HYDRATION CONTROL MIXTURE FOR MORTAR AND CEMENT COMPOSITIONS

Abstract

The present invention relates to a construction chemical composition, comprising a) at least one inorganic binder, b) less than 0.5 weight-%, based on the total amount of a), b) and c), of at least one compound of the general formula (I) and at least c) one alkali metal carbonate. Further the use of a hydration control mixture as a retarder for at least one inorganic binder, comprising an aluminate-containing binder is disclosed.

Claims

1-11. (canceled)

12. A construction chemical composition comprising a) at least one inorganic binder, b) less than 0.5 weight-%, based on the total amount of a), b) and c), of at least one compound of the general formula I ##STR00019## wherein X is selected from H or a cation equivalent K.sub.a wherein K is selected from an alkali metal, alkaline earth metal, zinc, iron, ammonium or phosphonium cation, and a is ⅟n wherein n is the valency of the cation; and c) at least one alkali metal carbonate wherein the composition does not comprise polyhydroxy compound B and/or salts or esters thereof, wherein the polyhydroxy compound B is selected from polyalcohols with a carbon to oxygen ratio of from C/O ≥ 1 to C/O ≤ 1.5 and mixtures thereof and wherein the composition does not comprise a water-soluble organic carbonate.

13. The construction chemical composition of claim 12, wherein the weight ratio of component b) to component c) is in the range from 5:1 to about 1:1000.

14. The construction chemical composition of claim 12, wherein the mixture comprises between 0.001 and 0.4 percent by weight of component b) and between 0.1 and 10 percent by weight of component c), based on the total amount of a), b) and c).

15. The construction chemical composition of claim 12, wherein the inorganic binder a) is selected from calciumsulfate hemihydrate, anhydrite, a latent hydraulic binder, a pozzolanic binder and/or aluminate-containing cement.

16. The construction chemical composition of claim 15, wherein the aluminate-containing cement is CEM cement in accordance with CEM classification as set forth in DIN EN 197-1.

17. The construction chemical composition of claim 15, wherein the aluminate-containing cement is a mixture of CEM cement and aluminate cement, in particular a mixture of CEM cement and high alumina cement or a mixture of CEM cement and sulfoaluminate cement or a mixture of CEM cement, high alumina cement and sulfoaluminate cement.

18. The construction chemical composition of claim 12, additionally comprising at least one dispersant, selected from polycarboxylate ether, a phosphorylated polycondensation product or a sulfonic acid and/or sulfonate group containing dispersant and mixtures thereof.

19. The construction chemical composition of claim 12, additionally comprising at least one compound selected from polycarboxylic acids or salts thereof whose milliequivalent number of carboxyl groups is 5.00 meq/g or higher, assuming all the carboxyl groups to be in unneutralized form; phosphonates which comprise two or three phosphonate groups and no carboxyl groups; and α-hydroxy carboxylic acids or salts thereof; a polyhydroxycompound with a carbon to oxygen ratio of C/O > 1.5; a polyhydroxycompound with a carbon to oxygen ratio of C/O < 1.0; and mixtures thereof.

20. The construction chemical composition according to claim 19, wherein the compound is a α-hydroxy carboxylic acid or salts thereof.

21. The construction chemical composition of claim 12, additionally comprising fillers.

22. A method comprising utilizing b) less than 0.5 weight-%, based on the total amount of a), b) and c), of at least one compound of the general formula I ##STR00020## wherein X is selected from H or a cation equivalent K.sub.a wherein K is selected from an alkali metal, alkaline earth metal, zinc, iron, ammonium or phosphonium cation and a is ⅟n wherein n is the valency of the cation; and c) at least one alkali metal carbonate as a retarder for a) at least one inorganic binder, comprising an aluminate-containing binder in building products, wherein the composition does not comprise polyhydroxy compound B and/or salts or esters thereof, wherein the polyhydroxy compound B is selected from polyalcohols with a carbon to oxygen ratio of from C/O ≥ 1 to C/O ≤ 1.5 and mixtures thereof and wherein the composition does not comprise a water-soluble organic carbonate.

Description

EXAMPLES

Example 1

[0181] The additive mixture comprising 0.12 % b.w.o.c. sodium glyoxylate and 0.7 % b.w.o.c. of sodium carbonate or propylene carbonate was added to dry mortar mixture comprising 1100 g Portland cement and 1650 g sand according to DIN EN 196-1 available from Normensand GmbH. After adding the mixing water (w/c = 0.35), the mortar mixture was mixed analogous to DIN EN 196-1 in a Toni-Mixer as follows:

TABLE-US-00002 0 - 60 s: Rilem level 1 60 - 90 s: Rilem level 2 90- 180 s: Pause 180 - 240 s: Rilem level 2

[0182] The compressive strength was measured after 3 h, 5.5 h and 24 h at 4x4 cm prisms. At each time 3 prisms were tested and the average of the values was calculated.

[0183] The results are shown in the following table 1.

TABLE-US-00003 Compressive strength [MPa] Ex.-No. Additive 3 h 5.5 h 24 h 1 sodium carbonate + sodium glyoxylate 3.78 4.55 31.5 Ref-1 propylene carbonate + sodium glyoxylate 1.20 1.23 30.2

[0184] The early compressive strength and the final compressive strength is improved in case of the additive comprising the Retardant 1 and glycerol in comparison to the use of Retardant 1 alone.

Example 2

[0185] The additive mixture comprising 0.10 % b.w.o.c. sodium glyoxylate and 0.7 % b.w.o.c. of sodium carbonate or ethylene carbonate was added to dry mortar mixture comprising 1100 g Portland cement and 1650 g sand according to DIN EN 196-1 available from Normensand GmbH. After adding the mixing water (w/c = 0.35), the mortar mixture was mixed analogous to DIN EN 196-1 in a Toni-Mixer as follows:

TABLE-US-00004 0 - 60 s: Rilem level 1 60 - 90 s: Rilem level 2 90 - 180 s: Pause 180 - 240 s: Rilem level 2

[0186] The compressive strength was measured after 3 h and 24 h at 4x4 cm prisms. At each time 3 prisms were tested and the average of the values was calculated.

[0187] The results are shown in the following table 2.

TABLE-US-00005 Compressive strength [MPa] Ex.-No. Additive 3 h 24 h Ref-2 ethylene carbonate + sodium glyoxylate 0.37 26.17 2 sodium carbonate + sodium glyoxylate 1.99 32.17

[0188] The examples show that the use of organic carbonates leads to significantly lower compressive strengths.

Example 3

[0189] In a further experiment, the storage of the dry mortar was simulated at elevated temperatures. The above additive mixture of Example 2 was added to the dry mortar. The dry mortar was stored at 60° C. for 72 hours. After the mortar had cooled, the mortar was mixed with the same amount of cement, sand and water as in Example 2. The following measured values were obtained:

[0190] The results are shown in the following table 3.

TABLE-US-00006 Compressive strength [MPa] Ex.-No. Additive 3 h 24 h Ref-3 ethylene carbonate + sodium glyoxylate 0.17 20.84 3 sodium carbonate + sodium glyoxylate 1.81 33.13

[0191] The example shows that the use of organic carbonate leads to significantly lower compressive strengths. The storage stability of inorganic carbonates is significantly better compared to organic carbonates.

Example 4

[0192] In this example the influence of glyoxylic acid dosage is shown.

[0193] The additive mixture comprising the appropriate amount of glyoxylic acid (table 4), 1.926 g of a 35 % solution of a dispersant (a copolymer with a side chain 3000 g/mol of Polyethylene glycol and 10 equivalents of acrylic acid), 23.4 g of K.sub.2CO.sub.3 and 0.06 g of sodium gluconate was added to 1700 g Portland cement together with the mixing water. The water amount was adjusted to w/c= 0.35. The mixing protocol according to EN 1996-1 was applied. Initial and final setting time were measure according EN13279-2 using a Dettki automatic Vicat measuring system. Strenght was determined after 5.5 h and 24 h with 16x4x4 cm prisms. The results are shown in the following table 4.

TABLE-US-00007 Experiment Dosage Glyoxylic acid [% b.w.o.c] Initial setting time [min] Final setting time [min] 5.5 h compressive strenght [N/mm.sup.2] 24 h compressive strenght [N/mm2] 1 0.01 49 53 2.57 12.1 2 0.05 40 75 2.735 4.70 3 0.10 67 137 2.65 3.23 4 0.30 368 391 n.m. 3.17 5 0.5 612 845 n.m. n.m. n.m. = not measurable