STORAGE STABLE CEMENT PASTES

Abstract

The present invention relates to substantially water free hydraulic cement pastes which remain shelf stable over extended time periods, for example, 100 days at room temperature. The substantially water free cement pastes comprise a deep eutectic solvent mixture of a polar organic carrier component, such as a hydrogen donor like a polyol, in association with an anhydrous cation containing component, and a hydraulic cement, preferably, an aluminate cement, or sulpho-aluminate cement. A preferred deep eutectic solvent mixture comprises K.sub.2CO.sub.3 and glycerol in molar ratios of from 1:1 to 1:6. The cement pastes are activated simply by addition of water or aqueous polymers to form thin set compositions.

Claims

1. A substantially water free cement paste composition comprising a deep eutectic solvent mixture of a polar organic carrier component, in association with an anhydrous cation containing component, and, further, a hydraulic cement, wherein the deep eutectic solvent is a liquid or fluid at 10° C. or less.

2. The substantially water free cement paste composition as claimed in claim 1, wherein the polar organic carrier component is chosen from glycerol, ethylene glycol, C.sub.3 to C.sub.18 alkane diols, urea, acetamide, 1-methyl urea, 1,3-dimethyl urea, thiourea, benzamide, carboxylic acids, polyols or carbohydrates, oligomers or polymers of a diol, oligomers or polymers of a polyol, oligomers or polymers of an organic acid, oligomers or polymers of a carbohydrate, oligourethanes, polypeptides, or two or more of these.

3. The substantially water free cement paste composition as claimed in claim 1, wherein the polar organic carrier component is chosen from glycerol, polyalkoxylated glycerol, ethylene glycol, urea, acetamide, 1-methyl urea, 1,3 -dimethyl urea, thiourea, carbohydrates, or two or more of these.

4. The substantially water free cement paste composition as claimed in claim 1, wherein the amount of the polar organic carrier component in the deep eutectic solvent mixture ranges from 40 to 99 mol. %, with the remainder comprising the anhydrous cation containing component.

5. The substantially water free cement paste composition as claimed in claim 1, wherein the anhydrous cation containing component is chosen from non-toxic quaternary ammonium containing materials, ammonium salts, organoammonium salts, simple salts of metals, salts of cyanamide, metal cations combined with non-volatile amines, onium salts; metal cations combined with organic nitrides, metal cations combined with organic sulfonates, metal cations combined with organic sulphonyl group containing compounds, or two or more of these.

6. The substantially water free cement paste composition as claimed in claim 5, wherein the anhydrous cation containing component is chosen from choline chloride (ChCl), (hydroxyethyl) trimethylammonium chloride, ammonium chloride, 1 -n-butyl-3-methylimidazolium salts, metal carbonates, semi-metal carbonates, metal halides, semi-metal halides, metal nitrates, metal nitrites, metal sulphates, metal phosphates, salts of cyanamide, metal citrates, metal acetates, metal cations combined with non-volatile amines, benzyltriphenylphosphonium halides, metal cations combined with (CF.sub.3CO.sub.2).sub.2N, metal cations combined with trifluoromethanesulfonate, metal cations combined with bis(trifluoromethanesulphonyl) imide, metal cations combined with tris(trifluoromethanesulphonyl) methide, or two or more of any of these.

7. The substantially water free cement paste composition as claimed in claim 1, wherein the deep eutectic solvent mixture comprises K.sub.2CO.sub.3 and glycerol in molar ratios of from 1:1 to 1:6, K.sub.2CO.sub.3 and ethylene glycol in molar ratios of from 1:3 to 1:8 or K.sub.2CO.sub.3 and propoxylated glycerol in molar ratios of from 1:16 to 1:30.

8. The substantially water free cement paste composition as claimed in claim 1, wherein the hydraulic cement is chosen from Ordinary Portland cement, aluminate cement, sulpho-aluminate cement, gypsum and their mixtures.

9. The substantially water free cement paste composition as claimed in claim 1, wherein the amounts of the deep eutectic solvent mixture range from 20 to 80 wt. %, based on the total weight of the composition.

10. The substantially water free cement paste composition as claimed in claim 1, wherein the amounts of the hydraulic cement solids range from 20 to 73 wt. %, based on the total weight of the composition.

Description

EXAMPLES

[0068] The following examples are used to illustrate the present invention without limiting it to those examples. Unless otherwise indicated, all temperatures are ambient temperatures (21-23° C.) and all pressures are 1 atmosphere. In the Examples that follow, RT means “room temperature” which is equivalent to ambient temperature.

[0069] Materials used in the Examples, below, include the following materials: Calcium aluminate cement 1 or CAC 1: Calcium aluminate cement (Calcium aluminate content: >90% (92 to 98%)), HiPercem™ cement (Calucem, Mannheim, Del.);

Calcium aluminate cement 2 or CAC 2: Ternal™ white cement (calcium aluminate content: 97 to 99.7%) (Imerys (Kerneos), Paris, FR);

[0070] Calcium aluminate cement 3: Ternal™ white cement which is stabilized with aqueous phosphoric acid, pH ˜7.

[0071] Polyol 1: Glycerine propoxylated polyether having a FW 300 g/mol and having an average of three (3) OH groups and a FW of about 300.

Example 1: Cement Paste Preparation and Storage

[0072] Deep eutectic solvent mixture preparation: First, part B, a deep eutectic solvent mixture was prepared by mixing K.sub.2CO.sub.3 and glycerol in a molar ratio of 1:4.8 in a mechanical mixer equipped with a polytetrafluoroethylene coated magnetic stirrer at 90° C. (in a water bath at that temperature) to form a stable carrier mixture until dissolved or 24 h, whichever is shorter.

[0073] Cement paste preparation: Calcium aluminate cement 1, Part A, with the deep eutectic solvent mixture, part B, in a weight ratio of 57.5:42.5 was mixed in a mechanical mixer at from 60 to 90° C. by adding Part A in ten roughly equal portions, wherein each portion was mixed for one (1) minute and then the resulting product was mixed for 5 more minutes. The paste was stored at room temperature (RT or 22° C.) over 100 days without hardening (FIG. 1). Stability results from visual inspection are as shown in Table 1, below.

Example 1A: Comparative Paste Preparation

[0074] As a comparative example, the Example 1 was repeated with glycerol only as Part B instead of a deep eutectic solvent mixture. It was not possible to form a paste. The glycerol and cement phase separated within <5 days after mixing and became compacted at the bottom of the vessel (FIG. 1). Stability results were as shown in Table 1, below.

Example 1 B: Comparative Paste Preparation in Water

[0075] As a comparative example, the Example 1 was repeated with water only as Part B instead of a deep eutectic solvent mixture. It was not possible to keep the mixture from setting after a short period.

TABLE-US-00001 TABLE 1 Cement paste composition stability Part A: Calcium Amount Part B: Amount aluminate of Part Deep eutectic of Part Name cement No. A (wt. %) solvent mixture B (wt. %) Paste Stability Ex. 1 1 57.5 K.sub.2CO.sub.3:Glycerol 42.5 yes Homogeneous (1:4.8 mol/mol) and Stable Comp. 1 57.5 Glycerol 42.5 no Sedimentation, 1A* hardening Comp. 1 57.5 Water 42.5 slurry Hydraulic 1B* hardening *Denotes comparative example.

[0076] As shown in Table 1, above, after 100 days storage, calcium aluminate cement 1 (CAC 1) mixed with solely glycerol in Comparative Ex. 1 A formed a sediment and hardened, i.e. it was unusable. In contrast, in inventive Example 1, CAC 1 stabilized in a deep eutectic solvent mixture exhibited a stable paste (Ex. 1). Likewise, in Comparative example 1B wherein CAC 1 was mixed with water, the result was not stable over time; rather the cement set and hardened and could not be dispersed.

Example 2: Cement and Deep Eutectic Solvent Mixture Variations and Setting Time

[0077] The cement pastes indicated in Table 2, below, were prepared using the indicated deep eutectic solvent mixtures and the indicated calcium aluminate cements, CAC 1 or CAC 2. To demonstrate the versatility of the present invention, the indicated deep eutectic solvent mixtures in Table 2, below were prepared by mixing potassium carbonate with each of glycerol, ethylene glycol or Polyol 1, as indicated in the table, in a mechanical mixer equipped with a polytetrafluoroethylene coated magnetic stirrer at 750 rpm at the following temperatures: For Examples 2A and 2B, from 60 to 90° C., and, for the remaining Examples 2C, 2D, 2E, 2F and 2G at 23° C. to form a stable carrier mixture. Each cement paste was formed at from RT by adding cement in ten equal portions to the indicated deep eutectic solvent mixture in a mechanical mixer and mixing each for about 1 minute; thereafter, mixing was continued for 5 minutes. All pastes were then activated with water and mixed until homogeneous for as long as 10 minutes to form hydraulic setting compositions and, subsequently filler was added (silica flour, Silverbond™ M500 silica, Sibelco, Antwerp, Belgium) and mixed for 2 to 4 minutes to form hydraulic setting compositions. During mixing with water, pH was adjusted to 12.7, if required with NaOH 50% w/w. The setting time (Vicat Hardening time) was tracked with a

[0078] Vicatronic E044N Vicat tester (Vicatronic, Ile-De-France, FR), wherein the tester dips a 300 g needle from a normal or 90° angle into the curing hydraulic setting composition formulation and measures the distance the needle penetrates at a 30 min time interval. The compositions are considered cured when the needle cannot penetrate the composition.

TABLE-US-00002 TABLE 2 Setting Performance Part B: Calcium Deep eutectic aluminate Paste Filler/ Water/ Vicat solvent mixture cement CAC Part B Paste CAC hardening Example (mol/mol) (CAC) No. (wt. %) (wt. %) (w/w) (w/w) time (h) pH 2A K.sub.2CO.sub.3:Glycerol 2 71 29 0.8 0.5 3 12.7 (1:4.8) 2B K.sub.2CO.sub.3:Glycerol 1 69 31 0.8 0.5 3 12.7 (1:4.8) 2C K.sub.2CO.sub.3:Ethylene 1 73 27 0.4 0.6 5 12.7 glycol (1:4.8) 2D K.sub.2CO.sub.3:Ethylene 2 71 29 0.2 0.5 7 12.7 glycol (1:4.8) 2E.sup.  K.sub.2CO.sub.3:Ethylene 1 73 27 0.4 0.6 3 12.7 glycol (1:4.8), Lithium sulphate monohydrate 1 wt. % vs. CAC 2F.sup.  K.sub.2CO.sub.3:Polyol 1 2 73 27 0.7 0.6 12 12.7 (1:16) 2G K.sub.2CO.sub.3:Polyol 1 1 73 27 0.7 0.6 12 12.7 (1:16)

[0079] All pastes in Table 2, above, were activated and react when mixed with water, showing that storage does not impede the hydraulic reaction of the cement. Comparing the Vicat hardening time of Example 2D with that of Example 2E shows that salt accelerators (lithium sulphate monohydrate) as in use additives can be used to further shorten the hardening time.

Example 3. Storage Stability of Some Cement Pastes

[0080] Substantially water free cement paste compositions were prepared as described in Example 2, above except using the compositions indicated in Table 3, below. Each composition was formed at from RT by adding the indicated cement in 5 equal portions to the indicated deep eutectic solvent mixture (50 g) in a mechanical mixer and mixing each for about 1 minute; thereafter, mixing was continued for 3 minutes. The pastes were transferred to plastic cups that were enclosed with a plastic lid, and sealed with semi-transparent laboratory sealing film (Parafilm M™, Pecheney Plastics Packaging, Chicago, Ill.) and stored under controlled conditions (23° C. and 50% rel. humidity). At the end of the indicated storage time, syneresis or separation of liquid from solid was visually evaluated and hardening was determined by evaluating whether the material is deformable by hand, by squeezing the plastic cup and check if paste deform pressing finger on the sample. Acceptable substantially water free cement paste compositions did not exhibit any syneresis or hardening.

TABLE-US-00003 TABLE 3 Storage stability Part B: Calcium Deep eutectic aluminate Paste Storage solvent mixture cement CAC Part B time Syneresis Hardening Example (mol/mol) (CAC) No. (wt. %) (wt. %) (days) (w/w) (w/w) 3A K.sub.2CO.sub.3:Ethylene 2 71 29 7 No No Glycol as 1:4.8 3B K.sub.2CO.sub.3:Ethylene 1 73 29 7 No Yes Glycol as 1:4.8 3C K.sub.2CO.sub.3:Ethylene 2 57.5 42.5 6 No No Glycol as 1:4.8 3E K.sub.2CO.sub.3:Polyol 1 2 71 29 26 No No (1:16)

[0081] As shown in Table 3, above, all of the inventive compositions were shelf stable in relation to syneresis and hardening except for Example 3B which hardened fully. Example 3B appears to have hardened, at least in part, because of the high 73 wt. %

[0082] weight ratio of CAC 2 and the very high calcium aluminate content of 97+ wt. % of CAC 2. Example 3A, in comparison, comprises an amount of calcium aluminate cement in the preferred proportion and uses a calcium aluminate cement having a calcium aluminate content averaging about 95 wt. % of the cement.