The present invention relates to a hydraulic composition, preferably mortar composition, in particular for stuffing mortar, a process for its manufacture, use for the preparation of mortars and tamping the mortar thus obtained.
Tunneling through tunneling involves, after the excavation of the ground and elimination of clearing, secure the space created by placing the segments against the walls and to fix the positioning of the segments formed by filling the annular space between the wall and the segments. According to technical constraints and terrain properties, filling the annular space can be achieved with gravel (inert filler) or with mortar (cohesive filling). To avoid misalignment of the segments sag, the material is injected within seconds after application, for example from pipelines located behind the tunnel boring machine.

Tunnel construction also requires the implementation of a mastic, in particular tail joint sealant which prevents the penetration of water, the mortar, to improve the life of metal brushes tunneling, etc. It is necessary to have good compatibility between the sealant and the jam mortar. In particular, the mortar should not go up in the cracks that may exist in the putty.

The international application WO 2009/068380 discloses a hydraulic mortar for backfilling of tunnels comprising a polysaccharide and a water reducing agent. These mortars, formulated in a single component, may not however be met with stringent requirements in terms of fluidity holding time, made necessary when the site is located far from the center in which is formulated mortar or when operations maintenance require stopping the construction site for several days.

The stuffing mortar must meet a set of demanding loads.

Thus, it must be fluid enough to fill the annular space perfectly. However, it is expected that the mortar develops a compressive strength rapidly to consolidate the tunnel by stiffening the line segments.

To meet these requirements, it has been proposed a two-component mortar as a solution, also called mortar A + B. The first component, often

designated as A mixture or slurry, the hydraulic binder comprises hydrated adjuvanted a retarder outlet and a stabilizer, for example a bentonite.

Once delivered on site from the central, the mixture is mixed with a mixture B comprising a setting accelerator. Usually, the two components are mixed in the pipes just before injection. The addition of component B provides rapid solidification of the mortar once injected. Typically, the mortar becomes pasty after a few seconds. However, the gelation time has to be adjusted carefully to allow fast settling of the segments while avoiding taking in pipes and their subsequent locking.

These two component jammed mortars are generally satisfactory but still improvable in several respects.

In particular, these mortars can lack robustness and does not fulfill all the desired performance criteria when the constituent materials vary.

Thus, it is observed for some bentonites used as stabilizers of the mixture A (or slurry) low homogeneity of the suspension. When the suspension is not homogeneous, the solid particles may settle, showing a water film on the surface, a phenomenon known as bleeding.

Gold mixture A should be sufficiently stable, fluid to be fed into the annular space, typically by pumping. It is further expected that the stability and rheological properties are maintained over time its transportation and storage on site, up to 72 hours. In addition, the stuffing mortar must be compatible with the stem seal putty to ensure sealing of the segments.

An object of the invention is to provide a hydraulic composition, preferably a mortar composition for use as mixture A in the two-component mortar jam, to satisfy the requirements indicated in tunnel construction by TBM and also solves the problems mentioned above.

Another object of the invention is to propose solutions more stable over time.

Yet another object of the invention is to propose solutions to overcome the variability of clay generally used as a rheology modifier.

Also, according to a first aspect, the invention provides a hydraulic composition, preferably mortar composition comprising:

- water;

- hydraulic binder;

- at least one retarding agent;

- at least one polysaccharide;

the weight ratio water / hydraulic binder is greater than 1, 5.

In the context of the present invention, it should be understood by "x greater than" or "less than x" that the terminal x is not included.

In the context of the present invention, it should be understood by "x greater than or equal to" or "less than or equal to x" that the x terminal is included.

In the context of the present invention, it is understood by "between x and y" that the terminals x and y are included.

In the context of the present invention the polysaccharide is used as a rheology control agent. Preferably, in the context of the present invention, the polysaccharide is selected from welan gums, diutan gums, celluloses or mixtures thereof. Preferably, the polysaccharide is selected from welan gum, and diutan gums, more particularly welan gums.

Preferably the polysaccharide is selected from polysaccharides having a d90 particle size of less than 300 μηι.

Preferably, the polysaccharide is selected from welan gums, diutan gums, celluloses or a mixture thereof having a d90 particle size of less than 300 μηι. Preferably, the polysaccharide is selected from welan gum, and diutan gums, welan gums more particularly having a particle size d90 less than 300 μηι.

The d90 is the diameter of more than 90% by volume of the particles. Thus, more than 90% by volume of the particles have a diameter less than 300 μηι.

The particle size distributions of particles are measured by any method known in the art. They may especially be measured using a particle size analyzer Mastersizer 2000 MALVERN INSTRUMENT. In principle, the angular variation of the intensity of light is scattered when the laser beam passes through the sample of dispersed particles. Large particles scatter light at small angles relative to the laser beam from a red light source (Helium / Neon) of 632.8 nm wavelength and smaller particles scatter light at angles greater (source of blue light wavelength of about 466 nm.

These data are analyzed to calculate the size of the particles that created the diffraction image with the Mie theory. The particle size is then represented by the diameter of the equivalent sphere having the same volume as the particle. By convention, the optical properties required for calculations have been defined as follows:

- Sample allowance index: 1 .68

- Sample absorption Index: 0.1

- allowance index of the dispersant (air): 1 .00

Preferably, the composition according to the invention comprises from 0.1 to 5 g / l by weight of polysaccharide, preferably from 0.3 to 2 g / l by weight based on the weight of the hydraulic composition.

Advantageously, the hydraulic composition of the invention may be used as mixture A in mortars bi-component.

Is meant in the present specification by the term "set retarding agent" means a compound which has the effect, when added to a hydraulic composition, to delay hardening hydraulically setting compared to the same hydraulic composition devoid of such a agent. This retardation increases the open time of the hydraulic composition, that is to say the length of time it is always fluid and manipulable. The set retarding agent is used to maintain the rheological properties, in particular the consistency or workability, indicated by the flow value Marsh cone, for an extended period.

Suitable retarding agents for compositions according to the invention, in particular of Mixture A, there may be mentioned sugars and their derivatives, carboxylic or hydroxycarboxylic acids, phosphonic acids and their salts, phosphates.

Among the sugars that may be mentioned in particular glucose and gluconates, including sodium gluconate.

Among the carboxylic or hydroxy carboxylic acids, those with a pK A of between 2 and 5 are preferred. Particularly preferred are acetic acid, gluconic acid, citric acid, tartaric acid, malic acid and salts thereof and mixtures thereof. Citric acid and gluconic acid and salts and mixtures thereof are particularly preferred.

From phosphonic acids and their salts, amino tri methylene phosphonic acid (ATMP), ethylene diamine tetra methylene phosphonic acid (EDTMP),

acid 1 -hydroxyéthylidène -1, 1-diphosphonic acid (HEDP), and salts thereof, especially sodium, are preferred.

Among the phosphates, sodium tripolyphosphate and tetrapotassium pyrophosphate are preferred.

Preferably, the set retarding agent is selected from phosphonates, sugars, preferably gluconates.

These retarders, sodium gluconate and EDTMP and mixtures thereof are particularly interesting in terms of cost / performance. The retarding agent content of decision in the composition of the invention is preferably in the ranges conventional and is adapted to the specific constraints of each site. Preferably, the plug must not occur before 72 hours after preparation of the composition according to the invention (or mixture A). For this, the set retarding agent is preferably used at 0.1 to 2% by dry weight of the weight of hydraulic binder, preferably 0.25 to 1% by weight dry weight of the hydraulic binder.

the term means "hydraulic binder" any compound having the property to hydrate in the presence of water and hydration which provides a solid having mechanical characteristics, including a cement such as a Portiand cement, cement aluminous, pozzolanic or a calcium sulfate anhydrous or semi-hydrated cement. The hydraulic binder may be a cement according to EN197-1 standard (2001) and in particular a Portiand cement, mineral additions, including milk, or a cement comprising mineral additions.

The term "cement" cement according to EN 197-1 (2001) and especially a type CEM I, CEM II, CEM III, CEM IV or CEM V according to standard EN 197-1 Cement (2012) . The cement may include mineral additives.

The term "mineral addition" means milk (as defined in the standard EN 197-1 Cement (2012) paragraph 5.2.2), the steel slags, pozzolanic materials (as defined in the standard NF Cement EN 197-1 (2012), paragraph 5.2.3), fly ash (as defined in the standard EN 197-1 Cement (2012) paragraph 5.2.4), calcined schists (as defined in the standard NF Cement EN 197-1 (2012), paragraph 5.2.5), limestone (as defined in the standard EN 197-1 Cement (2012) paragraph 5.2.6) or fume silica (as defined in the standard Cement NF EN 197-1 (2012) paragraph 5.2.7) or mixtures thereof. Other additions, not currently recognized by the standard EN 197-1 Cement (2012) may also be used. These include metakaolins,

Preferably, the weight ratio of water / hydraulic binder is greater than or equal to 1: 8, preferably between 2 and 10, preferably between 2.5 and 5.

The hydraulic composition according to the invention may further comprise additives including a biocide and a defoamer, preferably in an amount of 0.01 to 2% by weight relative to the total weight of the composition.

The hydraulic composition according to the invention may also include clays such as sepiolite, bentonite, montmorillonite, smectite, kaolinite, chlorite, illite. Without being bound by any theory, it is assumed that clay acts as a stabilizer of the hydraulic composition for use as mixture A in mortars bicomponent. However, quite surprisingly, the inventors found that the addition of clay was not necessary in the hydraulic composition of the invention. Thus, advantageously, the hydraulic composition of the invention is free of clay.

The hydraulic composition according to the invention preferably comprises 0 to 8%, in particular 0.5 to 5% by dry weight of clay.

Preferably, the composition according to the invention is free from dispersant, such dispersant polymer, such as for example the PCP (polyalkoxylated polycarboxylate), polynaphthalene sulfonate, polymelamine sulfonate, lignosulfonate.

Another object of the present invention relates to a preparation of a mortar stuffing method comprising the steps of:

(A) preparing a hydraulic composition according to the invention; and

(B) adding to the composition obtained in (a) a mixture B comprising a setting accelerator.

The present application also relates stuffing mortar obtained or "two-component mortar."

Is meant by the term "bi-component mortar" designate hydraulic binder-based mortars formulated into two components. The component called "Mix A" has an extended workability and pumpability allowing its

routing from the central and possible storage on site. Just before placing the mixture A is mixed with the mixture B comprising a setting accelerator which ensures almost immediate gelation and is accompanied by a development of compressive strength. In the context of the present invention mixture A is the hydraulic composition described above.

The setting accelerator ensures almost immediate solidification of the mortar and a rapid increase in compressive strength, thus securing the positioning of the segments. Suitable accelerators agents include such conventional accelerators such as calcium nitrate and sodium nitrite calcium and sodium thiocyanate, calcium and sodium, calcium formate and sodium, aluminum sulphate and sodium silicate. Among these accelerators, sodium silicate is preferred.

The two-component mortar according to the invention is prepared in the usual manner from a hydraulic composition according to the invention as a mixture A and mixture B. The formulation may also if necessary comprise a clay as specified above, in particular bentonite. However, advantageously, the specific choice of the hydraulic composition of the invention as mixture A may allow to avoid the use of a clay.

The mixture B is preferably a liquid formulation comprising at least one accelerator association engaged with optional additives, for example defoamer, biocide, etc. A mixture B as an aqueous solution is particularly preferred.

Introduced in a separate step just prior to injection into the annular gap, the mixture B is metered by volume amounting to 8 to 12% of the volume of hydraulic composition according to the invention (mixture A).

The preparation of the hydraulic composition according to the invention and the mixture B and mixture thereof can be done in conventional manner.

The invention will be better understood through the specific examples given below.

[EXAMPLES]

Unless otherwise indicated, all below described tests are carried out at 20 ° C and at ambient pressure.

A. Measurement of the flow time MARSH cone

measuring the flow time is measured with a standardized MARSH cone (capacity 1, 5 liter, orifice 4.8 mm in diameter) according to the following protocol derived from ASTM C939-10 (Roussel et al., Cement and Concrete Research, 2004):

o Seal with the finger the lower orifice flow cone

o Pouring the mortar through the mesh of the sieve to the security mark (1500ml)

o take a few ml mortar out of the receiving vessel to remove residual water and then again closing the lower orifice with a finger

o Establish the capacity of receiving one liter container under the orifice

o Activate the timer at the time of opening of the orifice

o measure the time necessary for the flow of one liter of mortar

The result is expressed in s / L, with an inherent measurement uncertainty of ± 0.5 s / L.

B. Measurement ressuaqe

the hydraulic composition is very diluted, it tends to settle over time despite the pivotal role of bentonite. Sedimentation is evaluated with the following protocol derived from ASTM C940-10:

o In a graduated cylinder of 200 mL plastic, introducing 200 mL of mortar A at the corresponding mark

o Leave the specimen resting on a vibration-free area

o For the desired maturity (3 h, 24 h, 48 h and 72 h) measuring the level of the supernatant water by selecting the associated graduation

o Calculate the level of bleed:

initial scale - graduation supernatant

R essuage =

initial Graduation

The result of PT is expressed as% by volume on average between two measurements. The uncertainty can be assessed ± 1%.

C. Polvsaccharides set œuyre in Examples

Table 1

The particle size is measured as specified above.

4 the polysaccharide has a viscosity, measured at 20 ° C with a Rotovisko device programmed to a shear rate between 2 and 55 s "1 to a concentrated aqueous solution at 1%, of 8600 mPa · s " 1 .

D. A mixture of Compositions according to the invention

Table 2

Hydraulic compositions, blend A, were prepared. These compositions were prepared with a Rayneri mixer equipped with a deflocculating paddle according to the following procedure:

In a bucket of 5 liters was charged the indicated amount of water. After started stirring at a speed of 1500 revolutions per minute (constant speed for the entire duration) was added the retarding agent and stirred for an additional 30 seconds. Finally, the cement was added and then the polysaccharide according to the invention and stirred for a further 30 seconds.

The respective grout formulation is shown in Table 2 above.

E. Results

The following results are obtained for hydraulic compositions correspond to tests 1 to 3 of the invention

Table 3

The results show that compositions 1, 2 and 3 according to the invention exhibit a rate of penetrant less than 10% at 72 hours and a flow time in the Marsh cone satisfactory. Test 4 shows that the polysaccharide 4 does not stabilize properly mortar and a major bleed is measured.

F. Protocol time qélification

The gel time is the time required for the mortar A + B to change from a liquid state to a gel. The mixture mixture of Protocol A with mixture B is next and is derived from Testing Procedures for Two-Component Annulus Grouts Phil Antunes, North American Tunneling 2012 Proceedings, (Ed. Matthew Fowler, Robert Palermo, Robert Pintabona, Michael Smithson Jr. released by EMS, 2012), pages 14-22:

o In a beaker 1, 5 liter, introducing a liter of hydraulic composition (mixture A)

o In a second beaker 1, 5 liter, introducing the desired amount of accelerator

B (of the order of 8 to 10% of the volume of mixture A)

o Trigger the stopwatch and mix the two components by pouring a beaker to another with a frequency on the order of seconds

o As soon as the mixture forms a gel which can not be transferred, stop the clock and note the gel time.

The gel time is measured in seconds and is usually between 10 and 30 seconds.

The gel time for test 2 is 17 seconds and that of test 3 is 20 seconds.

CLAIMS
1. - hydraulic composition comprising:
- water;
- hydraulic binder;
- at least one retarding agent;
- at least one polysaccharide selected from welan gum, diutan the gums, or mixture thereof;
the weight ratio water / hydraulic binder is greater than 1, 5.
2. - A composition according to claim 1, wherein the polysaccharide is selected from welan gums.
3. A composition according to any one of claims 1 to 2 wherein the polysaccharide is selected from polysaccharides having a D90 particle size less than 300 μηι.
4. - A composition according to one of claims 1 to 3 comprising from 0.1 to 5 g / L, preferably 0.3 to 2 g / L of polysaccharide.
5. - A composition according to any one of claims 1 to 4, wherein the set retarding agent is selected from sugars and derivatives thereof, carboxylic or hydroxycarboxylic acids, phosphonic acids and their salts, phosphates.
6. - A composition according to any one of claims 1 to 5, wherein the weight ratio of water / hydraulic binder is greater than or equal to 1: 8, preferably between 2 and 10, preferably between 2.5 and 5 .
7. - Use of a hydraulic composition according to any one of claims 1 to 6 as a mixture A in bi-component stuffing mortars.
8. - A process for preparing a tamping mortar comprising the steps of:
(A) preparing a hydraulic composition according to any one of claims 1 to 6; and
(B) adding to the composition obtained in (a) a mixture B comprising a setting accelerator.
9. - A method according to claim 8, wherein the setting accelerator is selected from calcium nitrate and sodium nitrite, calcium and sodium, calcium thiocyanate and sodium, calcium formate and sodium , aluminum sulfate and sodium silicate.
10. - bi-component tamping mortar comprising hydraulic composition according to any one of claims 1 to 6.