CEMENT AND CALCIUM SULFATE BASED BINDER COMPOSITION

Abstract

The invention concerns a composition containing a) 2 to 80 weight % of Ordinary Portland Cement with respect to the total weight of the composition b) 2 to 80 weight % of a calcium sulfate based binder with respect to the total weight of the composition, with the proviso that the weight ratio of a) Ordinary Portland Cement to b) calcium sulfate based binder is from 95/5 to 5/95 and c) at least one retarder for calcium sulfate based binders, the retarder being a chemical structure, which comprises from 3 to 70 amino acids. Also concerned is the use of the compositions for self-levelling underlayments, tile adhesives, non-shrink grouts, floor screeds and repair mortars.

Claims

1. Composition containing a) 2 to 80 weight % of Ordinary Portland Cement with respect to the total weight of the composition, b) 2 to 80 weight % of a calcium sulfate based binder with respect to the total weight of the composition, with the proviso that the weight ratio of a) Ordinary Portland Cement to b) calcium sulfate based binder is from 95/5 to 5/95 and c) at least one retarder for calcium sulfate based binders, the retarder being a chemical structure, which comprises from 3 to 70 amino acids.

2. Composition according to claim 1, in which the molecular weight of the c) retarder for calcium sulfate based binders is from 300 g/mol to 10,000 g/mol.

3. Composition according to claim 1, the retarder being in the case c-1) a polycondensation product comprising from 3 to 70 amino acids in the structure of the polycondensation product or the retarder being in the case c-2) a hydrolysis product of an oligo peptide and/or polypeptide, said hydrolysis product comprising from 3 to 70 amino acids, optionally from 3 to 70 -amino acids.

4. Composition according to claim 3, in which the polycondensation product of the case c-1) comprises peptide bonds.

5. Composition according to claim 3, in which the c) retarder for calcium sulfate based binders is the polycondensation product of the case c-1) and contains polycarboxylic acids and polyamines, the amine groups in the polyamines being primary and/or secondary amines, in a ratio so that the sum of all carboxylic equivalents in the polycarboxylic acids to the sum of all amine equivalents in the polyamines is in the range from 1/2 to 2/1, optionally the weight ratio of the sum of said polycarboxylic acids and polyamines is up to 50 weight % of the c) retarder for calcium sulfate based binders.

6. Composition according to claim 3, in which the polycondensation product of the case c-1) is the reaction product of the amino acids with formaldehyde and contains a repeating unit [NRCH.sub.2]; R.sup.1 is the same or is different and is a residue selected from (CH.sub.2)n-COOH and (CHR.sup.2)COOH; n is the same or is different and is an integer from 1 to 5; R.sup.2 is the same or is different and is selected from methyl, isopropyl, CH.sub.2CH.sub.2CH(Me).sub.2, CHMe-CH.sub.2CH.sub.3, CH.sub.2-phenyl, -4-hydroxy-benzyl, CH.sub.2-phenyl, CH.sub.2-(3)-indol, CH.sub.2OH, CHMeOH, CH.sub.2SH, CH.sub.2CH.sub.2SCH.sub.3, CH.sub.2CONH.sub.2, CH.sub.2CH.sub.2CONH.sub.2 and CH.sub.2COOH.

7. Composition according to claim 1, in which the b) calcium sulfate based binder is selected from the group of anhydrite, -bassanite and -bassanite or mixtures thereof.

8. Composition according to claim 1, in which at least one dispersant for Ordinary Portland Cement a) and calcium sulfate based binders b) is contained.

9. Composition according to claim 8, in which the dispersant for Ordinary Portland Cement a) and calcium sulfate based binders b) is a polymeric dispersant, which has anionic and/or anionogenic groups and polyether side chains, optionally the polyether side chains comprise poly alkylene glycol side chains.

10. Composition according to claim 9, where the polymeric dispersant comprises as anionic and/or anionogenic group at least one structural unit of the general formulae (Ia), (Ib), (Ic) and/or (Id): (Ia) ##STR00018## in which R.sup.1 is H or an unbranched or branched C.sub.1-C.sub.4 alkyl group, CH.sub.2COOH or CH.sub.2COXR.sup.3; X is NH(C.sub.nH.sub.2n) or O(C.sub.nH.sub.2n) with n=1, 2, 3 or 4, or is a chemical bond, where the nitrogen atom or the oxygen atom is bonded to the CO group; R.sup.2 is OM, PO.sub.3M.sub.2, or OPO.sub.3M.sub.2; with the proviso that X is a chemical bond if R.sup.2 is OM; R.sup.3 is PO.sub.3M.sub.2, or OPO.sub.3M.sub.2; (Ib) ##STR00019## in which R.sup.3 is H or an unbranched or branched C.sub.1-C.sub.4 alkyl group; n is 0, 1, 2, 3 or 4; R.sup.4 is PO.sub.3M.sub.2, or OPO.sub.3M.sub.2; (Ic) ##STR00020## in which R.sup.5 is H or an unbranched or branched C.sub.1-C.sub.4 alkyl group; Z is O or NR.sup.7; R.sup.7 is H, (C.sub.nH.sub.2n)OH, (C.sub.nH.sub.2n)PO.sub.3M.sub.2, (C.sub.nH.sub.2n)OPO.sub.3M.sub.2, (C.sub.6H.sub.4)PO.sub.3M.sub.2, or (C.sub.6H.sub.4)OPO.sub.3M.sub.2, and n is 1, 2, 3 or 4; (Id) ##STR00021## in which R.sup.6 is H or an unbranched or branched C.sub.1-C.sub.4 alkyl group; Q is NR.sup.7 or O; R.sup.7 is H, (C.sub.nH.sub.2n)OH, (C.sub.nH.sub.2n)PO.sub.3M.sub.2, (C.sub.nH.sub.2n)OPO.sub.3M.sub.2, (C.sub.6H.sub.4)PO.sub.3M.sub.2, or (C.sub.6H.sub.4)OPO.sub.3M.sub.2, n is 1, 2, 3 or 4; and where each M independently of any other is H or a cation equivalent.

11. Composition according to claim 9, where the polymeric dispersant comprises as polyether side chain at least one structural unit of the general formulae (IIa), (IIb), (IIc) and/or (IId): (IIa) ##STR00022## in which R.sup.10, R.sup.11, and R.sup.12 independently of one another are H or an unbranched or branched C.sub.1-C.sub.4 alkyl group; E is an unbranched or branched C.sub.1-C.sub.6 alkylene group, a cyclohexylene group, CH.sub.2C.sub.6H.sub.10, 1,2-phenylene, 1,3-phenylene or 1,4-phenylene; G is O, NH or CONH; or E and G together are a chemical bond; A is an unbranched or branched alkylene group with 2 to 5 carbon atoms or CH.sub.2CH(C.sub.6H.sub.5); n is 0, 1, 2, 3, 4 or 5; a is an integer from 2 to 350; R.sup.13 is H, an unbranched or branched C.sub.1-C.sub.4 alkyl group, CONH.sub.2 and/or COCH.sub.3; (IIb) ##STR00023## in which R.sup.16, R.sup.17 and R.sup.18 independently of one another are H or an unbranched or branched C.sub.1-C.sub.4 alkyl group; E is an unbranched or branched C.sub.1-C.sub.6 alkylene group, a cyclohexylene group, CH.sub.2C.sub.6H.sub.10, 1,2-phenylene, 1,3-phenylene, or 1,4-phenylene, or is a chemical bond; A is an unbranched or branched alkylene with 2 to 5 carbon atoms or CH.sub.2CH(C.sub.6H.sub.5); n is 0, 1, 2, 3, 4 or 5; L is C.sub.xH.sub.2x with x=2, 3, 4 or 5, or is CH.sub.2CH(C.sub.6H.sub.5); a is an integer from 2 to 350; d is an integer from 1 to 350; R.sup.19 is H or an unbranched or branched C.sub.1-C.sub.4 alkyl group; R.sup.20 is H or an unbranched C.sub.1-C.sub.4 alkyl group; and n is 0, 1, 2, 3, 4 or 5; (IIc) ##STR00024## in which R.sup.21, R.sup.22 and R.sup.23 independently of one another are H or an unbranched or branched C.sub.1-C.sub.4 alkyl group; W is O, NR.sup.25, or is N; V is 1 if WO or NR.sup.25, and is 2 if WN; A is an unbranched or branched alkylene with 2 to 5 carbon atoms or CH.sub.2CH(C.sub.6H.sub.5); a is an integer from 2 to 350; R.sup.24 is H or an unbranched or branched C.sub.1-C.sub.4 alkyl group; R.sup.25 is H or an unbranched or branched C.sub.1-C.sub.4 alkyl group; (IId) ##STR00025## in which R6 is H or an unbranched or branched C.sub.1-C.sub.4 alkyl group; Q is NR.sup.10; N or O; V is 1 if WO or NR.sup.10 and is 2 if WN; R.sup.10 is H or an unbranched or branched C.sub.1-C.sub.4 alkyl group; A is an unbranched or branched alkylene with 2 to 5 carbon atoms or CH.sub.2CH(C.sub.6H.sub.5); and a is an integer from 2 to 350.

12. Composition according to claim 8, where the polymeric dispersant is a phosphorylated polycondensation product comprising structural units (III) and (IV): (III) ##STR00026## in which T is a substituted or unsubstituted phenyl or naphthyl radical or a substituted or unsubstituted heteroaromatic radical having 5 to 10 ring atoms, of which 1 or 2 atoms are heteroatoms selected from N, O and S; n is 1 or 2; B is N, NH or O, with the proviso that n is 2 if B is N and with the proviso that n is 1 if B is NH or O; A is an unbranched or branched alkylene with 2 to 5 carbon atoms or CH.sub.2CH(C.sub.6H.sub.5); a is an integer from 1 to 300; R.sup.25 is H, a branched or unbranched C.sub.1 to C.sub.10 alkyl radical, C.sub.5 to C.sub.8 cycloalkyl radical, aryl radical, or heteroaryl radical having 5 to 10 ring atoms, of which 1 or 2 atoms are heteroatoms selected from N, O and S; where the structural unit (IV) is selected from the structural units (IVa) and (IVb): ##STR00027## in which D is a substituted or unsubstituted phenyl or naphthyl radical or a substituted or unsubstituted heteroaromatic radical having 5 to 10 ring atoms, of which 1 or 2 atoms are heteroatoms selected from N, O and S; E is N, NH or O, with the proviso that m is 2 if E is N and with the proviso that m is 1 if E is NH or O; A is an unbranched or branched alkylene with 2 to 5 carbon atoms or CH.sub.2CH(C.sub.6H.sub.5); b is an integer from 0 to 300; M independently at each occurrence is H or a cation equivalent; ##STR00028## in which V is a substituted or unsubstituted phenyl or naphthyl radical and is optionally substituted by 1 or two radicals selected from R.sup.8, OH, OR.sup.8, (CO)R.sup.8, COOM, COOR.sup.8, SO.sub.3R.sup.8 and NO.sub.2; R.sup.7 is COOM, OCH.sub.2COOM, SO.sub.3M or OPO.sub.3M.sub.2; M is H or a cation equivalent; and R.sup.8 is C.sub.1-C.sub.4 alkyl, phenyl, naphthyl, phenyl-C.sub.1-C.sub.4 alkyl or C.sub.1-C.sub.4 alkylphenyl.

13. Composition according to claim 1, in which 2 to 10 weight % of a calcium sulfate based binder b) are contained and the weight ratio of a) Ordinary Portland Cement to b) calcium sulfate based binder is from 90/10 to 70/30.

14. Composition according to claim 1, in which a calcium-silicate-hydrate based hardening accelerator for cementitious compositions is contained.

15. Composition according to claim 14, optionally dry mortar composition, in which the calcium-silicate-hydrate based hardening accelerator for cementitious compositions is a powder product.

16. Composition according to claim 14, in which the calcium-silicate-hydrate based hardening accelerator for cementitious compositions is an aqueous suspension.

17. Composition according to claim 16, in which the particle size d.sub.50 of the calcium-silicate-hydrate based hardening accelerator for cementitious compositions is smaller than 5 m, the particle size being measured by light scattering.

18. Composition according to claim 14, in which the calcium-silicate-hydrate based hardening accelerator for cementitious compositions was obtained in the form of a suspension by a process ) by a reaction of a water-soluble calcium compound with a water-soluble silicate compound, the reaction of the water-soluble calcium compound with the water-soluble silicate compound being carried out in the presence of an aqueous solution which contains at least one polymeric dispersant, which has anionic and/or anionogenic groups and polyether side chains, optionally poly alkylene glycol side chains, or was obtained in the form of a suspension by a process ) by reaction of a calcium compound, optionally a calcium salt, further optionally a water-soluble calcium salt, with a silicon dioxide containing component under alkaline conditions, characterized in that the reaction is carried out in the presence of an aqueous solution of at least one polymeric dispersant, which has anionic and/or anionogenic groups and polyether side chains, optionally poly alkylene glycol side chains, with the proviso that in the case of the calcium-silicate-hydrate based hydration accelerator in the composition being a powder product, the product in the form of a suspension obtained from said processes ) or ) was dried in a further step in order to obtain the powder product.

19. Composition according to claim 18 in which the calcium-silicate-hydrate based hardening accelerator for cementitious compositions was obtained in the form of a suspension by a process -1) in which the water-soluble calcium compound is selected from calcium hydroxide and/or calcium oxide and the water-soluble silicate compound is selected from an alkali metal silicate with the formula m SiO.sub.2.n M.sub.2O, wherein M is Li, Na, K or NH4 or mixtures thereof, m and n are molar numbers and the ratio of m:n is from about 2.0 to about 4 with the proviso that in the case of the calcium-silicate-hydrate based hydration accelerator in the composition being a powder product, the product in the form of a suspension obtained from said process -1) was dried in a further step in order to obtain the powder product.

20. Composition according to claim 18 in which the calcium-silicate-hydrate based hardening accelerator for cementitious composition is a powder product and in which before the drying step to obtain the powder product in the case a) at least one polymeric dispersant, which has anionic and/or anionogenic groups and polyether side chains, optionally poly alkylene glycol side chains, was added to the product in the form of a suspension obtained from the process ), ) or -1) or in the case b) at least one sulfonic acid compound of the formula (I) ##STR00029## in which A.sup.1 is NH.sub.2, NHMe, NMe.sub.2, N(CH.sub.2CH.sub.2OH).sub.2, CH.sub.3, C.sub.2H.sub.5, CH.sub.2CH.sub.2OH, phenyl, or p-CH.sub.3-phenyl, and K.sup.n+ is an alkali metal cation or a cation selected from the group of Ca.sup.2+, Mg.sup.2+, Sr.sup.2+, Ba.sup.2+, Zn.sup.2+, Fe.sup.2+, Fe.sup.3+, Al.sup.3+, Mn.sup.2+ and Cu.sup.2+ and n is the valency of the cation; was added to the product in the form of a suspension obtained from the process a), p) or a-1).

21. Composition according to claim 18, in which the calcium-silicate-hydrate based hardening accelerator for cementitious compositions was obtained in the form of a suspension by a process ) by reaction of a water-soluble calcium compound with a water-soluble silicate compound, characterized in that the reaction is carried out in the presence of an aqueous solution of a mixture of at least one polymeric dispersant, which has anionic and/or anionogenic groups and polyether side chains, optionally poly alkylene glycol side chains and at least one sulfonic acid compound of the formula (I) ##STR00030## in which A.sup.1 is NH.sub.2, NHMe, NMe.sub.2, N(CH.sub.2CH.sub.2OH).sub.2, CH.sub.3, C.sub.2H.sub.5, CH.sub.2CH.sub.2OH, phenyl, or p-CH.sub.3-phenyl, and K.sup.n+ is an alkali metal cation or a cation selected from the group of Ca.sup.2+, Mg.sup.2+, Sr.sup.2+, Ba.sup.2+, Zn.sup.2+, Fe.sup.2+, Fe.sup.3+, Al.sup.3+, Mn.sup.2+ and Cu.sup.2+ and n is the valency of the cation; with the proviso that in the case of the calcium-silicate-hydrate based hydration accelerator in the composition being a powder product, the product in the form of a suspension obtained from said process ) was dried in a further step in order to obtain the powder product.

22. Composition according to claim 14, in which the calcium-silicate-hydrate based hardening accelerator for cementitious compositions was obtained in a process ) by reaction of a water-soluble calcium compound with a water-soluble silicate compound, characterized in that the reaction is carried out in the presence of an aqueous solution containing at least one (co)polymer having carboxylic acid groups and/or carboxylate groups and sulfonic acid groups and/or sulfonate groups, where the ratio of the number of carboxylic acid groups and/or carboxylate groups to the sulfonic acid groups and/or sulfonate groups is from 1/20 to 20/1 with the proviso that in the case of the calcium-silicate-hydrate based hydration accelerator in the composition being a powder product, the product in the form of a suspension obtained from said process ) was dried in a further step in order to obtain the powder product.

23. Composition according to claim 1, which contains at least one of the additives selected from the group of redispersible powders, defoamers and stabilizers or mixtures thereof.

24. Composition according to claim 1, in which is contained up to 30 weight % with respect to the total weight of the composition of supplementary cementitious materials selected from the group of fly ash, silica fume and blast furnace slag or mixtures thereof.

25. (canceled)

Description

EXAMPLES

1. Preparation of Binder Compositions for SLU

[0228] Self-levelling underlayments (SLU) are commonly applied on floor screeds in order to level uneven, rough surfaces. The mortar levels itself under the influence of gravity and produces a plain smooth surface.

[0229] Table 1 shows the composition of the SLU mixes according to this invention (E1 to E10) and the reference examples (R1 to R4). Details of the materials used and the test conditions used are summarized in the following description.

[0230] The samples according to this invention E1 to E10 differ in the contents of component a) (OPC), component b) (calcium sulfate based binder b)) and component c). The examples E4, E6, E8 and E10 contain also a calcium-silicate-hydrate based hardening accelerator for cementitious compositions at various dosages.

[0231] Typically, the binder system for such a mortar is based on Ordinary Portland Cement (OPC). If fast setting and high early strength development are required, a rapid hardening mortar containing OPC, Calcium Aluminate Cement (CAC) and calcium sulfate is used in the state of the art. The complete formulation of such a ternary mortar binder system is shown in table 1 (reference example R1). Rapid set and hardening of this ternary binder system is caused by massive ettringite formation. The mixing water is bound chemically in the ettringite crystals, resulting in much faster drying. Ettringite also provides good shrinkage compensation. However, Calcium Aluminate Cement (CAC) is a relatively expensive formulation compound and formulations with said cement type cannot be used in outdoor applications as humidity has a negative effect on the durability of the hardened building products. Also it is possible to obtain higher compressive strength values at 28 days for the formulations with OPC in comparison to CAC based formulations.

[0232] Reference example R2 lacks a calcium sulfate based binder b) and also component c), reference example R3 does not contain the retarder for calcium sulfate based binders (component c)).

[0233] The cement used in this study is an Ordinary Portland Cement (OPC) equivalent to EN 197-1:2011 Type I cement (available from Heidelberger Cement). Its Blaine specific surface is 3400100 cm.sup.2/g.

[0234] A Calcium Aluminate Cement from Kerneos (Ciment Fondu) combined with alpha-bassanite from Knauf (plant Schwarze Pumpe) was used as binder for the reference SLU mix R1. Fine lime stone powder from Omyacarb, type AL 15 with a N.sub.2-BET surface of 1.154 m.sup.2/g and a mean particle diameter of 7.94 m and fine quartz sand from the producer Quarzwerke Frechen with a maximum grain size of 0.5 mm were added as filler to the SLU mixes. Commercial trisodium citrate dihydrate from Jungbunzlauer was used for the reference SLU mix (R1) to retard the binder hydration and to allow a sufficient workability time. As superplasticizer Melflux 4930 F available from BASF Construction Solutions GmbH, was used. This superplasticizer is based on a comb copolymer with a carboxylate backbone and polyether side chains. The polycarboxylate possesses a molecular mass (M.sub.w) of 26,000 g/mol and a polydispersity index of 1.45 (GPC analysis). The amount of superplasticizer was adjusted to provide an initial spread of 150.5 cm.

[0235] Every SLU mix contains a redipersible powder made from vinylacetate-ethylene copolymer (Wacker Vinnapas 5023 L), a powder defoamer based on fatty alcohol alkoxylates and polysiloxanes on an inorganic carrier (BASF Vinapor DF 9010 F) and a powder based high molecular weight synthetic polymer (BASF Starvis 3003 F) for stabilization and to avoid bleeding of the mix. BASF Starvis 3003 F is a copolymer of acrylic acid and acrylamide. Fresh SLUs were mixed in batches of 1000 g for 7:55 min in a planetary Hobart mixer according to EN 1937:1999. The mixing procedure is shown in table 2.

TABLE-US-00002 TABLE 2 mixing procedure 0 00 0 00- 20 s add powder to water 0 20 0 20- 60 s mixing (140 rpm) 1 20 1 20- 20 s cleaning vessel and 1 40 plates 1 40- 60 s mixing (285 rpm) 2 40 2 40- 300 s waiting 7 40 7 40- 15 s mixing (285 rpm) 7 55

TABLE-US-00003 TABLE 1 Materials and dry mortar composition R1 R2 R3 E1 E2 E3 E4 component supplier (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) OPC (CEM I 52.5N) HeidelbergerCement 8.3 36.5 30.0 30.0 30.0 30.0 30.0 Calciumaluminate Kernoes 23.6 cement Calciumsulfate Knauf 4.6 6.5 6.5 6.5 6.5 6.5 Lime stone powder Omyacarb 19.4 19.4 19.4 19.4 19.4 19.4 19.4 Fine quartz sand Quarzwerke 40.8 41.2 41.2 41.2 41.2 41.2 40.6 Frechen Redispersible powder Wacker 2.50 2.5 2.5 2.5 2.5 2.5 2.5 Lithiumcarbonat 0.10 Li.sub.2CO.sub.3 Citric acid (retarder) Jungbunzlauer 0.16 Defoamer BASF 0.15 0.15 0.15 0.15 0.15 0.15 0.15 Stabilizer BASF 0.15 0.10 0.07 0.07 0.07 0.07 0.05 Melflux 4930 F BASF 0.20 0.20 0.20 0.20 0.20 0.20 0.20 Comp. c).sup.1) Gelita GmbH 0.01 0.03 0.05 0.05 C-S-H (accel.).sup.2) 0.61 SUM of dry materials (wt. %) 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Water content (for 100 wt. % dry mortar) 20.0 19.0 19.0 19.0 19.0 19.0 19.0 E5 E6 E7 E8 E9 E10 E11 component supplier (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) OPC (CEM I 52.5N) HeidelbergerCement 32.0 32.0 28.0 28.0 26.0 26.0 7.0 Calciumaluminate Kernoes cement Calciumsulfate Knauf 4.5 4.5 8.5 8.5 10.5 10.5 28.0 Lime stone powder Omyacarb 19.4 19.4 19.4 19.4 19.4 19.4 19.4 Fine quartz sand Quarzwerke 41.2 40.5 41.5 40.7 41.5 40.8 42.8 Frechen Redispersible powder Wacker 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Lithiumcarbonat Li.sub.2CO.sub.3 Citric acid (retarder) Jungbunzlauer Defoamer BASF 0.15 0.15 0.15 0.15 0.15 0.15 0.15 Stabilizer BASF 0.07 0.05 0.07 0.05 0.07 0.05 0.10 Melflux 4930 F BASF 0.20 0.20 0.20 0.20 0.20 0.20 0.08 Comp. c).sup.1) Gelita GmbH 0.03 0.03 0.05 0.05 0.05 0.05 0.02 C-S-H (accel.).sup.2) 0.65 0.57 0.53 SUM of dry materials (wt. %) 100.0 100.0 100.0 100.0 100.0 100.0 100 Water content (for 100 wt. % dry mortar) 19.0 19.0 19.0 19.0 19.0 19.0 19.0 R: . . . Reference example (comparison) E: . . . Example according to this invention .sup.1)The gypsum retarder is Gelita Novotec 500, a protein hydrolysate available from the company Gelita Deutschland GmbH. .sup.2)The hardening accelerator is calcium-silicate-hydrate based and produced according to the teaching of WO 2010/026155 A1, table 2, example Acc. 25 on page 41. The solid content of the C-S-H accelerator is 21.5 weight %. The value given in the table is reflecting the addition of solid of the C-S-H accelerator to the mortar mix. The water content of the C-S-H suspension is included in the total water content.

2. Testing Procedures

[0236] To characterize the performance of the self-levelling underlayment formulations, the following parameters were determined: [0237] Flow spread values were measured according to EN 12706 at different times after preparation of SLU. These values characterize the ability of the fresh SLU to retain its fluidity over time (evolution of the spread over time). [0238] Setting times were determined according to DIN EN 13409:2002, EN 196-3 and DIN 1168 with a setting manipulator from Toni Technik GmbH. [0239] Flexural and compressive strength of the SLU at 1, 7 and 28 days were measured on 4.Math.4.Math.16 cm.sup.3 prisms according to the standard EN 196-1:2005 [0240] Dimensional shrinkage up to 28 days was measured on 4.Math.4.Math.16 cm.sup.3 prisms according to the standard DIN EN 13872:2004.

[0241] All measurements were done at 21 C. and 65% relative humidity. The experimental results are summarized in table 3.

TABLE-US-00004 TABLE 3 Testing results of different SLUs Testing results for the SLU samples Flexural Compressive Drying Setting strength strength shrinkage Flow spread (cm) (h) (MPa) (MPa) () Mixture 8 min 15 min 30 min 45 min 60 min initial final 1 d 7 d 28 d 1 d 7 d 28 d 1 d 7 d 28 d R1 15.5 15.3 14.9 13.9 13.3 2.8 2.9 3.6 4.6 8.9 12.1 19.6 31.5 0 0.03 0.32 R2 15.0 14.1 12.6 11.8 11.6 9.9 10.3 2.2 6.9 10.5 7.0 41.1 47.8 0 0.44 1.28 R3 15.2 14.0 12.6 3.0 3.0 1.3 1.4 E1 15.2 14.6 14.2 12.5 10.1 1.5 1.6 E2 15.3 15.0 14.1 13.2 12.5 2.4 2.5 E3 14.9 14.6 13.8 13.4 12.2 3.1 3.2 2.3 5.1 7.7 8.3 23.8 40.2 0 0.18 0.04 E4 15.2 14.6 14.0 13.5 11.6 3.4 3.5 3.2 5.3 7.6 12.3 25.9 40.0 0 0.11 0.18 E5 14.8 14.2 13.2 11.9 10.6 6.3 6.3 2.1 5.4 8.4 7.8 25.2 40.1 0 0.13 0.27 E6 16.0 15.0 14.1 13.4 12.9 6.0 6.1 3.4 5.6 7.6 13.6 27.1 41.3 0 0.09 0.27 E7 15.1 14.7 13.6 12.8 12.4 3.3 3.3 2.1 4.9 7.2 8.0 23.6 36.7 0 0.08 0.21 E8 15.5 15.0 14.1 13.4 12.8 3.6 3.7 3.3 5.1 7.7 12.5 25.3 39.6 0 0.05 0.27 E9 15.3 14.9 14.1 13.6 13.4 3.3 3.3 2.3 4.9 7.8 5.4 23.7 38.7 0 0.15 0.13 E10 15.9 15.2 14.8 13.7 13.7 3.6 3.7 3.1 5.2 8.6 11.8 26.4 39.3 0 0.06 0.32 R4 15.8 15.7 15.4 14.9 14.3 1.9 1.9 2.6 3.5 7.8 11.5 16.3 27.7 0 0.01 0.16

1.1 Effect of Component b) (Here -Bassanite) on the Shrinkage Reduction

[0242] In table 3 the effect of calcium sulfate addition on the dimensional shrinkage of the SLU is shown (drying shrinkage). In this set of experiments the calcium sulfate source consisted of a-bassanite. The a-bassanite was homogenized with the other formulation components of the SLU formulation in the dry state.

[0243] These results clearly show that the drying shrinkage of the SLU can be reduced by the addition of a-bassanite, the examples according to this invention should be compared with the reference example R2 (no component b contained), which shows a relatively strong shrinkage problem.

1.2 Effect of Selective Retarder for CaSO.SUB.4 .Based Binders (Comp. c) on Setting

[0244] Table 3 illustrates the effect of the addition of a-bassanite on the flow spread behavior and setting times of an SLU formulation. No retarder for calcium sulfate based binders (component c) is contained. It can be seen that the workability is less good due to lowered flow spread over time and the setting time becomes very short by the addition of -bassanite. Please refer in particular to the reference example R3. The open time is not long enough. The lowered flow spread is thought to be due to the fast setting and stiffening of the formulation over time, especially after 45 minutes. The examples according to this invention have a long enough period of open time.

[0245] A combination of -bassanite and the retarder (component c) in examples E1 to E10 show that the workability (flow spread) and the setting time are significantly improved, in particular versus R3. Open time is long enough.

1.3 Effect of Accelerator Calcium-Silicate-Hydrate (CSH) on Strength Development

[0246] The examples E4, E6, E8 and E10 show especially favorable early strength development and also a reasonably long open time (setting is not too early). The 24 hours strength values in table 3 are increased compared to the reference examples and the samples E1, E2, E3, E5, E7 and E9 without CSH.

[0247] It was also found experimentally that the reference sample R1 with the ternary binder system of Ordinary Portland Cement, Calcium Aluminate Cement and a calcium sulfate based binder has less good compressive strength development after 28 days compared to the samples according to this invention.

[0248] As a summary it is possible to obtain good workability (also over time), a long enough open time combined with an early enough setting and relatively good shrinkage behavior by the examples according to this invention. The use of calcium-silicate-hydrate as hardening accelerator additionally increases the early strength development.