DE2336321A1 - PLASTER MOLDED BODY AND METHOD OF MANUFACTURING THE SAME - Google Patents

Description

Applicant: Mitsubishi Petrochemical Company Limited 5-2, Marunouchi 2-Chome, Chiyoda-Ku, Tokyo / Japan

i plaster moldings ■ - °

; and methods of making the same

The invention relates to a molded plaster of paris.

'. The invention is used in high-density plasterboard and strength.

! It is known that plasterboard is made by mixing fired

% - or beta gypsum, or anhydrous gypsum with water and i with an accelerator for anhydrous gypsum and by cycling cure ¹ manufactured in a mold. Such plasterboards have ^! mostly a specific weight of 1.1 g / cm. Their mechanical strength is insufficient.

: The total amount of added water for the fired plaster • is measured within the limits between the equivalent

Amount of water to set the gypsum paste and the minimum ^! i Amount to create a fluidity of the vegetable. According to ; ' The following equation corresponds to a molar ratio of 1.5 I of the equivalent amount of water:,

CaSO ₄ * 1/2 H ₂ O + 1 ^ H ₂ O - ₄₃

Usually solidification occurs within 40 to

309885/1134

233632Ί!

60 minutes, setting and drying within 24 hours, so that the way of working takes quite a long time.

The object of the invention is to provide a plaster mold ^! body, in particular a plasterboard with high mechanical strength, high density made of a lamellar plaster of paris. This plasterboard should be suitable in particular as a wall panel, as a tile, as a ί floor panel and in a similar way.

According to the invention, this object is achieved by a molded plaster body containing gypsum crystals of lamellar structure. |

; The invention provides a building panel with a smooth surface

! and a pleasing exterior view / This building board is un-

I can be used indirectly as a cladding panel. It is imprinted

■ bar, for example in anastatic printing and in screen printing.

In a further development, the invention provides a method

j ready for the production of such a molded plasterboard that

; a hydraulically setting plaster is mixed with water,

i that the amount of this water is no less than

; binding of the plaster is required equivalent amount and

\ to maintain the mixture in a flowing state

! is sufficient and that the mixture is allowed to set under pressure

j is brought, the excess water from the mixture

■ occurs. . - ■

'.. The invention also enables the application of patterns

ι on the plate. The setting time is increased by a factor

■ 100 or even more shortened compared to the prior art.

i The slats within the plasterboard are according to the invention.

I with their (OIO) planes parallel to each other in an equal

! Direction aligned.

309885/1134

; The main advantages achieved by the invention are i following:

1. The method of mixing or kneading and the: Shaping is made easier because one works with an excess of water. :

2. The setting time or drainage time is shorter.

{It is only about 10 seconds. A setting and drying time , is not necessary.

j 3 · You can make a plaster of paris with ten times greater strength compared to known moldings within a short

■ Establish time since, according to the invention, the excess water is separated under pressure during solidification. :

. The mold space is after the separation of the water with inorganic Particle filled. . ;

-. 4. The initial strength of the shaped body after solidification is large enough that the plates. immediately after the

ι Drainage can be handled.

I 5 · 3 plaster moldings have a good dimensional stability against j heat and water, since the. mutual distance between the ^: inorganic particles is reduced by the application of pressure,

; so that the mutual adhesion of these particles is greater. 6. The plaster cast body has a smooth surface and is

; printable, as the mixture of plaster of paris and water as a result of the

• Excess water and very homogeneous as a result of kneading _: is and because the solidification and setting takes place under pressure.

! 7 · The plasterboard can have a three-dimensional pattern, a raised ■

'' or have an embossed pattern if the shape

, having a speaking pattern. The conventional screen printing technique,

I where a pattern by applying plaster powder or the like.

• is produced by means of a binding agent, is quite cumbersome 'in the implementation / the thickness of the order is usually

only 1 mm because the application is brittle and fragile. ", Venn too j a sculpture technique allows to produce thick orders! so this way of working is very complex. Against this can after

\ i

! the invention the! .luster directly during the press molding of the j molded plaster of paris are produced. The pattern is very firm and

i. : ■

309885/1134

j - 4 - I

: gives a good view even with a thickness of about 10 mm. ·

*8th. You get a plaster of paris with the desired ^!

I · ■!

{specific gravity by the pressure and / or the proportion

the organic filler, for example sand, fly ash or the like.

! i (is changed. In the context of the invention, it is preferable

! that the baked plaster of paris and / or anhydrous plaster of paris pulls i

! put 'water content between the equivalent or stoichiome- f

tric amount for setting the plaster and 50 times'

this amount lies. If the added amount is 50 times>

exceeds the equivalent value, the required form ι

! Excessively large. There is also a large mixing vessel for water j

jund plaster necessary. Therefore this ratio is uneconomical

llich. With regard to the flowability of the mixture at j

j - ι

■ When filling the mold, the amount of water should be between 1 and |

M0 times the equivalent amount, preferably between i

idem 4 and 10 times. j

j 2 '

Within the scope of the invention, the pressure is more than 1 kp / cm 1

! so that the molding time is shortened. A pressure of more than 4kp / cm j

list for the provision of a solid shaped body such as a

^ Base plate important. For economic reasons, the

■ - \ ο !

! Upper limit of the pressure at 500 kp / cm, preferably at about;

'■ 2'

■ 200 kgf / cm. A further improvement is achieved if the j

JWater on the outside of the mold under reduced pressure- \

; is sucked, as this supports the internal pressure. j

y y

jThe operation according to the invention is carried out at a temperature j

! carried out below 40 ° C, since the reaction between V / water

'and baked or water-free plaster is exothermic and!

; the strength of the plaster of paris at higher temperature '

! is impaired. The tensile strength decreases with a temperature ■

'at 40 ° C by about 20% compared to a temperature j

j from 20 ° C if the mixture of water and burnt j | ß-gypsum sets under pressure after dehydration. The lower one

The temperature limit is the freezing point of the mixture. The sub. '

309885/113

¹ limit is between about 0 ° G and 3S ⁰ G.

j So that when the hydraulically setting or setting of the hydraulically set

j the substance in a form under pressure the excess water

ι is removed, one must provide such a shape that only

I the water flows off and the hydraulically setting mixture

; is retained in shape. At least part of the shape

; e.g. the bottom part can consist of a porous material,

1 about a sintered metal. The bottom part can also contain water

! have access openings, e.g. a large number of capillary

i Openings or passages between the inside and the ί

I outside of the form. If the diameter of the outlet j

i openings is large, you can change the shape with a small pore ^j

■ j ■

■ Lay out fabric, such as paper, cardboard, fabric or a non- \

i '

j woven fiber sheet. The small-pore fabric can be in one piece

) as part of the surface of the plaster molding in the same

; be built in. j

j The pressure is applied at least as long as the ί

I hydraulically setting mixture flowing under the action of pressure

j is capable. j

I · ■ ι

I!

The invention is illustrated in the following individual examples under J

! Explained with reference to the accompanying drawings, in

1 which represent: ■

! ι

ι i

; 1 shows an electron microscopic photograph j

• of crystals of & gypsum,!

Γ I ¹ Xg. 2 an electron microscopic photograph ^:

i from crystals of ß-gypsum, j

I FIG. 3 shows an electron microscope photograph;

j 'j

<of lamellar plaster, j

Fig. 4 is a graph showing the relationship; between the compressive strength of a plaster J body depending on the service life, J

Fig. 5 is a graph showing the relationship j

309885/1134

between the flexural rigidity of a plaster of paris body according to the invention and the standing

■ time,

! 6 shows a section through an embodiment

a shape,

7 shows a section through another embodiment;

shape of a shape, j

j Fig. 8 is an X-ray diffraction image of a plaster of paris

ι shaped body with vertical irradiation

! on the surface caused by the pressure

'_ was applied,

ι Fig. 9 is an X-ray diffraction image of a plaster of paris molded body with parallel irradiation '

j to the surface exposed by the pressure \

j was hit,

i Fig. 10 is an X-ray diffraction image of a plaster of paris

j molded body made from a mixture of plaster of paris

i and Portland cement in a ratio of 1: 1 with

j perpendicular radiation to the surface,

■ which was acted upon by the pressure, and
! 11 is an X-ray diffraction image of a plaster of paris

i 'molded body' from a mixture of plaster of paris [

I and Portland cement in a ratio of 1: 1 with; i irradiation parallel to the surface that

j was pressurized. .

I ι

j The following individual examples are not intended as restrictive i

j meaning can be understood, but can be understood in the context of the

I can also be modified. ί

j I

I example 1

ι:

ι '

Fired ß-plaster of paris and water are used in a weight ratio of 2: 1;

(Molar ratio 1: 2.5) mixed and stirred. The mixture

is filled into a mold, the bottom part of which consists of a j

porous sintered metal. The mixture is in the bottom part J

309885/1134

• the form of squeezed so that Ü "berschußwasser removed ^and! The plaster is tied so that obtain a gypsum board! Is.

ι The mechanical properties of the plasterboard are used for

I downtimes between. 0 and 24 hours after solidification : determined and are given in Table 1.

: Table 1

Per pressure
ρ spec. Rigid
speed 24 pc. Compressive
speed 24 pc. Ligation: be
1 kp / cm weight 0 pc. 33 0 pc. 94 time - j
sec; f
1 0. 1.5 - 16 132 . 35 517 2700 2 1.0 1.6 53 153 139 619 10 3 4 _o 0 1.7 57 171 191 708 I! 4th 50 2.0 65 216 415 912 Il 5 100 2.1 74 249 450 ' ■ 1021 Il 6th 200 2.2 81 475 Il

The bending stiffness is specified in accordance with JIS K-6911-1970, the compressive strength according to JIS K - 6911-1970.

Example 2

I A mold having a large number of Wasseraustrittsöffnun- \ gen in the bottom part and a filter paper lining of the

Part of the bottom is used. The procedure follows the above example 1. The measured values are in the following table 2 specified.

309885/1134

Table 2

j
Per pressure
p spec. Rigid
speed 24 pc. Compressive
speed 24 pc. Ligation be kp / cm weight 0 pc. 35 0 pc. 97 Time
lake 1 0 1.5 17th 130 37 503 2700 2 1.0 1.6 52 152 135 620 10 3 1.7 57 175 190 715 Il 4th 50 ■ 2.0 67 199 419 850 Il 5 ■ 100 2.1 72 24o 433 962 Il 6th 150 2.2 75 247 459 1010 Il 7th 200 2.2 80 472 Il

\ Example 3

! A plasterboard is produced according to the working method of the example ^: using OC gypsum. The measurement values obtained are given in Table 3. i "Table 3

■!
; Per pressure spec. Rigid
speed 24 pc. Compressive
speed 24 8t. Ligation It 11 be lc "D / cm Π-pwi pTrh 64 196 0 pc. 161 0 pc. 621 Time
lake. 1 0 1.6 J J I69 72 695 .? 88o ^; 2 1.0 1.7 60 203 207 867 10 ^: 3 4.0 1.8 65 ? i _f 8 369 911 Il ί 4 50 2.1 75 252 435 1136 Il , 5 100 2.1 78 440 . 6th 200 2.2 81 493

3 0 9 8 8 5/1 1 3.4

- 9 - Example 4

Anhydrous plaster of paris and water are mixed and stirred in a weight ratio of 3: 2 with the addition of 3% by weight anhydrous ^ ^{1 potassium alum.} The mixture is molded according to the procedure of Example 1. The measured values are given in Table 4.

Table 4

Per pressure
. 2 spec. Rigid
speed 24 pc. Compressive
speed
f 24 pc. Ligation be kp / cm weight 29 72 ^¥ time O St. 105 0 pc. 475 lake ' 1 0 1.4 11 117 25th 507 2100 2 1.0 1.6 45 146 123 ' 681 10 3 4.o 1.7 49, • 163 138 703 Il if 50 1.9 62 185 386 948 Il 5 100 2.2 71 410 6th 200 2.2 74 437 "j

Examination of the plasterboard obtained showed that; that the gypsum crystals have a special structure that; differs from the particulate binding structure (CaSCL * 2HpO) of.% - gypsum (CaSO ^ · 1/2 H ₂ O) according to Pig. 1 and from the needle-shaped binding structure (CaSO ₂ , * 2H ₂ O) of ß-gypsum (CaSO ^ · 1/2 H ₂ O) according to Fig. 2. The crystals surprisingly show a lamellar structure according to FIG. which had obviously not yet been found.

This results in a plaster of paris with a lamellar crystal structure, whereas a solid plaster of paris that sets with water has so far only been in

309885/1134

233632Ί

.Χ-Porm or ß-Form has been classified. Fig. 3 shows the
Crystal structure of the new gypsum modification in one
electron microscopic photography. This modification is
clearly different from the modification according to FIGS. 1 and 2
different.

Normally, gypsum is divided into three classes depending on the water of crystallization: The modifications can
communicate with each other according to the following formula. j Molecular structure, crystal structure and configuration are under- '. been sought.

CaSO ₄

Heating in air or under reduced pressure

B-CaSO

170 ° C

Heating in the presence of water

170 ⁰ c

HI-CaSO

330 ° C

Mixture of LI-CaSO ₄ and

-CaSO,

The plaster modifications CaSO ₄ * 2H ₂ O, ^ - and ß-rCaSO ^ '^ H ^ O and
II- and IH-CaSO ₄ are referred to as crystalline or hydrous gypsum, calcined gypsum and anhydrous gypsum; the ; X -modifications of the baked gypsum differ from i the ß-modification in the crystal structure; the II modification and the HI modification of anhydrous plaster ^! differ from one another in their solubility in water, the II modification is insoluble, the III modification is soluble. ι

Well-known crystal structures are the particle shape of the ^ -modification and the needle shape of the ß-modificationj has
the plaster of paris according to the invention has a lamellate structure, so that
the plaster of paris molded body obtained has a higher density and a

309885/1134

possesses increased physical strength due to the stronger adhesion of the crystals. , Besides, the Reduced penetration of water. Various studies show the improvements in hardness, the Compressive strength, bending stiffness. The plaster of paris binds in a short time. The molded plaster body according to the invention does not lose its dimensional stability and strength so easily, if it has come into contact with water, as is the case with conventional plaster moldings.

Table 5 shows some properties of plaster of paris moldings conventional type, where the molding is done without pressure and a K or ß modification of plaster of paris is used.

Table 5

Type of plaster of paris. .) £, ß

Specific gravity 2.76 2.32

Required water content. *. (%) 35 90 Compressive strength ** (kp / cm ² ) 450 - 500 100 -

2
Flexural stiffness ** (kp / cm). 150 4-0

Setting time (minutes) 15-20 4-7

; * V. 'water content, which is necessary for the formation of CaSO ^.'2HpO;; is. ^:

! ** Physical parameters of CaSO.'2HpO ₁ according to ASTM C26

According to Table 5, a conventional method requires one much longer setting time and the mechanical parameters are not very good. ι

[By means of X-ray diffraction measurements, within the framework of the <

309885/1 134

; Invention clearly show the lamellar structure that one : Includes multitude of scales. The structural analysis agrees : coincides with the electron microscope image.

ι When a plasterboard is under pressure in a certain ■ Direction is generated during setting or dewatering, i form platelet-shaped crystals, which under formation ; aligned with a lamellar structure. This can be done: both through electron microscopic photography and through ■ i X-ray diffraction can be detected. The microphotography ! Fig. 3 is a section of a plaster mold made of

ß-plaster under pressure according to the invention produced : has been established, shows a lamellar crystal structure with: flakes or layers, which are perpendicular to the action direction of pressure are aligned. This is completely j different from the conventional crystal structure that is found ; made of ß-plaster with needle-shaped or fine leaf-shaped j crystals according to FIG. 2 or from / Jf gypsum with particles shaped or columnar crystals according to Fig. 1.

X-ray diffraction images of the specified sample with an angle of incidence parallel to the direction of action of the pressure, ie perpendicular to the surface of the molded body, hereinafter referred to as the Sp ^ direction and in the direction perpendicular to the direction of application of the pressure, namely parallel to the surface of the Shaped bodies, hereinafter referred to as the S ^ direction, are shown in FIGS. 8 and 9.

The S diffraction image in FIG. 8 shows the most intense diffraction maximum at an angle 2Θ = 11.69 ° (d = 7.56 cm "); in the S _R diffraction image the maximum at 20 = 11.69 ° is rather weak A comparison of the diffraction intensities at other points shows that the (010) plane is preferably parallel

j is aligned with that surface of the molded body j which was acted upon by the molding pressure.

309885/1134

Accordingly, the shaped bodies according to the invention have a lamellar structure where the crystal plane is oriented in a preferred direction is. The product of the invention consequently has improved physical properties that did not previously exist were achievable.

So far, hydraulic setting inorganic powders such as portland cement, slag cement with a high sulphate content, white cement, magnesia cement 3 to 10% by weight of plaster of paris.

Because the mixtures of these hydraulically setting substances with water shrink too much, if not sand, gravel or the like When substances are added, they have not been used to a practical extent. If gravel or sand is the hydraulically setting substance is added and when the mixture with water becomes a mortar for a wall hook kneaded or such a mixture is poured into a mold, the free water remains within the mortar, so that a long period of time is required for setting, curing and drying. As a result, such mixtures are not usable for series production.

So far, the ratio of the hydraulically setting is inorganic Substance such as cement according to the above list and water and sand have been selected through tests. For a cement mortar made of cement, sand and water is the Amount of water 20 to 30% by weight of the cement for one . viscous mortar and 60 to 70% by weight for one : low viscosity mortar. Such mortar slurries then harden.

] The invention also allows a use of the mentioned hy-

• Inorganic powder that binds hydraulically together with

j burned plaster of paris. You can create a solid molded body in this way

hold that one has the equivalent proportion for setting the

309885/1

hydraulic, setting inorganic powder Amount of water is added, which keeps the mixture flowable and that the mixture during the removal of the Y / water excess is kept under pressure. ;

In this case, a molding of high strength is obtained from the mixture of the hydraulically setting inorganic Powder with water without the need for an additive such as sand or gravel. A special stage of the hardening process and drying is not necessary.

In the context of the invention, you can use plaster of paris in connection with use one or more hydraulically setting inorganic powders such as white cement, portland cement, magnesia, cement, blast furnace cement, mortar, etc.

If in particular gypsum and a cement such as white cement or portland cement as a hydraulically setting inorganic

Θ p

Powder with a weight fraction of plaster of paris of more than 30% based on the total amount of the mixture is used, the product has a greater strength than if it is used alone consists of the hydraulically setting "inorganic powder.

In the context of the invention, a hydraulically setting inorganic powder is understood to mean a powder such as gypsum, gypsum mortar, hydraulic cement and mixtures of these substances, preferably gypsum-containing preparations such as gypsum, mortar and mixtures of gypsum and a hydraulic cement which are '' more than 3% by weight %, preferably 20% by weight of the mixture of the two. Portland cement normally contains a few%, about 3% by weight, gypsum. 10 and 11 are X-ray diffraction patterns for a molded article made from a mixture of plaster of paris and portland cement; Weight ratio 1: 1. Figs. 10 and 11 correspond to the * 'ig. 8 and 9 · Similar diffraction patterns are obtained when gypsum and Portland cement are mixed in different proportions

309885/1134

; . - ι ρ -

The electron microscopic photograph of the molding made of • a mixture of plaster of paris and portland cement in the ratio of; 1: 1 is identical lamellar structures, which are not pronounced ^one way.

: In the context of the invention, an inorganic ¹ or organic filler can also be added to the hydraulically setting! organic powders are added to the 1st ^strength: increases' ■ of the shaped body 2 changes the appearance thereof, and 3 x determines the specific gravity. \

Inorganic fillers may include: bauxite, fluorspar, cryolite ι j, graphite, synthetic graphite, colloidal _graphite,:

Silica, flint, silica sand, sulfur, barite, alumite,; Borax, refractory clay, 'slate, sillimanite, agalmatolite, ■,' refractory silica, dolomite, magnesite, peridotite, field ^! spat, pottery earth, wollastonite, lithium mineral, asbestos, mica, rock crystal, quartz, calcite, garnet, corundum, gilsonite,

! Vermiculite, perlite, pumice stone, puzolan soil including

j \

\ Fly ash, slate, swelled slate, kaolin clay, talc,; Bentonite, acid kaolin, diatomaceous earth, zeolite, metal minerals,

Andesine, granite, greywacke, serpentine, quartz gabbro, slate clay,: volcanic ash, metal powder, rock wool, glass fiber,; ■ carbon fiber, metal whisker, halloysite, montmorillonite, slag, kaolin fiber, red mud, sepiolite, attapulgite, palygorskite, broken glass, pieces of concrete. · · _:

■ Organic fillers can be: wood flour, wood shavings, hemp, '-. Wood wool, chips from stretched plastic films, stretched

Plastic fibers, in particular with a content of an inorganic. ganic filler, foam pieces, plastic pieces, Paper, rubber, bamboo, tissue, rush grass, pieces of sugar cane, Peanut shells, plastic oligomers.

The proportion of the inorganic or organic filler;

309885/1134

- Ιοί as an additive to the hydraulic, setting inorganic powder ! is preferably less than 97% by weight of the total weight

i of the mixture. If the content of gypsum or of hydraulic

j setting organic powder drops below 3% by weight, ι

j the product does not achieve sufficient strength because

! such a small amount of gypsum to incorporate all inorganic

I or organic fillers within the molded body are not

! is sufficient.

The molded plaster of paris according to the invention is preferably one

I Plasterboard with a thickness of 2 to 50 mm. Of course you can

'· The shaped body can also be formed in a different shape than

• Column, as a right-edged cylinder, as a block or the like .. '

^! These moldings can be either homogeneous or inhomogeneous

'-. speaking of their internal makeup or their structure or their

j chemical composition. An example of one

I such inhomogeneous body is a shaped body with an upper

ί surface layer made of pure plaster and a different core

j part, for example, made of white cement. The shaped body can also be a

; Surface made of a porous material such as paper or fabric

; to have,
ι

, Example 5

! After mixing and stirring white cement and water in one

; Weight ratio of 2: 1 turns the mixture into the same ; Form as described in Example 2 poured. The molding takes place under a pressure according to Table 6 during a Duration of 5 minutes. Then the molded body is taken out of the mold. The moldings remain there for a day. Series of measurements were then carried out, the results of which are given in Table 6.

309885/1134

Table 6

I.
Per pressure ,
spec. Rigid 57 •
- Pressure- be kp / cm weight speed 60 firm-> 71 ability j
I. 1 50 19th ^ 5O 2 100 20th * f8l- 5 150 22nd 535

Usually, a molded article of sufficient strength cannot be obtained from cement and water. But the invention makes it possible the provision of a molded article which is sufficient for practical needs. The mixture that without Applying pressure sets, does not give a special shape.

According to Examples 1, 2, 3 and 4, the specific Adjust the weight of the molding by changing the pressure.

Example 6

After the baked ß-plaster of paris, white cement and water have been mixed and kneaded in a weight ratio of 1: 1: 2, the mixture poured into the same form as described in Example 2. A pressure is applied for a period of 5 minutes

ρ
of 150 kp / cm applied. A molded body A with a specific weight of 2.0 is obtained.

A mixture of burnt ß-plaster of paris and water in a weight ratio of 1: 1 is molded in the same way. Of the The molded body B obtained has a specific weight of 1.9 In addition, a molded body C with a specific weight of 2.1 is produced.

j Finally, a kneaded mixture of fired

3.0988 5/1134

- 18 - 233632Ί

] ß-plaster, white cement and water in a weight ratio of 1: 1: 2 ! poured into said form and stand to set; calmly. The setting time is 6 minutes without pressure turn. A molded body D is obtained.

j These four shaped bodies are checked for their compressive strength and j flexural rigidity as a function of the respective service life j checked. The measured values are entered in FIGS. 4 and 5.

; The starting point of the time scale is 15 minutes ^; after removing the molding from the mold.

i Example 7

ΐ A mixture of white cement and water in weight ;. ratio 1: 2 is kneaded. Burnt ß-gypsum is added in the proportions given in Table 7. Then that will

i respective mixture in the same form as in example 2 '. 2

filled in and subjected to a pressure of 150 kp / cm.

; The molding is allowed to set for 5 minutes while

the time the excess water is deducted. ! »

. The molded body is removed from the mold and each

! after 10 minutes and after 1 day for its flexural rigidity : examined. The measured values are given in Table 7.

309885/1134

Table 7

Fro-% by weight of plaster of paris Ispec

be

[Weight

ι Biegesteifig- j I ness;

O 2.0 10 min ^: 1 day 1 3 1.9 71 128 2 10 2.1 I87 3 30th 2.0 121 213 50 2.0 162 240 5 6o 2.0 196 2cO 6th 8o ■ 2.2 191 257 7th 90 1.9 187 25k 8th 97 1.9 172 2 ^ 8 9 100 1.9 168 243 IO 164 240.

Example 8

In a thoroughly kneaded mixture of ß-gypsum, Portland cement, Red mud, water in a weight ratio of 1: 1: 3: 2 becomes 2% by weight of a composite strand made of polypropylene and Entered fortland cement distributed therein. The mixture will filled into the mold according to example 2. Moldings of different specific gravity are then obtained in each case depending on the pressure applied during the 5 minute setting period.

The moldings are on their flexural strength and on their Compressive strength checked 1 day after the seizure formation. The respective measured values are given in Table 8.

In the context of a comparative test, a molding in which the setting took place without pressure was so cracked that none

309885/1134

233632Ί

Specimen could be taken,

Table 8

Per
be shape
pressure
ρ
kp / cm spec.
weight i
Bend
stiff
keitp
Vp / ητη ¹ - pressure
strength
ρ
kp / cm 1 1 I0O3 78 182 2 20th 1.1 92 215 3 50 1.2 115 273 k 100 1Λ 131 3 ^ 0 5 150. 1.6 150 418 6th 200 1.8 173 504

Example 9

: It is a mixture of burnt ß-plaster, white cement

j and water prepared in a weight ratio of 1: 1: 3 '

'and also a mixture of asbestos and wood powder in the ι

; Weight ratio 5: 1. 7% by weight of the asbestos wood powder;

i Mixtures are added to the plaster of paris mixture. Then will

sintered diatomaceous earth in a weight proportion of 5i 80 »·

: 9C and 91% by weight added. The mixture is in the same

j form poured as in example 2. There will be a pressure of

ρ,

150 kp / cm applied for a period of 5 minutes.

. For comparison, moldings are unpressurized for M days! hardens.

! The molded bodies are checked for their flexural rigidity and compressive strength 1 day after the end of curing. the

I:

309885/1134

Results are given in Table 9.

Table 9.

Per
be shape
pressure
kp / cm Diatoms
Earth
Weight% spec.
weight Bend
stiff
speed
'ρ
kp / cm pressure
firm
speed
ρ
kp / cm 1 150 5 1.8 130 332 2 150 85 1.6 52 125 3 150 90 1.6 * f3 120 150 91 1.6 39 101 5 O 5 1.0 k2 113 6th 0 89 0.8 3 9 ? 0 90 0.8 3 9 8th 0 91 0.8 3 8th

Example 10

A device according to FIG. 6 is used here. A slurry of plaster of paris and water in a weight ratio of 2: 1 (1: 2.5 in the molar ratio) is in the chamber 3 of the Filled with a die, the bottom wall of which consists of a porous sintered metal 1. The contents of chamber 3 of the die

ο is applying pressure of 50 kp / cm for a duration from 10 see with the help of the ram 5, the ram decreases 5 has a three-dimensional pattern with an embossing 4, which is up to 1 mm deep and has an edge angle O = 89 °. During the pressurization, the excess water becomes dissipated through the wall made of sintered metal. Then it will be

3 0 9 8 8 5/1 134

- 22 removed the solidified molding. \

The shaped body has a raised pattern that corresponds exactly to the impression of the shaped stamp. The specific weight

2 '

is 2.0, the compressive strength 461 kp / cm and the bending stiffness 59 kp / cm ² *

'Example 11 ■

In a compression molding press according to FIG. 7, a slurry of plaster of paris and water in a weight ratio of 2: 1 is filled ^; so that the chamber 13 of the Matritzei2 is full. The volume I

the chamber 13 of the Matritzei2 is through the application of pressure from [ ι ο
; 50 kp / cm for a period of 1 minute using the press

I stempeis ^ decreased. The ram 15 has a pattern ″ ■

! with an imprint 14- 1 mm deep and one largest!

j edge angle θ = 92 °. The embossing14 is marked by a poly

! Lined with ethylene foil with a thickness of 200 / u. To '

• After pressing and dewatering, the ram and the: j film are removed. Then one obtains the solidified form ^; j body. The molded body has a convex pattern that corresponds exactly! - to the pattern of the press ram. The specific ί

! ρ

j weight is 1.9 »the compressive strength 447 kp / cm and the bending

! stiffness 56 kp / cm.

If you don't use polyethylene sheeting is part of the Pattern that corresponds to the edge angle exceeding 90 ° partially broken off, the molding does not look good,

! If the edge angle exceeds 90 °, so that a rear

i cutting occurs, the molding breaks away partially and

! looks bad when molded.

j By using a flexible film between the mold

i body and form this can be avoided.

A pattern with undercuts or with edge angles between 87 ° and 90 ° and a pattern with considerable depth

309885/1134

J can only be applied to salable moldings if you insert a flexible film between the molded body and the mold. This resilient film can have a thickness between 0.02 and 1 mm, preferably between 0.1 and 0.3 mm to have. The film consists of low density polyethylene, ethylene-vinyl acetate copolymers, polyvinyl chloride with Plasticizer additive, vinylidene chloride, cellophane, vinyl chloride-vinylidene chloride copolymers, High density polyethylene, nylon, polyester resin, or ethylene-propylene copolymer.

A pattern with an undercut can be obtained if the width L ″ at the mouth of the impression of the press ram 15 and the inside width Lp of the embossment is in the following relationship according to Fig. 7 adhere to

L ₂ -C (L ₁ 2t)
with t as the thickness of the film 16.

309885/1134

Claims (1)

Claims: j 1. Gypsum moldings containing gypsum crystals with lamellar i Structure. ι 2. Gypsum molded body according to claim 1, characterized in that! that a core part consists of ß-gypsum. j 3. Gypsum molded body according to claim 1 or 2, characterized; draws that the same is designed as a plate. · 4. Gypsum molded body according to one of claims 1 to 3 »characterized · characterized that within the crystals the (010) planes! lie in one direction. 5. Gypsum molded body according to claim 4, characterized in that the direction of the (010) planes coincides with the direction of action
of the pressure while sculpting the body. 6. Gypsum molded body according to claim 4 or 5 »thereby marked j distinguishes that the same essentially exclusively from ι Plaster of paris is made. 'j 7. Gypsum molded body according to claim 4 or 5? thereby marked ι draws that it consists of an intimate mixture of plaster of paris and a hydraulically setting inorganic powder. 8. Gypsum molded body according to one of claims 1 to 1, characterized in that the hydraulically setting inorganic powder j white cement, portland cement, magnesia ^{cement, blast furnace 1} cement and / or mortar is present and that the weight share> part of the plaster in the The total amount of gypsum and hydraulically setting inorganic powder is not less than 30% by weight. !, 9. A method for producing a plasterboard molding according to an i 309885/1 134 ί of claims 1 to 8, characterized in that a: j hydraulically setting gypsum is mixed with water so that ' : the amount of this water not less than that used to set j of the gypsum is the required equivalent amount and for the up-: ; Maintaining the mixture in a flowing state is sufficient; ; and that the mixture is made to set under pressure: [with the excess water emerging from the mixture. ι \ 10. The method of claim 9j characterized in that · 50 times the water in 1- to the equivalent amount is mixed beige. '! 11. The method according to claim 9 or 10, characterized in that j that the excess water through water outlet openings | a form that absorbs the mixture of plaster of paris and water, consisting of: is pressed. I. 12. The method according to claim 11, characterized in that j the water outlets in the lower part of the mold, in bendj j the printing application should be provided. ; ij ^: 13 · Method according to Claim 12, characterized in that the part of the shape j which has the water outlet openings is made from a porous sintered metal, ! 14. The method according to claim 12, characterized in that ! that part of the mold which has the water outlet openings; y y I made of an impermeable material with openings j will. j j 15 «A method according to claim 14, characterized in that ¹ inserted a porous film in said part of the mold through which the water exits. . | 16. The method according to any one of claims 11 to 15? through this
marked,
is applied. ο pi characterized in that a pressure between 1 kp / cm to 500 kp / em; 309 885/1134 17 ·, method according to any one of claims 9 to 16, characterized characterized in that a pattern is arranged on the inner surface of the mold which has a corresponding pattern on the plaster molding causes. 18, method according to claim 17 _? characterized in that; ι a flexible film is inserted between the mixture of plaster of paris and water and the molding die to create a pattern ^! j is transferred to the plaster molding, ' 19 · Method according to one of claims 9 to 18, characterized in that the working temperature between the Ge; freezing point of the mixture and 4-0 C is set. ^: j 20. The method according to any one of claims 9 to 19, characterized in that; characterized in that white cement, portland cement, magnesia; j cement, blast furnace cement, mortar and / or another hydrau- ' lisch-setting, inorganic powder is added to the gypsum and that water is 1.0 to 50 times the amount; * the equivalent value for setting the plaster and the ι additive is added. j 21. The method according to claim 20, characterized in that : Portland cement is added. · 22. The method according to claim 20 or 21, characterized in that! i that the weight ratio of the plaster of paris to the total amount! ■ of gypsum and hydraulically setting inorganic powder! is not less than 30%. 23. The method according to claim 18, characterized in that a film with a thickness between 0.02 mm and 1 mm is inserted, 3Q9885 / 1134 Blank page