Aluminous cement

Abstract

The present invention relates to an aluminous cement.

Claims

1. An aluminous cement containing at least 75 wt. % and at most 89 wt. % monocalcium aluminate (CA), CA in crystalline or amorphous form or as a mixture of crystalline and amorphous fractions, wherein the aluminous cement contains at least 53 wt. % aluminum oxide calculated as Al.sub.2O.sub.3 and has an A/C value, which is a ratio of Al.sub.2O.sub.3 (A) and CaO (C), based on wt. % in the range of from 1.45 to 1.85, wherein the aluminous cement contains at most 39 wt. % calcium oxide, wherein the aluminous cement has a Blaine fineness in the range of from 3500 to 6000 cm.sup.2/g, wherein the aluminous cement has a slope n in the range of from 0.7 to 1.5, and has a position parameter x′ of 8-30 μm in a Rosin-Rammler-Sperling-Bennet (RRSB) particle size grid according to DIN 66145 at the filing date of this application, and a color in the L*a*b* color system in the range of values: L*<85.

2. The aluminous cement according to claim 1, wherein the aluminous cement contains at least 0.1 wt. % iron calculated as Fe.sub.2O.sub.3.

3. The aluminous cement according to claim 1, wherein the aluminous cement contains at most 10 wt. % iron calculated as Fe.sub.2O.sub.3.

4. The aluminous cement according to claim 1, wherein the aluminous cement contains at least 0.2 wt. % silicon dioxide calculated as SiO.sub.2.

5. The aluminous cement according to claim 1, wherein the aluminous cement contains at most 4 wt. % silicon dioxide calculated as SiO.sub.2.

6. The aluminous cement according to claim 1, wherein the aluminous cement contains at least 77 wt. % and at most 87 wt. % CA.

7. The aluminous cement according to claim 1, wherein the slope n is in the range of from 0.8 to 1.4.

8. The aluminous cement according to claim 1, wherein the aluminous cement has a Blaine fineness in the range of from 3700 to 5500 cm.sup.2/g.

9. The aluminous cement according to claim 1, wherein the position parameter x′ is in the range of from 9 to 28 μm.

10. The aluminous cement according to claim 1, wherein the aluminous cement contains at least 0.1 wt. % carbon.

11. The aluminous cement according to claim 1, wherein the aluminous cement comprises other elements or oxides in various oxidation states and their related components Si, Mg, Sr, Ba, Ti, Zr, V, P, Cr, Mn, Zn oxides and/or other transition metals.

12. A binder in a chemical formulation for construction, wherein the binder comprises an aluminous cement according to claim 1.

13. A binder in a refractory formulation, wherein the binder comprises an aluminous cement according to claim 1.

Description

EXAMPLE 1

(1) Various raw material mixtures were melted in a laboratory furnace to produce the aluminous cement according to the invention. The crucibles filled with the respective raw meals were heated from room temperature at a heating rate of 3 k/min to temperatures of between 1650° C.−1750° C. and left there for 1 hour. The furnace was then switched off and the crucibles with the melt contained therein were slowly cooled. In the specific examples, the cooling process was carried out from an initial temperature of 1700° C. at a cooling rate of 25 K/min. At 1000° C., all the crucibles were removed from the furnace. The crucibles were further cooled to room temperature by the ambient air. The cooled clinker was prepared from the crucibles using a suitable tool and, after a storage period of 24 hours, was ground on a ball mill without the addition of grinding aids.

(2) Natural limestone, calcined white bauxite, red bauxite and fine-particled alumina, Al.sub.2O.sub.3(SO 143, DADCO) were used as starting materials. Table 2 shows the starting materials used for the production of the clinker according to the invention and the chemical compositions thereof.

(3) TABLE-US-00002 TABLE 2 Chemical composition of the starting materials (in accordance with EN 14647 196-2) Limestone Bauxite, calc. Bauxite, red Alumina Starting materials [%] [%] [%] [%] G.V. 43.66 0.39 13.32 3.00 SiO.sub.2 0.12 5.83 1.81 0.00 Al.sub.2O.sub.3 0.19 87.80 56.76 96.67 TiO.sub.2 0.01 3.96 2.67 0.00 MnO 0.01 0.01 0.02 0.00 Fe.sub.2O.sub.3 0.06 1.32 22.53 0.01 CaO 55.69 0.00 2.53 0.00 MgO 0.32 0.24 0.10 0.00

(4) Six clinker samples according to the invention were melted using the raw materials from Table 2. The mineralogical composition of these clinkers KCAC 1-6 can be found in Table 3. These values are compared with sample analyzes of the commercially available Istra 50™, HiPerCem®, Secar® 71 and Gorkal 70™ aluminous cements. The phase content was determined in each case using the Rietveld software HighScore Plus, version 4.6a from PANalytical BV, Almelo, the Netherlands. A Panalytical Cubix X-ray diffractometer with a fast XCelerator detector was used for the analysis.

(5) TABLE-US-00003 TABLE 3 Mineralogical composition of the clinker KCAC 1-6 and four commercial aluminous cements Istra HiPer Secar ® Gorkal KCAC1 KCAC2 KCAC3 KCAC4 KCAC5 KCAC6 50 ™ Cem ® 71 70 ™ [%] [%] [%] [%] [%] [%] [%] [%] [%] [%] CA 88.7 81.1 75.1 88.9 82.6 75.8 63.4 94.3 59.6 72.7 C.sub.4AF  0.2  1.1  1.3  2.1  4.9  7.8  1.3 — — — C.sub.12A.sub.7  1.7  1.8  1.8  1.8  2.1  2.4  2.1  0.9  0.4  0.3 C.sub.2AS  2.4  6.9 10.9  1.0  2.5  3.9 16.2 — — — Pleochroite  1.2  2.6  3.5  0.6  1.5  2.4  6.4 — — — C.sub.2S  1.8  2.4  3.5  1.0  1.7  2.6  5.6 — — — CT, C.sub.3FT  0.5  1.3  1.9  0.5  1.2  1.8  3.1 — — — Mg (Al, Fe).sub.2O.sub.4  0.1  0.6  0.4  0.5  0.7  1.2  1.9 — — — CA.sub.2  3.4  2.2  1.6  3.6  2.8  2.1 —  4.6 39.5 26.2 A — — — — — — —  0.2  0.5  0.8

(6) Table 4 shows the chemical composition of the six clinker samples KCAC 1-6 in wt. % ignition-loss-free material, as well as the percentage composition of the relevant raw mixture, also in wt. % ignition-loss-free material, using the raw material components. Table 2 compiled. This is compared with the sample analyzes of the commercially available Istra 50™, HiPerCem®, Secar® 71 and Gorkal 70™ aluminous cements.

(7) TABLE-US-00004 TABLE 4 Chemical analyses of the KCAC 1-6 clinker, its raw mixtures and four commercially available aluminous cements (ignition-loss-free analysis data) KCAC KCAC KCAC KCAC KCAC KCAC Istra HiPer Secar ® Gorkal Clinker 1 2 3 4 5 6 50 ™ Cem ® 71 70 ™ [%] [%] [%] [%] [%] [%] [%] [%] [%] [%] SiO.sub.2 0.70 1.57 2.43 0.24 0.48 0.71 5.34 0.24 0.27 0.28 Al.sub.2O.sub.3 62.63 59.65 56.48 61.92 57.69 53.56 50.86 64.15 69.25 70.19 TiO.sub.2 0.43 1.02 1.60 0.26 0.60 0.94 2.32 0.00 0.00 0.00 MnO 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.01 0.02 0.01 Fe.sub.2O.sub.3 0.19 0.38 0.58 2.15 5.04 7.92 2.27 0.06 0.08 0.09 CaO 35.70 36.88 38.26 35.15 35.87 36.49 38.38 34.32 29.72 28.77 MgO 0.23 0.27 0.32 0.21 0.23 0.24 0.48 0.42 0.20 0.21 A/C 1.75 1.62 1.48 1.76 1.61 1.47 1.33 1.87 2.33 2.44 value Raw materials [%] [%] [%] [%] [%] [%] Limestone 36.20 37.40 38.80 35.40 35.80 36.10 Bauxite, 10.70 25.50 40.20 — — — calcined Bauxite, — — — 8.10 19.20 30.30 red Alumina 53.10 37.10 21.00 56.50 45.00 33.60

(8) The clinker samples according to the invention were ground to Blaine finenesses of between 3800 and 4400 cm.sup.2/g. With an Fe.sub.2O.sub.3 content of 0.19 and 0.58%, respectively, KCAC1 and KCAC3 are low-iron versions having the highest content of monocalcium aluminate CA of 88.7% (KCAC1) and the lowest content of 75.1% (KCAC3). With 88.9% and 75.8%, respectively, KCAC4 and KCAC6 have the highest and the lowest content of monocalcium aluminate CA for the more iron-rich version of the aluminous cement according to the invention with an Fe.sub.2O.sub.3 content of 2.15% (KCAC4) and 7.92% (KCAC6), respectively.

(9) Table 5 summarizes the results of determining the Blaine fineness, the particle size parameters x′ and n in the RRSB particle size grid in accordance with DIN 66145, and the brightness value L, determined in accordance with the L*a*b* system, for these aluminous cements. In addition, the test results for four comparable, commercially available aluminous cements are shown (Istra 50™, HiPerCem®, Secar 71®, Gorkal 70®).

(10) The particle size parameters x and n were determined using a HELOS laser granulometer with RODOS T4.1 from Sympatec GmbH. The brightness values were measured using a Konica Minolta Chroma Meter CR-400, on the surface of compacted, smoothed and crack-free powder preparations as a double determination.

(11) TABLE-US-00005 TABLE 5 Blaine values, particle size and color parameters of the CAC 1-6 and four commercially available aluminous cements Blaine x′ Brightness value L Aluminous cement [cm2/g] [μm] n [L*a*b* system] CAC 1 4320 16.1 1.03 84.3 CAC 2 4030 19.8 0.98 81.4 CAC 3 3810 22.6 0.94 79.9 CAC 4 4360 14.9 1.02 73.2 CAC 5 4204 17.3 0.99 65.8 CAC 6 4010 19.5 0.95 60.1 Istra 50 ™ 3370 28.2 0.87 68.0 HiPerCem ® 4530 13.5 1.20 93.1 Secar ® 71 4130 26.8 0.81 92.5 Gorkal 70 ™ 4470 22.6 0.95 91.6

(12) Table 5 shows the Blaine finenesses of the aluminous cements CAC 1 to CAC 6 according to the invention and the corresponding parameters for Istra 50™, Secar® 71, Gorkal 70™ and HiPerCem®. The brightness values, expressed as L* in the CIE L*a*b* system, are below those of the more complexly produced Secar® 71, Gorkal 70™ and HiPerCem® aluminous cements.

(13) For the cements according to the invention and the comparative samples Istra 50™, Secar® 71, Gorkal 70™ and HiPerCem®, the water demand to achieve the standard stiffness, the setting times for paste and mortar, and the compressive strength development on standard mortar in the time range 6 to 24 hours were determined in accordance with EN 14647. In accordance with the provisions of EN 14647, the test procedure from EN 196-3 is used to determine the standard stiffness and the water demand required therefor. The compressive strength is determined in accordance with EN 14647 on a standard mortar that contains a standard sand content of 1350 g, 500 g aluminous cement and 250 g water. The setting times on the mortar were determined analogously to the procedure according to EN 196-3 on this standard mortar. The results of the tests of the water demand and the setting behavior on paste and mortar are shown in Table 6, and the results of the compressive strength tests are shown in Table 7. Tables 6 and 7 also show the test results for the four comparable, commercially available aluminous cements Istra 50™, HiPerCem®, Secar® 71, Gorkal 70™.

(14) TABLE-US-00006 TABLE 6 Blaine values, setting on paste and mortar of the cements CAC 1-6 and four commercially available aluminous cements Setting on Setting on Blain Water paste mortar value demand [h:min] [h:min] [cm.sup.2/g] [%] Start End Start End CAC 1 4320 35.6 6:08 6:23 3:40 4:10 CAC 2 4030 31.6 4:15 4:55 3:35 4:00 CAC 3 3810 31.0 4:10 4:15 3:25 3:53 CAC 4 4360 35.2 4:40 5:20 3:35 4:00 CAC 5 4204 32.2 4:30 5:10 3:20 3:40 CAC 6 4010 31.0 4:20 5:05 3:00 3:15 Istra 50 ™ 3370 25.3 4:10 4:25 3:10 3:40 HiPerCem ® 4530 34.0 6:08 6:28 3:50 4:15 Secar ® 71 4130 27.0 5:40 6:15 3:00 3:20 Gorkal 70 ™ 4470 30.0 5:10 5:20 2:40 2:50

(15) TABLE-US-00007 TABLE 7 Blaine values, compressive strengths of up to 24 hours of the cements CAC 1-6 and four commercially available aluminous cements Blaine Cement [cm.sup.2/g] Compressive strength [MPa] 6 h 8 h 10 h 14 h 16 h 18 h 24 h CAC 1 4320 30.2 48.8 54.3 55.3 56.5 58.0 66.1 CAC 2 4030 36.1 51.6 54.0 56.5 57.4 60.0 66.9 CAC 3 3810 27.6 49.4 60.5 64.3 64.5 65.1 67.3 CAC 4 4360 26.9 49.5 52.6 53.5 54.2 57.0 68.3 CAC 5 4204 41.6 53.1 56.4 58.5 60.6 63.3 66.4 CAC 6 4010 43.5 55.5 58.8 60.5 61.0 63.5 66.5 Istra 50 ™ 3370 20.8 50.8 60.0 71.7 72.1 72.7 74.9 HiPerCem ® 4530 52.4 57.4 60.7 63.5 63.6 64.2 64.4 Secar ® 71 4130 29.9 42.0 46.2 49.2 50.2 52.2 55.4 Gorkal 70 ™ 4470 38.8 43.8 47.1 48.7 49.4 51.1 50.6

(16) It is clear from Table 6 that the cements CAC 1 to CAC 6 according to the invention have the same good processing properties as commercially available aluminous cements.

(17) Table 7 shows that the cements CAC 1 to CAC 6 according to the invention in standard mortar have a significantly higher early strength up to 8 hours after preparation than the comparable high-quality white aluminous cements Secar® 71 and Gorkal 70™. After 24 hours, the strength level of the cements CAC 1 to CAC 6 is significantly higher than that of the commercially available cements Gorkal 70™, Secar® 71 and HiPerCem®.

EXAMPLE 2

(18) In a large-scale industrial test, three clinkers according to the invention and resulting cements were produced. The clinkers were produced in an L-shaped shaft furnace with a suitable refractory lining, as is standard in the aluminous cement industry. The furnace was fired with coal. The melting points were between 1,650° C. and 1,750° C. Limestone, alumina in the form of hydraulic or cement-bound briquettes and red bauxite were used as raw materials in suitable proportions. The chemical composition of the limestone, red bauxite and alumina corresponded to Table 2. A total of 32 tons of clinker were produced and the three clinkers according to the invention were then ground in a ball mill.

(19) Table 8 shows the phase distribution of the three clinkers PKCAC 1, PKCAC 2 and PKCAC 3 according to the invention, which were produced on a large scale. The chemical composition thereof is shown in Table 9.

(20) TABLE-US-00008 TABLE 8 Mineralogical composition of the clinkers PKCAC 1-3 PKCAC1 PKCAC2 PKCAC3 CA 88.3 87.0 86.7 C.sub.4AF 0.4 0.3 0.3 C.sub.12A.sub.7 2.3 2.8 2.8 C.sub.2AS 1.3 2.0 2.3 Pleochroite 3.1 3.2 3.3 C.sub.2S 0.5 0.0 0.7 CT, C.sub.3FT 1.3 1.5 1.4 Mg(Al, Fe).sub.2O.sub.4 2.3 2.7 1.9 CA.sub.2 0.5 0.5 0.6

(21) TABLE-US-00009 TABLE 9 Chemical composition of the clinkers PKCAC 1-3 PKCAC1 PKCAC2 PKCAC3 [%] [%] [%] SiO2 0.78 0.64 0.66 Al2O3 58.59 59.63 60.20 TiO2 0.73 0.63 0.63 MnO 0.03 0.03 0.03 Fe2O3 5.83 5.16 5.14 CaO 33.05 33.21 33.12 MgO 0.69 0.68 0.69 A/C value 1.77 1.80 1.82

(22) For the cements PCAC 1, PCAC 2 and PCAC 3 according to the invention ground from the clinkers PKCAC 1, PKCAC 2 and PKCAC 3 and the commercially available comparative cements, the grinding finenesses n are shown in Table 10. Blaine, the particle distribution and the brightness values L* compiled. Table 11 contains the values for the water demand and the setting on paste and mortar determined in accordance with EN 193. Table 12 contains the detailed data for the early strength development in the time range of between 6 and 24 hours. The strength development is reproduced in Table 12.

(23) TABLE-US-00010 TABLE 10 Blaine values, particle size distribution and L* values for the PCAC 1-3 and four commercially available cements Aluminous Blaine x′ Brightness value L cement [cm.sup.2/g] [μm] n [L*a*b* system] PCAC1 5900 9.4 0.78 63.1 PCAC2 4200 21.3 0.76 64.3 PCAC3 3340 29.0 0.79 61.2 Istra 50 ™ 3370 28.2 0.87 68.0 HiPerCem ® 4530 13.5 1.20 93.1 Secar ® 71 4130 26.8 0.81 92.5 Gorkal 70 ™ 4470 22.6 0.95 91.6

(24) TABLE-US-00011 TABLE 11 Blaine values, setting on paste and mortar of the cements PCAC 1-3 and four commercially available aluminous cements Blaine Setting on Setting on value Water paste [h:min] mortar [h:min] [cm.sup.2/g] [%] Start End Start End PCAC1 5900 24.0 5:30 6:30 1:40 2:08 PCAC2 4200 23.6 5:10 5:40 1:45 2:15 PCAC3 3340 23.0 5:00 5:30 1:52 2:21 Istra 50 ™ 3370 25.3 4:10 4:25 3:10 3:40 HiPerCem ® 4530 34.0 6:08 6:28 3:50 4:15 Secar ® 71 4130 27.0 5:40 6:15 3:00 3:20 Gorkal 70 ™ 4470 30.0 5:10 5:20 2:40 2:50

(25) TABLE-US-00012 TABLE 12 Blaine values, compressive strengths up to 24 hours of the cements PCAC 1-3 and four commercially available aluminous cements Blaine Cement [cm.sup.2/g] Compressive strength [MPa] 6 h 8 h 10 h 14 h 16 h 18 h 24 h PCAC 1 5900 23.9 65.8 68.2 nd nd 82.1 86.4 PCAC 2 4200 18.6 52.8 72.9 nd nd 80.6 84.1 PCAC 3 3340 19.1 64.2 73.0 nd nd nd 82.2 Istra 50 ™ 3370 20.8 50.8 60.0 71.7 72.1 72.7 74.9 HiPerCem ® 4530 52.4 57.4 60.7 63.5 63.6 64.2 64.4 Secar ® 71 4130 29.9 42.0 46.2 49.2 50.2 52.2 55.4 Gorkal 70 ™ 4470 38.8 43.8 47.1 48.7 49.4 51.1 50.6 nd: not determined

(26) It can be seen from Table 12 that the aluminous cements PCAC 1, PCAC 2 and PCAC 3 according to the invention can have a 6-hour compressive strength that is comparable to that of commercially available comparative products. However, the aluminous cements according to the invention already achieve significantly higher strength after 8 hours than commercially available aluminous cements. The strength after 24 hours of the aluminous cements PCAC 1, PCAC 2 and PCAC 3 according to the invention is significantly higher than that of the commercially available white aluminous cements, which are more complex to produce (Secar® 71, Gorkal 70™, HiPerCem®), and also higher than that of Istra 50™.

EXAMPLE 3

(27) With the aluminous cement according to the invention, different chemical mixtures for construction were produced in the form of a self-leveling spackling paste, using industry-standard binder components, additives and fillers, as are typical for products in the field of tile adhesives, leveling compounds, spackling pastes and repair mortars. Of the chemical formulations for construction, self-leveling spackling paste is a particularly challenging product. On the one hand, these formulations should have good to very good flow over the processing time of 30 minutes, and on the other hand, they must ensure high early strength and quick accessibility. As a rule, high-quality self-leveling spackling pastes have a high aluminous cement content.

(28) The composition of the various formulations is reproduced in Table 13 in full. The formulation components are divided into “binders,” “additives I and II” and “fillers.” Each of the basic formulations were produced with three aluminous cements according to the invention: the aluminous cements PCAC1, PCAC2, PCAC3 according to the invention, the commercially available comparative cements Secar® 71 (from Kerneos), Gorkal 70™ (from Gorka) and the comparative cement Istra 50™ (from Calucem).

(29) The seven mixtures were each produced with the same binder content and, over a period of 30 minutes after their preparation, were tested for their consistency by measuring the slump a5, a15 and a30, and were tested for their compressive strength development after 4, 6 and 24 hours on standard prisms 4 cm×4 cm×16 cm. The terms and abbreviations used in Table 13 are explained below.

(30) The term “binder” is understood to mean the following proportions of the formulation: Portland cement (OPC) Dyckerhoff White Speed CEM I 42.5 R, Dyckerhoff, aluminous cement (CAC) and calcium sulfate (HH) Alpha-Hemihydrate Special 40 W, from Casea.

(31) “Additives I” are additives having a primarily retarding and accelerating effect: tartaric acid L (+) p.a. (WS), from HARKE Chemicals GmbH; sodium carbonate wfr. p.a. (NaC), from Neolab, Art. No. 4750; and pure lithium carbonate (LiC), from Merck, Art. No. 5670.

(32) “Additives II” are those additives that primarily influence the consistency of the mixture: hydrated lime (CH), from Otterbein, Art. No. WKH II CL 90; liquefier ViscoCrete-225 P (VF), from SIKA; cellulose ether culminal MHPC-500 PF (CE), from Ashland; and defoamer Agitan P 801 (ES), from Munzing Chemie GmbH, redispersible polymer powder (RPP) ELOTEX FL 2280, from Akzo Nobel Chemicals AG.

(33) Fillers (F) are inert materials that are not involved in the hydraulic reactions. In the examples, quartz sand F34 (F1), from Quarzwerke GmbH, and limestone meal 40GU (F2), from Omya GmbH, were used.

(34) Percentages given in Table 13 relate to the percentage proportion of a component in the total weight of the mixture.

(35) All chemical mixtures for construction were mixed with a constant water/solids value (W/S value) of 0.21.

(36) Apart from the variation of the aluminous cement, no significant change was made within a formulation having a given binder content.

(37) The slump was tested in such a way that, in each case, 2000 g of the dry formulation mixture was weighed exactly and mixed in a mortar mixer according to EN 196 with 420 g demineralized water for 30 seconds at level I and then for 90 seconds at level II. The mixing water was placed in the mixer trough and the dry mixture was then added. The pourable mixture obtained was immediately distributed on 3 flow cones, i.e. annular aluminum vessels having a height of 35 mm and an inner diameter of 68 mm, which were arranged in a centered manner on 3 dry plexiglass slump plates provided with concentric graduations. 5 minutes after the start of mixing, the first cone was raised and the diameter of the mass flowing in a circle was determined as the mean value from two measurements taken perpendicularly to one another using the caliper, as the a5 value. The same procedure was followed after 15 and 30 minutes with the other two cones and the values a15 and a30 were determined.

(38) To determine the compressive strength after 4, 6 and 24 hours, the chemical mixtures for construction were produced in the same way and the pourable materials were poured into prism molds according to EN 196 after the end of mixing without additional compaction measures. The molds were stored in accordance with EN 196 and the prisms were tested according to the standard at the scheduled times.

(39) In Table 13, the aluminous cements PCAC 1, PCAC 2 and PCAC 3 according to the invention are compared with Istra 50™, HiPerCem™, Secar® 71 and Gorkal 70™ in a spackling paste. The formulation was produced with a constant binder content of 29.15%.

(40) TABLE-US-00013 TABLE 13 Spackling pastes containing the three aluminous cements PCAC 1-3 according to the invention and the commercially available comparative cements Istra 50, HiPerCem, Secar 71 and Gorkal 70 Alu- minous Istra HiPer Secar ® Gorkal cement PCAC1 PCAC2 PCAC3 50 ™ Cem ® 71 70 ™ Recipe OPC 5.93 5.93 5.93 5.93 5.93 5.93 5.93 [%] CAC 14.48 14.48 14.48 14.48 14.48 14.48 14.48 [%] HH [%] 8.74 8.74 8.74 8.74 8.74 8.74 8.74 Total 29.15 29.15 29.15 29.15 29.15 29.15 29.15 binder Additives I WS [%] 0.14 0.14 0.14 0.14 0.14 0.14 0.14 NaC 0.33 0.33 0.33 0.33 0.33 0.33 0.33 [%] LiC [%] 0.03 0.03 0.03 0.03 0.03 0.03 0.03 Additives II CH [%] 0.87 0.87 0.87 0.87 0.87 0.87 0.87 VF [%] 0.29 0.29 0.29 0.29 0.29 0.29 0.29 CE [%] 0.07 0.07 0.07 0.07 0.07 0.07 0.07 ES [%] 0.14 0.14 0.14 0.14 0.14 0.14 0.14 RPP 0.97 0.97 0.97 0.97 0.97 0.97 0.97 [%] Fillers F1 [%] 44.21 44.21 44.21 44.21 44.21 44.21 44.21 F2 [%] 23.80 23.80 23.80 23.80 23.80 23.80 23.80 W/S 0.21 0.21 0.21 0.21 0.21 0.21 0.21 value Slump a5 210 220 232 215 221 220 225 [mm] a15 222 231 220 222 236 232 226 [mm] a30 220 228 190 235 238 235 143 [mm] Compressive strength  4 h 2 6 22 2 28 2 2 [MPa]  6 h 19 23 25 2 30 2 3 [MPa] 24 h 28 32 33 24 37 27 24 [MPa]

(41) The slumps identified exhibit the comparatively good flowability and the considerably improved early strength development up to 24 hours when using the aluminous cement according to the invention in comparison with the commercially available comparative cements.

(42) Surprisingly, the aluminous cement according to the invention, in its embodiments, in particular in its low-iron configuration, still exhibits unexpectedly good refractory properties with regard to the cold compressive strength and length change after fire in refractory concrete mixes.