CA1123461A - Process of producing fiber-reinforced hardened body of gypsum system - Google Patents

Abstract

Abstract of the Disclosure A process of producing a fiber-reinforced hardened body of gypsum system comprises mixing gypsum and slag in a ratio by weight of the former to the latter between 3 : 7 and 7 : 3 to prepare a main starting material, adding to the main starting material 1 - 30% by weight of reinforcing fiber, 0.1 - 5% by weight of alkali salt substance, and 0.1 - 5% by weight of aluminum sulfate-containing substance, the respective amounts being based on the weight of the main starting material, further adding water to knead and mold the resulting starting material mixture, and curing the molded starting material mixture under normal con-dition or steam-curing tho molded starting material mixture at 90°C or below.

Description

34~

The present invention is concerned with a process of producing a fiber-reinforced hardened body o gypsum system, and more particularly it relates to a process of producing such a hardened body in which gypsum (CaS04~a~ o) and slag are used as the main starting material and reinforcing fiber is incorporated therewith.
Hitherto, gypsum~slag, and a mixture thereof have been utilized as described below:
(1) Utilization of hemihydrate and II-type anhydrate:

The utilization of hemihydrate (CaS04 1/2H20) and II-type anhydrate (CaSo4) is typified by a gypsum plaster board That is, hemihydrate is obtained by dehydration of 3/2 mole~ of the bound water contained in gypsum (CaS04 2H20~. To hemihydrate are added fillers etc., and further 70~ by weight or more of water is also added thereto, and the resulting mixture is kneaded and hardened to produce a board. As for II-type anhydrate, it is -obtained by calcination of gypsum at about 600C or more, and the obtained II-type anhydrate is ground. About 35% by weight of water is added to the anhydrate, and the mixtuEe is kneaded and 20 hardened to prepare a board. - ;
These hardened gypsum bodies are obtained by utilizing the self-hardening property of hemihydrate and II-type anhydrate.
The above mentioned methods of producing hardzned gypsum bodies require the dehydration of gypsum, and in particular, a large quantity of heat is needed in obtaining II-type anhydrate~
Further, any of these hardened gypsum bodies are poor in water resistance. Besideq, the hardened hemihydrate body is lower in strength since much water is required in obtaining such .

a hardened body. II-Type anhydrate i9 hardly susceptible to

- 2 -, ., .Z3~

hydration even when water is added theretoO For the purpose of hydrating II-type anhydrate, it is necessary to add an acceleratorO
However, even when such an accelerator is add~d, the hydration cannot be completed in a short period and proceeds slowly~ Because of this, the hardened II-type anhydrate body is liable to be ex-panded and destroyed in a long period of time and therefore, it is poor in the stability required for general materials.
(2) Composite materials of hemihydrate and portland cement:
The composite method has been studied for the purpose of `
improving the water resistance of hardened gypsum body. However, the composite of hemihydrate and portland cement is disadvantageous in that the composite material exhibits too rapid setting property and lacks workability. Owing to this, it is required to add a retarder. However, in some cases, the addition of a retarder re-sults in reducing the strength of the final product to a great extent.
Moreover, after completion of hardening of the hemihydrate body, calcium aluminate ~3CaOoA1203) in the cement and the hemi-hydrate react with each other to form ettringite (3CaOoAl203o3CaS040 20 31-32 ~ 0), and as a result, ~he hardened body is expanded and `
destroyed O `~

(3) Sulfated slag cement:
Sulfated slag cement is composed of 80 - 85% by weight of blast furnace slag, 10 - 15% by weight of anhydrate and about 5 by weight of portland cementO The latent hydraulic property of the blast furnace slag is utilized to produce a hardened body of sulfated slag cement. This hardened body is liable to be de-teroriated due to an embrittlement phenomenon in its surface, which is most disadvantageous. Besides, when a large amount of - 3 - ~ ;~

.. . . ...... . . . . .

~ L~ 23~6:~
II-type anhydrate is added to sulfated slag cement,~ the hardened body disadvantageously exhibits~a similar property to that of the hardened bodies as mentioned above (2), and its deterioration is promoted.
In the foregoing conventional utilization of gypsum, :
cases (1) and ~2) are based on the utilization o~ the self-hardening property possessed by hemihydrate and II-typ~ anhydrate, and in case (3), the anhydrate is uslsd as a stimulant for the hydration in a small amount. ~:
As for gypsum, it does not have self-hardening properties, and therefore it has not become by itself the material to be utilized.
The inventors have studied methods for developing the use of gypsumO As the result, they have found that a hardened body having rapid hardening properties, high strength and water re-sistance is obtained by using gypsum (CaSo402 ~ 0) having no self-hardening prope-~ty and slag having the latent hydraulic property as the main star~ing material and incorporating with the main starting material an alkali salt substance and an aluminum sulfate-containing substanceO Also, it has been found that when re-inforcing fiber is further used along with the main starting material and other ingredients as mentioned above, an improved hardened body can be obtainad which is remarkably excellent in the physical properties including impact strength, change in length and partlcu].arly bending strength According to one aspect of the invention, there is pro-vided a process of producing a fiber-reinforced hardened body of gypsum system which comprises mixing gypsum and slag in a:
ratio by weight of the former to the latter between 3 : 7 and , j ,. , ,-: , - ~ ,:: . -- ,. .:

3~

7 : 3 to prepare a main starting material, adding to the main starting material 1 - 30~ by weight of reinforcing fiber, Ool ~
5~ by weight of alkali salt substance and 0Ol - 5~ by weight of aluminum sulfate-containing substance, the respective amounts being based on the weight of the main start:ing material, further adding water to knead and mold the resulting starting materîal mix~ure, and curing the molded starting materi,al mixture under normal con-dition or steam-curing the molded sta:rting material mixture at 90 C
or below.
According to another aspect of the invention, there is provided a process of producing a fiber-reinforced hardened body of gypsum system which further adding a light-weight material to the ingredients for the process according to the first mentioned aspect of the invention In accordance with the third aspect of the invention, there is provided a process of producing a fiber-reinforced hardened body of gypsum system which further adding a fluorinated salt substance to the ingredients for the process~according to the first mentioned aspect of the inventionO ~ :
In accordance with the fourth aspect of the invention, ;;~
there is provided a process of producing a fiber-reinforced hardened body of gypsum system which further adding a light-weight . material and fluorinated salt substance to the ingredients for the process according to the first mentioned aspect of the inventionO :` ' The main sl:arting material for constituting the hardened body of the presenl: invention is composed of gypsum and slagO
Gypsum u~ed in the present invention includes artificial gypsum from exhaust gas desulfurization and phosphate plants, and other by-product gypsum, as well as natural gypsumO The gypsum - 5 ~ ::

- : . .. :. ~ . .. . .

.2~

is not restricted in terms of the crystal shape and is satis-factory if the amount of the ~ater deposited to the gyp~um is in the range within which the gypsum can be canveyed without disadvantage~ When the artiicial gypsum from exhaust gas de-sulfurization plant is used, it does not need selecting care-fully because the possible impurities, for example, calcium carbonate, calcium sulfite and soot do not have any influence on the physical properties of the resulting hardened bodyO
Slag used in the present invention may have a specific surface area of at least 3000 cm2/g. The preferred slag is glass like blast furnace slagO In addition, electric open-hearth furnace slag may be utilizedO `~
The mixing ratio by weight of gypsum to slag is de- :
termined in view of the strength of the resulting hardened body : :
and is preferably within the range between 3 : 7 and 7 : 3 as shown in the Examples given laterO ~
The alkali salt substance includes alkali metal salts, `:
for example sodium sulfate and potassium sulfate; and alkaline earth metal and alkali metal hydroxides, for example caustic ~ .
soda, caustic potash and slaked limeO It may be used in an amount of Ool ~ 5% by weight, preferably 105 ~ 300% by weight based `
on the weight of the ma~n.~tarting materialO :
The aluminum sulfate-containing substance includes, for example aluminum sulfate, preferably anhydrous aluminum sulfate, sodium alum, and potassium alumO The amount of the aluminum :
sulfate-containing substance may be 0.1 - 5~ by weight, pre- -ferably 0.5 - 200% by weight based on the weight of the main .
starting materialO ::
The fluorinated salt substance includes, for example r~

- 6 - :~

;, ~ . .:.:, ~

- ~3.f~3~

sodium fluoride~ potassium fluoride, sodium silicofluoride and potassium silicofluoride~ They may be used in an amount of 0.1 - 5% by weight, preferably 0O5 - 2.0~ by weight based on the weight of the main starting materialO
When the above described additives are used in an amount of 18ss than the lower limit, satisf actory results cannot be ob-tained, and on the contrary, when they are employed in an amount larger than the upper limitJ the strength of the resulting hardened body is decreasedO
As the reinforcing fiber used in the present invention, -~
inorganic fiber and organic fiber can be usedO The former in-cludes, for example asbestos (including chrysotile and amosite) roc~ wool~ glass fiber (including alkali-free glass fiber, for example E-glass fiber, and low alkali glass fiber, for example alkali-resistant glass fiber), and steel fiber (including iron system fiber)O The latter includesJ for example carbon fiber, polypropylene fiberJ nylon fiber and pulp fiber. The length of these fibers may be optionally selected taking account of the workability, processability of the resulting hardened body, 20 bending strength thereof and the likeO The length of fiber may :;
be 2 - 50mmJ and the preferred length is 2 ~ lOmmO The fibers may be used alone or in combination, and the preferred materials for the combination are asbestos and glass fiberJ asbestos and ~.
polypropylene fiberJ and the likeO
The addition of the reinforcing fiber not only promotes the formability and distortion-preventing ability of the hardened ~ ;
bodyJ but also contributes to enhancement in the physical pro~
perties of the hardened body, particularly bending strength. In addition, when the reinforcing fiber is incorporated, the material ~.23~

for forming the hardened body can be further easily extruded atthe time of using the extrusion molding method as the mo~ding method. The amount of the reinforcing fiber may be 1 - 30% by weight, preferably 10 - 25~ by weight based on the weight of the main starting materialO If the amount: is larger than 30% by weight, the bending strength of the resulting hardened body is in-stead decreased and its workability also is deteriorated.
As the light-weight material, inorganic and organic material may be usedO The inorganic light-weight material in-cludes, for example perlite, foamable light-weight aggregate, light sand, calcium silicate hydrate (for example, xonotlite and tobermolite), diatomaceous earth, tricalcium sulfoaluminate hydrate, and calcined zeoliteO The organic light-weight material includes, for example shavings, sawdust and foamed polystyreneO
In addition, sand suitable for use in cement concrete may be employed as the light-weight material for the purpose of improving the weather resistance property of the resulting hardened body.
Tha amount of the light-weight material may be 1 - 25% by weight, preferably 10 - 20~ by weight based on the weight of the main starting material. The light-weight material decreases the bulk specific gravity of the hardened bodyO However, if its amount is larger than the upper limit, workability is deteriorated, and when it is smaller than the lower limit, the desired effect cannot be attainedO
The above-mentioned additives including alkali salt sub-stance, aluminum sulfate-containing substance and fluorinated salt substance; reinforcing fiber and light-weight material may be added to the main starting material simultaneously or separately .. . - . ~ .

-- ~.234~

The method for molding the hardened body includes any of known methods, for example casting, pressure molding, extrusion molding and Hatschek wet machine-using methods. At the time of molding, various kinds of cement and finely powdered calcium carbonate may be mixed with other ingredients for the purpose of increasing the strength of the resulting hardened bodyO
The main starting material, additives, reinforcing fiber and light-weight material are suitably mixed in accordance with the present invention to prepare a starting material mixture for the formation of the hardened bodyO Water is then added to the starting material mixture, and kneading and molding are effectedO ~ ~;
At that time, the amount of water may be varied and determined according to the molding method to be employed, and therefore, its amount is not restricted as long as the purpose can be attained.
As to the curing carried out after kneading and molding ~-of the starting material mixture, not only normal curing but also steam curing at 90C or below may be employed. When the temperature is over 90C, the gypsum is dehydrated, and the resulting ettringite in the hardened body is decomposed, which causes undesired results The hardened body obtained in accordance with the present invention essentially comprises ettringite (3cao-Al2o3o3caso4--31-32H20) and excess gypsum unreacted with the hydrate of the slag.
The ettringite is such one that is formed by reaction of calcium oxide (CaO) and aluminum oxide (A1203), which are contained in the slag, with gypsum (CaSO42H29)0 ~he high initial strength possessed by the obtained hardened body i9 considered to be secured by the ettringite and is ensured upon long aging by the latent hydraulic property of the slagO
_ g_ ~-3~

As for the effect of additives, the alkali salt substance and aluminum sulfate containing substance accelerate cooperatively the formation of ettringite which attains the high strength, rapid hardening property and water resistance of the hardened body in its initial setO The fluorinated salt substance produces in-soluble fluoride in the hardened body so that the water resistance of such body is improved and deterioration of the body surface is preventedO
The reinforcing fiber has the effects of improving the bending strength and weather resistance prope~ty of the hardened body and increasing the formability and distortion-preventing a~ility of the molded body at the time of conducting extrusion molding and Hatschek wet machine-using methodsO The light-weight material has effects of decreasing the bulk specific gravity of the hardened body and improving the weather resistance thereof, and further it imparts workability to the hardened body and lightens the weight of such bodyO
The hardened body of the present invention is excellent in the rapid hardening property, strength, water resistance, weather 20 resistance and formability, and is inexpensive. ThereforeJ it can be used widely~ and is particularly useful as a building or con-, ~ ,.~.: , struction materialO
The invention will be understood more readily by referenceto the following examplesO However, these examples are intended to illustrate the invention and are not to be construed to limit the scope of the inventionO
In these examples, as the main starting materials, there are used artificial gypsum from a fuel gas desulfurization plant for metal refining and blast furnace granulated slagO The 30 granulated slag is such one that has the composition shown in Table- :

- ~.Z3~6~

1 given later and has been ground to regulate its specific surface area to 3800 cm2/g. Slaked lime is used as the alkali salt sub-stance and is that for use in industryO Other additives are the first class onesO
Parts and percent (%) are by weight unless otherwise specifiedO

Table - 1 : Composition of blast ~urna~e slag _ . _ ~ .. , .. ..
loss SiO2 A123 Fe23 CaOMgO TiO2MnO
(IgO) InsolO _ . . :
10 Ool9 1027 32036 14016 0.97 40017 6.o4 2000 loOO

To the main starting material composed of 50 parts of gypsum and 50 parts of slag were added 105~ of slaked lime and :~ ;
0.25%, 1.00% and 5000%, respectively, of aluminum sodium sulfate as the additive and 25% of asbestos (chrysotile) as the reinforcing fiberO 200% of water was then added to the mixture`s to prepare :-three kinds of samples, ~oO 1 - NoO 3, as sh~wn in Table - 20 The samples were separately kneaded, and thereafterg molded under a .`~
pressure of 100 Kg/cm2 into plate formO They were steam-cured at 20 60C for 24 hours to obtain hardened bodies, which were further cured naturally for 7 days. These hardened bodies NoO 1 - ~oO 3 were measured with respect to the physical properties, the rcsults ~ .
of which are shown in Table - 30 ;
EX~MPLE 2 , .
To the main starting material composed of 50 parts of ; ;
gypsum and 50 parts of slag were respectively added 105~ of slaked lime, 0.13%, 005~ and 1.25~ of aluminum sulfate and 0013~, 0050~ ~ -and 1.25~ of sodium silicofluoride as the additives, ana 25~ of - :~
asbestos (chrysotile) as the reinforcing fiberO Further, 200~ of - 11 - ;' ~:.

;23~

water was added to the mixtures, which were kneaded to prepare three kinds of samples No. 4 - No. 6 as shown in Table - 2D
After completion of kneading, the samples were molded under a pressure of 100 Kg/cm2 into plate form. These were steam-cured at 60C for 24 hours to obtain hardened bodies, which were further cured under natural conditions for 7 daysO The final hardened bodies ~o. 4 - NoO 6 were measured wi1:h respect to the physical properties, the results of which are shown in Table - 3O

Table-2 :
~ . ,_, _ .......... , Sample Main starting Additives As~estos Water ~o material O . l _ .
Gypswm slag Slakec ~ C _ .. .. . . . ~.,, l 5o 5o 1050.25 ~ ~ 25 200 2 5 5 105loOO _ _ 25 200 `~

3 5o 5o 1055O00 ~ ~ 25 200 ::

4 5o 5o 105 _Oo l 1 0~ 13 25 200 . 5 5o 5 1.5 _0O50 0.50 25 200 6 5 5 1O5 _lo2~ l.25 25 200 ~.:

* Based on the weight of the main startiny materialO

A: Aluminwm sodium sulfate B: Aluminum sulfate C: Sodium silicofluoride . ~,; `

, . . , . , , . ,, ,, ., ", .... .. .. .. . . ...

~2~34~

Table-3 Sample Bending Impact Brinell Length Water Bulk No. strength strength hardne~s change abæorp- speci~ic rate tion rate gravity , ........ . . .... _ . .
~Kg/cm2) (Kg 2 ---~ xlO (~) ~;

1 185 203 907 1801 17.2 1.74 2 261 2.9 1206 16~5 1607 1073 3 232 2.7 11.4 1502 16.9 1073 4 173 204 1005 17.6 16.8 1.72 278 302 13.2 1509 16.0 1075 ~
6 253 2.9 12.4 15.0 16.2 1074 ;

Aluminum sulfate (0O5%)J oO5% of sodium silicofluoride and 1-5 . ~..
2~5% and 5.o%, respectively, of slaked lime as the additives, and 25% of asbestos (chrysotile) as the reinforcing fiber were added ; `
to the main starting material composed of 50 parts of gypsum and 50 parts of slag. 200~ of water was added to the resulting mixtures, ;
which were kneaded to prepare three kinds of samples No. 7 - No. 9 as shown in Table-4. After kneading, samples were molded under a pressure of 100 kg/cm2 into plate form. These were cured at 20C, 80%RH for 21 days. The hardened bodies No. 7 - No. 9 thus obtained ;~
were measured with respect to the phyqical properties, the results of which are shown in Table-5.
Table-4 Ma n starl:ing Additives ¦Asbestos Iwater ¦

SNmoPle l _ 6 (parts) (%)~
. __ __ . . ... _ _ .......... .. .. . -::
7 5o 5C) 105 -5 -5 25 200 ;-8 5o 5o 2.5 oo5 o.5 25 200 3 9 5 5 5.o- - o 5 o 5 25 200 ~
,.

, * Based on the weight of the main starting material.

B: Aluminum sulfate C: Sodium silicofluoride Table-5 = Bending Impact Brinell Length Water Bulk Sample strength strength hardness change absorption specific No, ~ ._ raterate gravity (Kg/cm ) /cm2) xlO 4(~) . _ .
7 258 3. 1203 16091600 1-.75 8 202 2.4 9.9 18041609 1073 ~ ~-9 178 2 3 806 l9ol1706 1070 EX~MPLE
Three kinds of the main starting materials were preliminary prepared in which the mixing ratios of gypsum to slag were 7:3,

5:5, 3:7 ~by weight), respectivelyO To the main starting materials were respectively added 3.0~ of slaked lime, loO~ of aluminum sulfate, loO~ of sodium silicofluoride and 25~ of asbestos -(chrysotile). 200 parts of water was further added to the mixturesJ
which were kneaded to prepare three kinds of samples NoO 10 - NoO 12 as shown in Table-6 After kneading, the samples were molded under a pressure of 100 Kg/cm2 into plate formO These were steam-cured at 60C for 24 hours to obtain hardened bodies~ which were further cured naturally for 7 daysO The hardened bodies NoO 10 - NoO 12 were measured as to their physical properties, the results of which are shown in Table-7~ ~

- 14 - ;;

Table-6 Main startin~ Additives . _ . _.
Sample material Asbestos Water No. Gypsum ¦ Slag Slaked ¦ B ¦ C
~parts ) (%)* _ 10 3 7 3.0 ~1.0 1.0 25 ~ 200 11 5o 5o 3. 0 1.0 1 .025 200 _ 12 7 3 3.0 100 _100 25 200 *Based on the weight of the main starting material 8: Aluminum sulfate C: Sodium silicofluoride Table-7 - ~ ~
. ~e`ndlng Impact ~~~ ~rlnell Lengtn water ~3ul~c-- _ : ~:
Sample strength strength hardness change absorption specif ic NoO _ __ rate rategravity (Kg/cm~) ~--Km2cm--_ . x10-4 ( %) -) . .
180 2~5 lOo9 18.3 17011~72 11 240 208 llol 18~0 17~21~74 ~' 12 174 205 llo O 1802 17.01074 EX~PIE 5 Gypsum and slag were mixed in a mixing ratio of 1:1 (by weight) to prepare a main starting materialO As the reinforcing ~.
f iber, asbestos ( chrysotile ) was added in various amounts to the main starting material to prepare three kinds of mixtures with .
the respective rat:ios by weight of the main starting material to the reinforcing fiber being 900: loO~ 805 1~5 and 8~0 200o Further, to the mixtures were added the following: slaked lime 3o and alunninum sulfal:e in the respective amounts of 105~ based on the weight of the nnain starting material; a thickener (methyl cellulose) in an amount of Ool~ based on the weight of the main ;
-- 15 -- ~

3~
Starting material plus the asbestos; and water in an amount of 28%.
As the result, ~hree kinds of samples No. 13- I~o.15 shown in Table-8 were prepared. After kneading, the samples were extrusion-molded into hollow panels having an opening rate of 24%, which were then steam-cured at 60C for 24 hours to obtain hardened bodies. The bodies were further cured naturally for 7 days. The physical data for these hardened bodies No. 13- Na.15 were obtained, the results of which are shown in Ta~le-9.

Gupsum and slag were mixed in a ratio of 1:1 (by weight) to prepare a main starting material. Asbestos (chrysotile) as the reinforcing fiber, and perlite and sawdust as the light- `
weight material were added to the main starting material so that ~` -two kinds of mixtures were prepared which have respectively ratios by weight of the main starting material: reinforcing fiber : light-weight material of 8.0 : 1.0 : 1.0 and 7.5 : 1.0 :
1.5. To the mixtures were added slaked lime and aluminum sulfate, both being respectively in amounts of 1.5% based on the weight ;
of the main starting material, and a thickener (methyl cellulose) ;-20 in an amount of 0.3% based on the weight of the main starting ~
; .
material plus reinforcing fiber plus light-weight material.
Further, water was added in an amount;:of 40% when perlite was used as the light-weight material, and in an amount of 37% when the light-weight material is sawdust. As the result, four kinds of samples No. 16 - No. 19 were prepared. After kneading, the samples were extrusion-molded into hollow panels having the opening rate of 24%, wnich were then steam-cured at 60C for 24 hours to obtain hardened bodies. These bodies were further cured naturally for 7 days to obtain hardened bodies No. 16 -No. 19. The physical data thereof were measured, the results of which are shown in Table -9. ~ ;

~.

.

3~

~i~ a~oo~
.~ . .
~c 3 o ~ ~ .
~1 dP ~ ~ ';'"' .
o o o o o o o o ~ ,.
~ o ~ ~ ~ ,1 ,1 ~ . . . . . . . ~ , .
~ ~ ,~ ~.~
~ ~ U~ ~C : '` " ' o ~ s~
.~ ~ _ ,i ' ~
,~ ~ ~ ~ Id ~3 '~
. . . . . . . .,, , l¢ ~,~
c~ _ a~
~nl ~ i~ I I I I I-I~
.~ ~ "~, ~ $ tn a) _I h ~1 _I O
~ O : ;`

rl O
:: ~D a~ 3 ~ ~ ~ _ o U~ o o o o o '1~'~3 ~ ~ ~ 1 .~
_ ~ ¦ 3 0 ~ ~
5:: tJ` _ o U') o o 10 o U~ ::`
~1 11') ~`1 o o 1` o 1` ~
~,1 u~ ~ r ~ ~ ~ ~
~,,a E~ 1 o Old '' h ~ o Is~ o o U-) o In ,1 .~$ ~ ~ ~ o o ~ o ~
~ ~ ~ F4 m ~ ;
D __ ~ .

:~-O . ~ 1 Z; ,,, ' ;', ,', ~' . ' 3 4 6 ~

o .
r~
a) ~ ~ ~ I` ~ O
~ >1 ~ ~ ~ O O ~ ~
~a ~ ~
: ::
~ h m o :~
.,, * ul ~r ~ ~ o l` I` I` ~ r ~
~ ~ . . . . . . .

m ~ ~:
o 1~ ~ ~ In ~D ~
~ ~ . .... . .... .
s~ ~ ~_ 0~ CO ~ ~ I~
a) o ~1 ~ ~ ~ ~ ~ ~
3Q :
~11 ';
O ~r :
l` ~ ~ ~
1~ o. . . . . ..
~1 a~ ~ ~ IS~ 0 ~
~ ~ O X ~
_Ico ~
~I Q~~ O ~ ~ ~ ~ ~D . :
. . . . . . .
o ~o o ~ : , m~c .
a~
_~
co ~ ~ ~ oo ~ ~r ~ - '.
~ a) ~:. . . . . . .
H Ul _ ~ :

~ ~ _ rl ~ C)~ O ~ ~ ~9 ~ O
O ~~ 11~ ~ O ~ ~ _1 ~ ~ ~ ~ ~ ~0 ':
m ~q _ ~ :
. .

a~ '' ~
~ ~ * * ', ~ ~ ~ I
U~

- 1 8 - ;
-Gypsum and slag were mixed in a ratio of l:l (by weight)to prepare a main starting materialO Asbestos (chrysotile) as the reinforcing fiberJ and perlite and sawdust as the light-weight material were added to the main starting material so that two kinds of mixtures were obtained which have respectively ratios ; ;
by weight of main starting material : reinforcing fiber : light-weight material of 800 : loO : 1~0 and 7 O 5 1 O O 1 O 50 To the mixtures were added slaked lime in an amount of lo 5~ based on ~:
the weight of the main starting materialJ sodium silicofluoride in an amount of OD75% based on the weight of the mainstarting material, and a thickener (methyl cellulose) in an amount of 003 based on the weight of the mainstarting material plus reinforcing -fiber plus light-weight materialO Further, water was added in an amount of 40~ when perlite was used as the light-weight material, and in an amount of 37~ when the light-weight material is sawdust.
As the result, four kinds of samples ~oO 20-No.23are obtained as ;
shown in Table-100 After kneading, these samples were extrusion-molded into hollow panels having the opening rate of 24%, which were then steam-cured at 60C for 24 hours to obtain hardened bodiesO The bodies were further cured naturally for 7 days to produce the hardened bodies NoO 20 - ~oO 230 The physical data were measured, the results of which are shown in Table-llO

- 19 - ~' .

~3~23~

.
h o o 1` 1`
~ ~r ~r ~ ~
3 ~c ~
_ *
O o~

~ ~ o o o o ' ~ a) In ~ :
tQ C OOOO
a) * u~ n ~ . ~
m ~ r~ ,, ~, ~ . . . . ~ :
_ o o o o h ~ ~
~ .Y ~ u~ .~
l_l-rl ~ i ~ ~ .
C~1 . ¦ E3h ~ I 1~
E~ ~ a) ,~
.,1 .,1 O Lr) I I ~ rl ' .:
~ ~1 ,~ l ~4-1 h ~ Sl 0 ~
.S 11 '~ O ~ O ' ~
~.,1 ~ ~ ~~rl ~1 .: , h h ~o ~) o o o o.~ ~1 a) h ` `:
~ ~1 a~ h~1~1~1 ~1 t~ ~ 3 0 .Q ~ R ~a a P~ O O ~ ~ ~
E4 ~3 ~:C _. _ 3'5 ~ qO .`
_ .
~ ~ O U~ O U~
,1 ~ O 1~ 0~`
h u:l ~ r~ ~ ~ OO ~
~1 h rl u~ ,l ~i u~ ~4 R ~~ ~
h :1 o ~n oIt) 1~ . 0~,1 ~1 0 : :, ~ a) u~ . . . . ~m ~

~1 ~ ~ O ~ O1` ~-~: ~ ~ er ~ * m ~
_ __ '' ~ '.
o O
æ ~ , :~
. _ . :'

6~.
D .... ___ _ ~ :
~ o~O~I

D Ll D o o m ~

~h ~

~a~
Q ~ ~ ~lo ~`1 1~ 1~ _ . . . . .
~1 o`.P ~ ~~1 ~) p~ _ N t~ 3 .
_ ~ ' _l ~ ''.
~ r. ~ ~r 00 0 0 ~1 X /~,.
~;.

`'.

m~ ~1 ~
_ . ~^~~r ou~ O o , b- L). . . . ~ ~ ~ .
P~ ~ ~

~ ~ ~^ * *
~ O ~9 0 ~ u) ; ~
~ ~1 ~ ~ 1 :~
~ U~ ~ .~
l . , ,~ .
~i o ~ N ~ ~;
.____ N N N N

1~.2~6~

Gypsum and slag were mixed at a ratio of 1:1 (by weight) to prepare a main starting material. As the reinforcing fiber, asbestos (chrysotile) was added to the main starting material so that the mixture has a ratio of the main starting material :
reinforcing fiber of 8:2 (by weight). Further, as additional reinforcing fiber polypropylene fiber was incorporated in amounts of 0.3, 0.5 and 1.0%, respectively, based on the weight of the main starting material plus reinforcing fiber. Also, slaked lime and aluminum sulfate were incorporated in the respective amount of 1.5% based on the weight of the main starting material. Water was added in an amount 200% based on the weight of the main starting material plus reinforcing fiber. As the result, four kinds of samples No. 24 - No. 27 as shown in Table-12 were prepared. After kneading, these samples were ~¦
molded under a pressure of 100 kg/cm2 into plates, which were then cured at 20C, 80% R.H. for 21 days. The physical data of the hardened bodies No. 24 - No. 27 thus obtained were measured, the results of which are shown in Table-13. ~`~
... .. .

TABLE-12 ~ ~

Sample Main starting Fiber Additives Water ~ ;
No. materia~ l ~ -Gypsum ¦Slag tObses- P.P. lime l (Parts) (%)* (%)** (%)*
. . .... ._.... _ I . ,:
24 40 40 20 _ 1.5 1.5 200 ~ ~`

40 40 20 0.3 1.5 1.5 200 `

26 40 40 20 0.5 1.5 1.5 200 27 40 40 20 1.0 1.5 1.5 200 ..... .... _ x:: ~- *; ~- ~
* Based on the total weight of the main starting material and asbestos.
** Based on the weight of the main starting material -P.P. : Polypropylene B : Aluminum sulfate Table-13 ¦ Sample Bending Inpact Brinell Length Water Bulk ~oO strengt ¦strength hardness change absorp- specific rate tion rate gravity . . _ . _ . ~
(Kg/cm ) (/gcm2) xlO 4 (~) _...... . _ .

285 306 11.6 1502 1508 1074 26 292 308 11.9 14.9 1509 1075 27 281 306 1007 1408 1600 1075 ~:~

It is further understood by those skilled in the art that the foregoing description is a preferred embodiment of the disclosed invention and that various changes and modifications may be made in the invention without departing from the spirit .`
and scope thereof.

Claims (29)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process of producing a fiber-reinforced hardened body of gypsum system which comprises mixing gypsum and slag in a ratio by weight of the former to the latter between 3:7 and 7:3 to pre-pare a main starting material, adding to the main starting material 1 - 30% by weight of reinforcing fiber, 0.1 - 5% by weight of alkali salt substance and 0.1 - 5% by weight of aluminum sulfate-containing substance, the respective amounts being based on the weight of the main starting material, further adding water to knead and mold the resulting starting material mixture, and curing the molded starting material mixture under normal condition or steam-curing the molded starting material mixture at 90°C or below.

2. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 1 in which the alkali salt sub-stance is selected from alkali metal salt and alkaline earth metal salt.

3. A process of producing a fiber-reinforced hardened body according to claim 1 in which the alkali salt substance is selected from sodium sulfate, potassium sulfate, caustic soda, caustic potash and slaked lime.

4. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 1 in which the aluminum sulfate-containing substance is selected from aluminum sulfate, anhydrous aluminum sulfate, sodium alum and potassium alum.

5. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 1 in which the reinforcing fiber is selected from inorganic fiber and organic fiber.

6. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 1 in which the reinforcing fiber is selected from asbestos, rock wool, glass fiber, steel fiber, carbon fiber, polypropylene fiber, nylon fiber and pulp fiber.

7. A process of producing a fiber-reinforced hardened body of gypsum system which comprises mixing gypsum and slag in a ratio by weight of the former to the latter between 3:7 and 7:3 to prepare a main starting material, adding to the main starting material 1 - 30% by weight of reinforcing fiber, 1 - 25% by weight of light-weight material, 0.1 - 5% by weight of alkali salt substance and 0.1 - 5% by weight of aluminum sulfate-containing substance, the respective amounts being based on the weight of the main starting material, adding further water to knead and mold the resulting starting material mixture, and curing the molded starting material mixture under normal con-dition or steam-curing the molded starting material mixture at 90°C or below.

8. A process of producing a fiber-reinforced hardened body of gypsum according to claim 7 in which the alkali salt substance is selected from alkali metal salt and alkaline earth metal salt.

9. A process of producing a fiber-reinforced hardened body according to claim 7 in which the alkali salt substance is selected from sodium sulfate, potassium sulfate, caustic soda, caustic potash and slaked lime.

10. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 7 in which the aluminum sulfate-containing substance is selected from aluminum sulfate, anhydrous aluminum sulfate, sodium alum and potassium alum.

11. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 7 in which the reinforcing fiber is selected from inorganic fiber and organic fiber.

12. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 7 in which the reinforcing fiber is selected from asbestos, rock wool glass fiber, steel fiber, carbon fiber, polypropylene fiber, nylon fiber and pulp fiber.

13. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 7 in which the light-weight material is selected from inorganic light-weight material and organic light-weight material.

14. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 7 in which the light-weight material is selected from perlite, foamable light-weight aggregate, light sand, calcium silicate hydrate, diatomaceous earth, tri-calcium sulfoaluminate hydrate, calcined zeolite, shavings and foamed polystyrene.

15. A process of producing a fiber-reinforced hardened body of gypsum system which comprises mixing gypsum and slag in a ratio by weight of the former to the latter between 3:7 and 7:3 to prepare a main starting material adding to the main starting material 1 - 30% by weight of reinforcing fiber, 0.1 - 5% by weight of alkali salt substance, 0.1 - 5% by weight of aluminum sulfate-containing substance and 0.1 - 5% by weight of fluorinated salt substance, the respective amounts being based on the weight of the main starting material, adding further water to knead and mold the resulting starting material mixture, and curing the molded starting material mixture under normal condition or steam-curing the molded starting material mixture at 90°C or below.

16. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 15 in which the alkali salt sub-stance is selected from alkali metal salt and alkaline earth metal salt.

17. A process of producing a fiber-reinforced hardened body according to claim 15 in which the alkali salt substance is selected from sodium sulfate, potassium sulfate, caustic soda, caustic potash and slaked lime.

18. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 15 in which the aluminum sulfate-containing substance is selected from aluminum sulfate, anhydrous aluminum sulfate, sodium alum and potassium alum.

19. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 15 in which the reinforcing fiber is selected from inorganic fiber and organic fiber.

20. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 15 in which the reinforcing fiber is selected from asbestos, rock wool, glass fiber, steel fiber, carbon fiber, polypropylene fiber, nylon fiber and pulp fiber.

21. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 15 in which the fluorinated salt substance is selected from sodium fluoride, potassium fluo-ride, sodium silicofluoride and potassium silicofluoride.

22. A process of producing a fiber-reinforced hardened body of gypsum system which comprises mixing gypsum and slag in a ratio by weight of the former to the latter between 3:7 and 7:3 to prepare a main starting material, adding to the main starting material 1 - 30% by weight of reinforcing fiber, 1 - 25% by weight of light-weight material, 0.1 - 5% by weight of alkali salt substance, 0.01 - 5% by weight of aluminum sulfate-containing substance and 0.01 - 5% by weight of fluorinated salt substance, the respective amounts being based on the weight of the main starting material, adding further water to knead and mold the re-sulting starting material mixture, and curing the molded starting material mixture under normal condition or steam-curing the molded starting material mixture at 90°C or below.

23. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 22 in which the alkali salt substance is selected from alkali metal salt and alkaline earth metal salt.

24. A process of producing a fiber-reinforced hardened body according to claim 22 in which the alkali salt substance is selected from sodium sulfate, potassium sulfate, caustic soda, caustic potash and slaked lime.

25. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 22 in which the aluminum sulfate-containing substance is selected from aluminum sulfate, anhydrous aluminum sulfate, sodium alum and potassium alum.

26. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 22 in which the reinforcing fiber is selected from inorganic fiber and organic fiber.

27. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 22 in which the reinforcing fiber is selected from asbestos, rock wool, glass fiber, steel fiber, carbon fiber, polypropylene fiber, nylon fiber and pulp fiber.

28. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 22 in which the light-weight material is selected from inorganic light-weight material and organic light-weight material.

29. A process of producing a fiber-reinforced hardened body of gypsum system according to claim 22 in which the light-weight material is selected from perlite, foamable light-weight aggregate, light sand, calcium silicate hydrate, diatomaceous earth, tri-calcium sulfoaluminate hydrate, calcined zeolite, shavings and foamed polystyrene.