanied by stud under sawed joint and always poses, even lessen, the aforementioned drawbacks related to the presence of joints.

In addition, in the case of a non-structural pavement, the floor is primed for receiving and supporting it.

In known manner, during the construction of a building or a pavement-type structure or pavement, the ground is prepared to ensure the good performance of this construction. In particular, the soil undergoes modifications to, firstly, to receive said construction and, secondly, to remain stable for the entire life of this construction.

To do this, in a known manner, under said construction, directly on the ground, a distribution mat is produced. Such a mattress consists of a single layer of compacted material acting as a rigid support and fixed in time, absorbing some of the changes in the soil. It also makes it possible to level the floor surface as well, with a view to producing a construction on the upper face. It will be noted that between the surface of said mattress and the underside of the construction, a sliding layer is generally arranged, which can be made of sand with a tight intermediate layer in the form of a plastic film.

In addition, when the soil exhibits movement characteristics over time (ie, it consists of a soft or compressible material), it is then necessary to perform a soil improvement before the realization of said mattress. Soil improvement techniques involve modifying the characteristics of a soil by physical action (for example, vibrations) or by embedding a more resistant material in the soil or on the ground. In particular, a technique used is to make additional foundations in the ground and on which will rest the superimposed mattress and construction.

By way of example, ballasted columns can be made vertically in the soil, regularly spaced so as to form an anchor network intended to increase the bearing capacity of the soil and / or the shear strength, to reduce the absolute and differential settlements. as well as the time of consolidation, while avoiding the creation of draining elements.

In addition, such columns reduce the risks caused by liquefaction phenomena during earthquakes or significant vibrations. Indeed, the ballasted columns are made of granular materials, without cohesion, set up by repression in the soil and compacted by successive passes. Such a column therefore has no binder on its height.

Another known solution consists of vertical piles, made of bonded material, such as reinforced concrete.

In such configurations, a preliminary and precise geological study is needed to define the soil characteristics. From these results, the thickness and the material of the distribution mat are determined, as well as the need to achieve a soil improvement, and therefore its material, depth and density.

In addition, these calculations depend on the type of construction planned in the upper part and its use. For example, a residential building generates regular stresses totally different from an industrial pavement or pavement.

Indeed, the industrial pavements impose strong vertical stresses likely to deform locally or cross the distribution mattress to directly act on the soil which may be crowded. In addition, the ground, in reverse reaction, creates vertical stresses upwards likely to cross the mattress and deteriorate the upper construction. In sum, the distribution mattress must reduce the forces and forces from the construction and the soil, by diffusing them within its thickness.

The reinforcement of a non-structural pavement also has the role of taking up the downward vertical forces, ie the forces applied regularly or not on the pavement and which propagate downwards through the pavement, but up to 'to its base, namely its distribution mattress and its foundations. These efforts are quantified as downward vertical moments. According to these moments, theoretically quantified, the nature and the quantity of the foundations to be implanted, but also the thickness of the distribution mat, are determined. Then, these vertical descending moments serve as a basis for calculating the thickness of the pavement, but also its composition as the amount of metal fibers adjoined, as well as the density and the section of the frame that it encloses.

Finally, the characteristics related to the pavement and its base are only determined to ensure the recovery of these downward vertical moments, allowing the assembly thus formed to support the loads to be applied to the upper face of said pavement.

In other words, depending on the type of soil and the superior construction, the dimensions and the distribution of the soil reinforcement are determined, then the thickness of the distribution mat, and finally the thickness of the floor and floor. the section of his frame.

In addition, downward vertical moments have different values depending on the depth, always in function of the location of said reinforcements soil, especially during inclusions reinforced concrete.

These descending vertical moments are often calculated at the surface of the pavement and at its lower face. It can be seen that the moments can vary enormously, causing differences of tensions on the lower face. Indeed, if on the upper face the concrete of the pavement has an increased resistance to compression, it is not the case on the lower face where the elongation can be detrimental.

For a structural pavement, the current solution is therefore to introduce a frame at the bottom of the pavement to resume these lower descending moments, while a frame in the upper part takes the top down moments.

However, in the case of a non-structural pavement, the current solutions do not make it possible to compensate for these differences in the upper and lower descending moments, without the addition of an armature at the bottom of said pavement.

In addition, the solutions conceived in non-structural paving incorporating a reinforcement in the upper part, are intended to improve the surface resistance of the pavement, in particular to limit its shrinkage, without taking into consideration these downward vertical moments, whether they are higher or lower.

In this context, another major problem lies in the fact that the forces corresponding to the descending vertical moments generate, at the levels of the underbody and the ground reinforcements, inverse forces corresponding to ascending vertical moments. In particular, these upward vertical moments are irregular, higher at the inclusions to strengthen the ground, forming hard points, but only between said inclusions.

Theoretically, these moments are supposed to be taken up by the distribution mat and, in the case of a structural floor, by a frame located at the bottom of said floor. However, currently, for a non-structural pavement, these ascending moments are not purely and simply not taken into consideration.

The only solutions currently used consist in reinforcing the non-structural paving by the addition of a quantity of fibers, generally metallic, improving its resistance and the recovery of the forces of the upper and lower descending moments.

The present invention aims to overcome the disadvantages of the state of the art, proposing to otherwise use the strength offered by the reinforcement located in the upper part of a non-structural slab, consisting of a mixture of concrete and fiber.

In particular, during its development, the invention has made it possible to determine to what extent an armature located in the upper part, in the first upper third of the pavement, in particular with a minimum of 3 cm (cm) of upper coating, allows to take back some of the descending moments, not taken up by the fibers.

In other words, the armature in the upper part takes a difference between the upper and lower moments, when said higher moments are greater than the lower moments.

Thus, the invention makes it possible to determine the configuration of a tiling for a total moment, with only a reinforcement in the upper part that comes to relay the resistance offered by the addition of fibers.

• on réalise une amélioration du sol destiné à recevoir ledit dallage ;
• on réalise supérieurement à ladite amélioration, un matelas de répartition ;
• on recouvre ledit matelas d'une couche de glissement ;
• on réalise un dallage non structurel sur ladite couche

de glissement ; - on positionne une unique armature en partie supérieure dudit dallage, dans le premier tiers supérieur de son épaisseur ; - on coule un béton adjoint de fibres
sur toute la hauteur dudit dallage. Le document WO 2013/004959 décrit un procédé de ce type.To do this, the present invention relates to a method of constructing a non-structural pavement, which method comprises:

• an improvement is made to the soil intended to receive said pavement;
• it is superior to said improvement, a distribution mat;
• said mattress is covered with a sliding layer;
• a non-structural slab is made on said layer

sliding; a single armature is positioned at the top of said pavement, in the first upper third of its thickness; - a fiber concrete is poured
over the entire height of said pavement. The document WO 2013/004959 describes a process of this type.

Such a method is characterized in that it consists in: calculating the descending vertical moments greater than the surface of said pavement and the lower descending vertical moments on the lower face of said pavement, as a function of the load applied on said pavement; - deduce the difference between the calculated upper and lower moments; - Determine the section of the single armature according to said difference and the thickness of said tiling.

In addition, according to other additional nonlimiting features, if the result of said difference is positive, then the section of said armature is dimensioned so that it takes up at least the value of this difference, up to a maximum of the value of said higher moments.

Said armature can be positioned in the first upper third with a coating of at least three centimeters.

Said section of the frame can be determined at a maximum of 5.03 cm ² .

The thickness of said pavement can be determined between 15, 18, 20 and 25 cm.

Other features and advantages of the invention will emerge from the following detailed description of non-limiting embodiments of the invention, with reference to the appended figure, schematically showing a vertical sectional view of a construction, showing a Reinforced floor surmounted by a distribution mat receiving a tiling integrating an armature in the upper part, on which were modeled by arrows the support forces on the pavement and their distribution in the pavement, as well as the descending vertical moments.

The present invention consists of a method of constructing a non-structural slab 1 provided.

Such paving 1 is intended to be made in the upper part of a floor 2. To do this, the latter is primed.

In particular, an improvement 3 is made to said floor 2 intended to receive said pavement 1. Such a soil improvement 3 may consist of ballast columns made vertically in the floor 2, regularly spaced so as to form an anchor network designed to increase the bearing capacity of the soil and / or the shear strength, reduce the absolute and differential settlements, as well as the consolidation time, while avoiding the creation of draining elements. According to another embodiment, said improvement 3 of soil 2 may consist of vertical piles, made of bonded material, such as reinforced concrete. These piles are distributed evenly.

It will be noted that the soil improvement 3 is determined as a function of the nature of said soil 2, but also of the theoretical constraints that it will have to bear, namely the stresses that said pavement 1 will have to support and transmit to said soil 2.

Then, superior to said improvement 3, a distribution mat 4. The latter consists of one or more layers of compacted material, acting as a rigid support and fixed in time, absorbing a portion of the soil modifications 2. It also makes it possible to level the surface of the floor 2 as well, with a view to producing, on the upper face, said floor 1.

It will be noted that the distribution mat 4 is determined according to the nature of said floor 2 and its improvement 3, but also the theoretical constraints that it will have to bear, namely the stresses that said floor 1 will have to support and transmit to said mattress 4 .

Finally, said mattress 4 is covered with a sliding layer 5, in particular in the form of a plasticized film.

This assembly including the improvement 3 of soil 2, its mattress 4 and the sliding layer 5 constitutes the underbody. As mentioned above, the characteristics of the latter are determined with respect to the load that said pavement 1 will receive.

Then, a non-structural paving 1 is made on said slip layer 5.

An essential feature of the present invention resides in taking different account of the forces applied on the pavement 1 and their effects on the lower elements.

Referring to the figure, on the left side, was modeled as a solid arrow, a force representing an example of total load applied to the surface of the pavement 1. It will be noted that such a load can be, depending on the case , a uniformly distributed load (CUR), a point load (CP), or even a combination of these two loads.

This force is distributed through the pavement 1, in the form of several complementary forces 7. These complementary forces are descending, oriented in the direction of said force 6, but also diverging therefrom. These complementary forces 7 pass through the pavement 1, as well as the distribution mattress 4.

When they lie between the ground improvements 3, these complementary forces 7 propagate in the ground 2. On the other hand, if they meet said ground improvements 3, as visible in the figure and modeled by dashed arrows, reverse forces 8 are generated upwardly. In sum, at the level of the improvements 3, the force 6 applied on the surface of the pavement 1 is repelled by said improvements 3, but not between these improvements 3.

This phenomenon is reflected, in terms of moments, by the fact that the tiling 1 is then bent between the improvements 3 (while the latter offer support when the force 6 is applied vis-à-vis). This bending is modeled on the right part of the figure, showing a curvature between two improvements 3. One speaks then of higher stresses (CMC) due to the rigid inclusions 3 ground improvements.

As mentioned above, if in the upper part, this bending is compensated by the compressive strength of the concrete, this is not the case on the lower face of the tiling 1, then undergoes an elongation, likely to cause its tearing.

As can be seen in the figure, on the right, it is found that the upper and lower lower vertical moments 10 are equivalent when the force 6 is applied at the level, generally in the alignment, of the improvements 3 of soil 2.

On the other hand, the lower moments 10 are found to be larger than the higher moments 9 when they are situated between the improvements 3. This difference is modeled by the greater length of the arrow of the lower moments 10 with respect to the length of the arrow of higher moments 9.

An essential feature of the present invention is the fact of quantifying the difference of these moments 9,10.

It should be noted that the invention also makes it possible to quantify an inverse difference, namely when the higher moments 9 are greater than the lower moments 10.

To do this, the method according to the invention consists in calculating the upper downward vertical moments 9 on the surface of said tiling 1 and the lower downward vertical moments 10 on the lower face of said tiling 1, as a function of the load applied on said tiling 1.

Then, we deduce the difference between the calculated upper moments 9 and lower 10.

Then, instead of positioning an armature in the lower part of the floor 1 to resume the lower moments 10, the invention provides for only positioning a frame 11 in the upper part of said floor 1.

Indeed, in an inventive step, it has been demonstrated that, for a non-structural pavement 1, the fiber added to the concrete could take up most of the moments, they are higher 9 or lower 10. However, beyond a certain value, the amount of fiber becomes too important and it is currently necessary to add a lower reinforcement, where the lower moments 10 are more important that the higher moments 9.

Therefore, an inventive aspect resides in taking part of the moments through an armature 11 located in the upper part of the pavement 1, replacing the recovery granted by the fiber.

In particular, preferably, if the result of said difference is positive, then the section of said armature is dimensioned so that it resumes at least the value of this difference, up to a maximum of the value of said higher moments.

In other words, if the calculated value of the higher moments (Msup) is greater than that of the lower moments (Minf), then Msup> Minf then the fiber of the concrete takes again the said lower moments and the lower value of the higher moments (the said value lower is equivalent to the higher value). In addition, the armature then resumes the value of this positive difference between the upper and lower moments.

On the other hand, if the computed value of the higher moments is lower than that of the lower moments, so Msup <Minf, then it is the fiber alone that takes up the entirety of the upper and lower moments.

To do this, the section of a reinforcement 11 is determined as a function of the difference of the moments 9, 10.

The thickness of said paving 1 is also determined.

The latter can be determined between 15, 18, 20 and 25 cm.

Then, said armature 11 is positioned in the upper part of said paving 1, in the first upper third of its thickness.

More specifically, said armature 11 is positioned in the first upper third with a coating of at least three centimeters (cm). In other words, the armature 11 is positioned so that a thickness of at least 3 cm comes to cover it. The armature 11 is then in the upper part of said paving 1, but under at least 3 cm of concrete.

Finally, an additional concrete fiber is poured over the entire height of said paving 1.

Thus, the fiber-reinforced concrete comes back most of the moments 9,10 and the armature 11 located in the upper part takes up the difference of said moments 9,10, in particular and preferably when the value of the lower moments 10 is greater than the value of the higher moments 9, then the armature 11 comes back to the difference between these values.

According to the preferred embodiment, the section of the armature 11 is determined at a maximum of 5.03 cm ² (square centimeters). Indeed, beyond this section, it has been found that to facilitate the implementation, but also to improve the strength of the pavement 1, as well as for economic reasons, it is more profitable to introduce a second reinforcement in part bottom of paving 1.

• une reprise maximale des moments de 16,30 kNm/m (kiloNewton-mètre par mètre) pour un dallage 1 de 15 cm d'épaisseur ;
• une reprise maximale des moments de 20,37 kNm/m pour un dallage 1 de 18 cm d'épaisseur ;
• une reprise maximale des moments de 23,09 kNm/m pour un dallage 1 de 20 cm d'épaisseur ; et
• une reprise maximale des moments de 29,88 kNm/m pour un dallage 1 de 25 cm d'épaisseur.

The tests carried out during the implementation of the method of construction of a non-structural pavement 1 according to the invention made it possible to highlight the following results, namely, for a maximum section of the armature 11 of 5.03 cm ² .

• a maximum recovery of the moments of 16.30 kNm / m (kiloNewton-meter per meter) for a tiling 1 of 15 cm thick;
• a maximum recovery of the moments of 20.37 kNm / m for a tiling 1 of 18 cm thick;
• a maximum recovery of the moments of 23.09 kNm / m for a tiling 1 of 20 cm thick; and
• a maximum recovery of the moments of 29.88 kNm / m for a tiling 1 of 25 cm thick.

These values are given for information only and are in no way limiting.

Thus, when Msup> M inf, the armature positioned in the upper part offers a recovery of the higher moments to maximum height in kNm / m. These aforementioned values thus give intervals for which it is possible to choose the necessary height of tiling, for a section of frame of 5.03 cm ² .

Thus, the manufacturing method according to the invention makes it possible, from a positioning of a single and only reinforcement 11 in the upper part of a non-structural slab 1 made of fiber concrete, to allow the resumption of the differences between the moments upper and lower verticals 9 and lower 10.

In addition, the invention has highlighted the fact of taking up at least part of the upward vertical moments.

Claims (5)

1. A method for constructing a non-structural flooring (1), this method:

   - consisting in that:

   - an improvement (3) of the floor (2) intended to receive said flooring (1) is carried out;

   - above said improvement (3) is carried out a distribution mat (4);

   - said mat (4) is covered with a sliding layer (5);

   - a non-structural flooring (1) is carried out on said sliding layer (5);

   - a single framework (11) is positioned in the upper portion of said flooring (1), in the first upper third of its thickness;

   - a fiber-reinforced concrete is poured over the full height of said flooring (1);

   - wherein it consists in:

   - calculating the upper vertical descending torques at the surface of said flooring (1) and the lower vertical descending torques at the lower face of said flooring (1), depending on the load applied onto said flooring (1);

   - deriving the difference between the calculated upper and lower torques;

   - determining the cross-section of the single framework (11) depending on said difference and the thickness of said flooring (1).
2. The method for constructing according to claim 1, wherein, if the result of said difference is positive, then the cross-section of said framework is dimensioned (11) so that it adopts at least the value of this difference, up to a maximum of the value of said upper torques.
3. The method for constructing according to any one of the preceding claims, wherein said framework (11) is positioned in the first upper third with a coating of at least three centimeters.
4. The method for constructing according to any one of the preceding claims, wherein said cross-section of the framework (11) is determined at a maximum of 5.03 cm².
5. The method for constructing according to any one of the preceding claims, wherein the thickness of said flooring (1) is determined between 15, 18, 20 and 25 cm.

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