Hydraulically-Bonded Multilayer Panel

Abstract

The invention relates to a method for producing a hydraulically-bonded multilayer panel with at least one face layer and at least one core layer, wherein the method comprises the following steps a. introducing a flowable face mixture into a mold. The face mixture contains at least the following components i. face paste containing at least 1. hydraulic binder and 2. water; and ii. aggregate. The aggregate has a mean diameter d50 determined according to ISO 13320:2009 and/or according to EN 12620 of greater than 100.0 m; whereby a face mixture layer is formed; b. introducing a dry to earth-moist core mixture into the mold, wherein the core mixture contains at least the following components i. core paste containing at least 1. hydraulic binder, 2. fines, wherein the fines have a mean diameter d50 determined according to ISO 13320:2009 of up to 100.0 m, and 3. water; and ii. aggregate, wherein the aggregate has a mean diameter d50 determined according to ISO 13320:2009 and/or according to EN 12620 of greater than 100.0 m; whereby a core mixture layer is formed, and c. pressing the face mixture layer with the core mixture layer into the mold to form a hydraulically-bonded, directly strippable multilayer panel with at least one face layer and at least one core layer, wherein water contained in the face mixture layer is partially or completely pressed into the core mixture layer

Claims

1-45. (canceled)

46. A method for producing a hydraulically-bonded multilayer panel with at least one face layer and at least one core layer, wherein the method comprises the following steps: a. introducing a flowable face mixture into a mold, wherein the face mixture contains at least the following components: i. face paste containing at least 1. hydraulic binder and 2. water; and ii. aggregate, wherein the aggregate has a mean diameter d50 determined according to ISO 13320:2009 and/or according to EN 12620 of greater than 100.0 m; whereby a face mixture layer is formed; b. introducing a dry to earth-moist core mixture into the mold, wherein the core mixture contains at least the following components: i. core paste containing at least 1. hydraulic binder, 2. fines, wherein the fines have a mean diameter d50 determined according to ISO 13320:2009 of up to 100.0 m, and 3. water; and ii. aggregate, wherein the aggregate has a mean diameter d50 determined according to ISO 13320:2009 and/or according to EN 12620 of greater than 100.0 m; whereby a core mixture layer is formed, and c. pressing the face mixture layer with the core mixture layer into the mold to form a hydraulically-bonded, directly strippable multilayer panel with at least one face layer and at least one core layer, wherein water contained in the face mixture layer is partially or completely pressed into the core mixture layer wherein the fines contained in the core paste has a mean diameter d50 determined according to ISO 13320:2009 of 1.0 to 30.0 m, and in particular 1.0 to 5.0 m.

47. The method according to claim 46, wherein the core paste contains fines having a mean diameter d50 determined according to ISO 13320:2009 of 1.0 to 100.0 m in an amount of 5 to 45 vol %, relative to the total volume of hydraulic binder and fines contained in the core paste.

48. The method according to claim 46, wherein the core paste contains fines having a mean diameter d50, determined according to ISO 13320:2009, that is less than the mean diameter d50 determined according to ISO 13320:2009 of the hydraulic binder contained in the core paste.

49. The method according to claim 46, wherein the core paste contains fines having a mean diameter d50 determined according to ISO 13320:2009 of 30.1 to 100.0 m in an amount of 0 to 45 vol %, and in particular of 0 to 25 vol %, relative to the total volume of hydraulic binder and fines contained in the core paste.

50. The method according to claim 46, wherein the core paste contains fines having a mean diameter d50 determined according to ISO 13320:2009 of 1.0 to 30.0 m in an amount of 5 to 45 vol %, relative to the total volume of hydraulic binder and fines contained in the core paste.

51. The method according to claim 46, wherein the core paste contains fines having a mean diameter d50 determined according to ISO 13320:2009 of 1.0 to 5.0 m in an amount of 5 to 20 vol %, and in particular of 8 to 15 vol %, relative to the total volume of hydraulic binder and fines contained in the core paste.

52. The method according to claim 46, wherein the face paste contains, as a further component, fines, and in particular fines having a mean diameter d50 determined according to ISO 13320:2009 of up to 100.0 m.

53. The method according to claim 46, wherein the face paste contains fines having a mean diameter d50, determined according to ISO 13320:2009, that is less than the mean diameter d50 determined according to ISO 13320:2009 of the hydraulic binder.

54. The method according to claim 46, wherein the face paste contains fines having a mean diameter d50 determined according to ISO 13320:2009 of 1.0 to 30.0 m, and in particular 1.0 to 5.0 m.

55. The method according to claim 46, wherein the fines in step a. and/or step b. contain at least one inert rock flourpreferably an inert rock flour selected from the group consisting of limestone, dolomite, and quartz, or a combination thereof.

56. The method according to claim 46, wherein the fines in step a. and/or b. contain at least one hydraulically-active substance, and in particular a hydraulically-active, natural, or synthetically-produced substance.

57. The method according to claim 56, wherein the hydraulically-active substance is selected from the group consisting of granulated slag, microsilica, and fly ash, or a combination thereof.

58. The method according to claim 46, wherein the core paste contains 350 to 1,000 kg/m.sup.3, and in particular 500 to 1,000 kg/m.sup.3, of hydraulic binder, relative to the total dry weight of the core mixture.

59. The method according to claim 46, wherein the face paste contains 350 to 1,000 kg/m.sup.3, and in particular 500 to 1,000 kg/m.sup.3, of hydraulic binder, relative to the total dry weight of the face mixture.

60. The method according to claim 46, wherein the hydraulic binder in step a. and/or step b. is selected from the group consisting of cement, hydraulically-active additives, latent hydraulic or pozzolanic additives, siliceous binders, or a combination thereof.

61. The method according to claim 46, wherein the hydraulic binder in step a. and/or step b. is selected from the group consisting of cement, fly ash, microsilica, granulated slag, natural or artificial pozzolanas, geopolymers, metakaolin, calcined clays, or a combination thereof.

62. The method according to claim 46, wherein the hydraulic binder in step a. and/or step b. is cement, and in particular a cement selected from the group consisting of the CEM I and CEM II/A classes according to EN 197-1, or a combination thereof.

63. The method according to claim 46, wherein the core paste contains hydraulic binderin particular, cementin an amount of 60 to 95 vol %, and in particular of 65 to 80 vol %, relative to the total volume of hydraulic binder and fines contained in the core paste.

64. The method according to claim 46, wherein the core mixture contains 450 to 1,250 kg/m.sup.3, and in particular 600 to 1,250 kg/m.sup.3, of core paste, relative to the total dry weight of the core mixture.

65. The method according to claim 46, wherein the amount of core paste contained in the core mixture is calculated such that a paste saturation degree for the core mixture, calculated according to formula 1 specified in the description, is 1.0 to 1.5, and in particular 1.1 to 1.4.

66. The method according to claim 46, wherein the amount of core paste contained in the core mixture is calculated such that a paste layer thickness, calculated according to formula 2 specified in the description, for the core paste layer is at most 30.0 m, and in particular at most 20.0 m or 3.0 to 20.0 m.

67. The method according to claim 46, wherein the face mixture contains 450 to 1,250 kg/m.sup.3, and in particular 600 to 1,250 kg/m.sup.3, of face paste, relative to the total dry weight of the face mixture.

68. The method according to claim 46, wherein, prior to pressing according to step c., the core mixture introduced into the mold has a water binder mean value (W/B) of 0.10 to 0.40, and preferably 0.12 to 0.20, based upon the ratio of water to the sum of hydraulic binder and fines having a mean diameter d50 determined according to ISO 13320:2009 of 1.0 to 100.0 m, and in particular of 1.0 to 30.0 m.

69. The method according to claim 46, wherein, after pressing according to step c., the core mixture introduced into the mold has a water binder mean value of 0.20 to 0.45, and in particular of 0.21 to 0.28 or 0.22 to 0.24, based upon the ratio of water to the sum of hydraulic binder and fines having a mean diameter d50 determined according to ISO 13320:2009 of 1.0 to 100.0 m, and in particular of 1.0 to 30.0 m.

70. The method according to claim 46, wherein, after pressing according to step c., the face mixture layer has a consistency of at least consistency class F5 according to DIN 1045-2 and/or EN 206.

71. The method according to claim 46, wherein, prior to pressing according to step c., the core mixture layer has a consistency of at most consistency class F1 according to DIN 1045-2 and/or EN 206.

72. The method according to claim 46, wherein the core mixture and/or the face mixture contains, as a further constituent, 0.01 to 3.0 wt %, relative to the total dry weight of the hydraulic binder, admixture according to EN 934, wherein the admixture is optionally selected from the group consisting of concrete plasticizers, superplasticizers, stabilizers, air entraining agents, accelerators, retarders, and sealants, or a combination thereof.

73. The method according to claim 72, wherein the admixture according to EN 934 is a superplasticizer, and in particular a superplasticizer selected from the group consisting of surface-active substances, in particular naphthalene sulfonates and/or lignosulfonates, and dispersing substances, in particular melamine resins, polycarboxylates, and polycarboxylate ethers, or a combination thereof, and in particular polycarboxylate, polyacrylic ether, and polycarboxylate ethers.

74. The method according to claim 46, wherein the aggregate contained in the core mixture and/or face mixture is a mixture containing organic and/or inorganic substances, wherein the organic and/or inorganic substances are optionally selected from the group consisting of coarse rock flours, mineral aggregate including rock granules according to EN 12620, ceramic, glass, synthetic fibers, natural fibers, and biological constituentsin particular, grassor a combination thereof.

75. The method according to claim 46, wherein the aggregate and/or fines contained in the core mixture and/or the face mixture are rock granules according to EN 12620.

76. The method according to claim 75, wherein the aggregate and/or fines contained in the core mixture and/or the face mixture are rock granules according to EN 12620 based upon quartz, basalt, granite, lime, lime grit, or mixtures thereof.

77. The method according to claim 75, wherein the aggregate contained in the core mixture and/or face mixture is rock granules according to EN 12620 that have a mean diameter d50 determined according to ISO 13320:2009 of 0.101 mm to 5.000 mm, and in particular of 0.125 mm to 5.000 mm.

78. The method according to claim 46, wherein the aggregate contained in the core mixture and/or face mixture is a mixture that is optimized in its composition by means of methods for determining the optimal grading curve, such that a minimal cavity for aggregate mixtures with a smallest grain is greater than the mean diameter d50 determined according to ISO 13320:2009 of the hydraulic binder.

79. The method according to claim 46, wherein introducing the core mixture into the mold according to step b. takes place by applying the core mixture to the flowable face mixture layer formed according to step a.

80. The method according to claim 46, wherein the pressure during pressing according to step c. is at least 0.5 N/mm.sup.2, and in particular at least 10 N/mm.sup.2 or at least 15 N/mm.sup.2.

81. The method according to claim 46, wherein the pressing according to step c. takes place with a pressing time of 5 to 60 seconds, and in particular of 5 to 40 seconds or 5 to 15 seconds.

82. The method according to claim 46, wherein the pressing according to step c. takes place in at least two successive pressing processes at the same or different intensity.

83. A hydraulically-bonded multilayer panel producible by a method according to claim 46, wherein the core mixture layer has a degree of compaction, determined according to the formula 3 specified in the description, of 0.93 to 0.99, and in particular of 0.97 to 0.99 and/or wherein the core mixture layer has a packing density, determined according to the formula 4 specified in the description, of 0.75 to 0.85, and in particular of 0.78 to 0.83.

84. The hydraulically-bonded multilayer panel according to claim 83, wherein the hydraulically-bonded multilayer panel has a length of at least 300, 400, 500, 600, 700, or 800 mm, and in particular of 800 to 1,200 mm.

85. The hydraulically-bonded multilayer panel according to claim 83, wherein the hydraulically-bonded multilayer panel has a surface area of at least 0.16 m.sup.2, and in particular of 0.18 to 1.44 m.sup.2, 0.32 to 1.44 m.sup.2, 0.18 to 0.83 m.sup.2, or 0.32 to 0.83 m.sup.2.

86. The hydraulically-bonded multilayer panel according to claim 83, wherein the hydraulically-bonded multilayer panel has a thickness of at most 40.0 mm, and in particular of 15.0 to 40.0 mm.

87. The hydraulically-bonded multilayer panel according to claim 83, wherein the multilayer panel has a characteristic bending tensile strength, ascertained according to DIN EN 1339, after 7 days of hardening, of more than 7.5 N/mm.sup.2, and in particular of at least 8.5 N/mm.sup.2.

Description

DESCRIPTION OF THE INVENTION

[0124] The steps a. and b. of the method according to the invention can be carried out in the specified order (first step a., thereafter step b.) or in reverse order (first step b, thereafter step a.). In the former case, the dry to earth-moist core mixture is applied in the mold to the already formed flowable face mixture layer. This is the normal case. However, it is also possible, although less preferred, to first introduce the dry to earth-moist core mixture into the mold and to then apply the flowable face concrete mixture to the core mixture layer.

[0125] Both the core mixture and the face mixture can moreover contain one or more admixtures according to EN 934. The use of suitable admixtures which, on the one hand, already cause better dispersion and wetting of hydraulic binder, and in particular cement, and additives during the mixing process and, on the other hand, can reduce the frictional forces between the fines constituents, can have a positive effect on the processing and compactibility.

[0126] In a preferred embodiment, the core mixture and/or the face mixture contains, as a further component, 0.01 to 3.0 wt % admixture according to EN 934, relative to the total dry weight of the hydraulic binder. The admixture is preferably selected from the group consisting of concrete plasticizers, superplasticizers, stabilizers, air entraining agents, accelerators, retarders, shrinkage reducers, and sealants, or a combination thereof. The core mixture and/or the face mixture preferably contains, as a further component, 0.01 to 3.0 wt %, relative to the total dry weight of the hydraulic binder, superplasticizer. The superplasticizer is preferably selected from the group consisting of surface-active substancesin particular, naphthalene sulfonates and/or lignosulfonatesand dispersing substancesin particular, melamine resins, polycarboxylates, and polycarboxylate ethers, or a combination thereof. According to a particularly preferred embodiment, a polycarboxylate, polyaryl ether, or polycarboxylate ether is used as the superplasticizer.

[0127] During pressing according to step c. of the method according to the invention, water contained in the face mixture layer is partially pressed into the core mixture layer. According to a preferred embodiment of the invention, the pressure during pressing according to step c. is at least 0.5 N/mm.sup.2, in particular at least 10 N/mm.sup.2, and preferably at least 15 N/mm.sup.2. Preferably, the pressing according to step c. takes place with a pressing time of 5 to 60 seconds, and in particular of 5 to 40 seconds or 5 to 15 seconds.

[0128] The pressing according to step c. can take place in one pressing process or in at least two successive pressing processes at the same or different intensity. Preferably, the pressing is provided in one pressing process. According to a particularly preferred embodiment of the invention, the pressing takes place according to step c. in a hermetic press.

Hydraulically-Bonded Multilayer Panels

[0129] According to a further embodiment, the invention relates to a hydraulically-bonded multilayer panel which can be or is produced according to the method according to the invention.

[0130] The hydraulically-bonded multilayer panel according to the invention can have any dimensions. The multilayer panel of the invention is preferably a relatively large-size, hydraulically-bonded multilayer panel, e.g., a multilayer panel having a length of at least 300, 400, 500, 600, 700, or 800 mm. In a particularly preferred embodiment, the hydraulically-bonded multilayer panel according to the invention has a length of 800 to 1,200 mm.

[0131] The hydraulically-bonded multilayer panel according to the invention can have all customary surface dimensions and is not limited to large-size multilayer panels. However, the advantages of the invention emerge particularly clearly in the production of large-size multilayer panels. Preferably, the hydraulically-bonded multilayer panel according to the invention has a surface area of at least 0.16 m.sup.2, and in particular of 0.18 to 1.44 m.sup.2, 0.32 to 1.44 m.sup.2, 0.18 to 0.83 m.sup.2, or 0.32 to 0.83 m.sup.2. Particularly preferred is a hydraulically-bonded multilayer panel having a surface area of 0.32 to 1.44 m.sup.2.

[0132] The hydraulically-bonded multilayer panel according to the invention is not limited in its thickness and can be of any thickness. However, the advantages of the invention emerge particularly clearly in the production of relatively thin multilayer panels.

[0133] Accordingly, a hydraulically-bonded multilayer panel having a thickness of at most 40.0 mm, and in particular of 15.0 to 40.0 mm, is preferred.

[0134] The hydraulically-bonded multilayer panel according to the invention furthermore has a relatively high degree of compaction. The degree of compaction (VG) is to be understood as the ratio between the calculated maximum bulk density of the mixture of an idealized panel without air and the measured bulk density of the produced panel after the pressing process. The degree of compaction is calculated in particular according to formula (3):

[00006]$\begin{array}{cc}\mathrm{VG}=\frac{{}_{\mathrm{FB},\mathrm{id}}}{{}_{\mathrm{FB}}}& \left(3\right)\end{array}$ [0135] V.sub.G . . . degree of compaction [] [0136] .sub.FB,id calculated, theoretically maximum, bulk density of the mixture in the fresh state (without air) [kg/m.sup.3] [0137] .sub.FB . . . measured bulk density of the panel after the pressing process [kg/m.sup.3]

[0138] In a preferred embodiment, the core mixture layer has a degree of compaction determined according to formula (3) of 0.93 to 0.99, and in particular of 0.97 to 0.99.

[0139] The hydraulically-bonded multilayer panel according to the invention is further characterized by a relatively high packing density of the core mixture layer. The term, packing density, is understood to mean the packing density of all solids of the core layer mixture in the pressed state. The packing density can in particular be calculated as follows:

[00007]$\begin{array}{cc}P{D}_p=\frac{V_{F,\mathrm{id}}}{V_p}& \left(4\right)\end{array}$ [0140] PD.sub.p . . . packing density of all solids of the core layer mixture in the pressed state [] [0141] V.sub.F,id . . . idealized volume of all solids of the core layer mixture without taking into account the air volume [m.sup.3] [0142] V.sub.p . . . measured volume of the core layer mixture of the pressed panels without water [m.sup.3]

[0143] In a preferred embodiment, the core mixture layer has a packing density determined according to formula (4) of 0.75 to 0.85, and in particular of 0.78 and 0.83.

[0144] Furthermore, it is advantageous that the hydraulically-bonded multilayer panel has a characteristic bending tensile strength ascertained according to DIN EN 1339, after 7 days of hardening, of more than 7.5 N/mm.sup.2, in particular of at least 8.5 N/mm.sup.2, and particularly preferably at least 10.0 N/mm.sup.2.

[0145] The invention is explained in more detail below with reference to exemplary embodiments.

EXAMPLES

A. Core Paste and Face Paste

[0146] Various compositions for core paste and face paste have been developed and tested. For this purpose, the water demand at the saturation point (V.sub.w,s/V.sub.p) and the water binder mean value at the saturation point (w.sub.s/p) were ascertained.

1. Core Paste

[0147]

TABLE-US-00001 Core paste solids vol % V.sub.w, s/V.sub.p w.sub.s/b Comparative example 1 CEM I 52.5 N 100 0.84 0.27 Comparative example 2 CEM I 42.5 R 100 0.88 0.28 Comparative Example 3 CEM I 52.5 R 100 0.94 0.30 Example 1 CEM I 52.5 N 66 0.53 0.23 Quartz flour 22 Microsilica 12 Example 2 CEM I 42.5 R 66 0.54 0.24 Quartz flour 22 Microsilica 12 Example 3a CEM I 52.5 R 91 0.77 0.26 Microsilica 9 Example 3b CEM I 52.5 R 60 0.57 0.28 Dolomite flour 40

2. Face Paste

[0148]

TABLE-US-00002 Face paste solids vol % V.sub.w, s/V.sub.p w.sub.s/b Comparative example 4 CEM I 52.5 R 100 0.94 0.30 Example 4 CEM I 52.5 R 60 0.70 0.41 Dolomite stone flour 40

[0149] V.sub.w,s/V.sub.p means water demand of the powder (or of the fines in the sense of the invention) at the saturation point. For this purpose, the method according to Marquardt I., described in Marquardt I: Ein Mischungskonzept fr selbstverdichtenden Beton auf der Basis der Volumenkenngrolen and Wasseransprche der Ausgangsstoffe [Mixture concept for self-compacting concrete based upon volume parameters and water demands of the starting materials], dissertation, University of Rostock, 2001, is adopted and adapted to the present application. For this purpose, a particular amount of the dry powder was introduced into a mixer which is able to detect changes in the mixing energy input or its power consumption. Then, water was mixed in continuously at constant rotational speed, and the amount of added water was measured continuously with the aid of a flow meter. The peak level of the power consumption of the mixer, which corresponds to the maximum shear resistance, shows when the saturation point is reached. The mixture is earth-moist.

[0150] The water content in the mixture can be specified at any time i, usually as volumetric water-to-powder ratio (V.sub.w,i/V.sub.p). At the saturation point, this corresponds to the water demand at the saturation point (V.sub.w,s/V.sub.p).

[0151] w.sub.s/b means water binder mean value at the saturation point and refers to the ratio of water to the sum of hydraulic binder and fines in the sense of the invention.

[0152] A lower V.sub.w,s/V.sub.p or w.sub.s/b value indicates a lower voids content or a higher packing density. By filling the cavity between the binder particles, which would otherwise have to be filled with cavity water, a reduced water requirement arises in order to achieve comparable compactibility and strength.

[0153] The above-described paste solids compositions are particularly suitable for use in the production method according to the invention. Specifically, the core paste compositions according to the invention give the core mixture layer of the multilayer panel outstanding compactibility and strength, with a reduced water requirement. The inventive face paste compositions give the face layer of the multilayer panel outstanding processability, strength, and durability.

B. Production of a Multilayer Panel

[0154] From the above-specified face and core mixtures, a multilayer panel was produced as follows:

Example 5

Face Mixture

[0155] 166.9 kg/m.sup.3 CEM I 42.5 R, kg/m.sup.3 241 CEM I 52.5 N were mixed with 137.1 kg/m.sup.3 dolomite flour 0.0-0.3 mm, 161.8 kg/m.sup.3 fine quartz sand 0.0-0.5 mm F12, 529.2 kg/m.sup.3 fine granite sand (0.1-1.0 mm), 147.3 kg/m.sup.3 limestone grit (0.1-0.6 mm), 219.4 kg/m.sup.3 limestone grit (0.6-1.2 mm), and 361.5 kg/m.sup.3 limestone grit (1.5-3.0 mm) in an Eirich mixer 8 L (5 L effective volume) for 60 seconds at 200 rpm. Thereafter, 31.2 kg/m.sup.3 limestone flour (0.5-3.0 m; d50=1.2 m) and 31.2 kg/m.sup.3 mineral plasticizer (1.0-25 m; d50=4.5 m) were added and mixed for 120 seconds at 200 rpm. Subsequently, 270.8 kg/m.sup.3 water and 3.77 kg/m.sup.3 superplasticizer based upon polycarboxylate ether were added and mixed for 120 seconds at 200 rpm. Finally, the entire mixture was mixed for 120 seconds at 200 rpm. The face mixture obtained in this way had a slump after 7 minutes of 345 mm, which corresponds to a flowable consistency.

Core Mixture

[0156] 779.9 kg/m.sup.3 cement CEM I 42.5 R was mixed with 251.3 kg/m.sup.3 quartz flour (100-200 m), 703.6 kg/m.sup.3 fine limestone sand (0.3-0.8 mm), and 310.2 kg/m.sup.3 basalt 1-3 mm in an Eirich mixer 8 L (5 L effective volume) for 60 sec at 150 rpm. Thereafter, 126.09 kg/m.sup.3 water and 3.86 superplasticizer based upon polycarboxylate ether were added and mixed for 60 sec at 150 rpm. Subsequently, 218.4 kg/m.sup.3 quartz flour (2.0-100.0 m; d50=15 m) and 101.4 kg/m.sup.3 RW quartz flour (2.0-100.0 m; d50=5 m) were added and mixed for 120 sec at 150 rpm. Finally, 14.01 kg/m.sup.3 water were added and mixed for 60 sec at 150 rpm. A flowable core mixture was obtained.

Introduction and Pressing

[0157] The prepared flowable face mixture was introduced into an 800 mm 400 mm large hermetic press mold of the OCEM laboratory sliding table press type 100 and distributed as uniformly as possible in the mold. The layer thickness of the face mixture after introduction into the mold (i.e., the thickness of the face mixture layer) was approximately 6 mm. Subsequently, the prepared earth-moist core mixture was applied to the face mixture layer by means of a filling funnel and a slide in the most homogeneous layer thickness possible (approximately 29 mm). The core mixture layer and the face mixture layer were compressed in the hermetic press at a pressure of approximately 15.0 MPa for approximately 10 seconds. The multilayer panel obtained was stripped directly after pressing.

[0158] The W/B value of the core mixture layer was 0.159; the W/B value of the face mixture layer was 0.664.

[0159] After pressing, the core mixture layer had a layer thickness of 24 mm, and the face mixture layer had a layer thickness of 6 mm. The total thickness of the multilayer panel obtained was 30 mm. Despite its relatively small thickness, the multilayer panel had a characteristic bending tensile strength, ascertained according to DIN EN 1339, after 7 days of hardening, of 10.9 N/mm.sup.2 and was characterized by excellent load-bearing capacity and outstanding usability.