DISPERSANT FOR REDUCING THE MIXING TIMES OF MINERAL BINDER SYSTEMS

Abstract

Methods of using a comb polymer K for reducing the mixing time of a mineral binder composition with water, where the comb polymer K has a polymer backbone and side chains, and the comb polymer K includes at least one monomeric unit M1, including acid groups, and at least one monomeric unit M2, including side chains, the monomeric units M1 and M2 being arranged in a non-statistical sequence along the polymer backbone.

Claims

1. A method for shortening a mixing time of a mineral binder composition with water, the method comprising: adding water to a dry mineral binder composition and a comb polymer K, and attaining a homogeneous mixture, where the mixining time is the time interval be the addition of the water to the dry mineral binder composition and the comb olymer K, and the attainment of the homogeneous mixture, and the mixing time is shortened compared to the mixing time of an identical mineral binder composition containing a comb polymer having a random sequence of the monomer units along the polymer backbone and none of the comb polymer K, and where the homogeneous mixture and the identical mineral binder composition without the comb polymer K have a comparable processability after the end of the respective mixing time necessary to obtain homogeneity; wherein the comb polymer K comprises a polymer backbone and side chains, the comb polymer K comprises at least one monomer unit M1 comprising acid groups and at least one monomer unit M2 comprising side chains, and the at least one monomer units M1 and M2 are arranged in a nonrandom sequence along the polymer backbone.

2. The method as claimed in claim 1, wherein the mixing time is shortened by at least 20%.

3. The method as claimed in claim 1, wherein the homogeneous mixture has a content of mineral binder in the range from 450 to 1600 kg/m.sup.3.

4. The method as claimed in claim 1, wherein a weight ratio of water to a mineral binder is in the range from 0.10 to 0.40.

5. The method as claimed in claim 1, wherein the dry mineral binder composition comprises flour particles, and the weight ratio of water to an amount of the flour particles present in the homogeneous mixture is in the range from 0.12 to 0.35.

6. The method as claimed in claim 1, wherein the homogeneous mixture is a high performance or ultrahigh performance concrete or a high performance or ultrahigh performance mortar.

7. The method as claimed in claim 1, wherein the homogenous mixture is a self-compacting concrete.

8. The method as claimed in claim 1, wherein the at least one monomer unit M1 has the formula I, ##STR00004## and the at least one monomer unit M2 has the formula II, ##STR00005## where the radicals le are each, independently of one another, COOM, SO.sub.2OM, OPO(OM).sub.2 and/or PO(OM).sub.2, R.sup.2 and R.sup.5 are each, independently of one another, H, CH.sub.2COOM or an alkyl group having from 1 to 5 carbon atoms, R.sup.3 and R.sup.6 are each, independently of one another, H or an alkyl group having from 1 to 5 carbon atoms, R.sup.4 and R.sup.7 are each, independently of one another, H, COOM or an alkyl group having from 1 to 5 carbon atoms, or where R.sup.1 together with R.sup.4 form a ring comprising COOCO (anhydride), the moieties M are, independently of one another, H.sup.+, an alkali metal ion, an alkaline earth metal ion, a divalent or trivalent metal ion, an ammonium ion or an organic ammonium group; m=0, 1 or 2, p=0 or 1, the moieties X are each, independently of one another, O, NH or NR.sup.8, the radicals R.sup.8 are each, independently of one another, a group of the formula -[AO].sub.nR.sup.a, where A=C.sub.2- to C.sub.4-alkylene, R.sup.a is H, a to C.sub.20-alkyl group, -cyclohexyl group or -alkylaryl group, and n=2 to 250.

9. The method as claimed in claim 1, wherein a molar ratio of the at least one monomer unit M1 to the at least one monomer unit M2 in the comb polymer K is in the range from 0.5 to 6.

10. The method as claimed in claim 1, wherein the comb polymer K has a polydispersity of less than 1.5.

11. The method as claimed in claim 1, wherein the comb polymer K is a block copolymer or a copolymer having a gradient structure.

12. The method as claimed in claim 1, wherein the mineral binder composition further comprises at least one member selected from the group consisting of a dispersant and a further comb polymer, where the monomer units of the further comb polymer are distributed purely randomly along the polymer backbone.

13. A process for producing a concrete or mortar, the process comprising; mixing a dry mineral binder composition with water and a comb polymer K to form a homogeneous binder composition, wherein the comb polymer K comprises a polymer backbone and side chains, where the comb polymer K comprises at least one monomer unit M1 comprising acid groups and at least one monomer unit M2 comprising side chains, wherein the at least one monomer units M1 and M2 are arranged in a nonrandom sequence along the polymer backbone; wherein a mixing time of the homogenous binder composition containing the comb polymer K is reduced, by at least 20%, in particular by at compared to a mixing time of a mineral binder composition containing a comb polymer having a random sequence of the monomer units along the polymer backbone and no comb polymer K, where the homogenous binder composition and the mineral binder composition with no comb polymer K have an identical composition except for the comb polymer and have a comparable processability after the end of the respective mixing time necessary to obtain homogeneity, where the homogenous binder composition is a self-compacting concrete, a high performance concrete, an ultrahigh performance concrete or a high performance or ultrahigh performance mortar, wherein the homogenous binder composition has a content of mineral binder of more than 350 kg/m.sup.3, a content of flour particles of from 450 to 2000 kg/m.sup.3 and a weight ratio of water to mineral binder of from 0.1 to 0.4.

14. A mineral binder composition mixed with water, the mineral hinder composition containing at least one comb polymer K, wherein the mineral binder composition is a self-compacting concrete, a high performance concrete, an ultrahigh performance concrete or a high performance or ultrahigh performance mortar, wherein the mineral binder composition mixed with water has a content of mineral binder of more than 350 kg/m.sup.3, a content of flour particles of from 450 to 2000 kg/m.sup.3 and a weight ratio of water to mineral binder of from 0.1 to 0.4: wherein the at least one comb polymer K comprises a polymer backbone and side chains where the at least one comb polymer K comprises at least one monomer unit M1 comprising acid groups and at least one monomer unit M2 comprising, side chains, wherein the at least one monomer units M1 and M2 are arranged in a nonrandom sequence along the polymer backbone.

15. A shaped body, the shaped body being obtained by curing the mineral binder composition as claimed in claim 14.

Description

EXAMPLES

[0173] 1. Determination of molecular weight and Polydispersity of the Polymers and also the Solids Content of the Polymer Solutions

[0174] The weight average molecular weight M.sub.W and the polydispersity of the polymers were determined by gel permeation chromatography (GPC) using polyethylene glycol (PEG) as standard.

[0175] Column cascade used: three 8300 mm Suprema GPC columns (10 m, 21000 , 130 , with precolumn), from PSS Polymer Standards Service, Germany

[0176] Eluent: 0.1N NaNO.sub.3 solution, the pH of which has been set to 12 by means of NaOH

[0177] Flow rate: 0.8 ml/min

[0178] Detector: RI detector 2414 from Waters, USA

[0179] Temperature of column ovens and detector: 45 C.

[0180] The evaluation was carried out using the evaluation software Waters Breeze 2 (Waters, USA) as method relative to polyethylene oxide standard (PSS Polymer Standards Service, Germany).

[0181] The solids content of the polymer solutions was determined using a halogen drier model HG 63 from Mettler Toledo, Switzerland.

[0182] 2. Production of the Polymers

[0183] 2.1 Block Copolymer P1

[0184] To produce the block copolymer P1 by means of RAFT polymerization, 57.4 g of a 50% strength by weight aqueous solution of methoxypolyethylene glycol 1000 methacrylate (0.03 mol; average molecular weight of the polyethylene glycol 1 000 g/mol) and 30.1 g of deionized water were placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer and an inert gas inlet tube. The reaction mixture was heated to 80 C. while stirring vigorously. A gentle inert gas stream (N.sub.2) was passed through the solution during heating-up and the entire remaining reaction time.

[0185] 756 mg of 4-cyano-4-(thiobenzoyl)pentanoic acid (2.7 mmol; RAFT agent) were then added to the mixture. After the substance had completely dissolved, 135 mg of azobisisobutyronitrile (0.82 mmol; initiator) were added. From then on, the conversion was determined at regular intervals by means of HPLC.

[0186] As soon as the conversion, based on methoxypolyethylene glycol methacrylate, was more than 80 mol %, 9.32 g of methacrylic acid (0.11 mol) were added to the reaction mixture. The mixture was allowed to react for a further 2 hours and subsequently to cool. A clear, slightly reddish, aqueous solution remained. The solids content of the solution was set to 30% by weight by addition of water.

[0187] The molar ratio of methacrylic acid to methoxypolyethylene glycol methacrylate is 3.7. The molecular weight M.sub.W of the polymer is 24 000 g/mol and the polydispersity is 1.2.

[0188] 2.2 Random Copolymer P2

[0189] 22 g of methoxypolyethylene glycol 1000 methacrylate (0.021 mol, average molecular weight of the polyethylene glycol 1 000 g/mol), 129 g of methoxypolyethylene glycol 3000 methacrylate (0.042 mol, average molecular weight of the polyethylene glycol 3 000 g/mol), 26.6 g (0.37 mol) of acrylic acid and 188 g of water were mixed in a reservoir. In a second reservoir, 1.9 g (0.01 mol) of Na.sub.2S.sub.2O.sub.5 were dissolved in 25 g of water, and 2.4 g (0.01 mol) of Na.sub.2S.sub.2O.sub.8 were dissolved in 25 g of water in a third reservoir. 100 g of water were placed in a multineck flask provided with reflux condenser, mechanical stirrer, thermometer and inlet for the solutions and heated to 90 C. While stirring and heating to 85-90 C., the solutions from the reservoirs were metered in simultaneously and uniformly via separate inlets over a period of 4 hours by means of metering pumps. After the metered addition was complete, the reaction mixture was stirred at 85-90 C. for a further 30 minutes. After cooling, the pH of the solution was set to 5 by addition of a 30% strength by weight NaOH solution. The solids content of the solution was set to 30% by weight by addition of water.

[0190] The molar ratio of acid monomer to methoxypolyethylene glycol methacrylate is 5.9. The molecular weight M.sub.W of the polymer is 32 000 g/mol and the polydispersity is 2.4.

[0191] 2.3 Random Copolymer P3

[0192] Copolymer P3 was obtained by polymer-analogous esterification of a copolymer of acrylic acid and methacrylic acid (average molecular weight Mw of about 4 000) with methoxypolyethylene glycol 3000 (polyethylene glycol terminated at one end by a methoxy group and having an average molecular weight Mw of 3000). The solids content of the solution was set to 30% by weight by addition of water.

[0193] The molar ratio of acid groups to polyethylene glycol chains in the polymer is 4.5. The molecular weight M.sub.W of the polymer is 48 000 g/mol and the polydispersity is 2.4.

[0194] 2.4 Random Copolymer P4

[0195] Copolymer P4 was obtained by polymer-analogous esterification of a copolymer of acrylic acid and methacrylic acid (average molecular weight Mw of about 4 000) with methoxypolyethylene glycol 1000 (polyethylene glycol terminated at one end by a methoxy group and having an average molecular weight Mw of 1000) and methoxypolyethylene glycol 3000 (polyethylene glycol terminated at one end by a methoxy group and having an average molecular weight Mw of 3000). The solids content of the solution was set to 20% by weight by addition of water.

[0196] The molar ratio of acid groups to polyethylene glycol chains in the polymer is about 1.6. The molecular weight M.sub.W of the polymer is 30 000 g/mol and the polydispersity is 2.6.

[0197] 3. Tests in concrete mixtures

[0198] 3.1 Production of the concrete mixture and measurement methods for trial 1 and trial 2

[0199] Concrete production: Cement, silica dust, sand and gravel were mixed for 15 seconds in a twin-screw mixer and the water in which the polymer had been dissolved was subsequently added. The concrete was subsequently mixed until a homogeneous, readily flowing consistency had been attained and the mixing time required for this was noted. The fresh concrete properties were subsequently determined. All concrete mixtures were prepared using one and the same concrete mixer.

[0200] The mixing time was determined as follows:

[0201] After addition of the water containing the comb polymer, the concrete was mixed for 60 seconds and the homogeneity and consistency were determined visually and by means of shoveling by hand. If necessary, mixing was continued and the homogeneity and consistency was tested at regular intervals. In this way, it was assessed whether the mixture was dry or moist, inhomogeneous or homogeneous or stiff or soft and flowable. The mixing time is the time interval between the addition of water and attainment of homogeneous, soft and flowable consistency of the concrete, with only the pure mixing time without stoppage times being counted.

[0202] The air content of the concrete mixture was determined in accordance with JIS A 1128.

[0203] The slump flow was determined in accordance with JIS A 1150.

[0204] The 50 cm flow time is determined together with the slump flow and is the time required by the concrete in order to attain a diameter of 50 cm after lifting up the slump cone.

[0205] The L-flow test indicates the flow velocity of the concrete and is a measure of the concrete viscosity. It was measured in accordance with JSCE-F-514.

[0206] Setting commencement and end of setting of the concrete were determined by means of a penetration test in accordance with JIS A 1147 on a mortar sample obtained by sieving of the concrete.

[0207] 3.2 Trial 1

[0208] The concrete mixture used for test purposes in trial 1 has the composition described in Table 1.

TABLE-US-00001 TABLE 1 Component kg/m.sup.3 Moderate heat cement* 1030 Silica dust 77 Crushed sand having a fineness modulus of 350 3.01 Gravel having a maximum size of 20 mm 863 Water (including the comb polymer solution) 155 Antifoam 0.03 Comb polymer corresponding to Table 2 As per Table 2 *Cement having a low heat of hydration (low content of C3S)

[0209] Table 2 shows the comb polymers used and the amounts thereof which are added and also the mixing times required for homogeneous mixing and the fresh concrete properties of the concrete mixtures.

TABLE-US-00002 TABLE 2 Point in time of measurement** Reference 1 Example 1 Example 2 Polymer P2 P1 P1 Amount added (%)* 1.6 1.6 1.26 Mixing time (min.) 9 5 5 Reduction in the mixing 56 56 time compared to the reference (%) Slump flow (cm) 0 min 65 79 73 30 min 66 72 60 min 67 69 50 cm flow time (sec.) 0 min 22.9 9.7 16.6 30 min 30.2 21.0 60 min 34.2 27.6 L-flow test (cm/sec.) 0 min 2.7 6.8 4.2 Air (%) 0 min 1.4 1.3 1.3 Setting commencement 11:15 14:40 11:10 (hh:mm) End of setting (hh:mm) 12:40 15:45 12:30 *% by weight of polymer solution based on weight of binder (cement plus silica dust) **time elapsed after end of mixing

[0210] 3.3 Trial 2

[0211] The concrete mixture used for test purposes in trial 2 has the composition described in Table 3.

TABLE-US-00003 TABLE 3 Component kg/m.sup.3 Moderate heat cement* 773 Crushed sand having a fineness modulus of 678 3.01 Gravel having a maximum size of 20 mm 819 Water (including the comb polymer solution) 170 Antifoam 0.03 Comb polymer solution corresponding to Table As per Table 4 4 *Cement having a low heat of hydration (low content of C3S)

[0212] Table 4 shows the comb polymers used and the amounts thereof which are added and also the mixing times required for homogeneous mixing and the fresh concrete properties of the concrete mixtures.

TABLE-US-00004 TABLE 4 Point in time of measurement** Reference2 Example3 Example4 Polymer P3 P1 P1 Amount added (%)* 1.14 1.14 0.95 Mixing time (min.) 4.0 2.5 2.5 Reduction in the mixing 62.5 62.5 time compared to the reference (%) Slump flow (cm) 0 min 67 90 79 50 cm flow time (sec.) 0 min 6.7 5.1 7.3 Air (%) 0 min 1.2 0.5 0.5 Setting commencement 4:55 n.m. 3:50 (hh:mm) End of setting (hh:mm) 7:09 n.m. 6:00 *% by weight of polymer solution based on weight of cement **time elapsed after end of mixing n.m. . . . not measured

[0213] 3.4 Production of the Concrete Mixture and Measurement Methods for Trial 3

[0214] Concrete production: Cement, slag sand, silica dust and sand were mixed for 30 seconds in a mechanical mixer and the water in which the polymer had been dissolved was subsequently added. The concrete was subsequently mixed for 6 or 3 minutes, as shown in Table 6. The fresh concrete properties were subsequently determined. All concrete mixtures were prepared using one and the same concrete mixer.

[0215] The slump flow was determined in accordance with DIN-EN 12350-2 immediately after mixing and after 30 minutes.

[0216] The homogeneity of the mixture after the prescribed mixing time was assessed visually and evaluated with grades from 1 to 5, where 1 means inhomogeneous and 5 means completely homogeneous.

[0217] The processability of the mixture after the prescribed mixing time was assessed by manual shoveling of the concrete and assessment of the resistance and the viscosity and evaluated with grades from 1 to 5, where 1 means very hard and viscous and 5 means very soft and with good flow and the values 2, 3 and 4 mean corresponding intermediate stages.

[0218] 3.5 Trial 3

[0219] The concrete mixture used for test purposes in trial 3 has the composition described in Table 5.

TABLE-US-00005 TABLE 5 Component kg/m.sup.3 Cement (CEM I 42.5) 325 Slag sand 150 Silica dust 50 Sand 0-16 mm (contains 6.4% by weight of 1760 particles below 0.125 mm) Water* 140 Comb polymer solution corresponding to As per Table 6 Table 6 *including the comb polymer solution

[0220] Table 6 shows the comb polymers used and the amounts thereof which are added and also the mixing times and the fresh concrete properties of the concrete mixtures.

TABLE-US-00006 TABLE 6 Reference 3 Example 5 Amount of polymer P1 0 2.75 added (%)* Amount of polymer P3 2.75 0 added (%)* Amount of polymer P4 1.3 1.3 added (%)* Mixing time wet (min.) 6 3 Slump flow immediate (cm) 69 78 Slump flow after 30 min. (cm) 70 70 Processability 2 2 Homogeneity 5 5 *% by weight of polymer solution based on weight of cement