Plasticizer for geopolymers

Abstract

The use of an additive, including at least one water-soluble polymer, which is a homo-or copolymer of at least one monoethylenically unsaturated carboxylic acid, and optionally at least one alkali silicate as a liquefier for geopolymers. The additive can be produced in a simple and inexpensive manner and is particularly suitable for liquefying geopolymers, in particular geopolymers containing metakaolin.

Claims

1. A method comprising plasticizing at least one geopolymer that comprises a powder component that comprises at least 10% by weight of metakaolin, based on 100% by weight of the powder component, wherein the plasticizing includes combining an additive A with the at least one geopolymer, the additive comprising at least one water-soluble polymer which is a homo- or copolymer consisting of repeating units that are formed from at least one monoethylenically unsaturated carboxylic acid that has been partly or fully neutralized with an alkali metal ion, wherein the at least one monoethylenically unsaturated carboxylic acid is selected from acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, or itaconic acid, and optionally at least one further co-monomer that is selected from allyl alcohol, ethylene, propylene, vinylsulfonic acid, methallylsulfonic acid, acrylamido-2-methylpropanesulfonic acid, acrylamide, alkyl esters of methacrylic acid, or hydroxyalkyl esters of methacrylic acid, and at least one alkali metal silicate S.sub.1, wherein the alkali metal silicate S.sub.1 is present in an amount of 10 to 100 parts by weight, based on 100 parts by weight of the water-soluble polymer, both calculated in solid form.

2. The method as claimed in claim 1, wherein the water-soluble polymer is a homopolymer of acrylic acid or a copolymer consisting of repeating units that are formed from acrylic acid and the at least one further co-monomer.

3. The method as claimed in claim 1, wherein the water-soluble polymer has an average molecular weight M.sub.w in the range from 1,000 to 20,000 g/mol.

4. The method as claimed in claim 1, wherein the water-soluble polymer is a homopolymer of acrylic acid in the form of the sodium salt and having an average molecular weight M.sub.w in the range from 2,000 to 8,000 g/mol.

5. The method as claimed in claim 1, wherein the at least one alkali metal silicate S.sub.1 has a molar ratio of SiO.sub.2 to M.sub.2O in the range from 0.8 to 3.6, where M is Na and/or K.

6. The method as claimed in claim 1, wherein the additive A is in the form of an aqueous solution, an aqueous suspension, or a dry or moist powder.

7. The method as claimed in claim 1, wherein the powder component comprises 10% to 60% by weight of metakaolin, based on 100% by weight of the powder component.

8. The method as claimed in claim 1, wherein the powder component of the at least one geopolymer further comprises fly ash and/or blast furnace slag.

9. The method as claimed in claim 1, wherein the at least one geopolymer comprises an aqueous component containing at least one alkali metal silicate S2.

10. The method as claimed in claim 9, wherein the alkali metal silicate S2 is a potassium silicate.

Description

EXAMPLES

(1) Working examples are adduced hereinafter, which are intended to elucidate the invention described in detail. It will be appreciated that the invention is not restricted to these described working examples.

(2) “GP” stands for “geopolymer mixture”.

(3) “Ref.” stands for “reference example”.

(4) “Ex.” stands for “example”.

(5) Description of Test Methods

(6) The solids content of the solutions was determined with a halogen drier from Mettler Toledo.

(7) The SiO.sub.2, Na.sub.2O and K.sub.2O contents and the alkali metal silicate content of the alkali metal silicate solutions were taken from the manufacturers' datasheets.

(8) The average molecular weight M.sub.w of the polymers was determined by means of gel permeation chromatography (GPC).

(9) GPC Measurement Conditions Columns: PSS Suprema 10 μm, 2×1000 Â, 1×30 Â, all 8×300 mm with precolumn, from PSS Polymer Standards Service, Germany Eluent: 0.1N NaNO.sub.3 adjusted to pH 12 with NaOH Flow rate: 0.8 mL/min Temperature (column oven and detector): 45° C. In-line degasser AF, Waters Pump: Varian Pro Star Model 220 Detector: Waters 2414 RI detector Standards: polymethacrylic acid sodium salt M.sub.w 1′220, 3′180, 8′210, 34′900, 163′000 from PSS Polymer Standards Service Concentration of the standards, dissolved in the eluent: 1 mg/mL Concentration of the samples calculated in solid form, dissolved in the eluent: 10 mg/mL Evaluation software: Breeze™ 2, Waters

(10) The Compositions were Tested as Follows:

(11) Slump was determined to EN 1015-3. The values in the tables are based on the diameter of the mortar directly after the raising of the slump cone and awaiting the end of the flow movement without lifts of the flow table. Slump serves as a measure of the flowability of the composition, a high slump showing high flowability of the composition or a good effect of the plasticizer present. Slump was determined immediately and, if appropriate, after 10, 20, 30 and 45 minutes after the mixing of the mortar.

(12) For the determination of compressive strength of the hardened compositions, prisms of 4×4×16 cm were produced, demolded after 24 hours and stored at 20° C. and 65% relative air humidity and tested to EN 196-1.

(13) Materials Used

(14) Metaver® R, metakaolin, Newchem, Switzerland

(15) Metastar™ 501, metakaolin, Imerys, USA

(16) EFA®-Füller, fly ash, BauMineral, Germany

(17) SH 20 foundry sand, blast furnace slag, HeidelbergCement, Germany

(18) Untervaz foundry sand, blast furnace slag, Holcim, Switzerland

(19) WG-1: aqueous potassium silicate solution having an alkali metal silicate content of 41% by weight and a molar SiO.sub.2/K.sub.2O ratio of 3.

(20) WG-2: aqueous potassium silicate solution having an alkali metal silicate content of 48% by weight and a molar SiO.sub.2/K.sub.2O ratio of 1.

(21) WG-3: aqueous potassium silicate solution having an alkali metal silicate content of 30% by weight and a molar SiO.sub.2/K.sub.2O ratio of 2.

(22) WG-4: aqueous potassium silicate solution having an alkali metal silicate content of 45% by weight and a molar SiO.sub.2/K.sub.2O ratio of 1.5.

(23) WG-5: aqueous sodium silicate solution having an alkali metal silicate content of 42.6% by weight and a molar SiO.sub.2 /K.sub.2O ratio of 1.5.

(24) NaMS: sodium metasilicate pentahydrate, Sigma Aldrich, Switzerland.

(25) PA-15: Sokalan® PA 15 (from BASF), polyacrylic acid sodium salt, M.sub.w=2′400 g/mol, solids content of the aqueous solution 45% by weight, pH (10% solution) 8.

(26) PA-25: Sokalan® PA 25 XS (from BASF), polyacrylic acid, M.sub.w=4′000 g/mol, solids content of the aqueous solution 49% by weight, pH 2.8.

(27) PA-40: Sokalan® PA 40 (from BASF), polyacrylic acid sodium salt, M.sub.w=14′500 g/mol, solids content of the aqueous solution 35% by weight, pH 7.

(28) PA-70: Sokalan® PA 70 PN (from BASF), polyacrylic acid sodium salt, M.sub.w=43′800 g/mol, solids content of the aqueous solution 30% by weight, pH 5.

(29) PA-80: Sokalan® PA 80 S (from BASF), polyacrylic acid, M.sub.w, =79′500 g/mol, solids content of the aqueous solution 35% by weight, pH (10% solution) 2.

(30) Dolapix SPC 7 (from Zschimmer & Schwarz Chemische Fabriken), dispersant and plasticizer, aqueous solution having a solids content of 52% by weight, containing a water-soluble polymer having carboxyl groups having an average molecular weight M.sub.w of 3′200 g/mol and a sodium silicate, pH 13, specimen from 2013.

(31) Quartz sand: Quarzwerke Austria, Austria.

(32) In the assessment of the results in tables 1 to 7, it is important to take into account that the geopolymer composition, for every new batch of metakaolin and fly ash, owing to variations in the composition of these raw materials, particularly of the fly ash, had altered properties and in some cases had to be adjusted. This adjustment was made by slight variation in the amount of alkali metal silicate and in the amount of KOH. Within a test series, the same geopolymer composition was used in each case with identical batches of metakaolin and fly ash. This explains the different values of Ref. 1, Ref. 12 and Ref. 13.

(33) Test Series 1—Workability and Hardening of Geopolymers Composed of Metakaolin and Fly Ash

(34) Metaver® R and EFA® Füller HP were introduced into a forced mixer from Hobart in the amounts specified in table 1 and the powder was mixed at level 1 for 1 minute. Within 30 seconds, while stirring at level 1, 348 g of WG-4 and 10 g of water were added. Mixing was continued at level 1 for a further 30 seconds and then at level 2 for a further 2 minutes. If the geopolymer was not homogeneous enough after these 3 minutes of mixing time of the wet mixture, mixing was continued until the mixture was homogeneous, but for not more than 8 minutes. Subsequently, the slump of each composition was determined. The results are reported in table 1.

(35) TABLE-US-00001 TABLE 1 GP 1.sup.1) GP 2.sup.2) GP 3.sup.2) GP 4.sup.2) GP 5 GP 6 GP 7 Metaver ® 864 785.5 576 518.4 259.5 86.4  0 R [g] EFA ®- 0 78.5 288 345.6 604.5 777.6 864 Füller [g] Metakaolin 1:0 10:1 2:1 1.5:1 1:2.3 1:9 0:1 to fly ash [parts by weight] Slump [mm] immediate n.m..sup.3) n.m..sup.3) n.d..sup.4) n.d..sup.4) 229 290 278 10 min. n.m..sup.3) n.m..sup.3) 146 154 246 297 288 20 min. n.m..sup.3 n.m..sup.3 175 182 254 293 288 30 min. n.m..sup.3) n.m..sup.3) 185 195 265 293 286 45 min. n.m..sup.3) n.m..sup.3) 162 198 268 279 278 Solid after yes yes yes yes yes yes no 24 hours .sup.1)mixing time 8 minutes .sup.2)mixing time 5 minutes .sup.3)not measurable, too tough and sticky .sup.4)measurement not made owing to prolonged mixing time

(36) Test Series 2—Workability of Geopolymers with Sodium Silicate/Potassium Silicate

(37) 259.5 g of Metaver® R and 604.5 g of EFA® Füller HP were mixed in a forced mixer from Hobart at level 1 for 1 minute. Within 30 seconds, with continued stirring, the waterglass (WG-4 or WG-5) and the water according to table 2 were added. Mixing was continued at level 1 for a further 30 seconds and then at level 2 for a further 2 minutes. If the geopolymer was not homogeneous enough after these 3 minutes of mixing time of the wet mixture, mixing was continued until the mixture was homogeneous, but for not more than 8 minutes. Subsequently, the slump of each composition was determined. The results are reported in table 2.

(38) TABLE-US-00002 TABLE 2 GP 5 GP 8.sup.1) WG-4 [g] 348   0 WG-5 [g]   0 348 Water [g]  10   1.5 Total water in the geopolymer [g] 201 201 Slump [mm] immediate 229 n.d..sup.2) 10 min. 246 134 20 min. 254 n.m..sup.3) 30 min. 265 n.m..sup.3) 45 min. 268 n.m..sup.3) Compressive strength after 24 hours  23.0  17.4 [MPa] .sup.1)mixing time 5 minutes .sup.2)measurement not made owing to prolonged mixing time .sup.3)not measurable, too tough and sticky

(39) Test Series 3—Test of Plasticizing Action of Commercial Plasticizers for Cement and Gypsum in Comparison

(40) 329 g (21.9 parts by weight) of Metaver® R and 767 g (51.1 parts by weight) of EFA® Füller HP were mixed in a forced mixer from Hobart at level 1 for 1 minute. Within 30 seconds, with continued stirring, a solution of 348 g (23.2 parts by weight) of WG-1 and 56 g (3.7 parts by weight) of a 50% by weight aqueous KOH solution was added. Within a further 30 seconds, the plasticizer according to table 3 was added in the dosage specified and the composition was mixed at level 2 for a further 2 to 3 minutes. Subsequently, the slump of each composition was determined. The results are reported in table 3.

(41) TABLE-US-00003 TABLE 3 Slump [mm] Plasticizer Dosage .sup.1) immediate 20 min. 45 min. Ref. 1  none 0   178 166 140 Ref. 2  Ultrazine NAS .sup.2) 0.75 115 108 np .sup.6) Ref. 3  Ultrazine NAS .sup.2) 1.5  100 np .sup.6) np .sup.6) Ref. 4  Ultrazine NAS .sup.2) 3.0  np .sup.6) np .sup.6) np .sup.6) Ref. 5  Borrement CA 120 .sup.3) 1.5  100 np .sup.6) np .sup.6) Ref. 6  Borrement CA 120 .sup.3) 3.0  np .sup.6) np .sup.6) np .sup.6) Ref. 7  Sikament ® FF-86 .sup.4) 3.0  100 np .sup.6) np .sup.6) Ref. 8  Na gluconate 0.1  187 123 108 Ref. 9  Sika ® ViscoCrete ® 1.5  100 np .sup.6) np .sup.6) 120P .sup.5) Ref. 10 Sika ® ViscoCrete ® 3.0  100 np .sup.6) np .sup.6)) 120P .sup.5) .sup.1) parts by weight of solids per 100 parts by weight of geopolymer .sup.2) Na lignosulfonate powder (from Borregaard) .sup.3) Ca lignosulfonate powder (from Borregaard) .sup.4) sulfonated melamine condensate powder (from Sika) .sup.5) polycarboxylate ether powder (from Sika) .sup.6) not processible (too stiff)

(42) Test Series 4—Test of Plasticizing Action of Polyacrylic Acid and Mixtures of Polyacrylic Acid with Alkali metal Silicate

(43) A geopolymer was prepared analogously to test series 3.

(44) Added to this geopolymer in each case was the plasticizer specified in table 4 in the dosage specified, and the slump of the composition was determined as described for test series 3.

(45) The Plasticizers used were Produced as Follows:

(46) PA-25 pH 2.8: PA-25 was diluted with water to a solids content of 37.7% by weight.

(47) PA-25 pH 8: PA-25 was adjusted to a pH of 8 by addition of NaOH and the solids content was adjusted to 37.7% by weight by addition of water.

(48) For ex. 4 to ex. 6, according to table 4, the amount of sodium metasilicate pentahydrate (NaMS) specified was mixed with the amount of PA-25 pH 8 specified, and this mixture was used as plasticizer.

(49) TABLE-US-00004 TABLE 4 Slump [mm] Plasticizer Dosage immediate 20 min. 45 min. Ref. 11 PA-25 pH 2.8  3.0 .sup.1) np .sup.3) np .sup.3) np .sup.3) Ex. 1 PA-25 pH 8    2.0 .sup.1) 213 206 177 Ex. 2 PA-25 pH 8    3.0 .sup.1) 211 204 167 Ex. 3 PA-25 pH 8    5.0 .sup.1) 186 172 136 Ex. 4 PA-25 pH 8    3.0 .sup.1) 226 229 214 NaMS  7.0 .sup.2) Ex. 5 PA-25 pH 8    3.0 .sup.1) 237 237 221 NaMS 10.3 .sup.2) Ex. 6 PA-25 pH 8    3.0 .sup.1) 252 263 242 NaMS 17.2 .sup.2) Ex. 7 Dolapix SPC 7  2.0 .sup.1) 233 228 210 Ex. 8 Dolapix SPC 7  3.0 .sup.1) 252 247 232 .sup.1) parts by weight of solids per 100 parts by weight of powder component (metakaolin and fly ash) of the geopolymer .sup.2) parts by weight of NaMS per 100 parts by weight of PA-25 pH 8 solution .sup.3) not processible (too stiff and sticky)

(50) Test Series 5—Test of Plasticizing Action of Polyacrylic Acid and Mixtures of Polyacrylic Acid with Alkali Metal Silicate

(51) A geopolymer having the following composition was prepared analogously to test series 3:

(52) 21.6 parts by weight of Metaver® R

(53) 50.4 parts by weight of EFA® Füller HP

(54) 21.2 parts by weight of WG-1

(55) 6.8 parts by weight of KOH (50% aqueous solution)

(56) Added to this geopolymer in each case was the plasticizer specified in table 5, and the slump of the composition was determined as described for test series 3.

(57) The Plasticizers used were Produced as Follows:

(58) The respective polyacrylic acid solution was adjusted to pH 13 by addition of NaOH and used as such in examples 9 to 12. In examples 13 to 16, 17.2 g of sodium metasilicate pentahydrate (NaMS) in each case, based on 100 g of the polyacrylic acid solution, were also mixed into the polyacrylic acid solutions of pH 13.

(59) The plasticizers used were dosed such that 3.0 parts by weight of polyacrylic acid solids were present per 100 parts by weight of powder component (metakaolin and fly ash) of the geopolymer.

(60) TABLE-US-00005 TABLE 5 SC .sup.1) Slump [mm] Plasticizer % by wt. 5 min. 20 min. 45 min. Ref. 12 none 220 226 224 Ex. 9 PA-15 pH 13 45 250 260 265 Ex. 10 PA-25 pH 13 37 255 250 251 Ex. 11 PA-40 pH 13 35 235 228 214 Ex. 12 PA-70 pH 13 30 235 230 214 Ex. 13 PA-15 pH 13 45 256 270 278 with NaMS Ex. 14 PA-25 pH 13 37 268 269 269 with NaMS Ex. 15 PA-40 pH 13 35 247 238 225 with NaMS Ex. 16 PA-70 pH 13 30 248 242 227 with NaMS .sup.1) solids content of the polyacrylic acid solution of pH 13

(61) Test Series 6—Test of the Effect of Polyacrylic Acid and Mixtures of Polyacrylic Acid with Alkali Metal Silicate on Flow Characteristics and Development of Strength

(62) A geopolymer having the following composition was prepared analogously to test series 3:

(63) 21.6 parts by weight of Metaver® R

(64) 50.4 parts by weight of EFA® Füller HP

(65) 21.2 parts by weight of WG-1

(66) 3.4 parts by weight of KOH powder

(67) In the case of this geopolymer, KOH in powder form was dissolved in WG-1.

(68) For the reference mixture Ref. 13 and examples 17 and 18, 3.4 parts by weight of water were also added. For examples 19 to 22, only 1.6 parts by weight of water were added, in order to compensate for the amount of water that was introduced by the alkali metal silicate solution in the plasticizer.

(69) Added to the geopolymer in each case was the plasticizer specified in table 6 as described for test series 3, and the slump and compressive strength of the composition were determined.

(70) The Plasticizers used were Produced as Follows:

(71) The respective polyacrylic acid solution was brought to a pH of 13 by addition of NaOH and the solids content was adjusted to 31% by weight by adding water, and it was used as such for examples 17 and 18. For examples 19 to 22, a sufficient amount of alkali metal silicate solution, WG-2 or WG-3 according to table 6 was mixed into the polyacrylic acid solutions of pH 13 and solids content 31% by weight that an amount of 11.2 parts by weight of solid alkali metal silicate based on 100 parts by weight of polyacrylic acid solution was present.

(72) The plasticizers used were dosed such that 3 parts by weight of polyacrylic acid solids were present per 100 parts by weight of powder component (metakaolin and fly ash) of the geopolymer.

(73) TABLE-US-00006 TABLE 6 Compressive Slump [mm] strength [MPa] 20 45 24 28 Plasticizer 5 min. min. min. hours 7 days days Ref. 13 none 194 216 213 —.sup.1) —.sup.1) —.sup.1) Ex. 17 PA-15.sup.2) 300 302 301 7.7 19.7 28.0 Ex. 18 PA-25.sup.2) 271 274 274 9.8 18.2 27.5 Ex. 19 PA-15.sup.2) with 305 310 314 9.3 21.5 29.3 WG-2 Ex. 20 PA-25.sup.2) with 278 286 290 11.2 20.9 31.6 WG-2 Ex. 21 PA-15.sup.2) with 308 317 310 10.1 19.8 30.3 WG-3 Ex. 22 PA-25.sup.2) with 277 278 280 9.3 20.0 28.7 WG-3 .sup.1)not measured .sup.2)aqueous solution of pH 13 with solids content 31% by weight

(74) Test Series 7—Test of the Effect of a Mixture of Polyacrylic Acid with Alkali Metal Silicate on Flow Characteristics and Development of Strength

(75) 440 g of Metaver® R, 440 g of Metastar™ 501, 240 g of EFA® Füller HP, 240 g of SH20 foundry sand, 240 g of Untervaz foundry sand, 197 g of 0.06-0.3 mm quartz sand, 265 g of 0.1-0.6 mm quartz sand, 348 g of 0.3-0.9 mm quartz sand, 386 g of 0.7-1.2 mm quartz sand, 513 g of 1.5-2.2 mm quartz sand and 688 g of 2.0-3.2 mm quartz sand were mixed in a Hobart forced mixer at level 1 for 1 minute. Within 30 seconds, with continued stirring, 1120 g of WG-4 were added. Within a further 30 seconds, the plasticizer according to table 7 was added in the dosage specified and the composition was mixed at level 2 for a further 2 to 3 minutes. Subsequently, the slump of the composition was determined. The results are reported in table 7.

(76) TABLE-US-00007 TABLE 7 Com- pressive strength Slump [mm] [MPa] Plasticizer immediate 10 min. 20 min 30 min 7 days Ref. 14 none 248 262 247 n.p.sup.1) 57.4 Ex. 23 106.7 g 260 278 287 245 57.5 Dolapix SPC 7 .sup.1)not processible