CA2057263C - Process for producing gypsum building materials - Google Patents
Process for producing gypsum building materialsInfo
- Publication number
- CA2057263C CA2057263C CA 2057263 CA2057263A CA2057263C CA 2057263 C CA2057263 C CA 2057263C CA 2057263 CA2057263 CA 2057263 CA 2057263 A CA2057263 A CA 2057263A CA 2057263 C CA2057263 C CA 2057263C
- Authority
- CA
- Canada
- Prior art keywords
- process according
- slurry
- building material
- calcium sulphate
- hemihydrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
- C04B28/145—Calcium sulfate hemi-hydrate with a specific crystal form
- C04B28/147—Calcium sulfate hemi-hydrate with a specific crystal form beta-hemihydrate
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
The invention relates to a process for producing light-weight, panel- or block-shaped gypsum building materials provided with a pore structure, in particular wall panels, calcium sulphate alpha-hemihydrate, water in a slightly more than stoichiometric quantity and, if appropriate, setting retarders and/or accelerators for gypsum and additives being mixed to form a pourable suspension and being subjected to suitable forming, wherein ground calcium sulphate alpha-hemihydrate having a Blaine specific surface area greater than 2000 cm2/g, if appropriate together with calcium sulphate beta-hemi-hydrate in a quantity of up to about 30% by weight, relative to the calcium sulphate alpha-hemihydrate, and a previously prepared surfactant foam of a defined apparent density in the range from 40 to 80 kg/m3 and a uniform defined pore size, which foam is mixed into the suspension before forming in a quantity for adjusting the apparent density of the gypsum building material to a defined value in the range from 300 to 1200 kg/m3, are used.
Description
20~72~3 Process for producing gypsum h~ in~ materials The invention relates to a process for producing light-weight, panel- or block-shaped gypsum b~ n~
materials provided with a pore ~LLUOLu è!~ in particular wall panelY, calcium sulphate alpha-hemihydrate, water in a slightly more than stnirhi~ LLic quantity and, if appropriate, setting retarders and/or accelerators for gypsum and additives being mixed to form a pourable suspension and being subjected to suitable forming.
From German Of fenlegungsschrift 1, 571, 575, such a process for producing gypsum b~ iin~ materials is known, in which unground calcium sulphate alpha-hemi-hydrate is uYed as gypsum, with which a pourable suspen-sion is formed, to which calcium carbonate is added which is reacted with slllrhl~rir acid to produce carbon dioxide.
The gas bubbles thus generated in the suspension lead to a pore ~L,u- LuLt, in the finif~h-~d product. Such a generation of gas bubbles in the suspension, however, leads to problems with respect to a uniform distribution thereof over the cross-section, in particular since the gaY bubbles tend to rise and the gypsum particles tend to se~i ~, 80 that the quality of the porous = gypsum products is impaired. To reduce this problem, the sul-phuric acid is added immediately before pouring, 80 that the gas bubbles form substAn~A1 ly in the poured suspen-sion, which thus expands in the mould. In addition, it is pointed out that preformed foams do not give good results in this connection, since they retard setting and thus have themselves time to rollArge, and the viscosity is 3 0 impaired .
According to German Offenleglln~srhr~ ft 2,442,021, anhydrite is used as gypsum, while gas is generated in the suspension p oduced by catalytic decom-position of llydLOgen peroxide. The porosified suspension is poured into moulds before the maximum ~YpAn~ n haY
been reached. Apart from the fact that anhydrite does not lead to 8trengths as high as those obtained with calcium-sulphate alpha-hemihydrate, problems here again reYult _ _ _ _ _ . . .. . _ . _ .. . . _ ~ - 2 - 20~72~3 from the rising of gas bubbles and se~l~ t1n~ of gypsum particles .
In addition, it is known from German Offenlegungsschrift 2,546,181 to add a foaming agent to a suspensLon o~ gypsum, water and additives in the presence of a foam-stabilising additive and to foam up the mixture. Such foaming-up, however, does not lead to a substantially uniform and r~~ i nt~ ~ nAhle mean foam pore size but, instead, these sizes fluctuate within a wide range, 80 that there are pores from sink hole size down to f ine pores, whereby the density and quality of the foamed gypsum ~L~Jdu~;Ls l~ ri ~ are impaired.
It is known from German Off~nl-~g~ln~rhrift 2,740,018 to use calcium sulphate alpha-hemihydrate together with a proportion of dihydrate and to foam up the suspension using an added foam former, the dihydrate being; nt~ndf~d to prevent a coalescence of foam bubbles .
Since, however, the foam is generated in the suspension, a well defined pore size and number of pores cannot be set, with the result that the end products show coLLe~oQding fluctuations in density and quality.
Finally, it is known from German Off~nleg~ln~ ;rhrift 2,548,912 to prepare, in a mixer, an aqueous surfactant foam of a ~lLLU~iLULe which is complicated due to the use of rhimirAl~ used in addition to the surfactant, gypsum in the form of, for instance, hemihydrates then being added to the foam. The additional ~h-~m~rAlf~ are ~nf-~n~ d to gerve for st:-hili~ation of the foam.
It is the ob~ect of the invention to provide a process of the type ~ r~iherl at the outset, by means of which light-weight gypsum b~ n~ materials can be .~,duced with air pores of substAnt~Ally constant size in as uniform as possible a distribution, coupled with high strength and a predet~rm~ nl~d apparent density of the product .
This ob~ect is achieved by using ground calcium sulphate alpha-hemihydrate having a Blaine speciflc surface area greater than 2000 cm2/g, preferably about 3 2057Z6~
3000 to 4000 cm2/g, lf approprlate together wlth calclum sul-phate beta-hemlhydrate ln a ~uant lty of up to about 30% by welght, preferably 5 to 20% by welght, relatlve to the calclum sulphate alpha-hemlhydrate, and prevlou31y prepared surfactant foam of a-deflned apparent denslty in the range from 40 to 80 kg~m3 and a uniform defined pore slze, which foam is mixed into the suspension before forming in a quantlty for ad~ustlng the apparent denslty of the gypsum bullding material to a deflned value in the range from 300 to 1200 kg~m3, preferably 400 to 800 kg/m3, especially 500 to 600 kg~m3.
According to the present invent ion there i8 provided a process for preparing a~ llght-weight tabular or block-shaped plaster buildlng materlal havlng a pore structure, whlch pro-cess comprlses mixing calcium sulphate alpha-hemihydrate and a substantially superscoichiometric amount of water to form a fibre-free castable slurry followed by shaplng the slurry, wherein the calclum sulphate has a Blaine specif ic surface area greater than 2000 cm2/g and a surfactant foam having a deflned bulk denslty ln the range of from 40 to 80 kg/m3 and havlng a unlform, deflned pore size in the range of from 100 to 500 ,um 18 mlxed lnto the slurry, before shaplng, ln an amount to obtaln a bulk denslty of the plaster buildlng mater-lal ln the range of from 300 to 1200 kg/m3 to produce a flbre-f ree slurry .
The use of ground calclum sulphate alpha-hemlhydrate havlng a 13laine speclfic surface area greater t~lan 2000 cm2/g, preferably about 3000 to 4000 cm2/g, leads to a sufflclently h igh 3a 23448-181 reactlvlty of the gypsum and to part lcle slzes whlch allow the use of a prevlously prepared surfactant foam whlch 18 prepared ln a deflned apparent denslty ln the range from 40 to 80 kg/m3 and a vlrtually unlform, deflned pore slze tthe pore dlameters have a relatlvely narrow Gausslan dlstrlbutlon) and ls mlxed wlth the suspenslon before pourlng, wlthout stablllzlng addltlves belng necessary and wlthout there belng a rlsk of the foam prematurely collapslng or belng crushed. In addltlon, sedlmentatlon effects and thlxotrophy effects are ellmlnated by grlndlng the calclum sulphate alpha-hemlhydrate whlch effects hl~h final strengths.
The quantlty of foam added depends on the deslred apparent den~lty of the end products, whlch 18 thereby ad~usted to a deslred value ln the range from 300 to 1200 kg/m3, preferably 400 to 800 kg/m3, especlally 500 to 600 kg/m3, startlng from the sollds content, the water requlred for setting and the correspondlng quantlty of foam, slnce the process allows e~act dosage. Thls glves homogeneous products of good and unlform strength and a predetermlned apparent dens lt y .
Due to the fact that water 18 used ln the least posslble excess over the stolchlometrlc quantlty - the settlng of a spreadlng dlmenslon analogously to DIN 1154, whlch 18 20 cm or sllghtly greater, wlth at most _ 4 _ 20572~
1.5 times the stoi~hi~ LLIC quantity of water i8 preferred - there are hardly any water pores, which might impalr the strength, in the webs which surround the air pores in the end product. In addition, drying after release from the mould, if n~c~qsary at all, is thereby m~ n iml ~C-Ci .
Calcium sulphate beta-hemihydrate can be used in a quantity of up to about 3O96 by welght, preferably 5 to 2096 by weight, relative to calcium sulphate alpha-hemi-hydrate. Since the calcium sulphate beta-hemihydrate is in the form of very fine particles, it promotes the crP~ml n~lg of the s~qpc~nRinn formed and, in the case of relatively coarse calcium sulphate alpha-hemihydrate (down to the lower limit of the specific surf~ce area), serves to 8~h~ l i qe the suspension.
If a previously prepared surfactant foam with coarser pores is used, calcium sulphate alpha-hemihydrate of coarser grain size can also be used without crushing the f oam pores and 8~ tion rh~n~ - occurring .
Finer foam pores demand a finer grain size of the calcium sulphate alpha-hemihydrate. A surfactant foam having a uniform pore size, that is to say a pore size having only a narrow range of vAr~t~nn, in the range from 100 to 500 ~m, especially 150 to 200 ~m, is advantageous. The surfactant used can, for example, be sodium dodecylsulphate. Advantageously, the foam is produced by means of a foam gun at a defined water/surfactant/air ratio and a defined foaming length, 80 that a substan-tially uniform pore size results.
Additives which can be uged are l~an materials, fillers, dyestuffs, wetting agents and/or aggregates .
Waste and grinAing dust arising in the production of the gyp~um b~ n~ r t~r~lq can be re-used for preparing the suspension.
The suspension can be cast either cnnt~nl~n~ly to give a strand, which is LL~1~O1 Led in its longitudinal direction and cut after appropriate 501ir~f~nat~nn, or in moulds. Before casting, the suspension can be mixed with _ _ _ _ _ _ _ _ _ _ _ _ . . . . .. .. .... ... . ..
_ 5 _ 20~72~3 an additlve consisting of a~ c~ rAtor~s) and/or retarder ( s ) which control the so 1 i ~1 i f i ration characteris -tics .
For load-bearing kllil~in~ ?~ ts, it is advantageous, rl~r~n~i~ns~ on the intended application, to replace up to about 90% by weight of gypsum, that is to say calcium.. sulphate alpha- and if appropriate beta-hemihydrate by a substitute in the form of ground blast furnace slag sand and/or lignite ash and/or bit~-mi nr~lR coal ash and/or f~ Red-bed ash, the substitutes preferably having a Blaine ~peci f~ surface area greater than 3000 cmZ/g. The blast fumace sl~- sand and/or the ash can also be used together with ground silica. In particular, a lime carrier in the form of l,y-lLc.Led lime, Portland cement or the like, which crntr1h~tes to the cv., i_yull-ding reactivity of the ground blast furnæe slag sand or of the ash, is then added for AlkAl ~Ration of the suspension in a small quantity, preferably in a quantity from 3 to 15% by weight.
Thus, 10 to 25% by weight of calcium sulphate alpha-hemihydrate can preferably be used together with 90 to 75% by weight of ground blast fumæe sla~ sand and/or ash and, i~ appropriate, ground silica and II~ L~d lime, the latter in an additional quantity of 3 to 15% by weight, for the production of blanks which obtain their early strength by the calcium.. sulphate alpha-hemihydrate, 80 that they can be handled and hence stacked, are trans-portable and can be i~ v ~ d into an autoclave, where they are exposed to a treatment with saturated steam under a ~L~_8-~UL~ of up to 16 bar and a temperature of up to about 200~C for 4 to 8 hours, 80 that calcium hydro-silicate phases form which provide the final strength.
100 parts by weight of gypsum can also be used with up to 120 parts by weight of a~yLc:~-tes, if appro-priate together with a lime carrier. In this case, a heat L- ~i of the gypsum b~ n~ material rPleARed from the mould is then advAntA~c-~us, wherein the gypsum huilrlin~ material is sub~ected to a LL- : with saturated steam under i _,h~ri~ pressure, especially at _ _ _ _ _ _ _ , . _ _ . . _ . .
- 6 - 2~5 7~
about 70 to 100C for 4 to 8 hours, to an autoclave treatment espeeially for 4 to 8 hours at a t~ _ t~rR of up to about 140 C or to the aetion o heating ~PnPratPd by a high-frequency field, especially in the range from about 70 to 100C.
In general, it is advAntA~eol~ to sub~ect the gypsum b-il~n~ material, released from the mould, with a gypsum/substitute weight ratio below about 50:50 to one of the three abu~ i onPd heat treatments and, at above about 50:50, to an autoclave treatment under a pressure of up to about 16 bar and a t~ La e of up to about 2 0 0 C f or 4 to 8 hours .
If desired, ground pumice and/or trass can also be used in combination with lime carriers, for instance hydrated lime. These are also used, like the ashes mentioned, especially with the sp~c~fir surface area indicated for blast furnace slag sahd.
The invention is RYrlAInRd below in more det~il with reference to the attached illustrations, in which Figure 1 rl1~ Lically shows an instAllAti~n for carrying out the process for producing wall panels, and Figures 2 and 3 show details of two possible ;, -'~ q of side edges of the wall panels ~Ludu. ~:d by means of the installation of Figure l.
rhe instAl lAti~n shown comprises a stock tank 1 for calcium sulphate alpha-hemihydrate having a Eilaine speeifie surfaee area greater than 2000 cmZ/g~ a stock tank 2 for calcium sulphate beta-hemihydrate, a stoek tank 3 for ground b~ast furnace slag sand and a stoek tank 4 for hy~lr~l-l irAl ly reactive ash. ~he stock tanks 1 to 4 are co,~n~_Led via appropriate lines to a tandem mixer 5 ( in plaee of whieh a mixer with a du..n-, LLe&u stoek tank for the foamed mixture to be east can also be used) whose mixing units 6 run altprnAt~ly. Water is fed to the mixing units 6 via a line 7, and these are also connected to a foam gun 8 for producing a surfactant foam having a substAnt~Ally uniform, ~L~de~f- ;nP~ pore size and a predetRrminPd C~p~L~llL density. In addition, a retarder for gypsum can be added from an appropriate stock tank 9 _ 7 _ 20~ 72~3 to the particular mixer unit 6.
Water in a slightly more than s~oi~ h ~ ~ LL1C
quantity ls added to a mixer unit 6 together with a predet-orminDd quantity of retarder, whereupon predeter-mined quantities of solids from the stock tanks l to 4 are added and mixed with one another to give a suspen-sion. Finally, a predet~rmin~ quantity of surfactant foam from the foam gun 8 is mixed in. The f1niRh~d mix is transferred via a cOllVe~yur 10~ for example a screw collve~yUL~ into a channel of a c~ntinl~nuR casting unit ll formed with appropriate C~I~V~UL belts. At the inlet of the co,.v~yur lO, an additive, consisting of one or more ~t cDl~rAtors and/or one or more retarders for the mix, can be added from co~ unding stock tanks 12 under iine control for controlling the ~ f i ~-Ation charac-teristics of the mix. The strand formed by casting into the channel is transferred Ln its longitudin~l direction and, at the end of the ch~nnel where it has reached an adequate strength, cut h~r~ ntAl ly by a severing device 13. A cutting device 14, which runs along in the direc-tion of cul.v~y~ of the stand and can be ~:Lu l.~d to a startlng po~ition, serves for vertical severing of the issuing strand to give a stack of panels 15 which is then gripped by a transfer device 16 and set down on a carrlAge 17. DDr~n~in~ on whether blast furnace slag sand and/or ash were or were not used for the production, the stacks on the carriage 17 are taken to an appropriate ~ftertreatment and/or, if appropriate, packed after prior grinding .
Simultaneously with the h~ri~ln~Al severing of the soli~if~pd~ but not yet fully h~rrlDnPd strand, appropriate grooves 18 can be milled into the side, 80 that the wall panels 14 can be A - Ie~l via a groove-and-tongue DngAI ~ or the like.
During the productLon of the strand, an appro-priate reinro L for the gypsum building _ _ R
can also be introduced, if this is desired. For this purpose, ground waste paper, a fibre pulp of CPl l~ se and waste paper, mineral and/or glass fibres or other - 8 - 20~7~ 3 reinforcements, fabrics or mat6 can be used, in ord~r to achieve an i " v~ ~ in the bending tensile strength, dowel extraction strength and nailing ability.
materials provided with a pore ~LLUOLu è!~ in particular wall panelY, calcium sulphate alpha-hemihydrate, water in a slightly more than stnirhi~ LLic quantity and, if appropriate, setting retarders and/or accelerators for gypsum and additives being mixed to form a pourable suspension and being subjected to suitable forming.
From German Of fenlegungsschrift 1, 571, 575, such a process for producing gypsum b~ iin~ materials is known, in which unground calcium sulphate alpha-hemi-hydrate is uYed as gypsum, with which a pourable suspen-sion is formed, to which calcium carbonate is added which is reacted with slllrhl~rir acid to produce carbon dioxide.
The gas bubbles thus generated in the suspension lead to a pore ~L,u- LuLt, in the finif~h-~d product. Such a generation of gas bubbles in the suspension, however, leads to problems with respect to a uniform distribution thereof over the cross-section, in particular since the gaY bubbles tend to rise and the gypsum particles tend to se~i ~, 80 that the quality of the porous = gypsum products is impaired. To reduce this problem, the sul-phuric acid is added immediately before pouring, 80 that the gas bubbles form substAn~A1 ly in the poured suspen-sion, which thus expands in the mould. In addition, it is pointed out that preformed foams do not give good results in this connection, since they retard setting and thus have themselves time to rollArge, and the viscosity is 3 0 impaired .
According to German Offenleglln~srhr~ ft 2,442,021, anhydrite is used as gypsum, while gas is generated in the suspension p oduced by catalytic decom-position of llydLOgen peroxide. The porosified suspension is poured into moulds before the maximum ~YpAn~ n haY
been reached. Apart from the fact that anhydrite does not lead to 8trengths as high as those obtained with calcium-sulphate alpha-hemihydrate, problems here again reYult _ _ _ _ _ . . .. . _ . _ .. . . _ ~ - 2 - 20~72~3 from the rising of gas bubbles and se~l~ t1n~ of gypsum particles .
In addition, it is known from German Offenlegungsschrift 2,546,181 to add a foaming agent to a suspensLon o~ gypsum, water and additives in the presence of a foam-stabilising additive and to foam up the mixture. Such foaming-up, however, does not lead to a substantially uniform and r~~ i nt~ ~ nAhle mean foam pore size but, instead, these sizes fluctuate within a wide range, 80 that there are pores from sink hole size down to f ine pores, whereby the density and quality of the foamed gypsum ~L~Jdu~;Ls l~ ri ~ are impaired.
It is known from German Off~nl-~g~ln~rhrift 2,740,018 to use calcium sulphate alpha-hemihydrate together with a proportion of dihydrate and to foam up the suspension using an added foam former, the dihydrate being; nt~ndf~d to prevent a coalescence of foam bubbles .
Since, however, the foam is generated in the suspension, a well defined pore size and number of pores cannot be set, with the result that the end products show coLLe~oQding fluctuations in density and quality.
Finally, it is known from German Off~nleg~ln~ ;rhrift 2,548,912 to prepare, in a mixer, an aqueous surfactant foam of a ~lLLU~iLULe which is complicated due to the use of rhimirAl~ used in addition to the surfactant, gypsum in the form of, for instance, hemihydrates then being added to the foam. The additional ~h-~m~rAlf~ are ~nf-~n~ d to gerve for st:-hili~ation of the foam.
It is the ob~ect of the invention to provide a process of the type ~ r~iherl at the outset, by means of which light-weight gypsum b~ n~ materials can be .~,duced with air pores of substAnt~Ally constant size in as uniform as possible a distribution, coupled with high strength and a predet~rm~ nl~d apparent density of the product .
This ob~ect is achieved by using ground calcium sulphate alpha-hemihydrate having a Blaine speciflc surface area greater than 2000 cm2/g, preferably about 3 2057Z6~
3000 to 4000 cm2/g, lf approprlate together wlth calclum sul-phate beta-hemlhydrate ln a ~uant lty of up to about 30% by welght, preferably 5 to 20% by welght, relatlve to the calclum sulphate alpha-hemlhydrate, and prevlou31y prepared surfactant foam of a-deflned apparent denslty in the range from 40 to 80 kg~m3 and a uniform defined pore slze, which foam is mixed into the suspension before forming in a quantlty for ad~ustlng the apparent denslty of the gypsum bullding material to a deflned value in the range from 300 to 1200 kg~m3, preferably 400 to 800 kg/m3, especially 500 to 600 kg~m3.
According to the present invent ion there i8 provided a process for preparing a~ llght-weight tabular or block-shaped plaster buildlng materlal havlng a pore structure, whlch pro-cess comprlses mixing calcium sulphate alpha-hemihydrate and a substantially superscoichiometric amount of water to form a fibre-free castable slurry followed by shaplng the slurry, wherein the calclum sulphate has a Blaine specif ic surface area greater than 2000 cm2/g and a surfactant foam having a deflned bulk denslty ln the range of from 40 to 80 kg/m3 and havlng a unlform, deflned pore size in the range of from 100 to 500 ,um 18 mlxed lnto the slurry, before shaplng, ln an amount to obtaln a bulk denslty of the plaster buildlng mater-lal ln the range of from 300 to 1200 kg/m3 to produce a flbre-f ree slurry .
The use of ground calclum sulphate alpha-hemlhydrate havlng a 13laine speclfic surface area greater t~lan 2000 cm2/g, preferably about 3000 to 4000 cm2/g, leads to a sufflclently h igh 3a 23448-181 reactlvlty of the gypsum and to part lcle slzes whlch allow the use of a prevlously prepared surfactant foam whlch 18 prepared ln a deflned apparent denslty ln the range from 40 to 80 kg/m3 and a vlrtually unlform, deflned pore slze tthe pore dlameters have a relatlvely narrow Gausslan dlstrlbutlon) and ls mlxed wlth the suspenslon before pourlng, wlthout stablllzlng addltlves belng necessary and wlthout there belng a rlsk of the foam prematurely collapslng or belng crushed. In addltlon, sedlmentatlon effects and thlxotrophy effects are ellmlnated by grlndlng the calclum sulphate alpha-hemlhydrate whlch effects hl~h final strengths.
The quantlty of foam added depends on the deslred apparent den~lty of the end products, whlch 18 thereby ad~usted to a deslred value ln the range from 300 to 1200 kg/m3, preferably 400 to 800 kg/m3, especlally 500 to 600 kg/m3, startlng from the sollds content, the water requlred for setting and the correspondlng quantlty of foam, slnce the process allows e~act dosage. Thls glves homogeneous products of good and unlform strength and a predetermlned apparent dens lt y .
Due to the fact that water 18 used ln the least posslble excess over the stolchlometrlc quantlty - the settlng of a spreadlng dlmenslon analogously to DIN 1154, whlch 18 20 cm or sllghtly greater, wlth at most _ 4 _ 20572~
1.5 times the stoi~hi~ LLIC quantity of water i8 preferred - there are hardly any water pores, which might impalr the strength, in the webs which surround the air pores in the end product. In addition, drying after release from the mould, if n~c~qsary at all, is thereby m~ n iml ~C-Ci .
Calcium sulphate beta-hemihydrate can be used in a quantity of up to about 3O96 by welght, preferably 5 to 2096 by weight, relative to calcium sulphate alpha-hemi-hydrate. Since the calcium sulphate beta-hemihydrate is in the form of very fine particles, it promotes the crP~ml n~lg of the s~qpc~nRinn formed and, in the case of relatively coarse calcium sulphate alpha-hemihydrate (down to the lower limit of the specific surf~ce area), serves to 8~h~ l i qe the suspension.
If a previously prepared surfactant foam with coarser pores is used, calcium sulphate alpha-hemihydrate of coarser grain size can also be used without crushing the f oam pores and 8~ tion rh~n~ - occurring .
Finer foam pores demand a finer grain size of the calcium sulphate alpha-hemihydrate. A surfactant foam having a uniform pore size, that is to say a pore size having only a narrow range of vAr~t~nn, in the range from 100 to 500 ~m, especially 150 to 200 ~m, is advantageous. The surfactant used can, for example, be sodium dodecylsulphate. Advantageously, the foam is produced by means of a foam gun at a defined water/surfactant/air ratio and a defined foaming length, 80 that a substan-tially uniform pore size results.
Additives which can be uged are l~an materials, fillers, dyestuffs, wetting agents and/or aggregates .
Waste and grinAing dust arising in the production of the gyp~um b~ n~ r t~r~lq can be re-used for preparing the suspension.
The suspension can be cast either cnnt~nl~n~ly to give a strand, which is LL~1~O1 Led in its longitudinal direction and cut after appropriate 501ir~f~nat~nn, or in moulds. Before casting, the suspension can be mixed with _ _ _ _ _ _ _ _ _ _ _ _ . . . . .. .. .... ... . ..
_ 5 _ 20~72~3 an additlve consisting of a~ c~ rAtor~s) and/or retarder ( s ) which control the so 1 i ~1 i f i ration characteris -tics .
For load-bearing kllil~in~ ?~ ts, it is advantageous, rl~r~n~i~ns~ on the intended application, to replace up to about 90% by weight of gypsum, that is to say calcium.. sulphate alpha- and if appropriate beta-hemihydrate by a substitute in the form of ground blast furnace slag sand and/or lignite ash and/or bit~-mi nr~lR coal ash and/or f~ Red-bed ash, the substitutes preferably having a Blaine ~peci f~ surface area greater than 3000 cmZ/g. The blast fumace sl~- sand and/or the ash can also be used together with ground silica. In particular, a lime carrier in the form of l,y-lLc.Led lime, Portland cement or the like, which crntr1h~tes to the cv., i_yull-ding reactivity of the ground blast furnæe slag sand or of the ash, is then added for AlkAl ~Ration of the suspension in a small quantity, preferably in a quantity from 3 to 15% by weight.
Thus, 10 to 25% by weight of calcium sulphate alpha-hemihydrate can preferably be used together with 90 to 75% by weight of ground blast fumæe sla~ sand and/or ash and, i~ appropriate, ground silica and II~ L~d lime, the latter in an additional quantity of 3 to 15% by weight, for the production of blanks which obtain their early strength by the calcium.. sulphate alpha-hemihydrate, 80 that they can be handled and hence stacked, are trans-portable and can be i~ v ~ d into an autoclave, where they are exposed to a treatment with saturated steam under a ~L~_8-~UL~ of up to 16 bar and a temperature of up to about 200~C for 4 to 8 hours, 80 that calcium hydro-silicate phases form which provide the final strength.
100 parts by weight of gypsum can also be used with up to 120 parts by weight of a~yLc:~-tes, if appro-priate together with a lime carrier. In this case, a heat L- ~i of the gypsum b~ n~ material rPleARed from the mould is then advAntA~c-~us, wherein the gypsum huilrlin~ material is sub~ected to a LL- : with saturated steam under i _,h~ri~ pressure, especially at _ _ _ _ _ _ _ , . _ _ . . _ . .
- 6 - 2~5 7~
about 70 to 100C for 4 to 8 hours, to an autoclave treatment espeeially for 4 to 8 hours at a t~ _ t~rR of up to about 140 C or to the aetion o heating ~PnPratPd by a high-frequency field, especially in the range from about 70 to 100C.
In general, it is advAntA~eol~ to sub~ect the gypsum b-il~n~ material, released from the mould, with a gypsum/substitute weight ratio below about 50:50 to one of the three abu~ i onPd heat treatments and, at above about 50:50, to an autoclave treatment under a pressure of up to about 16 bar and a t~ La e of up to about 2 0 0 C f or 4 to 8 hours .
If desired, ground pumice and/or trass can also be used in combination with lime carriers, for instance hydrated lime. These are also used, like the ashes mentioned, especially with the sp~c~fir surface area indicated for blast furnace slag sahd.
The invention is RYrlAInRd below in more det~il with reference to the attached illustrations, in which Figure 1 rl1~ Lically shows an instAllAti~n for carrying out the process for producing wall panels, and Figures 2 and 3 show details of two possible ;, -'~ q of side edges of the wall panels ~Ludu. ~:d by means of the installation of Figure l.
rhe instAl lAti~n shown comprises a stock tank 1 for calcium sulphate alpha-hemihydrate having a Eilaine speeifie surfaee area greater than 2000 cmZ/g~ a stock tank 2 for calcium sulphate beta-hemihydrate, a stoek tank 3 for ground b~ast furnace slag sand and a stoek tank 4 for hy~lr~l-l irAl ly reactive ash. ~he stock tanks 1 to 4 are co,~n~_Led via appropriate lines to a tandem mixer 5 ( in plaee of whieh a mixer with a du..n-, LLe&u stoek tank for the foamed mixture to be east can also be used) whose mixing units 6 run altprnAt~ly. Water is fed to the mixing units 6 via a line 7, and these are also connected to a foam gun 8 for producing a surfactant foam having a substAnt~Ally uniform, ~L~de~f- ;nP~ pore size and a predetRrminPd C~p~L~llL density. In addition, a retarder for gypsum can be added from an appropriate stock tank 9 _ 7 _ 20~ 72~3 to the particular mixer unit 6.
Water in a slightly more than s~oi~ h ~ ~ LL1C
quantity ls added to a mixer unit 6 together with a predet-orminDd quantity of retarder, whereupon predeter-mined quantities of solids from the stock tanks l to 4 are added and mixed with one another to give a suspen-sion. Finally, a predet~rmin~ quantity of surfactant foam from the foam gun 8 is mixed in. The f1niRh~d mix is transferred via a cOllVe~yur 10~ for example a screw collve~yUL~ into a channel of a c~ntinl~nuR casting unit ll formed with appropriate C~I~V~UL belts. At the inlet of the co,.v~yur lO, an additive, consisting of one or more ~t cDl~rAtors and/or one or more retarders for the mix, can be added from co~ unding stock tanks 12 under iine control for controlling the ~ f i ~-Ation charac-teristics of the mix. The strand formed by casting into the channel is transferred Ln its longitudin~l direction and, at the end of the ch~nnel where it has reached an adequate strength, cut h~r~ ntAl ly by a severing device 13. A cutting device 14, which runs along in the direc-tion of cul.v~y~ of the stand and can be ~:Lu l.~d to a startlng po~ition, serves for vertical severing of the issuing strand to give a stack of panels 15 which is then gripped by a transfer device 16 and set down on a carrlAge 17. DDr~n~in~ on whether blast furnace slag sand and/or ash were or were not used for the production, the stacks on the carriage 17 are taken to an appropriate ~ftertreatment and/or, if appropriate, packed after prior grinding .
Simultaneously with the h~ri~ln~Al severing of the soli~if~pd~ but not yet fully h~rrlDnPd strand, appropriate grooves 18 can be milled into the side, 80 that the wall panels 14 can be A - Ie~l via a groove-and-tongue DngAI ~ or the like.
During the productLon of the strand, an appro-priate reinro L for the gypsum building _ _ R
can also be introduced, if this is desired. For this purpose, ground waste paper, a fibre pulp of CPl l~ se and waste paper, mineral and/or glass fibres or other - 8 - 20~7~ 3 reinforcements, fabrics or mat6 can be used, in ord~r to achieve an i " v~ ~ in the bending tensile strength, dowel extraction strength and nailing ability.
Claims (29)
1. A process for preparing a light-weight tabular or block-shaped plaster building material having a pore structure, which process comprises mixing calcium sulphate alpha-hemihydrate and a substantially superstoichiometric amount of water to form a fibre-free castable slurry followed by shaping the slurry, wherein the calcium sulphate has a Blaine specific surface area greater than 2000 cm2/g and a surfactant foam having a defined bulk density in the range of from 40 to 80 kg/m3 and having a uniform, defined pore size in the range of from 100 to 500 µm is mixed into the slurry, before shaping, in an amount to obtain a bulk density of the plaster building material in the range of from 300 to 1200 kg/m3 to produce a fibre-free slurry.
2. A process according to claim 1 wherein the building material is a wall board.
3. A process according to claim 1 further comprising mixing a plaster setting retardant or accelerator into the castable slurry.
4. A process according to claim 1 further comprising mixing calcium sulphate beta-hemihydrate into the castable slurry in an amount of up to 30% by weight based on the calcium sulphate alpha-hemihydrate.
5. A process according to claim 1, wherein the surfactant foam is produced with a foam gun at a particular water/surfactant/
air ratio and a particular foaming path.
air ratio and a particular foaming path.
6. A process according to claim 1, wherein up to 1.5 times the stoichiometric amount of water is added to the slurry such that the slurry containing the surfactant foam has a spreading dimension in accordance with DIN 1164 which is 20 cm or somewhat larger.
7. A process according to any one of claims 1 to 6, wherein the slurry is continuously cast to form a strip transported in its longitudinal direction, which strip is cut after appropriate solidification.
8. A process according to any one of claims 1 to 6, wherein the slurry is cast into a mould.
9. A process according to claim 7, wherein prior to casting, the slurry is mixed with an additive to control a solidification characteristic and which additive comprises an accelerator or retardant.
10. A process according to claim 8, wherein prior to casting, the slurry is mixed with an additive to control a solidification characteristic and which additive comprises an accelerator or retardant.
11 11. A process according to any one of claims 1 to 6, wherein dust obtained from gutting and grinding the building material obtained is reused in forming the slurry.
12. A process according to any one of claims 1 to 6, wherein the plaster building material removed from a mould is dried.
13. A process according to any one of claims 1 to 6, wherein up to about 90% by weight of the calcium sulphate component is replaced by a substitute of milled slag sand, brown coal, bituminous coal, fluidized-bed ash, or a mixture thereof with quartz flour.
14. A process according to claim 13, wherein the substitute has a Blaine specific surface area greater than 3000 cm2/g.
15. A process according to claim 14, wherein from 10 to 25%
by weight of the building material is calcium sulphate and the remainder is the substitute.
by weight of the building material is calcium sulphate and the remainder is the substitute.
16. A process according to claim 13, wherein a lime-containing material is added to the slurry.
17. A process according to claim 16, wherein the lime-containing material is in the form of calcium hydroxide or portland cement.
18. A process according to claim 17, wherein from 3 to 15%
by weight of the lime-containing material is added.
by weight of the lime-containing material is added.
19. A process according to any one of claims 14 to 18, wherein the plaster building material is formed in a mould, removed from the mould and subjected to heat treatment.
20. A process according to claim 19, wherein the plaster building material removed from the mould is subjected to a treatment with saturated steam.
21. A process according to claim 20, wherein the plaster building material removed from the mould has a weight ratio of plaster to substitute material below about 50:50 and is subjected to a treatment with saturated steam under atmospheric pressure at from 70 to 100°C for from 4 to 8 h.
22. A process according to claim 20, wherein the plaster building material removed from the mould has a weight ratio of plaster to substitute material above about 50:50 and is subjected to an autoclave treatment under a pressure of up to about 16 bar and a temperature of up to about 200°C for from 4 to 8 h.
23. A process according to claim 19, wherein the plaster building material removed from the mould is subjected to heating by means of a high-frequency field.
24. A process according to claim 23, wherein the building material is heated at from 70 to 100°C.
25. A process according to any one of claims 1 to 6, 14 to 18 or 21 to 24, wherein the calcium sulphate alpha-hemihydrate has a Blaine specific surface area of from about 3000 to 4000 cm2/g.
26. A process according to any one of claims 1 to 6, 14 to 18 or 21 to 24 further comprising adding calcium sulphate beta-hemihydrate to the slurry in an amount of from 5 to 20% by weight based on the calcium sulphate alpha-hemihydrate.
27. A process according to any one of claims 1 to 6, 14 to 18 or 21 to 24, wherein the surfactant foam has a defined pore size in the range from 150 to 200 µm.
28. A process according to any one of claims 1 to 6, 14 to 18 or 21 to 24, wherein the bulk density of the plaster building material is in the range from 400 to 800 kg/m3.
29. A process according to any of claims 1 to 6, 14 to 18 or 21 to 24, wherein the bulk density of the plaster building material is in the range from 500 to 600 kg/m3.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4039319.4 | 1990-12-10 | ||
| DE19904039319 DE4039319A1 (en) | 1990-12-10 | 1990-12-10 | METHOD FOR PRODUCING PLASTER BUILDING MATERIALS |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2057263A1 CA2057263A1 (en) | 1992-06-11 |
| CA2057263C true CA2057263C (en) | 1996-12-31 |
Family
ID=6419949
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2057263 Expired - Fee Related CA2057263C (en) | 1990-12-10 | 1991-12-09 | Process for producing gypsum building materials |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5227100A (en) |
| EP (1) | EP0490160B1 (en) |
| JP (1) | JPH05238850A (en) |
| AT (1) | ATE113573T1 (en) |
| CA (1) | CA2057263C (en) |
| DE (2) | DE4039319A1 (en) |
| DK (1) | DK0490160T3 (en) |
| ES (1) | ES2066323T3 (en) |
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| DE4011793C1 (en) * | 1990-04-12 | 1991-12-12 | Redco N.V., Kapelle-Op-Den-Bos, Be | |
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| US5858083A (en) * | 1994-06-03 | 1999-01-12 | National Gypsum Company | Cementitious gypsum-containing binders and compositions and materials made therefrom |
| US5685903A (en) * | 1994-06-03 | 1997-11-11 | National Gypsum Company | Cementitious gypsum-containing compositions and materials made therefrom |
| CA2158820C (en) * | 1994-09-23 | 2004-11-23 | Steven W. Sucech | Producing foamed gypsum board |
| US5718759A (en) * | 1995-02-07 | 1998-02-17 | National Gypsum Company | Cementitious gypsum-containing compositions and materials made therefrom |
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| US6613424B1 (en) * | 1999-10-01 | 2003-09-02 | Awi Licensing Company | Composite structure with foamed cementitious layer |
| US6443258B1 (en) * | 1999-10-01 | 2002-09-03 | Awi Licensing Company | Durable porous article of manufacture and a process to create same |
| US6387172B1 (en) | 2000-04-25 | 2002-05-14 | United States Gypsum Company | Gypsum compositions and related methods |
| EP1349818A4 (en) * | 2000-08-07 | 2007-02-28 | Lafarge Platres | Lightweight gypsum board product and method of manufacture |
| AU2001284330A1 (en) | 2000-09-04 | 2002-03-22 | Symons, Michael Windsor | Method for the production of a hydraulic binder foam |
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| US6699915B2 (en) * | 2001-09-03 | 2004-03-02 | W.R. Grace & Co.-Conn. | Foamed fireproofing composition and method |
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| ES2343958T3 (en) * | 2004-02-24 | 2010-08-13 | Lafarge Platres | PROCESS AND APPLIANCE FOR MANUFACTURING A CELL BODY BASED ON A HYDRAULIC LINK. |
| US7332114B2 (en) | 2005-02-04 | 2008-02-19 | Lafarge Platres | Process for manufacturing sound absorbing cement tile |
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| AT509011B1 (en) * | 2009-10-15 | 2011-10-15 | Geolyth Mineral Technologie Gmbh | MINERAL FOAM |
| CN102180647A (en) * | 2011-01-28 | 2011-09-14 | 内蒙古科技大学 | Desulfurized building gypsum water-proof building block |
| US9828441B2 (en) | 2012-10-23 | 2017-11-28 | United States Gypsum Company | Method of preparing pregelatinized, partially hydrolyzed starch and related methods and products |
| US10399899B2 (en) | 2012-10-23 | 2019-09-03 | United States Gypsum Company | Pregelatinized starch with mid-range viscosity, and product, slurry and methods related thereto |
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| JP7382723B2 (en) * | 2013-10-07 | 2023-11-17 | クナウフ ギプス カーゲー | Method for producing gypsum plasterboard |
| ES2925735T3 (en) | 2013-10-07 | 2022-10-19 | Knauf Gips Kg | Method for producing a plasterboard |
| US10421251B2 (en) | 2015-06-24 | 2019-09-24 | United States Gypsum Company | Composite gypsum board and methods related thereto |
| US10662112B2 (en) | 2015-10-01 | 2020-05-26 | United States Gypsum Company | Method and system for on-line blending of foaming agent with foam modifier for addition to cementitious slurries |
| US20170096369A1 (en) | 2015-10-01 | 2017-04-06 | United States Gypsum Company | Foam modifiers for gypsum slurries, methods, and products |
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| US11225046B2 (en) | 2016-09-08 | 2022-01-18 | United States Gypsum Company | Gypsum board with perforated cover sheet and system and method for manufacturing same |
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| EP4134355A1 (en) * | 2021-08-12 | 2023-02-15 | Sika Technology AG | Self-foaming gypsum compositions |
| DE102021125435A1 (en) | 2021-09-30 | 2023-03-30 | Bauhaus-Universität Weimar, Körperschaft des öffentlichen Rechts | Process for providing a gypsum-based building material |
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| US3359146A (en) * | 1964-03-27 | 1967-12-19 | United States Gypsum Co | Method of producing gypsum articles having improved strength to density ratio |
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| GB1437040A (en) * | 1973-12-06 | 1976-05-26 | Nat Res Dev | Gypsum plaster products and their method of manufacture |
| DE2442021A1 (en) * | 1974-09-03 | 1976-03-18 | Bayer Ag | PROCESS FOR MANUFACTURING POROUS BODIES ON THE BASIS OF PLASTER, IN PARTICULAR ANHYDRITE |
| FR2306950A1 (en) * | 1975-04-09 | 1976-11-05 | Champion Int Corp | PROCESS FOR THE PREPARATION OF A FIRE-RESISTANT GYPSUM-BASED FLAME RETARDANT COMPOSITION, AND ITS APPLICATIONS |
| DE2546181B2 (en) * | 1975-10-15 | 1979-03-08 | Hoechst Ag, 6000 Frankfurt | Process for the production of gypsum foam and structural elements made therefrom |
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| US4057608A (en) * | 1976-04-19 | 1977-11-08 | Showa Denko Kabushiki Kaisha | Process of continuous manufacture of light-weight foamed concrete |
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| DE2739188C2 (en) * | 1977-08-31 | 1986-02-13 | Ytong AG, 8000 München | Process for the production of aerated concrete |
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| DE3419558A1 (en) * | 1984-05-25 | 1985-12-19 | Babcock-BSH AG vormals Büttner-Schilde-Haas AG, 4150 Krefeld | METHOD AND SYSTEM FOR THE PRODUCTION OF PLASTER FIBER PANELS |
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| DE4008084A1 (en) * | 1990-03-14 | 1991-09-19 | Pro Mineral Ges | METHOD FOR PRODUCING PLASTER PANELS, ESPECIALLY OF FLOOR PLATES |
-
1990
- 1990-12-10 DE DE19904039319 patent/DE4039319A1/en not_active Withdrawn
-
1991
- 1991-11-26 EP EP19910120119 patent/EP0490160B1/en not_active Revoked
- 1991-11-26 DK DK91120119T patent/DK0490160T3/en active
- 1991-11-26 DE DE59103421T patent/DE59103421D1/en not_active Expired - Fee Related
- 1991-11-26 AT AT91120119T patent/ATE113573T1/en not_active IP Right Cessation
- 1991-11-26 ES ES91120119T patent/ES2066323T3/en not_active Expired - Lifetime
- 1991-12-09 CA CA 2057263 patent/CA2057263C/en not_active Expired - Fee Related
- 1991-12-10 JP JP32601391A patent/JPH05238850A/en active Pending
- 1991-12-10 US US07/805,492 patent/US5227100A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| ATE113573T1 (en) | 1994-11-15 |
| DE4039319A1 (en) | 1992-06-11 |
| EP0490160B1 (en) | 1994-11-02 |
| CA2057263A1 (en) | 1992-06-11 |
| DK0490160T3 (en) | 1995-04-24 |
| EP0490160A1 (en) | 1992-06-17 |
| US5227100A (en) | 1993-07-13 |
| JPH05238850A (en) | 1993-09-17 |
| DE59103421D1 (en) | 1994-12-08 |
| ES2066323T3 (en) | 1995-03-01 |
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