STABLE PCE AND POLYSACCHARIDE VMA COMPOSITIONS FOR CONCRETE ADMIXTURES AND THEIR USES

Abstract

The present invention provides aqueous compositions that are stable after at least a 24 hour period comprising a polysaccharide viscosity modifying additive and more than 60 wt. %, based on the weight of total solids in the compositions of one or more polycarboxylate ether, the compositions comprising an acid chosen from an organic acid having 1 hydroxy group or less, a strong acid containing a single hydrogen, an ascorbic acid, and mixtures thereof, the compositions having a pH of less than the pH of the polycarboxylate ether itself, or from 1.0 to 6.0. The present invention enables stable concentrates of aqueous polycarboxylate ethers and polysaccharide viscosity modifying agents for use in hydraulic binder applications, the compositions having a total solids content of 10 wt. % to as high as 65 wt. %.

Claims

1. An shelf stable aqueous compositions comprising one or more polysaccharide viscosity modifying additive, one or more polycarboxylate ether (PCE), and an acid chosen from organic acids having 1 hydroxy group or less, strong acids containing a single hydrogen, and ascorbic acids, wherein the pH value of the aqueous compositions is less than the pH of the PCE itself, and, further wherein, the aqueous compositions comprise more than 60 wt. %, based on the total solids in the composition, of the one or more polycarboxylate ether.

2. The aqueous composition as claimed in claim 1 comprising the polysaccharide viscosity modifying additive in an amount of from 1 to 40.1 wt. %, based on the total solids in the composition.

3. The aqueous composition as claimed in claim 1, wherein the polysaccharide viscosity modifying additive and the polycarboxylate ether solids of the composition may comprise more than 70 wt. % of the total solids of the composition.

4. The aqueous composition as claimed in claim 1, wherein the total solids in the aqueous composition ranges from 10 to 65 wt. %.

5. The aqueous composition as claimed in claim 1, wherein the polysaccharide viscosity modifying additive is chosen from cellulose ethers.

6. The aqueous composition as claimed in claim 5, wherein, the polysaccharide viscosity modifying additive is chosen from hydroxyalkyl-methyl-cellulose, hydroxyethyl cellulose (HEC) and ethyl hydroxyethyl cellulose (EHEC).

7. The aqueous composition as claimed in claim 1, wherein the acid is chosen from an organic acid having 1 hydroxy group or less is a monocarboxylic acid, a dicarboxylic acid, a ketocarboxylic acid, a hydroxy dicarboxylic acid, a polycarboxylic acid, a hydroxy polycarboxylic acid, a strong acid containing a single hydrogen, an ascorbic acid, and mixtures thereof.

8. The aqueous composition as claimed in claim 1, wherein the pH is from 1.0 to 6.0.

9. The aqueous composition as claimed in claim 8, wherein the pH is 5.5 or less.

10. A method of making the aqueous compositions as claimed in claim 1 comprising combining an aqueous mother liquor of a polycarboxylate ether with a powder of a polysaccharide viscosity modifying additive and the acid, in any order, in the presence of shear to form a visibly homogeneous composition.

Description

EXAMPLES

[0045] The following examples serve to illustrate the invention. Unless otherwise indicated, the preparations and test procedures are carried out at ambient conditions of temperature and pressure.

[0046] Compatibility:

[0047] To check the compatibility of polysaccharide viscosity modifying additives (VMAs) and the polycarboxylate ether (PCE) superplasticizer, the VMAs were added in solid form to the superplasticizer in a glass container during stirring using a magnetic stirrer. The original pH of the investigated polycarboxylate ether aqueous composition solution is around pH 6. When adding a VMA (see Table 1, below) in solid form to this superplasticizer solution a precipitation was observed. The investigated VMA's were not compatible with the superplasticizer. After adjusting the pH of this mixture to a value of pH 5 using acetic acid, a stable solution without precipitates was observed.

[0048] Performance of acidified 1K PCE/VMA aqueous compositions was tested by adding the compositions in Table 1, below, to a mortar system containing 50 g cement. To compare performance of the aqueous compositions with standard dosage uses of viscosity modifying additives, the same VMA is added to the sand/cement mix as a dry powder, separately from a superplasticizer, and the fresh mortar properties (slump and bleeding) were tested twice for each example.

[0049] Slump:

[0050] A measure of how much a mortar is able to flow under its own weight after 15 strokes on a jolting table according to DIN EN 1015-3:2007-05 (Beuth Verlag GmbH, Berlin, Del., 2007), by placing a cone funnel (slump cone) having a bottom opening diameter of 100 mm, a top opening diameter of 70 mm and a height of 60 mm with the bottom opening on a wetted glass plate (wetted 10 seconds before testing), filling the cone with mortar and then quickly pulling the cone vertically off from the plate to fully release the mortar onto the plate of a Jolting Table (available from Toni Technik, Berlin, Del.) followed by subjecting the mortar to 15 strokes. Once the mortar ceases to spread, measure the diameter of the resulting mortar cake in four locations spaced equally around the mortar cake. The average of the four diameters is the slump value for the mortar. An acceptable result is a slump value that does not differ more than 30 mm from the slump value obtained by the same composition when the same amount of the same polycarboxylate ether and the same amount of the same viscosity modifying agent are separately added to the composition, preferably not more than 20 mm, or, more preferably, not more than 15 mm.

[0051] Table 1, below, gives compositions of viscosity modifying additives added to 5 g of GLENIUM 51 polymer (a partially neutralized 37 wt. % solids aqueous solution of a sodium polycarboxylate ether BASF, Leverkusen, Del., pH 71). These compositions were used in full to prepare an aqueous composition in a mortar formula containing 500 g cement.

TABLE-US-00001 TABLE 1 VMA-PCE Compositions (4C-5C are Comparative) VMA Quantity added to 5 g Example VMA GLENIUM 51 1A Cellosize QP 4400 H (HEC).sup.1 0.250 g 2A Walocel MKX 6000 PF 01 (HEMC).sup.1 0.250 g 3A MethocelA4M (MC).sup.1 0.250 g 4C Sika Stabilizer 4R (Starch Ether) 3.846 g* 5C Kelco-Crete 80 (Diutan Gum) 0.250 g *Sika Stabilizer 4R is supplied as a solution having a solids content of 6.5 wt. %; 1. HEC MS = 2.0, viscosity = 4400-6000 cP (2 aqu. solution, #4 SPINDLE @ 60 RPM): HEMC DS = 1.5-1.75, MS = 0.22-0.33, viscosity = 5500-7000 mPas (ROTOVISKO, D = 2.55 sec1, 2 aqu. solution, 20 C.) The Dow Chemical Co., Midland, MI, USA 2. Sika AG, Baar (ZG), CH, 3. CP-Kelco, Atlanta, GA, USA.

[0052] The mortars tested contained the materials shown in Table 2, below. To prepare mortars for testing, first all of the dry components were added together and mixed to make a dry mix. Then the water and polycarboxylate ether or polycarboxylate ether mixture from Table 1, above, with viscosity modifying additive was added into the mixing bowl of a ToniMIX mixer (available from Toni Technik, Berlin, Del.). While mixing, the dry mix was added to the mixing bowl, mixing for 30 seconds on level one and then for 30 seconds on level two (higher speed). After allowing the mixture to rest for 90 seconds to dissolve soluble additive, the mortar was then mixed again for 60 seconds on level two. The resulting mixture serves as a mortar. The results are shown in Table 3, below. As shown in Table 3, below, with a pH adjustment to pH 5 the aqueous composition of the present invention becomes homogeneous without precipitations. Comparing the performance of the conventional, separate addition of VMA and PCE in the formulation with addition of the aqueous composition of VMA and PCE adjusted to pH5, it can be seen that they all perform equally well. The slump value is in the preferred range for all examples tested and the formulations do not bleed. Thus, adjusting the aqueous composition pH to 5 with acetic acid results in a homogeneous mixture which still performs.

TABLE-US-00002 TABLE 2 Mortar Formulation and Results Component Identity Mass Cement Heidelberger PUR CEM I 42.5 R, 500.0 g Heidelberg, DE Water/Cement 0.5 Superplasticizer Glenium 51 polycarboxylate 5.0 g or See ether (BASF, Ludwigshafen, DE)) table 1 VMA See Table 1 See table 1 Aggregate 1 Quarzsand H32 from Quarzwerke 500.0 g GmbH, Frechen, DE. Aggregate 2 Sand having a particle size of 600.0 g 0.1-1.0 mm (M.u.E. Tebbe-Neuenhaus OHG, Bottrop, DE) Aggregate 3 Sand having a particle size of 400.0 g 1.0-2.0 mm (M.u.E. Tebbe-Neuenhaus OHG Bottrop, DE)

TABLE-US-00003 TABLE 3 Results Appearance of the VMA/PCE Slump Bleeding Mixture separate VMA/ separate VMA/ original Addition of PCE Addition PCE pH (not at VMA and Mixture of VMA Mixture Example adjusted) pH 5 PCE at pH 5 and PCE at pH 5 1A precipitate stable 216 212 No No 2A precipitate stable 214 226 No No 3A precipitate stable 235 236 No No 4C.sup.1 precipitate stable 158 170 No No 5C.sup.1 precipitate stable 171 175 No No 6C.sup.1 w/o stable n.a. 236 n.a. Yes n.a. VMA .sup.1Comparative Example.

[0053] Shelf Stability:

[0054] To test the shelf stability of the aqueous compositions of the present invention, the indicated mixtures of the polycarboxylate ether and the viscosity modifying additive, with proportions indicated in Tables 4 and 5, below, were acidified with the indicated acid and checked for stability, then let to stand for about 24 hours and rechecked for stability and pourability. Stable compositions are labeled as stable and unstable compositions are labelled precipitate. A pourable composition was labeled as x and a composition that was too viscous to pour was labeled o, which is unacceptable.

[0055] As shown in Tables 4, 5, and 6, below, a variety of acids and viscosity modifying additives can be included in the aqueous compositions of the present invention to give a stable concentrate for one to add to mortar or cement. In general, acids with two hydroxyl groups failed to give a stable aqueous composition. See Comparative Examples 49-52 with tartaric acid. The exception was the ascorbic acids which had only 1 carboxyl group and are easily oxidized to eliminate at least two of its hydroxyl groups. See Examples 33-36, 41-44 and 58. Examples 53-57 and 59-60 show that methyl cellulose is not a preferred viscosity modifying additive, but works with ascorbic acid in the aqueous composition at a pH below 5. Starch ethers are not preferred but give stable mixes on mixing. See Comparative Examples 61-73.

[0056] As shown in Tables 4, 5 and 6, below, all inventive Examples were stable and pourable after 24 hours. Comparative Examples 4 and 8 show clearly that polyprotic strong acids will not even give stable aqueous compositions of just a polycarboxylate ether. As shown in Comparative Examples 18-19 and 27-28, too high a solids content of the polysaccharide VMA results in compositions that are not pourable and cannot be used in accordance with the present invention. As shown in Comparative Examples 45-48, strong polyprotic acids fail to give stable compositions in accordance with the present invention. As shown in Comparative Examples 49-52, carboxylic acids with two hydroxyl groups fail to give stable compositions in accordance with the present invention. As shown in Comparative Examples 53-57, and inventive Example 58, ascorbic acids give stable compositions of polycarboxylate ether and methyl cellulose, especially at a lower pH. Finally, as shown in Comparative Examples 61-73, diutan gums fail to give stable compositions in accordance with the present invention.

TABLE-US-00004 TABLE 4 Shelf Stability Results (All Examples contain PCE.sup.1) Example Upon Pour- Pour- (VMA) Wt. %.sup.1 Acid pH Mixing able after 24 hr able 1* (none) No VMA HCl 5 stable x stable X 2* (none) No VMA citric acid 5 stable x stable X 3* (none) No VMA acetic acid 5 stable x stable X 4* (none) No VMA sulfuric acid 5 precipitate x precipitate X 5* (none) No VMA formic acid 5 stable x stable X 6* (none) No VMA succinic acid 5 stable x stable X 7* (none) No VMA D-iso-ascorbic acid 5 stable x stable X 8* (none) No VMA phosphoric acid 5 stable x precipitate X 9* (none) No VMA tartaric acid 5 stable x stable X 10* (HEMC.sup.2) 2.5 w/o 6 stable x precipitate X 11* (HEMC.sup.2) 5.0 w/o 6 stable x precipitate X 12 (HEMC.sup.2) 2.5 HCl 5 stable x stable X 13 (HEMC.sup.2) 2.5 HCl 4 stable x stable X 14 (HEMC.sup.2) 5.0 HCl 5 stable x stable X 15 (HEMC.sup.2) 5.0 HCl 4 stable x stable X 16 (HEMC.sup.2) 10.0 HCl 5 stable x stable X 17 (HEMC.sup.2) 10.0 HCl 4 stable x stable X 18* (HEMC.sup.2) 20.0 HCl 5 stable stable 19* (HEMC.sup.2) 20.0 HCl 4 stable stable 20 (HEMC.sup.2) 2.5 citric acid 5 stable x stable X 21 (HEMC.sup.2) 5.0 citric acid 5 stable x stable X 22 (HEMC.sup.2) 5.0 citric acid 4 stable x stable X 23 (HEMC.sup.2) 10.0 citric acid 5 stable x stable X 24 (HEMC.sup.2) 10.0 citric acid 4 stable x stable X 25 (HEMC.sup.2) 12.5 citric acid 5 stable x stable X 26 (HEMC.sup.2) 15.0 citric acid 5 stable x stable X 27* (HEMC.sup.2) 17.5 citric acid 5 stable stable 28* (HEMC.sup.2) 20.0 citric acid 5 stable stable 21 (HEMC.sup.2) 5.0 acetic acid 5 stable x stable X 22 (HEMC.sup.2) 10.0 acetic acid 5 stable x stable X 23 (HEMC.sup.2) 5.0 sulfuric acid 4 precipitate x precipitate X 24 (HEMC.sup.2) 10.0 sulfuric acid 5 precipitate x precipitate X 25 (HEMC.sup.2) 5.0 formic acid 5 stable x stable X 26 (HEMC.sup.2) 5.0 formic acid 4 stable x stable X .sup.1Wt. % VMA on the basis of total VMA plus PCE (Glenium 51 polymer, BASF, 37 wt. % solids); .sup.22. Walocel MKX 6000 PF 01 (Dow); *Comparative Example.

TABLE-US-00005 TABLE 5 Shelf Stability Results (All Examples contain PCE.sup.1) Example Upon Pour- after Pour- (VMA) Wt. %.sup.1 Acid pH Mixing able 24 hr able 27 (HEMC.sup.2) 10.0 formic acid 5 stable x stable X 28 (HEMC.sup.2) 10.0 formic acid 4 stable x stable X 29 (HEMC.sup.2) 5.0 succinic acid 5 stable x stable X 30 (HEMC.sup.2) 5.0 succinic acid 4.3 stable x stable X 31 (HEMC.sup.2) 10.0 succinic acid 5 stable x stable X 32 (HEMC.sup.2) 10.0 succinic acid 4.3 stable x stable X 33 (HEMC.sup.2) 5.0 ascorbic acid 5 stable x stable X 34 (HEMC.sup.2) 5.0 ascorbic acid 4.4 stable x stable X 35 (HEMC.sup.2) 10.0 ascorbic acid 5 stable x stable X 36 (HEMC.sup.2) 10.0 ascorbic acid 4.4 stable x stable X 37 (HEMC.sup.2) 5.0 malic acid 5 stable x stable X 38 (HEMC.sup.2) 5.0 malic acid 4 stable x stable X 39 (HEMC.sup.2) 10.0 malic acid 5 stable x stable X 40 (HEMC.sup.2) 10.0 malic acid 4 stable x stable X 41 (HEMC.sup.2) 5.0 D-iso-ascorbic acid 5 stable x stable X 42 (HEMC.sup.2) 5.0 D-iso-ascorbic acid 4.4 stable x stable X 43 (HEMC.sup.2) 10.0 D-iso-ascorbic acid 5 stable x stable X 44 (HEMC.sup.2) 10.0 D-iso-ascorbic acid 4.4 stable x stable X 45* (HEMC.sup.2) 5.0 phosphoric acid 5 stable x precipitate X 46* (HEMC.sup.2) 5.0 phosphoric acid 4 precipitate x precipitate X 47* (HEMC.sup.2) 10.0 phosphoric acid 5 stable x precipitate X 48* (HEMC.sup.2) 10.0 phosphoric acid 4 precipitate x precipitate X 49* (HEMC.sup.2) 5.0 tartaric acid 5 stable x precipitate X 50* (HEMC.sup.2) 5.0 tartaric acid 4 stable x precipitate 51* (HEMC.sup.2) 10.0 tartaric acid 5 stable x precipitate X 52* (HEMC.sup.2) 10.0 tartaric acid 4 stable x precipitate 53* (MC).sup.3 5.0 citric acid 5 stable x precipitate X 54* (MC).sup.3 10.0 citric acid 5 stable x precipitate X 55* (MC).sup.3 5.0 succinic acid 5 stable x precipitate X 56* (MC).sup.3 5.0 ascorbic acid 5 stable x precipitate X 57* (MC)3 10.0 ascorbic acid 5 stable x precipitate X 58 (MC).sup.3 10.0 ascorbic acid 4.4 stable x stable X 59* (MC).sup.3 5.0 malic acid 5 stable x precipitate X 60* (MC).sup.3 10.0 malic acid 5 stable x precipitate X .sup.1Wt. % VMA on the basis of total VMA plus PCE (Glenium 51 polymer, BASF, 37 wt. % solids); .sup.2Walocel MKX 6000 PF 01 HEMC (Dow); .sup.3Methocel A4M methyl cellulose (Dow); *Comparative Example.

TABLE-US-00006 TABLE 6 Shelf Stability Results (All Examples contain PCE.sup.1) Example Upon Pour- Pour- (VMA) Wt. %.sup.1 Acid pH Mixing able 24 hr rable 61*.sup.,2 2.5 citric acid 5 stable x precipitate x 62*.sup.,2 2.5 succinic acid 5 stable x precipitate x 63*.sup.,2 2.5 ascorbic acid 5 stable x precipitate x 64*.sup.,2 2.5 malic acid 5 stable x precipitate x 65*.sup.,2 5.0 citric acid 5 stable x precipitate x 66*.sup.,2 10.0 citric acid 5 stable x precipitate x 67*.sup.,2 10.0 citric acid 4 stable x precipitate x 68*.sup.,2 5.0 succinic acid 4.3 stable x precipitate x 69*.sup.,2 10.0 succinic acid 5 stable x Precipitate x 70*.sup.,2 5.0 ascorbic acid 5 stable x Precipitate x 71*.sup.,2 10.0 ascorbic acid 5 stable x Precipitate x 72*.sup.,2 5.0 malic acid 5 stable x Precipitate x 73*.sup.,2 10.0 malic acid 5 stable x Precipitate x .sup.1Wt. % VMA on the basis of total VMA plus PCE (Glenium 51 polymer, BASF, 37 wt. % solids); .sup.2KelcoCrete Diutan Gum (CP Kelco); *Comparative Example.