USE OF COMB POLYMERS AS INERTING AGENTS FOR NON-SWELLING LAYER- SILICATES

Abstract

Use of a comb polymer as an inerting agent for non-swelling layer-silicates, the comb polymer including: a) at least one poly(alkylene oxide) side chain-bearing monomer unit M1 without ionic groups, b) optionally at least one cationic monomer unit MC, wherein the molar ratio of the cationic monomer units MC to the side chain-bearing monomer units M1 is equal to or less than 0.1, preferably less than 0.05, c) optionally at least one anionic monomer unit MA, wherein the molar ratio of the anionic monomer units MA to the side chain-bearing monomer units M1 is less than 1, preferably equal to or less than 0.5, and c) optionally at least one non-ionic monomer unit M3, wherein the molar ratio of the non-ionic monomer units M3 to the side chain-bearing monomer units M1 is less than 7, preferably equal to or less than 3.

Claims

1. A method comprising adding a comb polymer to a mineral binder composition containing non-swelling layer-silicates and a dispersant, the comb polymer being added in an amount effective such that the comb polymer acts as an inerting agent for the non-swelling layer-silicates and improves the effect of the dispersant in the mineral binder composition, said comb polymer comprising: a) at least one poly(alkylene oxide) side chain-bearing monomer unit M1 without ionic groups, b) optionally at least one cationic monomer unit MC, wherein the molar ratio of the cationic monomer units MC to the side chain-bearing monomer units M1 is equal to or less than 0.1, c) optionally at least one anionic monomer unit MA, wherein the molar ratio of the anionic monomer units MA to the side chain-bearing monomer units M1 is less than 1, and d) optionally at least one non-ionic monomer unit M3, wherein the molar ratio of the non-ionic monomer units M3 to the side chain-bearing monomer units M1 is less than 7.

2. The method of claim 1, wherein the side chain-bearing monomer unit M1 includes a structure of the formula I ##STR00010## wherein R.sup.1, and R.sup.2, in each case independently, are H or an alkyl group having 1 to 5 carbon atoms, R.sup.3, in each case independently, is H, an alkyl group having 1 to 5 carbon atoms, or mixtures thereof, or a group with formula —(CH.sub.2).sub.m—[C═O].sub.p—X—R.sup.4, m=0, 1 or 2, p=0 or 1, X, in each case independently, is —O— or —NH—, R.sup.4 is a group of the formula -[AO].sub.n—R.sup.a where A=C.sub.2- to C.sub.4-alkylene, R.sup.a is H, a C.sub.1- to C.sub.20-alkyl group, -cycloalkyl group or -alkylaryl group, and n=2-250.

3. The method of claim 1, wherein the cationic monomer unit MC in the polymer includes a monomer which has a structure of the formula II, ##STR00011## wherein R.sup.5, in each case independently, is -[D].sub.d-[E].sub.e—F, with D=—(COO)— and/or —(CONH)—, E=an alkylene group having 1 to 5 carbon atoms, F═—N.sup.+ R.sup.10R.sup.11R.sup.12, —S.sup.+ R.sup.10R.sup.11R.sup.12, and/or —P.sup.+ R.sup.10R.sup.11R.sup.12, wherein R.sup.10, R.sup.11 and R.sup.12 are independently of one another H, an aliphatic hydrocarbon moiety having 1 to 20 C atoms, a cycloaliphatic hydrocarbon moiety having 5 to 8 C atoms and/or an aryl moiety having 6 to 14 C atoms; whereby d=0 or 1, e=0 or 1, and R.sup.6, R.sup.7 and R.sup.8, in each case independently, are H or an alkyl group having 1 to 5 carbon atoms.

4. The method of claim 1, wherein the anionic monomer unit MA in the polymer includes a monomer which has a structure of the formula III, ##STR00012## wherein R.sup.13, in each case independently, is —COOM, —SO.sub.2—OM, O—PO(OM).sub.2 and/or —PO(OM).sub.2, R.sup.14 and R.sup.15, in each case independently, are H or an alkyl group having 1 to 5 carbon atoms, R.sup.16, in each case independently, are H, —COOM or an alkyl group having 1 to 5 carbon atoms, or where R.sup.13 forms a ring together with R.sup.16 to give —CO—O—CO—, and M independently from each other is H.sup.+, an alkali metal ion, an alkaline earth metal ion, a di- or trivalent metal ion, an ammonium ion and an organic ammonium group.

5. The method of claim 1, wherein the non-ionic monomer M3 has a structure of the formula IV, ##STR00013## wherein R.sup.6′, R.sup.7′, R.sup.8′, m′ and p′ are the same as defined for R.sup.6, R.sup.7, R.sup.8, m and p, Y, in each case independently, is a chemical bond or —O—, Z, in each case independently, is a chemical bond, —O— or —NH—, and R.sup.20, in each case independently, is an alkyl group, cycloalkyl group, alkylaryl group, aryl group, hydroxyalkyl group or acetoxyalkyl group, each having 1-20 carbon atoms.

6. The method of claim 1, wherein the comb polymer, with respect to the total number of monomer units present in the comb polymer, comprises: a) 95-100 mol % of the at least one poly(alkylene oxide) side chain-bearing monomer unit M1, b) 0-1 mol % of the at least one cationic monomer unit MC, c) 0-1 mol % of the at least one anionic monomer unit MA, and d) 0-1 mol % of the at least one non-ionic monomer unit M3.

7. The method of claim 1, wherein the comb polymer, with respect to the total number of monomer units present in the comb polymer, comprises: a) 30-70 mol % of the at least one poly(alkylene oxide) side chain-bearing monomer unit M1, b) 0-1 mol % of the at least one cationic monomer unit MC, c) 0-1 mol % of the at least one anionic monomer unit MA, and d) 30-70 mol % of the at least one non-ionic monomer unit M3.

8. The method of claim 1, wherein the comb polymer essentially consists of the at least one poly(alkylene oxide) side chain-bearing monomer unit M1 and, optionally, the non-ionic monomer unit M3.

9. The method of claim 1, wherein the comb polymer consists of the at least one poly(alkylene oxide) side chain-bearing monomer unit M1 and the at least one cationic monomer unit MC.

10. The method of claim 1, wherein the comb polymer is a block polymer, whereby, at least 75 mol % of the total number of the at least one side chain-bearing monomer units M1 are arranged in a first block of the block copolymer and wherein the block copolymer comprises a second block in which at least 75 mol % of the total number of the at least one cationic monomer units MC are arranged.

11. The method of claim 1, wherein the amount of the comb polymer added to the mineral binder composition is an amount that is effective for reducing or inhibiting adverse effects of non-swelling layer-silicates on the effectiveness of PCE-based dispersants the mineral binder composition.

12. A composition comprising a comb polymer and a mineral binder, aggregates, and/or non-swelling layer-silicates; wherein comb polymer comprises: a) at least one poly(alkylene oxide) side chain-bearing monomer unit M1 without ionic groups, b) optionally at least one cationic monomer unit MC, wherein the molar ratio of the cationic monomer units MC to the side chain-bearing monomer units M1 is equal to or less than 0.1, c) optionally at least one anionic monomer unit MA, wherein the molar ratio of the anionic monomer units MA to the side chain-bearing monomer units M1 is less than 1, and d) optionally at least one non-ionic monomer unit M3, wherein the molar ratio of the non-ionic monomer units M3 to the side chain-bearing monomer units M1 is less than 7.

13. The composition of claim 12, wherein the non-swelling layer silicates are one or more member selected from the group consisting of 1:1 phyllosilicate minerals, 2:1 phyllosilicate minerals, and 2:1:1 phyllosilicate minerals.

14. The composition of claim 12, wherein the composition comprises 0.01-10 wt.-% of the comb polymer relative to the weight of the mineral binder.

15. A method comprising adding (i) a comb polymer, and (ii) a dispersant to a mineral binder composition comprising non-swelling layer-silicates, the comb polymer being added in amount effective for plasticizing the mineral binder composition; wherein comb polymer comprises: a) at least one poly(alkylene oxide) side chain-bearing monomer unit M1 without ionic groups, b) optionally at least one cationic monomer unit MC, wherein the molar ratio of the cationic monomer units MC to the side chain-bearing monomer units M1 is equal to or less than 0.1, c) optionally at least one anionic monomer unit MA, wherein the molar ratio of the anionic monomer units MA to the side chain-bearing monomer units M1 is less than 1, and d) optionally at least one non-ionic monomer unit M3, wherein the molar ratio of the non-ionic monomer units M3 to the side chain-bearing monomer units M1 is less than 7.

16. The method of claim 15, wherein the dispersant for the mineral binder composition is a polycarboxylate ether which is chemically and/or structurally different from the comb polymer.

17. The method of claim 1, wherein the dispersant for the mineral binder composition is a polycarboxylate ether which is chemically and/or structurally different from the comb polymer.

18. The method of claim 1, wherein the comb polymer, with respect to the total number of monomer units present in the comb polymer, comprises: a) 99.5 mol-% of the at least one poly(alkylene oxide) side chain-bearing monomer unit M1, b) 0 mol-% of the at least one cationic monomer unit MC, c) 0 mol-% of the at least one anionic monomer unit MA, and d) 0 mol-% of the at least one non-ionic monomer unit M3.

19. The method of claim 1, wherein the comb polymer, with respect to the total number of monomer units present in the comb polymer, comprises: a) 40-50 mol-% of the at least one poly(alkylene oxide) side chain-bearing monomer unit M1, b) 0 mol-% of the at least one cationic monomer unit MC, c) 0 mol-% of the at least one anionic monomer unit MA, and d) 40-50 mol-% of the at least one non-ionic monomer unit M3.

Description

EXEMPLARY EMBODIMENTS

1. Preparation Examples of Comb Polymers

1.1 Comb Polymer P1 (Non-Ionic Homopolymer)

[0215] For the preparation of a non-ionic homopolymer by means of controlled free radical polymerization, a round-bottom flask equipped with a reflux condenser, stirrer system, thermometer and a gas inlet tube was initially charged with 57.4 g of 50% methoxy polyethylene glycol.sub.1000 methacrylate (0.027 mol; average molecular weight: 1000 g/mol; appr. 20 ethylene oxide units per molecule) and 18 g of deionized water. The reaction mixture was heated to 80° C. with vigorous stirring. A gentle inert N.sub.2 gas stream is passed through the solution during the whole reaction time. 378 mg of 4-cyano-4-(thiobenzoylthio)pentanoic acid (1.35 mmol) were then added to the mixture. Once the substance had fully dissolved, 67 mg of AIBN (0.41 mmol) were added. From then on, the conversion was regularly checked by means of HPLC.

[0216] When the conversion, based on methoxy polyethylene glycol methacrylate, had reached 90%, the reaction was stopped. A clear, reddish, aqueous solution was obtained having a solids content of around 40 wt. % which was diluted with water to obtain a solids content of around 30 wt. %. The comb polymer thus obtained is a homopolymer comprising about 20 side chain-bearing monomeric units and is referred to as comb polymer P1.

1.2 Comb Polymer P2 (Non-Ionic Homopolymer)

[0217] For the preparation of a non-ionic homopolymer by conventional free radical polymerization, a round-bottom flask equipped with a reflux condenser, stirrer system, thermometer and a gas inlet tube was initially charged with 186 g of deionized water. At a temperature of 100° C., 796 g of 50% methoxy polyethylene glycol.sub.1000 methacrylate (0.37 mol, average molecular weight: 1000 g/mol; appr. 20 ethylene oxide units per molecule) was added within 180 minutes. Additionally a solution of 4.5 g sodium hypophosphite and 6.7 g of water was added within 175 minutes and a solution of 0.93 g sodium persulfate and 5.0 g water was added within 190 minutes. Once all the solutions were added, the reaction mixture was cooled down. A clear, colorless solution was obtained having a solids content of around 40 wt. % which was diluted with water to obtain a solids content of around 30 wt. %. This polymer is referred to as comb polymer P2.

1.3 Comb Polymer P3 (Non-Ionic Homopolymer)

[0218] Non-ionic homopolymer P3 was prepared by conventional free radical polymerization. A round-bottom flask equipped with a reflux condenser, stirrer system, thermometer and a gas inlet tube was initially charged with 8.5 g methallyl-terminated polyethylenglycol (0.0085 mol; average molecular weight: 1000 g/mol; appr. 20 ethylene oxide units per molecule), 2.32 g of 2-hydroxyethylacrylate (0.02 mol), and 18 g of deionized water. The molar ratio of methallyl-terminated polyethylenglycol to 2-hydroxyethylacrylate is thus 1:2.3. The reaction mixture was heated to 80° C. with vigorous stirring. A gentle inert N.sub.2 gas stream is passed through the solution during the whole reaction time. 378 mg of 4-cyano-4-(thiobenzoylthio)pentanoic acid (1.35 mmol) were then added to the mixture. Once the substance had fully dissolved, 67 mg of AIBN (0.41 mmol) were added. From then on, the conversion was regularly checked by means of HPLC. When the conversion, based on methallyl-terminated polyethylenglycol, had reached 90%, the reaction was stopped. A clear, reddish, aqueous solution was obtained having a solids content of around 36 wt. % which was diluted with water to obtain a solids content of around 30 wt. %. This polymer is referred to as comb polymer P3.

1.4 Comb Polymer P4 (Non-Ionic Homopolymer)

[0219] Comb polymer P4 was prepared in the same way as comb polymer P3 above. The only difference being that the molar ratio of methallyl-terminated polyethylenglycol to 2-hydroxyethylacrylate was 1:1.

1.5 Comb Polymer P5 (Non-Ionic Homopolymer)

[0220] Comb polymer P4 was prepared in the same way as comb polymer P3 above. The only difference being that the molar ratio of methallyl-terminated polyethylenglycol to 2-hydroxyethylacrylate was 1:5.

Mineral Binder Compositions

[0221] The mortar mixture used for test purposes had the dry composition described in Table 1.

TABLE-US-00001 TABLE 1 Dry composition of mortar mixture Component Amount [g] Cement (CEM I 42.5N; Normo 4; available 750 g from Holcim Schweiz) Limestone filler (<125 μm) 141 g* Sand 0-1 mm 738 g Sand 1-4 mm 1107 g Sand 4-8 mm 1154 g Non-swelling layer-silicates for proportions see (kaolinite, biotite, illite) tables 3-10 *In the following experiments the limestone filler was partly replaced with layer-silicates kaolinite, biotite or illite having particle sizes <125 μm so that the combined content of limestone and layer-silicate in the mortar tests was always 141 g. The amount of kaolinite, biotite or illite used in each experiment are given in below tables 3-10.

[0222] The used kaolinite, biotite, and illite were analyzed by XRD (X-ray diffraction) using a Bruker D8 ADVANCE. The samples were analyzed in reflection mode using the following conditions: measuring range between 3 and 65° 2θ, step size: 0.015° 2θ, and time/step: 1.0 s. The quantitative mineral phase analysis is based on the Rietveld method.

[0223] The used kaolinite consists of 83% kaolinite, 6% quartz, 9% microcline, and 2% illite. The used illite consists of 57% illite, 32% quartz, 7%, chlorite, and 4% dolomite. The used biotite is a pure mineral phase.

[0224] To make a mortar mixture two procedures were followed:

[0225] Procedure A: The sands, the limestone filler, the cement and the non-swelling layer-silicates (if added) were dry-mixed in a Hobart mixer for 1 minute. Within 30 seconds, the mixing water (ratio of water to cement w/c is indicated in the tables below) was added and the mixture was mixed for a further 2.5 minutes. The total wet mixing time was 3 minutes in each case. Prior to the addition to the mortar mixture, the respective comb polymer and optionally a PCE-type superplasticizer (Sika® ViscoCrete® 3082; available from Sika, Schweiz) were mixed into the mixing water (for proportions see tables below).

[0226] Procedure B (mixing in accordance with EN 480-1): The water is split in 50% wetting water and 50% of rest water. The sands, the limestone filler, the cement and the non-swelling layer-silicates (if added) were dry-mixed in a Hobart mixer for 1 minute. The wetting water was added and after 30 seconds of mixing, the mortar was stored for 2 min in the mixer without stirring (mixer was covered with a foil to avoid water evaporation). Afterwards the mixer was started again, cement was added and after 30 seconds of mixing, the rest water was added and the mixture was mixed for a further 2.5 minutes. Prior to the addition to the mortar mixture, the respective comb polymer and optionally a PCE-type superplasticizer (polymethacrylate partially esterified with polyethyleneglycol (appr. 23 EO units), molar ratio acid:ester groups appr. 1:2) were mixed into the rest water (for proportions see results section).

Testing Procedures

[0227] To determine the effectiveness of the comb polymers according to the present invention in the mortar mixture, the dispersing effect was determined by measuring the flow table spread (FTS) of a series of mortar mixtures was measured in accordance with EN 1015-3 at different times.

[0228] Also, the temperature curve of the mineral binder compositions (mortar mixtures, cement pastes) was recorded as control of hydration and setting behavior, respectively, after mixing. Thereby, the time to onset of the global temperature maximum was determined as a measure of the setting time.

[0229] The air content was measured according to EN 12350-7.

[0230] In the tests, all of the admixtures (comb polymer and optionally PCE) have been added as aqueous solutions or dispersions with a content of active ingredients of 30 wt.-%. Kaolinite, biotite, and illite were added as a powder.

[0231] The dosages of PCEs, comb polymers and non-swelling layer-silicates are given in the following tables 1-8 in wt-% relative to the weight of cement.

4 Results

[0232] Table 2 gives an overview of a first series of tests conducted and the results achieved. Mixing procedure B was followed for experiments R1, R2, and E1. Experiments R1 and R2 are experiments conducted for comparative purposes without the addition of a comb polymer according to the invention. Experiment E1 uses the comb polymer P1 which is according to the present invention.

TABLE-US-00002 TABLE 2 (all wt.-% are given with respect to the cement content in the mineral binder composition) Experiment Components R1 R2 E1 w/c ratio 0.47 0.47 0.47 Kaolinite [wt. %] 0 0 0 Comb Polymer 0 B1 P1 Proportion [wt.-%] 0.5 0.5 PCE [wt.-%] 0.5 0 0 FTS.sup.# [mm] after  0 min 204 238 132 30 min 195 221 — 60 min 176 194 — Setting time [h] 14.8 15.3 10.2 B1 = MasterSuna SBS 3890 (BASF), PCE with ethylenoxide side chains; not according to the present invention .sup.#= flow table spread according to EN 1015-3. The time “0 min” corresponds to the first measurement immediately after the mixing of the mortar sample.

[0233] The experiments show the water reduction capabilities of the different comb polymers and the PCE via workability with constant dosage and constant w/c.

[0234] The data in Table 2 clearly shows that the inventive comb polymer does not have any significant plasticizing effect when compared to standard PCEs or to commercially available, water reducing clay blockers (i.e. MasterSuna SBS 3890, a PCE with ethylenoxide side chains). The inventive comb polymers also have a significantly lower influence on the setting time, i.e. less retardation, when compared to more conventional comb polymers or to commercially available clay blockers which is advantageous.

[0235] Table 3 shows the results of a set of experiments with added kaolinite. Mixing procedure B was followed for experiments R3-R5 and E2. Experiments R3-R5 are experiments conducted for comparative purposes without the addition of a comb polymer according to the invention. Experiment E2 uses a comb polymer according to the present invention.

TABLE-US-00003 TABLE 3 (all wt.-% are given with respect to the cement content in the mineral binder composition) Experiment Components R3 R4 R5 E2 w/c ratio 0.46 0.46 0.46 0.46 Kaolinite [wt. %] 0 7.5 7.5 7.5 Comb polymer 0 0 B1 P1 Proportion [wt.-%] 0.24 0.24 PCE [wt.-%] 0.5 0.5 0.5 0.5 FTS.sup.# [mm] after  0 min 200 150 194 196 30 min 192 130 178 180 60 min 168 — 166 170 Setting time [h] 14.2 12.7 15.3 12.3 B1 = MasterSuna SBS 3890 (BASF), PCE with ethylenoxide side chains; not according to the present invention .sup.#= flow table spread according to EN 1015-3. The time “0 min” corresponds to the first measurement immediately after the making-up of the mortar sample.

[0236] As can be deduced from the results given in Table 3 the addition of kaolinite leads to a reduced flow of the respective mortar composition. The addition of comb polymers B1 and P1 is an effective mean to block the effect of kaolinite on the flow. It can further be seen from the results given in Table 3 that a comb polymer P1, which is according to the present invention, has no retarding effect while the commercial clay blocker B1 shows a strong retarding effect. Comb polymer P1 is thus advantageous.

[0237] Table 4 shows the results of a set of experiments with added biotite. Mixing procedure B was followed for experiments R3, R6, and E3. R3 and R6 are experiments conducted for comparative purposes without the addition of a comb polymer according to the invention. Experiment E3 uses a comb polymer according to the present invention.

TABLE-US-00004 TABLE 4 (all wt.-% are given with respect to the cement content in the mineral binder composition) Experiment Components R3 R6 E3 w/c ratio 0.46 0.46 0.46 Biotite [wt. %] 0 5 5 Comb polymer 0 0 P1 Proportion [wt.-%] 0.2 PCE [wt.-%] 0.5 0.5 0.5 FTS.sup.# [mm] after 0 min 200 146 186 Setting time [h] 14.2 12.7 12.2 .sup.#= flow table spread according to EN 1015-3. The time “0 min” corresponds to the first measurement immediately after the making-up of the mortar sample.

[0238] As can be deduced from the results given in Table 4 the addition of biotite leads to a reduced flow of the respective mortar composition. The addition of comb polymer P1 is an effective mean to block the effect of biotite on the flow. It can further be seen from the results given in Table 4 that a comb polymer P1, which is according to the present invention, has no retarding effect.

[0239] Table 5 shows the results of a set of experiments with added illite. Mixing procedure B was followed for experiments R3, R7, and E4. Experiment R3 and R7 are experiments conducted for comparative purposes without the addition of a comb polymer according to the invention. Experiment E4 uses a comb polymer according to the present invention.

TABLE-US-00005 TABLE 5 (all wt.-% are given with respect to the cement content in the mineral binder composition) Experiment Components R3 R7 E4 w/c ratio 0.46 0.46 0.46 Illite [wt. %] 0 5 5 Comb polymer 0 0 P1 Proportion [wt.-%] 0.2 PCE [wt.-%] 0.5 0.5 0.5 FTS.sup.# [mm] after 0 min 200 164 200 Setting time [h] 14.2 11.8 11.5 .sup.#= flow table spread according to EN 1015-3. The time “0 min” corresponds to the first measurement immediately after the making-up of the mortar sample.

[0240] As can be deduced from the results given in Table 5 the addition of illite leads to a reduced flow of the respective mortar composition. The addition of comb polymer P1 is an effective mean to block the effect of illite on the flow. It can further be seen from the results given in Table 5 that the comb polymer P1, which is according to the present invention, has no retarding effect.

[0241] Table 6 shows the results of a second set of experiments with added illite. Mixing procedure B was followed for experiments R3, R8, R9, and E5. Experiments R3, R8, and R9 are experiments conducted for comparative purposes without the addition of a comb polymer according to the invention. Experiment E5 uses a comb polymer according to the present invention.

TABLE-US-00006 TABLE 6 (all wt.-% are given with respect to the cement content in the mineral binder composition) Experiment Components R3 R8 R9 E5 w/c ratio 0.46 0.46 0.46 0.46 Illite [wt. %] 0 10 10 10 Comb polymer 0 0 B1 P1 Proportion [wt.-%] 0.8 0.8 PCE [wt.-%] 0.5 0.5 0.5 0.5 FTS.sup.# [mm] after  0 min 200 128 196 198 30 min 173 171 60 min 156 148 Setting time [h] 14.2 11 15.3 12.5 B1 = MasterSuna SBS 3890 (BASF), PCE with ethylenoxide side chains; not according to the present invention .sup.#= flow table spread according to EN 1015-3. The time “0 min” corresponds to the first measurement immediately after the making-up of the mortar sample.

[0242] As can be deduced from the results given in Table 6 the addition of high amounts of illite leads to a much more reduced flow of the respective mortar composition and, thus, requires higher dosages of comb polymers to offset the effect of illite. The addition of comb polymers B1 or P1 is an effective mean to block the effect of illite on the flow. Again, it can be seen from the results given in Table 6 that a comb polymer P1, which is according to the present invention, has no retarding effect while a commercial clay blocker shows a strong retarding effect. Comb polymer P1 is thus advantageous.

[0243] Table 7 shows the results of a set of experiments with added kaolinite in which inventive comb polymers are compared to single MPEG side chain molecules. Mixing procedure A was followed for experiments R10-R14 and E6. Experiments R10-R14 are experiments conducted for comparative purposes without the addition of a comb polymer according to the invention. Experiment E6 uses a comb polymer according to the present invention.

TABLE-US-00007 TABLE 7 (all wt.-% are given with respect to the cement content in the mineral binder composition) Experiment Components R10 R11 R12 R13 R14 E6 w/c 0.48 0.48 0.48 0.48 0.48 0.48 Kaolinite 0 7.5 7.5 7.5 7.5 7.5 [wt. %] Comb polymer 0 0 0 0 0 P1 Proportion 0.27 [wt.-%] MPEG 0 0 B2 B3 B4 0 Proportion 0.27 0.27 0.27 [wt.-%] PCE [wt.-%] 0.5 0.5 0.5 0.5 0.5 0.5 FTS.sup.# [mm] after  0 min 188 153 154 164 177 190 30 min 155 140 138 150 153 176 60 min 152 135 — 142 155 170 B2 = methoxy polyethylene glycol.sub.1000 (average molecular weight: 1 000 g/mol) B3 = methoxy polyethylene glycol.sub.3000 (average molecular weight: 3 000 g/mol) B4 = methoxy polyethylene glycol.sub.5000 (average molecular weight: 5 000 g/mol) .sup.#= flow table spread according to EN 1015-3. The time “0 min” corresponds to the first measurement immediately after the making-up of the mortar sample.

[0244] As evident from Table 7, single MPEG side chains are less effective when compared with the inventive comb polymer P1.

[0245] Table 8 compares the effectiveness of the inventive comb polymer P1, which was produced via a controlled free-radical polymerization, and the inventive comb polymer P2, which was produced via conventional free-radical polymerization. Mixing procedure B was followed for experiments R3, R15, E7, and E8. Experiments R3 and R15 are experiments conducted for comparative purposes without the addition of a comb polymer according to the invention. Experiment E7 and E8 uses a comb polymers according to the present invention.

TABLE-US-00008 TABLE 8 (all wt.-% are given with respect to the cement content in the mineral binder composition) Experiment Components R3 R15 E7 E8 w/c ratio 0.46 0.46 0.46 0.46 Kaolinite [wt. %] 0 7.5 7.5 7.5 Comb polymer 0 0 P1 P2 Proportion [wt.-%] 0.25 0.25 PCE [wt.-%] 0.5 0.5 0.5 0.5 FTS.sup.# [mm] after  0 min 200 152 201 200 30 min 192 131 176 183 60 min 168 — 164 160 Setting time [h] 14.2 12.1 12.0 12.0 .sup.#= flow table spread according to EN 1015-3. The time “0 min” corresponds to the first measurement immediately after the making-up of the mortar sample.

[0246] It is evident from Table 8 that both inventive polymers P1 and P2, having similar side chain lengths of 1′000 g/mol, show a similar effectiveness in blocking the effect of layer-silicates, although they were produced with different polymerization processes.

[0247] Table 9 shows the results of another set of experiments with added kaolinite comparing a comb polymer of the present invention to a polycation type clay blocking additive. Mixing procedure B was followed for experiments R3, R16, R17, and E9. Experiments R3, R16, and R17 are experiments conducted for comparative purposes without the addition of a comb polymer according to the invention. Experiment E9 uses a comb polymer according to the present invention.

TABLE-US-00009 TABLE 9 (all wt.-% are given with respect to the cement content in the mineral binder composition) Experiment Components R3 R16 R17 E9 w/c ratio 0.46 0.46 0.46 0.46 Kaolinite [wt. %] 0 7.5 7.5 7.5 Comb polymer 0 0 B2 P1 Proportion [wt.-%] 0.25 0.25 PCE [wt.-%] 0.5 0.5 0.5 0.5 FTS.sup.# [mm] after  0 min 200 152 193 201 30 min 192 131 185 176 60 min 168 — 156 164 Setting time [h] 14.2 12.1 12.4 12.0 B2 = Floset EVA 250 L (SNF Floerger), polycation prepared from epichlorhydrine and dimethylamine; not according to the present invention .sup.#= flow table spread according to EN 1015-3. The time “0 min” corresponds to the first measurement immediately after the making-up of the mortar sample.

[0248] As can be deduced from the results given in Table 9 the addition of kaolinite leads to a reduced flow of the respective mortar composition. The addition of polycation B2 and P1 is an effective mean to block the effect of kaolinite on the flow and P1 is as efficient as B2 despite of its completely different structure.

[0249] Table 10 shows the results of another set of experiments with added kaolinite comparing a comb polymer of the present invention to a polycation type clay blocking additive. Mixing procedure B was followed for experiments R18, R19, and E10-E13. Experiments R18 and R19 are experiments conducted for comparative purposes and not according to the invention. Experiments E10-E13 are according to the present invention.

TABLE-US-00010 TABLE 10 (all wt.-% are given with respect to the cement content in the mineral binder composition) Experiment Components R18 R19 E10 E11 E12 E13 w/c ratio 0.45 0.45 0.45 0.45 0.45 0.45 Kaolinite 0 7.5 7.5 7.5 7.5 7.5 [wt. %] Comb polymer P1 P3 P4 P5 Proportion 0.7 0.7 0.7 0.7 [wt.-%] PCE [wt.-%] 0.5 0.5 0.5 0.5 0.5 0.5 FTS.sup.# [mm] after  0 min 195 157 198 203 201 190 30 min 168 136 179 180 178 157 60 min 157 118 173 171 162 140 Setting time [h] 11.3 11.5 12.6 13.3 13.3 14.0 .sup.#= flow table spread according to EN 1015-3. The time “0 min” corresponds to the first measurement immediately after the making-up of the mortar sample.

[0250] As can be seen from the above table 10, the presence of kaolinite strongly reduces the effect of a PCE (compare examples R18 and R19). All polymers P1, P3, P4 and P5 are able to block the effect of kaolinite.