Industrial floor comprising a non-adhering wear layer on a concrete base

An industrial floor, comprising at least one covering layer on a new or existing concrete base, said covering being not bound to the concrete base and obtained from a composition based on at least one hydraulic binder, said floor further comprising, between the concrete base and the covering layer, from the upper face of the concrete base: (a) a smoothing layer enabling the flatness/roughness of said upper face to be less than 2 mm under a 2 meter rule; (b) on the smoothing layer, at least one separating layer for preventing the first covering layer from adhering to the smoothing layer on the base; (c) on the separating layer, at least one covering layer having a maximum of 30 mm.

FIELD OF THE INVENTION 
The invention relates to an improved industrial floor composed of at least 
two layers: 
a concrete first layer, hereafter referred to as the "concrete base", in 
which a shrinkage phenomenon may manifest itself or be manifested at the 
time of setting or hardening; 
and at least one other layer, referred to hereafter as the "wear or 
covering layer", which is not bound to the concrete base. This second 
layer may preferably be obtained from a composition based on at least one 
hydraulic binder and/or at least one organic binder. 
BACKGROUND OF THE INVENTION 
The invention further relates to a method for the production of such an 
improved floor. 
The expression "industrial floor" is intended to mean a sheltered floor 
supporting all the economic activity of industrial buildings with widely 
varied activities, excluding so-called pedestrian floors: factories, 
warehouses, workshops, laboratories, partially sheltered unloading bays, 
station platforms, etc. The industrial floor is then intended to receive 
high static and dynamic loads. 
Whereas the covering is directly in contact with the external mechanical 
stresses, it is the role of the concrete base to receive them, transmit 
them or distribute them in the floor so that the covering is not degraded 
rapidly and the industrial floor does not require excessively frequent 
renovations. 
Owing to technical advances, the external stresses to which industrial 
floors are subjected are becoming more and more important: in this regard, 
mention may be made of the heavy traffic of transporters, high-level 
storage, etc. 
In parallel with this technical advance, there is an increasing requirement 
for an industrial floor to remain constantly flat and to keep a smooth 
non-slippery surface (that is to say one which does not contain holes, 
projections, cracks or other obstacles), in order: 
to allow unimpeded and completely safe movement of people and machines, in 
particular transporters, and consequently in order not to cause industrial 
accidents; 
to be comfortable and aesthetic, or have a decorative appearance, and to be 
easy to maintain in order to improve the working environment; 
to limit the repair work which may lead to business being interrupted. 
This is why there is a particular requirement for industrial floors to 
fulfil at least all of the following mechanical characteristics: 
a response to traffic which is sufficient to withstand the movement of the 
machines as well as their weight; 
resistance to puncturing under the effect of heavy loads through reduced 
surface areas such as a storage structure, etc.; 
compressive and flexural/tensile strengths to withstand heavy loads; 
impact resistance which is sufficient to withstand, without bursting or 
cracking, predictable quantified impacts during the design of the floor, 
of the type involving the sudden depositing of heavy components, falling 
objects, etc.; 
and, where appropriate, a response to thermal stresses resulting from the 
working temperature (for example the risk of the industrial floor 
freezing) or thermal variations which it may undergo. 
Furthermore, essentially for economic reasons, the choice of a type of 
industrial floor is determined according to the production time (in the 
case in point, preparing or making the concrete base, making the covering 
and the time required before commissioning), location and climatic 
conditions, etc. 
To satisfy these requirements, a covering in the form of an incorporated 
screed (i.e. a wear layer fitted on fresh concrete) or an attached screed 
(i.e. a wear layer fitted on hardened concrete) is most often provided on 
the concrete bases. 
More particularly, in the case of an attached screed, the upper layer of 
the concrete base is provided with surface roughness and, if necessary, is 
covered with a product in order to make an adhesion bridge between the 
base and the covering. 
However, these industrial floors in which the covering adheres to the 
concrete base must, for the most part, include a large and sufficient 
number of joints, or else there is a considerable risk of random cracks 
occurring on the visible surface of the floor. In fact, these joints 
essentially serve to compensate for the phenomena of differential 
expansion between the covering and the concrete, to isolate a part of the 
floor (in particular around posts and machine bases) in order to allow 
vertical movements of any origin and to compensate for the phenomena of 
shrinkage of the concrete when it sets. 
Thus, concrete is a material whose volume decreases when it sets and 
hardens --this is a shrinkage phenomena. Shrinkage is measured in microns 
per meter: for ordinary concretes, it may exceed 1000 microns per meter. 
The consequence of shrinkage is the almost inevitable occurrence of cracks 
in the concrete. Furthermore, because of their large linear dimensions, 
poured concrete bases lead to shrinkages which are large in terms of 
absolute value. 
Tackling the deep-rooted causes of the occurrence of shrinkage phenomena is 
not always industrially feasible, because there are many such causes and, 
although some of them are fairly well known, others are still poorly 
understood. 
All these shrinkage phenomena, and therefore the occurrence of cracks in 
the concrete during or after the end of setting, give rise, depending on 
the extent of the cracks, to often expensive repairs and an unaesthetic 
appearance. 
As indicated above, in view of the fact that it is not possible to avoid 
shrinkage under economically acceptable conditions, attempts are made to 
channel it and control it so that its detrimental effects are minimized. 
Thus, in order to channel and control the cracking due to shrinkage, as 
soon as the concrete has sufficient consistency, the following: 
"le Bulletin du ciment" cement bulletin! No. 5, May 1990 (chapter entitled 
"Screed--floor covering structures, cement-based screed. Instructions for 
design and implementation"); 
and "le Document Technique Unifie(D.T.U.) Unified Technical document! of 
September 1982 (volume 1794, No. 26.2, entitled "Screed and slabs based on 
hydraulic binders); 
recommend cutting out the shrinkage joints, which are made: 
every 25 m.sup.2 and at most every 8 m if the surface is intended to remain 
uncovered or to receive a film of paint; 
every 50 m.sup.2 and at most every 10 m in other cases. 
In practice, the person skilled in the art knows that he should provide 
shrinkage, expansion and isolation joints: 
at most every 5 m, in order to limit random cracking phenomena; 
and in all regions where tensile stress concentrations may lead to random 
cracking, such as, for example, thickness discontinuities or interruptions 
in the continuity of the surface owing to the presence of a pillar, a 
window, a door or a projecting corner. 
In fact, as mentioned above, further to their use with regard to shrinkage 
phenomena, joints are conventionally arranged in large-area industrial 
floors in order to limit the occurrence of shear stresses resulting from 
the differential expansions between the concrete base and the covering. 
These expansions are generally due either to thermal and hygrometric 
variations or to mechanical deformations caused by the forces to which the 
industrial floor is subjected, in particular when it is loaded. 
Conventionally, the joints are made as soon as possible, most often by 
mechanical sawing. 
The effect of cutting out the joints is to create a weak section in the 
concrete which will therefore crack preferentially. The other desired 
effect is the straight, sharp appearance of the surface crack, which 
allows it to be treated using various known methods: sections, filling 
coatings, etc. 
A well-known technique for decreasing or even eliminating the propagation 
of cracks from the concrete base to the covering consists in providing an 
intermediate layer between them in order to make the covering not adhere 
to the concrete base. In such a case, the covering (or wear screed) is 
referred to as "floating". 
The main problem resulting from this technique resides in the poor 
mechanical performance of "floating" coverings. In fact, under the effect 
of loads of the type encountered in industrial activity, such as 
transporter traffic, this type of covering is highly susceptible to 
cracking. 
One solution to this problem could be to provide thick coverings (at least 
5-6 cm), but this is equivalent to forming a new slab with mechanical 
characteristics similar to those of the concrete base. The latter solution 
is not satisfactory, on the one hand, for economic reasons and, on the 
other hand, because of the raise in the final level of the floor which 
results therefrom. This is why the use of a floating screed is usually 
reserved for the production of residential or pedestrian floors, that is 
to say floors intended to be subjected to moderate-to-low intensity 
external stresses. 
The object of the present invention is to overcome all the abovementioned 
drawbacks of known techniques for producing floors, in the case of 
industrial floors. More particularly, the invention aims to reduce or even 
eliminate the occurrence of random cracks at the surface of floor, these 
cracks possibly resulting from normal and high-intensity mechnical-type 
stresses encountered in an industrial environment and/or because the base, 
prepared using a concrete, can exhibit a shrinkage phenomena and 
subsequently dimensional variations different from those of the covering. 
The invention also aims to limit the number of joints necessary for a floor 
not to crack, or even eliminate them, in particular in the following 
cases: 
floors located in buildings subjected to low hygrometric and/or thermal 
variations; 
floors supporting little or no concentrated loading, such as car parks; 
floors having little or no discontinuity, such as posts, windows, etc. 
To this end, the invention proposes an improved floor for industrial use, 
comprising at least one covering layer on a new or existing concrete base, 
characterized in that the covering is not bound to the concrete base and 
in that the upper face of the concrete base is treated successively in the 
following way: 
a) smoothing this upper face so that its flatness/roughness is less than 2 
mm under a 2 meter rule (under the conditions of D.T.U. 26-2 but with 
different requirements), it being possible to obtain this smoothing by 
mechanical floating, but preferably by applying at least one layer of a 
self-smoothing product (hereafter referred to as the smoothing layer), it 
being furthermore necessary for this smoothing layer to adhere to the 
concrete base; 
b) depositing at least one means for preventing the first covering layer 
from adhering to the smoothed surface (hereafter referred to as the 
"separating means"); 
c) depositing one (or more) covering layer (or layers) which is reinforced 
over the entire area to be treated which is poured over the separating 
means, the thickness of this coating being a maximum of 30 mm. 
In contrast to the techniques conventionally used for producing industrial 
floors, the Applicant recommends separation (i.e. non-adhering) of the 
covering from the concrete base after smoothing of its upper face, 
preferably with the aid of a self-smoothing product which adheres to the 
concrete. 
It has in fact been found that the great propensity of floating coverings 
(or screed) to crack under the effect essentially of the mechanical 
stresses encountered in an industrial activity did not result only from 
the possible weakness of the floating covering at the cracks in the 
concrete base, but above all from the irregularity of the contact surface 
between the base and its covering, and consequently as a result of the 
fact that either the covering does not bear completely on the support or 
these irregularities cause localized tensile stress concentrations which 
initiate cracks in the covering. 
Thanks to the invention, the upper surface of the concrete base is 
improved, and therefore the regularity of the contacts between the base 
and the covering. As a result of this, it has been observed that the 
covering can then received and distribute the mechanical stresses to which 
it is subjected, and effectively oppose the occurrence of random cracks 
and various deformations on the visible face of the industrial floor. 
As indicated above, the invention relates both to the production of a floor 
from an existing and renovated concrete base, and to that of a new 
concrete base. For the sake of simplicity, the term "new floor" will be 
used to denote a floor which has a new base, as opposed to a "renovated 
floor" which has a renovated base. 
In its usual form, the invention does not obviate the production of the 
concrete base while respecting the rules of the art, in particular as 
regards the production of segmenting joints, in particular respecting the 
maximum distance between joints and sawing within the time limits. 
According to an advantageous embodiment of the invention, applicable only 
to a new floor, one or more sections chosen from a material which adheres 
little or not at all to concrete are arranged on the foundations. The said 
sections, by reducing the cross-section of the concrete base at the 
sections, make it possible to induce substantially vertical cracking at 
each inducer if the tensile stresses in the concrete resulting from the 
shrinkage are sufficient. Then the concrete is poured over the foundations 
and the said sections, in order to form the concrete base. 
This advantageous embodiment of the invention makes it possible to make the 
distribution of the induced cracks due to the shrinkage of the concrete 
more dense and to distribute them better over the surfaces. It is then 
conceivable to increase significantly the distances between the joints cut 
out from the concrete base, or even eliminate them completely, because it 
is thus possible to guarantee good mechanical performance of the covering 
plumb with the induced cracks, on the one hand by the presence of the 
reinforcement, and on the other hand by the control of the width of the 
induced cracks, which is limited in this case. 
DETAILED DESCRIPTION OF THE INVENTION 
The precise composition of the concrete of which the base is made is not 
critical. However, it will be clearly understood that the invention is 
useful when the nature of the concrete, the working and climatic 
conditions during manufacture of the floor and the conditions under which 
the floor is used make the occurrence of shrinkage phenomena and 
dimensional variations in this layer become critical. 
The invention is particularly well-suited to standardized concrete 
compositions in which, essentially, at least one hydraulic binder, 
granulates in proportions which are well-dosed according to the rules of 
the art, and various inorganic or organic adjuvants are found. 
The proposed invention does not obviate adherence to the traditional rules 
of the art, as regards concrete manufacture and implementation. Thus, it 
is recommended to respect the concrete manufacture standards, in 
particular as regards water/cement ratios, concrete grading distribution 
curves, granulate shape coefficients, mixing times and temperature. 
It is furthermore strongly recommended, in the case of an industrial floor, 
to choose a concrete composition which allows the base to achieve both: 
a compressive strength of the order of 10 MPa or more, preferably at least 
equal to 20 MPa (according to EN Standard 196-1 of March 1990), and 
a flexural/tensile strength at least of the order of 2.2 MPa or more, 
preferably at least equal to 2.5 MPa; 
a good surface condition (little roughness, absence of chalking) so that 
the tear resistance of the base is of the order of 1-1.5 MPa, or even at 
best of the order of 2 MPa. 
In the case of a new floor containing one or more sections (refer to the 
aforementioned advantageous embodiment of the invention), the presence of 
the sections allows favourable distribution of the cracks over the entire 
area of the floor. This is why, in this case, it is easier to use concrete 
compositions incorporating setting and hardening accelerator compounds, 
which tend to enhance the shrinkage phenomena. 
According to an advantageous variant of the invention, the upper face of 
the concrete base is first of all covered with a smoothing layer in order 
to overcome the well-known difficulty of smoothing with the desired 
precision using mechanical means. 
To form the smoothing layer, use is made of a composition made of a 
material which can both form a smooth surface and adhere to the concrete 
base. It is furthermore recommended to provide a composition which, once 
hardened, makes it possible to obtain a minimum compressive strength of 
the order of 10 MPa, preferably at least equal to 20 MPa. Still more 
preferably, a conventional self-smoothing cementing composition is chosen. 
Normally, a 3 mm thickness for the smoothing layer is sufficient to obtain 
correct smoothing. Greater thicknesses may be necessary for smoothing very 
rough concretes. 
If necessary, in order to complete the smooth appearance of the upper 
surface of the smoothing layer, before pouring the self-smoothing product, 
a layer is deposited in order to improve the adherence and control the 
porosity of the surface of the base using an impregnation product which 
also serves as a sealing filler and is referred to by specialists by the 
terms "bonding primer" or "adhesion primer". This impregnation product 
also makes it possible to prevent the appearance of surface chalking. The 
impregnation product most often used is a composition in the aqueous phase 
or of an allowed solvent of a resin (homo-, co- or even terpolymer) which 
may be a vinyl acetate, a versatate, an ethylenic derivative, an epoxy, a 
polyurethane, a neoprene, a styrene-butadiene, a styrene-acrylic, etc. 
According to another important characteristic of the invention, once the 
desired smoothing has been obtained, the following are successively 
deposited on the new or renovated concrete base: 
1. one (or more) separating means for making the wear layer (or covering) 
not adhere to, depending on the case, the smoothed surface of the base or 
the smoothing layer. In this way, the covering undergoes virtually no 
tensile stresses due to the dimensional variations which may occur in the 
base, regardless of their causes (cracks, hygrometric and/or thermal 
variations, strong external stresses). The reduction in friction with the 
base is furthermore made possible by virtue of the absence of retention 
points on the base, the upper face of which has been made smooth, 
preferably thanks to the smoothing layer. The separating means used are 
preferably products which either do not adhere to the smoothing layer or 
do not adhere to the wear layer, or else do not adhere to either of these 
two layers. Suitable separation products are paraffins, silicones, 
petroleum-based waxes, stearates such as magnesium stearates and any other 
product, generally essentially organic. The thickness of the layer formed 
with the single or multiple separating means is designed to ensure that 
the covering does not adhere to the smoothing layer: it is recommended to 
provide a thickness of the order of 100 .mu.m to 200 .mu.m. It is possible 
to use greater thicknesses, for example 3 mm or more, on condition that 
the material used withstands, without deforming, the pressure of the 
screed in use. As soon as the smoothing layer can support an operator and 
the machines useful for manufacturing the floor, without impairing the 
smoothing, the anti-adhesion products may be applied thereto manually or 
mechanically (for example by spraying). Further separating means which may 
be used are thin films of non-adhesive products, for example films made 
with polyolefins such as polyethylene or any other materials which can be 
deposited over large areas on the smoothed base, on condition that they do 
not adhere to the smoothed base or to the covering. However, when it is in 
the form of a thin film, the separating means must be deposited with great 
caution so as not to create surface irregularities such as folds or air 
pockets, and thereby lead to an irregular surface appearance and impair 
the perfect application of the covering onto the base. This is why it is 
recommended to stretch it and adhesively bond it onto the smoothing layer. 
2. one or more covering layers which are poured onto the separating means. 
In practice, the separating means is firstly covered with a reinforcement, 
then the coating is poured on top to form the reinforced covering. The 
main selection criterion for the reinforcement resides in its capacity to 
give a good distribution of the tensile stresses which result from the 
stresses to which the covering is subjected. Furthermore, so that the 
covering layer benefits fully from the technical effects provided by the 
reinforcement, the latter is advantageously laid on means making it 
possible to raise the reinforcement, partly or fully, above the separation 
layer, these means optionally forming an integral part of the 
reinforcement. In this way, the armature is fully embedded in the mass of 
the layer forming the covering. The reinforcement is generally in the form 
of a lattice and may be made of any material which is compatible with the 
materials of the floor, so long as it has sufficient tensile strength. By 
way of example, mention may be made of metal or treated glass-fibre 
grills, which may be in the form of large plates or wide strips. 
If the covering is composed of a plurality of superposed layers, the 
reinforcement is integrated in the thickest layer. 
The format and the size of the meshes defined by the lattice-shaped 
reinforcement may also vary. They often depend on the type of material 
forming the reinforcement, as a result of the manufacturing techniques. 
However, care will be taken that the dimensions of the meshes of the 
reinforcement are greater than the dimensions of the particles and/or 
fibres contained by the covering composition, in order to avoid a sieving 
effect with regard to this composition. 
Finally, the choice of the density of the meshes and of the material of the 
reinforcement is, of course, dependent on the level of tensile strength 
which it is desired to develop for the reinforcement. 
Once the reinforcement is laid, the last step for forming the floor 
according to the invention consists in pouring one or more layers to form 
the covering. It is recommended to provide a thickness at least equal to 
10 mm for the covering, since with a smaller thickness there is a risk 
that the mechanical flexural strength of the industrial floor may be 
insufficient. The thickness of the covering layer may be up to 30 mm, as 
previously indicated. However, essentially for economic reasons, it will 
be preferable to adopt a thickness of the order of 15 mm. It will be noted 
that the invention permits a considerable reduction in the thickness of 
those screed, when it is compared with the known conventionally, which are 
typically 50 mm to avoid cracking. 
A major benefit of the invention is that the precise composition of the 
covering layer is not critical. This composition is essentially chosen in 
accordance with the characteristics which it is desired to give the 
covering layer (in particular minimum shrinkage) and the use which will be 
made of the finished floor. 
Nevertheless, it is preferable to use covering layer compositions 
comprising at least one hydraulic binder and at least one organic binder, 
since under these conditions the method according to the invention has 
proved to be very effective (absence of cracking on the upper surface of 
the pavement). 
After this last step, as soon as the covering is sufficiently hardened, a 
multilayer floor is obtained which can be used as it is or optionally 
covered with one or more finishing layers. 
According to another advantageous alternative embodiment of the invention 
indicated above, the known principle of crack direction is retained, but 
with an important modification: the cracking is induced via the bottom of 
the floor using sections, and it is directed upwards, in a substantially 
vertical plane, in line with the sections, in contrast to the cutting out 
of shrinkage joints, the induction of which takes place from the base 
towards the bottom of the pavement. The concrete base is thus weakened by 
reducing its cross-section in line with the sections: therefore, if the 
tensile stresses resulting from the shrinkage are sufficient, the cracking 
will take place precisely in line with the sections. 
Then, according to the invention: 
the surface of the concrete is smoothed as soon as it has reached 
sufficient strength to withstand light loads such as the weight of one or 
more operators, preferably before the occurrence of induced cracking, and 
more preferably with the aid of at least one smoothing layer; 
next, at least one separating means, a reinforcement in the form of a 
lattice and at least one layer for forming the covering are deposited in 
succession. 
The concrete base is advantageously weakened so that to form induced 
cracking in line with most or all of the sections, and thus to prevent the 
formation of wide infrequent cracks. 
To do this, the sections are preferably spaced apart from one another by a 
distance ranging from approximately 1 meter to 10 meters. More preferably, 
the provisions of the D.T.U. of September 1982 (which are specified above) 
are followed, which leads to arrangement of the sections at least every 5 
meters, so that they define areas of no greater than 25 m.sup.2. 
Furthermore, care is taken to arrange the sections in all regions where 
tensile stress concentrations may lead to undesirable cracking, such as, 
for example, thickness discontinuities or interruptions in the continuity 
of the surface due to the presence of a pillar, a window, a door or a 
projecting corner. 
Despite the probable occurrence of cracks in the base because of the 
shrinkage, the Applicant Company has observed the absence of occurrence of 
visible cracks at the surface of the covering. This shows that the 
separation of the covering from the smoothed base allows the covering not 
to crack when it bears on a smooth base having cracks of limited width. 
The sections must be made of a material which adheres little or not at all 
to concrete, this being in order to minimize the bonding of the concrete 
to the sections. They must furthermore be sufficiently rigid. By way of 
examples of materials which can be used for manufacturing sections, 
mention may be made of plastics such as polyethylene or polypropylene, 
which are perfectly suitable so long as they are sufficiently rigid to 
support the concrete base without deforming. They may also be wooden. 
The format of these sections may vary. They are preferably chosen with a 
height of at least one sixth of the height intended for the concrete base, 
so that they indeed reduce the area of its cross-section by at least one 
sixth. More preferably, the height of the sections is at least equal to 
one third of the height of the base. The best results as regards the 
aesthetics of new floors according to the invention were obtained when the 
height of the sections is at least equal to one half of the height of the 
base. 
The other aspects of the format are not critical, and are intended only to 
facilitate laying and/or fastening on the foundations of the floor, 
transport or else lengthwise division in order to adjust the dimensions. 
According to a first advantageous variant, the section has a cross-section 
substantially in the shape of a "V" which is inverted on the foundations 
of the industrial floor, this being so that the projecting angle of the 
"V" is directed towards the upper surface of the base. 
According to a second advantageous variant, the section has a cross-section 
substantially in the shape of a "T" which is inverted on the foundations 
of the industrial floor, this being so that the vertical bar of the "T" is 
arranged vertically and directed towards the upper surface of the base. 
More preferably, according to a third advantageous variant, the section has 
a cross-section substantially in the shape of a "Y" which is arranged 
stably on the foundations of the industrial floor, so that one of the 
branches of the "Y" is arranged vertically and directed towards the upper 
surface of the base. 
As indicated above, once the profiled crack inducers are laid, and 
preferably fastened on the foundations of the industrial floor using a 
suitable fastening means such as nails, the concrete is poured in order to 
form the base, then, as soon as the base has reached sufficient mechanical 
strength, the surface of the concrete is smoothed, advantageously by 
covering it with at least one smoothing layer; then the smoothed surface 
is successively covered with at least one separating means, a 
reinforcement in the form of a lattice, then at least one layer to form 
the covering. 
ADVANTAGES OF THE INVENTION 
Surprisingly, the invention makes it possible to give this thin covering, 
which is not bound to the concrete base, industrial-level mechanical 
performance, which is consequently greatly superior to that encountered in 
the case of known residential and pedestrian floors, and thus to transfer 
all the advantages of this covering construction technique to industrial 
contexts. 
The advantages of the invention are therefore as follows: 
1. the interruption in the transmission of random cracks from the base to 
the surface of the covering. 
2. the bridging of the shrinkage joints of the base by the covering, 
without damage to the latter, on condition that these joints are properly 
designed, that is to say that the amplitude of their movements is 
predictable and limited. In the case of new industrial floors, the 
technique of inducing shrinkage cracks by sections is combined with the 
floor manufacturing technique recommended in the present invention. This 
results in the possibility of producing industrial floors without random 
cracks, with greatly increased spacings between joints the spacing 
between, be noted that the spacing between the joints depends, as for the 
base amongst other things, on the working conditions of the floor, the 
loads in place and the thermal and hygrometric variations of the 
surroundings. In the case when these constraints are normal (i.e. 
variations in the degree of hygrometry of the order of 40% and thermal 
variations less than 30.degree. C.), surface areas of more than 1000 
m.sup.2 without joints may be envisaged. In contrast to the sawing 
technique, the invention, with the advantageous variants using the 
smoothing layer and the crack inducer sections, allows a considerable 
acceleration in the rate of production of the concrete base. Rates of more 
than 2000 m.sup.2 /day are thus easily achieved. 
3. for renovation, it is essential to have added (over)thicknesses which 
are as small as possible compared to the original level (in particular 
because of the creation of slopes, the level of the machine installation 
station, the available roof height, etc.). The invention, which respects 
the abovementioned conditions, is therefore suitable for the renovation of 
industrial floors. 
4. ease of repair: the main difficulty encountered in current techniques 
resides in the removal of the spoiled adhesive screed. The invention makes 
it possible to remove it rapidly, with very fast mechanical means and 
minimal interference (noise, dust, vibrations, occupation of premises, 
equipment, etc.). 
5. furthermore, the development of the technique is such that, in order to 
give the best response to constraints of flatness, finishing and floor 
performance in general, in particular industrial floors, there is a 
current requirement to deposit a finishing layer with the distinctive 
characteristics of the concrete of the base. This floor manufacturing 
technique is therefore advantageously reconciled with this technological 
trend. 
INDUSTRIAL APPLICATIONS 
Because of the advantages listed above, the invention is particularly 
suitable for industrial floors intended, for example, for car parks, 
industrial or commercial buildings and, more particularly, for: 
industries in which the presence of joints causes problems 
(agro-foodstuff); 
or alternatively when the long-term stability of the floors cannot but be 
limited because of the activities carried out (heavy engineering, chemical 
industries, agro-foodstuff, cold rooms, iron and steel, etc.) 
The invention is furthermore suitable for the production of residential and 
pedestrian floors (for example, those in hospital or school buildings).

The invention is now illustrated by way of two particular embodiments. 
EXAMPLES 
Manufacture of a 200 m.sup.2 unjointed industrial floor in industrial 
premises used for storage and delivery frequently of loads of 7 tonnes per 
m.sup.2 (stacked pallets), in cold weather with variations of from 
0.degree. to 7.degree. C. 
The foundations 
The foundations of the industrial floor are a standard layer made from a 
mixture of rough quarry granulates, and the foundations furthermore 
comprise a roller-compacted insulating plastic sheet under the 
foundations. 
The concrete base 
It is made of non-reinforced concrete and is 17 cm high. Sections 
commercialised by the company MIERS under the brand name "CONCRACK" are 
placed every 5 meters on the foundations in order to form a grid with 
"meshes" of 25 m.sup.2 surface area: these sections, which have a "Y" 
cross-section shape, have a height of 50 mm and are made from rigid 
polypropylene. The "CONCRACK" sections are fixed on the foundations using 
nails. The location of the sections is accurately determined. 
The concrete is then introduced with a railless manual rule. The poured 
concrete comprises: 
sand: 820 kg/m.sup.3, including 191 kg/m.sup.3 of fine sand; 
gravel: 938 kg/m.sup.3 ; 
hydraulic binder (Portland cement CPA 55): 370 kg/m.sup.3 ; 
mixing water: 197 .+-.7 kg/m.sup.3; 
a fluidifier: 0.25% of the weight of hydraulic binder. 
Such a concrete guarantees a 35 MPa characteristic strength at 28 days 
according to Standard NF P 18305. 
The concrete is quick-setting. It is in fact possible to walk on the 
concrete ten hours after pouring. 
The temperature varied from 3.degree. to 5.degree. C. during the 
preparation of the base. 
An adhesion primer is then applied over the entire area of the base, in a 
single layer. This primer consists of an aqueous-phase dispersion of vinyl 
copolymers. This primer is left to dry for two hours. Consumption is of 
the order of 200 g per m.sup.2 of surface area. 
The smoothing layer is then applied onto the upper face of the base, in 
order to make it smooth and to eliminate all possible retention points 
therefrom. The product applied is a smoothing coating essentially based on 
cement, commercialised by the company OMNIPLASTIC under the brand name 
OMNIPLAN. This coating is chosen because of the level of its mechanical 
characteristics, which allow it to withstand the indirect load of 
industrial mechanical stresses. 
This product is applied quickly using the application pump of brand name 
SERVAPLAN, described in European Patent Application No. 92420025.6, with a 
mean thickness of 3 to 4 mm. 
The smoothing product is then left to harden for 24 hours, this time being 
sufficient for it to be able to withstand foot traffic. 
The smoothing layer is then covered with a viscous liquid product, which 
makes it possible to avoid adhesion between the wear layer and the 
smoothing layer. This product creates a strong, leaktight and completely 
non-adhesive film. It consists of petroleum derivatives in aqueous 
dispersion, commercialised under the brand name ELVECURE by the company 
CHRYSO. The consumption of this product is 150 grams per m.sup.2. This 
product is left to dry for 4 hours, to make it able to withstand being 
walked on by a person. 
After 4 hours, small elements, making it possible to support the lattice, 
are distributed at regular intervals, spaced apart by approximately 40 cm, 
on the separating means. This lattice is a galvanized metal lattice with a 
mesh size of 10 mm.times.10 mm and a wire diameter of 1 mm. This lattice 
is rolled out over the entire area to be treated. 
The covering or wear layer 
2 cm of a covering intended to form the wear layer is then poured. To do 
this, use is made of the automatic SERVAPLAN pump. Application takes 
approximately 2 hours. 
The coating used to form the wear layer is composed of: 
Portland cement: 18% to 25% 
alumina cement: 1% to 10% 
fillers: 5% to 25% 
silica sands: 35% to 65% 
organic binder: 0.5% to 5% 
fluidifier: 0.05% to 1% 
setting regulator: 0.01% to 0.3% 
Other components may be added to this formulation, with a view to improving 
the characteristics and performance of the coating (colorants, hardeners, 
retarders, etc.). 
The covering is left as it is for 18 hours, then a liquid product making it 
possible to inhibit the evaporation of water from the hydraulic covering, 
and thereby prevent it from cracking prematurely, is applied. This 
product, called a curing agent, is specially designed to allow the 
subsequent application of any other aesthetic coverings: paints, textiles, 
plastics or the like. 
The floor is left free of traffic for 48 hours, then returned to heavy use 
within 5 days without any damage: storage of 1.2 tonne pallets on 5 
levels, handling by lifter trucks with solid-tire wheels. 
No cracking occurred anywhere 28 days after pouring. 
Another building site example: manufacture of a 150 m.sup.2 unjointed 
renovated industrial floor in cold weather with variations of from 
+1.degree. C. to +15.degree. C. 
The base 
The base of the wear layer is dry, aged concrete with suitable 
characteristics, with proper cohesion but containing irregularly 
distributed cracks. 
The whole is stabilized. 
Preparation of the base 
All of the old concrete is cleaned then carefully vacuumed in order to 
remove any non-adhering part and to make the surface uniform. 
An adhesion primer is then applied over the entire area, in a single layer. 
This primer consists of an aqueous-phase dispersion of vinyl copolymers. 
This primer is left to dry for two hours. Consumption is of the order of 
200 g per m.sup.2 of surface area. 
The smoothing layer is then applied onto the upper face of the base, in 
order to make it smooth and to eliminate all possible retention points 
therefrom. The product applied is a smoothing coating essentially based on 
cement, commercialised by the company OMNIPLASTIC under the brand name 
OMNIPLAN. This coating is chosen because of the level of its mechanical 
characteristics, which allow it to withstand the indirect load of 
industrial mechanical stresses. 
This product is applied quickly using the application pump of brand name 
SERVAPLAN, described in European Patent Application No. 92420025.6, with a 
mean thickness of 3 to 4 mm. 
The smoothing product is then left to harden for 24 hours, this time being 
sufficient for it to be able to withstand foot traffic. 
The smoothing layer is then covered with a viscous liquid product, which 
makes it possible to avoid adhesion between the wear layer and the 
smoothing layer. This product creates a strong, leaktight and completely 
non-adhesive film. It consists of petroleum derivatives in aqueous 
dispersion, commercialised under the brand name ELVECURE by the company 
CHRYSO. The consumption of this product is 150 grams per m.sup.2. 
This product is left to dry for 4 hours, to make it able to withstand being 
walked on by a person. 
After 4 hours, small elements, making it possible to support the lattice, 
are distributed at regular intervals, spaced apart by approximately 40 cm, 
on the separating means. The lattice is a glass lattice with a mesh size 
of 1 cm. This lattice is rolled out over the entire area to be treated. 
This self-adhesive lattice adheres locally to the floor and is thus 
prevented from accidentally rising. 
The covering or wear layer 
2 cm of a covering intended to form the wear layer is then poured. To do 
this, use is made of the automatic SERVAPLAN pump. Application takes 
approximately 2 hours. 
The coating used to form the wear layer is composed of: 
Portland cement: 18% to 25% 
alumina cement: 1% to 10% 
fillers: 5% to 25% 
silica sands: 35% to 65% 
organic binder: 0.5% to 5% 
fluidifier: 0.05% to 1% 
setting regulator: 0.01% to 0.3% 
Other components may be added to this formulation, with a view to improving 
the characteristics and performance of the coating (colorants, hardeners, 
retarders, etc.). 
The covering is left as it is for 18 hours, then a liquid product making it 
possible to inhibit the evaporation of water from the hydraulic covering, 
and thereby prevent it from cracking prematurely, is applied. This 
product, called a curing agent, is specially designed to allow the 
subsequent application of any other aesthetic coverings: paints, textiles, 
plastics or the like. 
The floor is left free of traffic for 48 hours, then returned to heavy use 
within 5 days without any damage: storage of 1 tonne electric motors, 
handling by lifter trucks with solid-tyre wheels. 
No cracking occurred anywhere 28 days after pouring.