Bag and its use to provide admixture for a hydraulic composition

Abstract

A bag is used to provide an admixture for a hydraulic composition, wherein a wall of the bag includes a layer, the layer including a water-soluble polymer, and wherein an admixture is present in the wall of the bag.

Claims

1. A method comprising utilizing a bag to provide an admixture for a hydraulic composition, wherein a wall of the bag comprises a layer, said layer comprising a water-soluble polymer, the water-soluble polymer comprising a film-forming polymer which is a polyvinyl alcohol having a melting temperature from 155 to 185 C. and a melt flow rate higher than 3.0 g/10 min under 2.16 kg at 230 C. as measured according to the method described in the NFT 51-016 Standard, and wherein the admixture for the hydraulic composition is present in the wall of the bag.

2. The method according to claim 1, wherein the wall of the bag comprises the or another water-soluble polymer which comprises the or another admixture.

3. The method according to claim 1, wherein the bag comprises an internal layer which comprises a water-soluble polymer, and an external layer which is insoluble in water.

4. The method according to claim 1, wherein the bag contains cement, aggregates and/or mineral additions.

5. The method according to claim 1, wherein the film-forming polymer has a melting temperature and/or a melt flow rate such that at least 80% by mass of the bag dissolves after 10 minutes of mixing in a concrete mixer.

6. The method according to claim 1, wherein the admixture comprises a clay-inerting agent.

7. The method according to claim 6, wherein the clay-inerting agent comprises a water-soluble polyvinyl alcohol having a viscosity of 8 to 45 mPa.Math.s measured at 20 C. in an aqueous solution comprising 4% by mass of dry extract in a Hoppler viscosimeter according to the DIN 53015 Standard.

8. The method according to claim 1, wherein the admixture comprises an air-entraining agent.

9. The method according to claim 8, wherein the air-entraining agent comprises a water-soluble polyvinyl alcohol having a hydrolysis rate less than 98%.

10. A process for the production of a hydraulic composition comprising water, aggregates and a hydraulic binder, wherein a bag as described in claim 1 is used.

11. A bag to provide an admixture for a hydraulic composition, the bag comprising a wall that comprises a layer, said layer comprising a water-soluble polymer, the water-soluble polymer comprising a film-forming polymer which is a polyvinyl alcohol having a melting temperature from 155 to 185 C. and a melt flow rate higher than 3.0 g/10 min under 2.16 kg at 230 C. as measured according to the method described in the NFT 51-016 Standard, and wherein the admixture for the hydraulic composition is present in the wall of the bag.

Description

EXAMPLES

Raw Materials

(1) The following materials were used in the following examples: Cement: cement of type CEM I 52.5 N CE CP2 NF (from Le Havre-Lafarge plant). Limestones: Limestone 1: limestone which comprises approximately 90% by mass passing through the 100 m sieve (Supplier: OMYA; brand name: Betocarb HP Entrain); Limestone 2: limestone which comprises approximately 90% by mass passing through the 100 m sieve (Supplier: OMYA; brand name: Betocarb HP Erbray). Clays: Clay 1: Montmorillonite from Sardinia (Supplier: Socodis; brand name: MCC3); Clay 2: Illite from Le Puy (Supplier: Socodis); Clay 3: Kaolinite (Supplier: AGS; brand name: BS3). Aggregates: the materials from the following list were used (the ranges of aggregates are given in the list in the form of d/D wherein <<d>> and <<D>> are as defined in the XPP 18-545 Standard): Sand 1: siliceous sand with a diameter less than or equal to 0.315 mm (Supplier: Fulchiron; brand name: PE2LS); Sand 2: 0/1 rounded siliceous sand from the St Bonnet quarry; (Supplier: Lafarge); Sand 3: 0/5 rounded siliceous sand from the St Bonnet quarry; (Supplier: Lafarge); Standardized sand: siliceous sand conforming with the EN 196-1 Standard (Supplier: Socit Nouvelle du Littoral); Coarse aggregate: 5/12 rounded siliceous aggregate from the St Bonnet quarry; (Supplier: Lafarge); and Coarse aggregate 2: 12/20 siliceous aggregate from the St Bonnet quarry; (Supplier: Lafarge). Superplasticizer: SP: polycarboxylate superplasticizer (Supplier: Chryso; brand name: Optima 206). Thermoplastic polyvinyl alcohols (PVA): PVA-1: PVA having a melting temperature of 159 C. and a melt flow index from 13.0 to 19.0 g/10 min under 2.16 kg at 190 C. (Supplier: Kuraray; brand name: LP TC 251); PVA-2: PVA having a melting temperature of 182 C. and a melt flow index from 3.5 to 4.5 g/10 min under 2.16 kg 230 C. (Supplier: Kuraray; brand name: LP TC 661); PVA-3: PVA having a viscosity of 4.0 mPa.Math.s and a hydrolysis rate of 88%; solution having 9.3% of PVA by dry mass and 1% of anti-foaming agent by mass relative to the PVA (Supplier: Air Product; brand name: Surfynol MD20); PVA-4: PVA having a viscosity of 40.0 mPa.Math.s and a hydrolysis rate of 88%; solution having 3.8% of PVA by dry mass and 1% of anti-foaming agent by mass relative to the PVA (Supplier: Air Product; brand name: Surfynol MD20); PVA-5: PVA having a viscosity of 23.0 mPa.Math.s and a hydrolysis rate of 88% (Supplier: Kuraray);

Example 1

Measurement of the Dissolution of a Film of Polymer in a Mortar

(2) Measurement of the dissolution was carried out on an equivalent microconcrete, the formula of which is given in Table 1 below.

(3) TABLE-US-00001 TABLE 1 Formula of mortar for Example 1 Components Mass (g) Cement 479.7 Limestone 1 358.8 Standardized sand 1350 Sand 1 200 Total water 324.4 SP 2.88

(4) The tested PVA films were bought directly in the form of films produced by extrusion. The PVA films were cut into square pieces, 8.9 cm by 8.9 cm, for the dissolution tests.

(5) TABLE-US-00002 TABLE 2 Mixing procedure Start time Final time Actions 0:00 0:30 Add 93 g of pre-wetting water and sands whilst stirring at low speed (140 rpm) 0:30 1:00 Mix at low speed 1:00 5:00 Leave to rest 5:00 6:00 Add the cement, the Limestone 1 and the PVA film, and mix at low speed 6:00 6:30 Add the mixing water (231.4 g) whilst stirring at low speed 6:30 8:00 Mix at low speed 8:00 9:00 Add the SP and mix at low speed 9:00 10:00 Mix at high speed (280 rpm) 10:00 Measure the spread 12:00 14:00 Mix at high speed 15:00 Measure the spread

(6) The batches were made in a Perrier mixer.

(7) The spread measurement was carried out in a truncated bottomless mould, which is a reproduction at the scale of the Abrams cone (refer to the NF P 18-451 Standard of 1981): Top diameter: 50+/0.5 mm; Bottom diameter: 100+/0.5 mm; Height: 150+/0.5 mm.
The other equipment required for this measurement was a glass plate and a steel rod with a spherical tip having a diameter of 6 mm and a length of 300 mm.

(8) The procedure for the spread measurement was the following: place the cone on the glass plate; fill the cone in three layers of identical volumes and tap the mortar 15 times with the rod between each layer; level the top surface of the cone; lift the cone vertically; measure the spread, that is to say, the diameter of the obtained disc of mortar, according to four diameters at 45 using a calliper square.
The result of the spread measurement was the average of the four obtained values.

(9) After the last spread measurement the mortar was placed in a bucket filled with cold water. The mix was stirred using a big spoon, then the supernatant was passed through a 2 mm sieve. The operation was renewed four times. The quantity of PVA film remaining on the sieve was then determined. The results are given in Table 3 below.

(10) TABLE-US-00003 TABLE 3 Results of the dissolution of two PVAs in a mortar PVA Evaluation of the dissolution PVA-1 100% dissolution PVA-2 95 to 98% dissolution

(11) According to Table 3 hereinabove, the tested PVAs (PVA-1 and PVA-2) dissolved satisfactorily in the mortar (more than 80% dissolution).

Example 2

Inerting Tests with PVAs

(12) The inerting performances of two PVAs (PVA-3 and PVA-4) were evaluated from the mortar spread values with or without the presence of clay. Clay inerting agents generally make it possible to at least partially neutralise deleterious effects due to the presence of clay in a hydraulic composition, in particular on the superplasticizers.

(13) Table 4 below, lists the formulae of the tested mortars.

(14) TABLE-US-00004 TABLE 4 Formulae of tested mortars for Example 2 Test 1 Test 2 Test 3 Test 4 Components Mass (g) Mass (g) Mass (g) Mass (g) Cement 480.0 480.0 480.0 480.0 Limestone 2 359.0 359.0 359.0 359.0 Standardized sand 1350.0 1350.0 1350.0 1350.0 Sand 1 200 169 169 169 Clay 1 0.0 10.3 10.3 10.3 Clay 2 0.0 10.3 10.3 10.3 Clay 3 0.0 10.3 10.3 10.3 Pre-wetting water 100.8 100.8 22.5 70.5 Mixing water 222.1 222.1 222.1 222.1 SP 4.5 4.5 4.5 4.5 PVA (in the form 0.0 0.0 81.4 33.3 of a solution) (PVA-4) (PVA-3)

(15) The procedure for the production of the mortar is given in Table 5 below.

(16) TABLE-US-00005 TABLE 5 Procedure for production of the mortar for Example 2 Start time Final time Actions 0:00 0:30 Add 93 g of pre-wetting water and sands whilst stirring at low speed (140 rpm) 0:30 1:00 Mix at low speed 1:00 5:00 Leave to rest 5:00 6:00 Add the cement, the Limestone 2 and Clays, and mix at low speed 6:00 6:30 Add the mixing water (231.4 g) and PVA whilst stirring at low speed 6:30 8:00 Mix at low speed 8:00 9:00 Add the SP and mix at low speed 9:00 10:00 Mix at high speed (280 rpm) 10:00 Measure the spread 12:00 30:00 Mix at high speed 30:00 Measure the spread

(17) The spread measurements were carried out at 10 minutes and 30 minutes following the same procedure as for Example 1. The density was measured at 10 minutes from the specific gravity determined according to the procedure described below in Example 3.

(18) Table 6 below gives the results.

(19) TABLE-US-00006 TABLE 6 Results of the inerting tests Spread Spread at 10 min at 30 min Density Test (mm) (mm) at 10 min 1 360 380 2.28 2 165 110 3 255 230 2.28 4 325 280 2.28

(20) According to Table 6 hereinabove, when comparing Test 1 with Test 2, the addition of clay without PVA had a negative impact on the spread and rheological retention. The spread at 10 minutes did decrease from 360 mm to 165 mm. Furthermore, the spread between 10 and 30 minutes for Test 1 increased by 20 mm, whilst the spread between 10 and 30 minutes for Test 2 decreased by 55 mm.

(21) The spread at 10 minutes improved in Test 3 (presence of PVA-4) with 255 mm compared to Test 2 (absence of PVA) with 165 mm. The spread loss between 10 and 30 minutes was only 25 mm for Test 3. In contrast, it should be noted that the value of 255 mm spread at 5 minutes was good. The spread at 10 minutes improved in Test 4 (presence of PVA-3) with 325 mm compared to Test 2 (absence of PVA) with 165 mm. The spread loss in Test 4 between 10 and 30 minutes was 45 mm, but the spread at 30 minutes was 280 mm, which is a satisfactory value.

Example 3

Air-Entrainment Tests with PVAs

(22) The air-entraining performance of a PVA (PVA-5) was evaluated.

(23) The formula of the micro concrete on which the tests were carried out was the same as the formula in Example 1 (see Table 1).

(24) Table 7 below, provides the densities for each of the constituents of the tested mortar.

(25) TABLE-US-00007 TABLE 7 Determination of the density of each of the constituents of the tested mortar in Example 3. Components Mass (g) Volume (ml) Density Cement 479.7 152.29 3.15 Limestone 1 358.8 131.43 2.73 Standardized sand 1350 509.43 2.65 Sand 1 200 74.88 2.67 Total water 324.4 319.17 1.02 SP 2.88

(26) The production procedure of the mortar is given in Table 8 below.

(27) TABLE-US-00008 TABLE 8 Production procedure of the mortar for Example 3 Start time Final time Actions 0:00 0:30 Add 93 g of pre-wetting water and sands whilst stirring at low speed (140 rpm) 0:30 1:00 Mix at low speed 1:00 5:00 Leave to rest 5:00 6:00 Add the cement, the Limestone 1 and mix at low speed 6:00 6:30 Add the mixing water (231.4 g) and PVA whilst stirring at low speed 6:30 8:00 Mix at low speed 8:00 9:00 Add the SP and mix at low speed 9:00 10:00 Mix at high speed (280 rpm) 10:00 or 30:00 Measure the spread and the density

(28) The spread measurement procedure was the same procedure as the one described in Example 1.

(29) The principle of the entrained air measurement was the following. It was possible to calculate the theoretical density of the mortar without air when knowing the density of each of the mortar's constituents (see Table 7). The density of the mortar comprising a PVA was measured following the procedure described hereinafter. It was possible to deduce the quantity of entrained air by calculating the difference between the measured density and the theoretical density.

(30) The measurement procedure of the entrained air was the following: slowly pour mortar in a 732-ml plastic beaker of known mass; gently tap the bottom of the beaker on the work top to settle the mortar as it is poured; add a slight excess of mortar; level the mortar using a metal ruler; wipe the edges of the beaker and weigh it; deduce the density, then the percentage of air for comparisons between the theoretical density and the measured density.

(31) The obtained results are given in Table 9 below.

(32) TABLE-US-00009 TABLE 9 Results of the measurements of entrained air with PVA Entrained PVA/ Spread at Spread at air/mortar Cement 10 minutes 30 minutes at 10 minutes (ppm) (mm) (mm) (mass %) PVA-5-1 0 320 289 0.86 PVA-5-2 100 335 302 6.88 PVA-5-3 200 338 331 5.6 PVA-5-4 500 339 319 9.29 PVA-5-5 1000 312 313 16.01

(33) According to Table 9 hereinabove, PVA-5 gave satisfactory values of entrained air. For an addition of 100 ppm of PVA-5, the obtained mortar had 6.88% of entrained air.

Example 4

Tests with Water-Soluble Bags

(34) Water-soluble bags were produced by thermal welding using films of PVA-1. Three thicknesses of film were tested (Bag-1: 100 m, Bag-2: 75 m and Bag-3: 50 m).

(35) 45 liters of concrete were produced in a concrete mixer. The formulation of the concrete was reported in Table 10 below. The production procedure of the concrete was reported in Table 11 below.

(36) A control concrete was produced without a bag of PVA. The other concretes (Concrete-1, Concrete-2 and Concrete-3) were produced from Bag-1, from Bag-2 and from Bag-3 respectively, comprising 13.51 kg of Cement.

(37) TABLE-US-00010 TABLE 10 Formulation of concrete for Example 4 Quantity for 45 L Materials (kg) Cement 13.51 Sand 1 3.76 Sand 2 18.09 Sand 3 20.55 Coarse aggregates 1 8.67 Coarse aggregates 2 32.71 Total water 8.24 including the pre-wetting water 3.37 including the mixing water 4.87

(38) TABLE-US-00011 TABLE 11 Production procedure of the concrete for Example 4 Start time Final time Action Put the sands and aggregates in a concrete mixer. 0 0 min 30 Start up the concrete mixer at 20 rpm and add the pre-wetting water. 0 min 30 1 min 00 Mix at 20 rpm. 5 min 00 6 min 00 Add the cement or the bag of cement and mix at 20 rpm. 6 min 00 6 min 30 Add the mixing water 6 min 30 12 min 00 Mix at 20 rpm.
AMechanical Loading and Handling Resistance of the Bags

(39) The three bags (Bag-1, Bag-2 and Bag-3) were manually loaded with 13.51 kg of cement and were handled in a typical manner (lift, carry and lay).

(40) Bag-1, which had a thickness of 100 m, was the most satisfactory in terms of its mechanical resistance to loading and handling. The bag was not torn.

(41) Bag-2, which had a thickness of 75 m, resisted to the test without being torn, but appeared to be near the tearing point. It was nevertheless considered to be satisfactory.

(42) Bag-3, which had a thickness of 50 m and a single layer was not thick enough to bear 13.51 kg of cement. The film was found to have stretched.

(43) BConcrete Spreads and Entrained Air

(44) The concretes obtained by following the procedure in Table 11 hereinabove were tested for their spread and their quantity of entrained air. The spread was measured according to the procedure described in the above examples. The quantity of entrained air was measured with a concrete air meter (Supplier: Controlab). The results were given in Table 12 below.

(45) TABLE-US-00012 TABLE 12 Results in terms of spread and entrained air for Example 4 Spread at Spread at Entrained air Concrete 15 min (cm) 30 min (cm) (mass %) Control 17.5 13.5 1.60 Concrete-1 20.0 16.0 5.85 Concrete-2 19.5 18.0 4.80 Concrete-3 19.0 16.5 4.25

(46) According to Table 12 hereinabove, the three tested bags made it possible to improve the spread and the quantity of entrained air of the concretes.

(47) Moreover, the three bags dissolved in a satisfactory manner during mixing in the concrete mixer.