Hydraulic composition for grout

Abstract

A hydraulic composition including water; a hydraulic binder; at least one setting retarder; and at least one polysaccharide; the weight ratio of the water/hydraulic binder being greater than 1.5, methods of using the composition as a mixture in a grout and a corresponding method for preparing a grout and the grout thereby obtained.

Claims

1. A hydraulic composition comprising: water; hydraulic binder; at least one setting retarder; at least one polysaccharide chosen from welan gums, diutan gums, or their mixture; the ratio by weight water/hydraulic binder being greater than 1.5.

2. The hydraulic composition according to claim 1, wherein the polysaccharide is a welan gum.

3. The hydraulic composition according to claim 1 wherein the polysaccharide is a polysaccharide having a particle size d90 less than 300 m.

4. The hydraulic composition according to claim 1 comprising from 0.1 to 5 g/L of polysaccharide.

5. The hydraulic composition according to claim 1, wherein the setting retarder is selected from the group consisting of sugars, sugar derivatives, carboxylic acids, hydroxycarboxylic acids, phosphonic acids, phosponic acid salts, and phosphates.

6. The hydraulic composition according to claim 1, wherein the water/hydraulic binder weight ratio is greater than or equal to 1.8.

7. (canceled)

8. A process for preparing a grout comprising the steps of: (a) preparing a hydraulic composition according to claim 1; and (b) adding to the composition obtained in (a) a mixture B comprising a setting accelerator.

9. The process according to claim 8, wherein the setting accelerator is selected from the group consisting of calcium nitrate, sodium nitrate, calcium nitrite, sodium nitrite, calcium thiocyanate, sodium thiocyanate, calcium formate sodium formate, aluminum sulphate and sodium silicate.

10. A two-component grout comprising the hydraulic composition according to claim 1.

11. The hydraulic composition according to claim 4 comprising from 0.3 to 2 g/L of polysaccharide.

12. The hydraulic composition according to claim 6 wherein the water/hydraulic binder weight ratio is between 2 and 10.

13. The hydraulic composition according to claim 6 wherein the water/hydraulic binder weight ratio is between 2.5 and 5.

Description

EXAMPLES

[0062] Unless otherwise indicated, all the tests described below are carried out at 20 C. and at ambient pressure.

[0063] A. Measurement of the Flow Time at the MARSH Cone

[0064] The measurement of the flow time is measured with a standardized MARSH cone (1.5 liter capacity, 4.8 mm diameter orifice) according to the following protocol derived from ASTM C939-10 (Roussel et al., Cement and Concrete). Research, 2004): [0065] Close the lower flow hole of the cone with the finger [0066] Pour the mortar through the mesh of the safety screen up to the mark (1500 mL) [0067] Pour a few ml of mortar out of the receiving container to flush out the residual water and then again close the bottom hole with the finger. [0068] Place the capacity receptacle one liter under the orifice [0069] Trigger the timer when opening the orifice [0070] Measure the time required for the flow of a liter of mortar

[0071] The result is expressed in s/L, with an intrinsic measurement uncertainty of 0.5 s/L.

[0072] B. Penetrant Measurement

[0073] As the hydraulic composition is very diluted, it tends to settle over time despite the structuring role of the bentonite. Sedimentation is evaluated with the following protocol derived from ASTM C940-10: [0074] In a 200 mL plastic graduated cylinder, introduce 200 mL of mortar A to the corresponding level. [0075] Leave the test piece at rest on a vibration-free surface [0076] At the desired times (3 h, 24 h, 48 h, and 72 h), measure the level of the water supernatant by noting the associated graduation [0077] Calculate the degree of bleeding:

R bleeding=Initial levelSupernatant level/Initial level

[0078] The bleeding result is expressed as a % by volume on an average between two measurements. Uncertainty may be estimated to 1%.

[0079] C. Polysaccharides Used in the Examples

TABLE-US-00001 TABLE 1 Granulometry (* m) Polysaccharide d90 Polysaccharide 1 Diutan gum 152 Polysaccharide 2 Wellan gum 289 Polysaccharide 3 Diutan gum 107 Polysaccharide 4 Methyl cellulose Hydroxyethyl

[0080] The particle size is measured as specified above.

[0081] The polysaccharide 4 has a viscosity, measured at 20 C. with a Rotovisko apparatus programmed on a shear rate of between 2 and 55 s.sup.1 on a 1% concentrated aqueous solution of 8600 mPa.Math.s.sup.1.

[0082] D. Mixing Compositions A According to the Invention

TABLE-US-00002 TABLE 2 Setting Hydraulic binder Quantity Test Polysaccharide retarder Cement (type) Cement (g) water (g) 1 Polysaccharide 1 EDTMP CEM I 52,5N 300 800 1.1 g/L of mixture A 2 g/L Xeuilley 2 Polysaccharide 2 EDTMP CEM I 52,5N 300 800 1.2 g/L of mixture A 2 g/L Xeuilley 3 Polysaccharide 3 EDTMP CEM I 52,5N 300 800 1 g/L of mixture A 2 g/L Xeuilley 4 Polysaccharide 4 EDTMP CEM I 52,5N 300 800 2 g/L of mixture A 2.5 g/L Xeuilley

[0083] Hydraulic compositions, mixture A, were prepared. These compositions were prepared with a Rayneri kneader equipped with a deflocculating blade according to the following procedure:

[0084] In a 5 liter bucket, the indicated amount of water was introduced. After stirring at a speed of 1500 rpm (fixed rate for the duration), the setting retarder was added and stirred for a further 30 seconds. Finally, the cement and the polysaccharide according to the invention were added and stirred for a further 30 seconds.

[0085] The respective formulation of the slurries is shown in Table 2 above.

[0086] E. Results

[0087] The following results are obtained for the hydraulic compositions corresponding to the tests 1 to 3 of the invention

TABLE-US-00003 TABLE 3 Composition Penetrant penetration test according to the Marsh cone flow time(s) (%) invention 10 min 24 h 48 h 72 h 3 h 24 h 48 h 72 h Test 1 33 41 41 39 0 0 5 10 Test 2 29 32 35 39 0 0 0 0 Test 3 32 38 50 68 0 0 0 0 Test 4 29 30 33 35 10 50 50 50

[0088] The results show that compositions 1, 2 and 3 according to the invention have a bleeding rate of less than 10% at 72 h and a satisfactory Marsh cone flow time. Test 4 shows that the polysaccharide 4 does not stabilize the mortar correctly and a large bleed is measured.

[0089] F. Gel Time Protocol

[0090] The gel time is the time that the mortar A+B takes to pass from a liquid state to a gel. The mixing protocol of mixture A with mixture B is as follows 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. published by EMS, 2012) pages 14-22: [0091] In a 1.5 liter beaker, introduce one liter of hydraulic composition (mixture A) [0092] In a second 1.5-liter beaker, introduce the desired amount of accelerator B (of the order of 8 to 10% of the mixing volume A) [0093] Trigger the timer and mix the two components by pouring from one beaker to another with a frequency of the order of a few seconds [0094] As soon as the mixture forms a gel that can no longer be decanted, stop the stopwatch and record the gel time.

[0095] The gel time is expressed in seconds and is usually between 10 and 30 seconds. The gel time for test 2 is 17 seconds and that for test 3 is 20 seconds.