WO1989010333A1 - Process for manufacture of plates, especially for construction use - Google Patents

Process for manufacture of plates, especially for construction use Download PDF

Info

Publication number
WO1989010333A1
WO1989010333A1 PCT/DK1989/000093 DK8900093W WO8910333A1 WO 1989010333 A1 WO1989010333 A1 WO 1989010333A1 DK 8900093 W DK8900093 W DK 8900093W WO 8910333 A1 WO8910333 A1 WO 8910333A1
Authority
WO
WIPO (PCT)
Prior art keywords
fibres
sheets
matrix
lime
cement
Prior art date
Application number
PCT/DK1989/000093
Other languages
French (fr)
Inventor
Bent Tram
Jens Peter Nielsen
Original Assignee
Bent Tram Consultants A/S
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Bent Tram Consultants A/S filed Critical Bent Tram Consultants A/S
Publication of WO1989010333A1 publication Critical patent/WO1989010333A1/en

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
    • C04B28/18—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 mixtures of the silica-lime type
    • 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
    • C04B28/02—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 hydraulic cements other than calcium sulfates
    • C04B28/04—Portland cements
    • 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
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00034—Physico-chemical characteristics of the mixtures
    • C04B2111/00215—Mortar or concrete mixtures defined by their oxide composition
    • 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

Definitions

  • the invention relates J to a process for manufacturing sheets, especially building sheets, which process includes stages beginning with producing a matrix by dry, semidry or aqueous mixing of hydraulic cement or lime, fly-ash and dry product from flue-gas desulphurization; shaping the said matrix into sheets; compacting the sheets and setting plus precuring them, which matrix on a dry-weight oasis contains:
  • hydraulic cement preferably Portland-cement, or lime in the form of quicklime or hydrated lime, or any mixture of cement and lime;
  • fly-ash consisting of small solid particles in the flue-gas, separated in filters which the smoke are forced through
  • dry product produced in a process that shall reduce the content of sulphur-dioxide in the flue-gas.
  • dry desulphurization process also known as atomization-absorption-desulphurization, that is of interest.
  • the method is characterized in, that the flue-gas is led into a chamber, where there by use of an atomization-wheel is produced a fine milk of lime spray, calcium-hydroxide suspended in water.
  • the hot flue-gas reacts chemically with the lime, by which there in particular is a reaction between the content of sulphur-dioxide and calcium-hydroxide in flue-gas, and to some extent the oxygen in the chamber.
  • Tne chemical reaction results in that the original content of sulphurdioxide in the flue-gas practically can be completely eliminated, as it is transformed into calcium-sulphite and calcium-sulphate, being the main constituents in the cry powdered by-product, that is the end-product of the process.
  • the utilization of these by-products have previously been, concentrated on manufacturing products, that are suitable for road construction, building foundations, aggregates for concrete, blocks etc., that is for use where a fairly high compression strength is required.
  • Thin fibre-reinforced sheets are widely used in the construction industry for cladding-purposes. Such sheets are manufactured by a number of known methods, and of various materials.
  • chip-boaros can be mentioned, which consists of wood-chips and -fibres, possible fillers, and an organic or inorganic binder;
  • gypsum fibre-boards which as the name indicates, consists of a gypsum-matrix, reinforced mainly with cellulose-fibres and possible organic or inorganic fibres;
  • fibre-cement-sheets where it concerns a cement-based binder, possibly combined with a pozzolanic material, and reinforced with inorganic fibres such as asbestos, fibre glass, mineral fibres, or organic fibres such as cellulose, plastic fibres, or a combination hereof.
  • the cement binder can also be completely or partially replaced by quicklime or hydrated lime, just as there can be incorporated different fillers and/or materials that serves specific purposes, for example improve the fire properties.
  • the dry product typically contains a number of ingredients such as calcium-hydroxide, calcium-carbonate, plus more or less of fly-ash, depending on to which extent this material has been separated from the flue-gas, before the desulphurization-process take place.
  • the fly-ash typically contains silicon-dioxide, aluminium- and iron-oxides, plus a number of other substances. Looking at fly-ash and dry product together, there are ingredients in these materials that can be made to react in a hydrothermal curing-process, so-called autoclaving, and form calcium-silicate-nydrateswith good physical-mechanical properties.
  • the matrix additionally contains 2-25%, preferably 5-25%, and in particular 10-20% fibreformed material, and that the precured sheets go through a final hardening by autoclaving.
  • the ratio between length and diameter is at least 10:1, and preferably 50:1, plus that the diameter of the fibres is in the interval 1-200 ⁇ m, preferably 5-100 ⁇ m, and in particular 10-50 ⁇ m, as dealt with in claim no 2, by means of which the reinforcement with cellulose fibres can be optimized.
  • the fibre-formed material can as stated in claim no 3 with advantage consist of asbestos, glass fibres, mineral wool fibres, steel fibres, aramid fibres, and cellulose fipres from plants, preferably cellulose fibres from pine, flax, elephant grass, and eucalyptus, and in particular fibres extracted from paperwaste, newspapers and magazines, as all these fibres possess a strength that makes them suitable for use as reinforcement in the sheets, and as the fibres are inexpensive, available in large amounts, and moreover often is found as by-products.
  • a matrix-composition is obtained, that is particularly suitable for curing in an autoclave in a vapour atmosphere of high pressure, as there in this case during the curing process is formed calcium-silicates with outstanding physical-mechanical properties.
  • Hatschek-process which for example is described in AT patent no 5970, and the Magnani-process, among other places described in Heribert Hiendl "Asbestzementmaschinen" page 42, 1964, and filterpressing, where the slurry is dewatered in a press, where either the press-table or the piston, or both are provided with holes, a net or similar arrangements, that allows the excess water to be drained off, when the slurry is put under pressure.
  • the sheets can be manufactured by a dry or semi-dry method.
  • the included dry material for exampl e cement , l i me , f l y-ash and dry product i s mixed with the likewise dry fibres.
  • the mixed, dry mass is continuously laid out in a constant thickness on a conveyer belt.
  • the dry product is wetted in a special unit, possibly while air is sucked off.
  • the wetted material is compacted, either in a press, that is synchronised to follow the belt during the compression, a continuously belt-press, or by means of a roller or another suitable compaction unit.
  • the subsequent steps in the manufacturing process are by and large identical.
  • the sheets are after the formation stored, possibly supported by stable templates, in a period of 1 to 24 hours, preferably 2 to 24 hours, and in particular 2 to 20 hours, at a temperature of 15 to 80 oC, preferably 20 to 60 oC, and in particular 30 to 50 oC. During this storing a development of the strength will occur, resulting in that the sheets gain stability, and thus if necessary can be stripped and stacked.
  • the sheets must subsequently be cured in an autoclave in an atmosphere of saturated steam of high pressure and high temperature.
  • the autoclaving temperature snail be within the interval 120-210 oC, preferably 140-210 oC, and in particular 160-210 oC.
  • the autoclaving process should proceed for a period of 3-24 hours, preferably 3-16 hours, and in particular 3-14 hours.
  • the special characteristics of the sheets, manufactured according to this invention is the combination of raw materials, combined with the autoclave treatment.
  • the characteristic raw materials are the following. Raw materials.
  • Hydraulic cement for example Portland cement, trass cement, blast furnace slag cement, fly-ash cement, and pozzolan cement.
  • Portland cement is a preferred type.
  • the proportion of cement in the sheets is 5- 60 percent by wei ght , preferabl y 8-40 percent by weight, and in particular 10-30 percent by weight.
  • the proportion of cement can partly or totally be substituted by lime as described below.
  • Lime Quicklime with the chemical formula CaO, and/or slaked lime, also called hydrated lime, which in chemical terms is designated as Ca(OH) 2 .
  • Fly-ash Waste product, which is separated from flue- gas from combustion plants, in particular plants where the fuel is coal or oil.
  • the fly-ash mainly consists of ball-formed particles of a size of 2-200 ⁇ m.
  • the main ingredients of the particles are typically 30-75% SiO 2 , 15-25% Al 2 O 3 , 3-10% Fe 2 O 3 , and
  • Dry product The by-product from the so-called atomization-absorption-desulphurization process, which is used for eliminating especially SO 2 from the flue-gas in combustion plants, in particular plants where the fuel is oil or coal.
  • the dry product consists of particles, often scale-formed, in the size field of 0.1-50 ⁇ m.
  • the chemical composition of the particles are typically 40-70% CaSO 3 , 5-12%
  • CaSO 4 5-10% Ca(OH) 2 , and 5-10% CaCO 3 .
  • dry product will in practice be mixed with a varied amount of fly-ash, as mentioned above.
  • dry product is used in the following without additional comments, the clean dry product without the content of fly-ash is considered.
  • the proportion of dry product in the sheets is 10-50 percent by weight, preferably 12- 40 percent by weight, and in particular 15- 35 percent by weight.
  • Fibres The fibre material contributes particularly to reinforce the sheet, and to make it more tough.
  • a number of different fibre types can be used for this purpose, both organic an inorganic fibres.
  • the characteristic of suitable fibres are, that the ratio between their typical length and diameter must be at least 10:1, and preferably at least 50:1, that their typical diameter should be in the interval of 1-200 ⁇ m, preferably 5-100 ⁇ m, and in particular 10-50 ⁇ m, and that they must be durable in an alkaline environment.
  • Suitable fibres are for example asbestos, glassfibers, and mineral wool fibres, in particular fibres with good alkaline resistance, steel fibres, cellulose fibres from plants, polymer-based fibres, in particular such fibres that can stand the high temperature during autoclaving.
  • the fibres for reinforcement are cellulose fibres from plants, for example cellulose fibres from pine, flax, elephant grass, abaca hemp and coir, which all are relatively long fibres, and for example cellulose fibres from birch, straw, and eucalyptus, which are relatively short fibres.
  • cellulose fibres from paperwaste such as office wastepaper, paperbag-waste, plus second hand newspapers and magazines, are used.
  • reinforcement fibres which is composed of a mix of two or more of the types of fibres, mentioned above.
  • cellulose fibres are used, and particularly where also the thinslurry technique is used, it can be advantageous to fibril late the fibres, among other things to improve the filtration properties.
  • the fibrillation can also result in tnat the fipres are better anchored in the matrix-material, and thus contributes to an improved reinforcing effect.
  • Such a fibrillation can be obtained by grinding the fibres in a so-called cellulose-refiner.
  • the degree of grinding can be measured in a so- called Schopper-Riegler device, and is indicated in the unit °SR.
  • a suitable degree of grinding is 20-80 °SR, in particular 30-65 oSR.
  • the proportion of fibre-mass in the sheets is 2-25 percent by weight, preferably 5-25 percent by weight, and in particular 10-20 percent by weight.
  • the weight ratio between the components containing silicate, and the lime-equivalent components is determined from a wish to develop the strongest and most stable calcium-silicate-hydrates during the autocla tain this the molar ratio between equivalent CaO and SiO 2 is chosen to 0.5-1.1, in particular 0.8-0.9, as the reaction depth in the individual particles is taken into consideration.
  • some materials such as dispersants, that contributes to a better mixing of the raw materials; flocculants, that can boost the dewatering of slurry for the above-mentioned thin-slurry production process; compounds, that influences the hydration process, for example by accelerating or retarding it; fillers, that changes certain properties, for example improves the properties with respect to fire, or which increases or reduces the stiffness of the material.
  • dispersants that contributes to a better mixing of the raw materials
  • flocculants that can boost the dewatering of slurry for the above-mentioned thin-slurry production process
  • compounds that influences the hydration process, for example by accelerating or retarding it
  • fillers that changes certain properties, for example improves the properties with respect to fire, or which increases or reduces the stiffness of the material.
  • Example 1 A set of test sheets was manufactured with the following composition:
  • the fibres were disintegrated in water in the ratio 1:50 (fibres:water), and the mixture was worked intensively in a turbine-mixer, until the fibres were separated. Then the rest of the dry matter was added to the fibre-watermixture, and the intense working was continued until the slurry had a homogenous consistency. From the slurry sheets were manufactured in the following way:
  • a measured quantity of slurry was poured in a box-formed container, of which the bottom was formed like a sievesheet, covered with a fine-meshed wire-mesh.
  • a funnelformed extension to the container was positioned under the sieve-sheet, and this was connected to a vacuum-pump, so that a vacuum in the size of 0.02 MN/m 2 couId be established.
  • the excess water was drained out of the slurry, by means of which the slurry was converted to a partly dewatered filter-cake. In order to further remove the excess water, and increase the density of the filtercake, this was transferred to a filterpress, and pressed with different pressure levels.
  • the pressed sheets was stored, wrapped in plastic film, for 18 hours at a temperature of 25oC. Afterwards they were placed in an autoclave, and autoclaved for 12 hours at a temperature of 180oC and with an equivalent steam pressure of approx. 1 MN/m 2 .
  • This example illustrates the importance of autoclaving for the properties of the sheets.
  • Modulus of rupture 4.3 MN/m 2
  • a sample was cut out from sheet no 4 in example 1 and the sheet from example 2.
  • the two samples were stored for 2 weeks in a vessel filled with water. Afterwards they were taken out of the water and examined.
  • Sheet no 4 from example 1 was visually assessed to be completely intact, and still possessed good strength and solidness.
  • the sheet from example 2 was partly disintegrated, and had very little strength and cohesion.
  • This example illustrates lime as a binder in a sheet, A, which is compared with sheets B and C, where the binder is rapid hardening Portland cement, which sheets A, B, and C were made as the sheets 1, 2, 3, and 5 from example 1.
  • Component Dry matter composition in percent by weight

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

A process for manufacturing sheets for building purposes is shown, which sheets consist of a matrix of hydraulic cement or lime, fly-ash and dry product from desulphurization of flue-gas, which matrix, after mixing with water, is formed into sheets, that are compressed before setting and precuring, and the characteristic of the method, according to the invention is, that the matrix also contains 2-25 %, preferably 5-25 %, and in particular 10-20 % fibre-formed material, plus that the precured sheets go through a final curing by autoclaving. The matrix is composed so that the molar ratio between equivalent CaO and SiO2 has a value betweeen 0.5 and 1.1, preferably between 0.8 and 0.9, and the autoclaving is carried out at temperatures between 120-210°C, preferably within the interval 160-210°C.

Description

Process for manufacture of plates, especially for construction
The invention relates J to a process for manufacturing sheets, especially building sheets, which process includes stages beginning with producing a matrix by dry, semidry or aqueous mixing of hydraulic cement or lime, fly-ash and dry product from flue-gas desulphurization; shaping the said matrix into sheets; compacting the sheets and setting plus precuring them, which matrix on a dry-weight oasis contains:
5-60%, preferably 8-40%, and in particular 10-30% hydraulic cement, preferably Portland-cement, or lime in the form of quicklime or hydrated lime, or any mixture of cement and lime;
20-60%, preferably 30-60%, and in particular 40-60% fly-ash;
plus 10-50%, preferably 12-40%, and in particular 15- 35% dry product, which is produced by a reaction between the SO2 content in flue-gas and a fine-grained spray of milκ of lime in an atomization-absorptiontype flue-gas-desulphurization plant, and which main ingredient is calcium-sulphite.
In recent years, due to environmental motives, a utilization is increased of products, which comes from purification of flue-gas from power-plants, district-heatingplants, and similar energy producing plants, which mainly uses coal or fuel-oil as fuel. This utilization is based on an appropriate way to get rid of these products, instead of depositing them in nature with environmental disadvantages to follow, and in addition that utilization and disposal of the products gives an economical running of the plants where the products are manufactured.
In particular, there are two by-products, namely fly-ash, consisting of small solid particles in the flue-gas, separated in filters which the smoke are forced through, and the so-called dry product produced in a process that shall reduce the content of sulphur-dioxide in the flue-gas. A number of processes that serves this purpose is known, and the chemical reactions the processes are based upon are different, just as the by-products are. In this context it is mainly the so-called dry desulphurization process, also known as atomization-absorption-desulphurization, that is of interest. The method is characterized in, that the flue-gas is led into a chamber, where there by use of an atomization-wheel is produced a fine milk of lime spray, calcium-hydroxide suspended in water. The hot flue-gas reacts chemically with the lime, by which there in particular is a reaction between the content of sulphur-dioxide and calcium-hydroxide in flue-gas, and to some extent the oxygen in the chamber. Tne chemical reaction results in that the original content of sulphurdioxide in the flue-gas practically can be completely eliminated, as it is transformed into calcium-sulphite and calcium-sulphate, being the main constituents in the cry powdered by-product, that is the end-product of the process. The utilization of these by-products have previously been, concentrated on manufacturing products, that are suitable for road construction, building foundations, aggregates for concrete, blocks etc., that is for use where a fairly high compression strength is required.
For instance it is known from DE offenlegungsschrift no 35 18 410 and EP patent specification no 0 059 214 to manufacture products within the building and construction industry, where the mix of dry product from flue-gasdesulphurization, fly-ash, and a hydraulic binder such as Portland-cement is used. Furthermore is it known from US patent no 3.785.840 to utilize slaked lime/dolomite as a hydraulic binder.
To increase the use of the mentioned by-products it would be desirable to be able to use the by-products for manufacturing sheets, for instance sheets for cladding-purposes in the construction-industry.
Thin fibre-reinforced sheets are widely used in the construction industry for cladding-purposes. Such sheets are manufactured by a number of known methods, and of various materials. As an example chip-boaros can be mentioned, which consists of wood-chips and -fibres, possible fillers, and an organic or inorganic binder; gypsum fibre-boards, which as the name indicates, consists of a gypsum-matrix, reinforced mainly with cellulose-fibres and possible organic or inorganic fibres; fibre-cement-sheets, where it concerns a cement-based binder, possibly combined with a pozzolanic material, and reinforced with inorganic fibres such as asbestos, fibre glass, mineral fibres, or organic fibres such as cellulose, plastic fibres, or a combination hereof.
The cement binder can also be completely or partially replaced by quicklime or hydrated lime, just as there can be incorporated different fillers and/or materials that serves specific purposes, for example improve the fire properties.
Normally, to this kind of sheets for construction, a number of performance requirements are put forward, which has relation to their use in building constructions. Of these requirements, some typical examples can be mentioned.
There can be requirements to the capacity of the sheets to withstand the action of fire, in the form of requirements of a non-combustible material, or a certain fire proofness. There can be requirements to the strength of the sheets, normally bending strength, rigidity, and impact strength, requirements to the behaviour of the material when it is exposed to humidity, heavy drying, or alternating between frost and thaw. In relation to the building process, there are also a number of qualities of the sheets which are of importance. How easy is it to cut the sheets, and which methods and tools are required? Do the sheets possess nail- and screw-holding power? Finally the economical aspects are essential, as the production costs are of importance for the sales possibilities.
Besides calcium-sulphite and calcium-sulphate the dry product typically contains a number of ingredients such as calcium-hydroxide, calcium-carbonate, plus more or less of fly-ash, depending on to which extent this material has been separated from the flue-gas, before the desulphurization-process take place. The fly-ash typically contains silicon-dioxide, aluminium- and iron-oxides, plus a number of other substances. Looking at fly-ash and dry product together, there are ingredients in these materials that can be made to react in a hydrothermal curing-process, so-called autoclaving, and form calcium-silicate-nydrateswith good physical-mechanical properties.
There are in return, especially in the case of the dry product, also substances like the above mentioned calciumsulphite and calcium-sulphate, which in relation to calcium-silicate-hydrate-formation, can be expected to have a harmful effect, as especially sulphate might react with calcium-silicate and form the mineral ettringite. Ettringite takes up more volume than the components which are the basis of it's formation. Therefore the forming of ettringite might often cause development of internal stresses in the material, resulting in a formation of microscopic cracks in the structure of the material, with a reduction in strength and durability as a consequence. So it is rather doubtful whether the two mentioned byproducts can be combined in materials, wmch shall generate good strength- and durability-properties, as the mentioned cracks will make a sheet of this material permeable, making the sheets unqualified for building-purposes, where frost periods can cause destruction of the sheets, when the water in the cracks enlarges, when freezing to ice. So the intention of this invention is to state a procedure for manufacturing sheets, in particular building sheets, which is free from the above mentioned disadvantages with permeability and crack formation, by means of which the sheets must be able to be manufactured possessing a good strength, in particular bending strength, and that they can maintain the properties in humid or even frozen condition, regardless of the temperature of the surroundings.
This intention can be attained by a process as mentioned in the introduction, which method according to this invention is specific, as the matrix additionally contains 2-25%, preferably 5-25%, and in particular 10-20% fibreformed material, and that the precured sheets go through a final hardening by autoclaving.
It is known, for a number of purposes, to use fibres as reinforcement in a material, which- is to be strengthened, or where prevention of cracks are desired, but the reinforcement in connection with the final hydrothermal curing-procedure results in surprisingly dense and strong sheets, with a high bending strength, that is properties which make the sheets manufactured according to the invention extremely suitable for use as building sheets, which to a great extent fulfil the previous mentioned requirements, which often are made for such sheets, while at the same time a high degree of by-products contributes to make the sheets inexpensive to produce.
If cellulose fibres are used, it is advantageous that the ratio between length and diameter is at least 10:1, and preferably 50:1, plus that the diameter of the fibres is in the interval 1-200 μm, preferably 5-100 μm, and in particular 10-50 μm, as dealt with in claim no 2, by means of which the reinforcement with cellulose fibres can be optimized.
The fibre-formed material can as stated in claim no 3 with advantage consist of asbestos, glass fibres, mineral wool fibres, steel fibres, aramid fibres, and cellulose fipres from plants, preferably cellulose fibres from pine, flax, elephant grass, and eucalyptus, and in particular fibres extracted from paperwaste, newspapers and magazines, as all these fibres possess a strength that makes them suitable for use as reinforcement in the sheets, and as the fibres are inexpensive, available in large amounts, and moreover often is found as by-products.
By the method, stated in claim no 4, a dimension of the fipres is reached, that in an advantageous way contributes to an increase in the strength of the reinforcement.
When the matrix is composed as stated in claim no 5, a matrix-composition is obtained, that is particularly suitable for curing in an autoclave in a vapour atmosphere of high pressure, as there in this case during the curing process is formed calcium-silicates with outstanding physical-mechanical properties.
These physical-mechanical properties are optimized, if the curing-process, as dealt with in claim no 6, is carried out at temperatures between 120 and 210 ºC, preferably between 150 and 210 °C. The procedure, of the present invention, is explained more specified in the following.
The basis of the procedure is, that the dry matter in the sheets, that is binder, possible filler, other materials and fibres, are mixed and suspended in water to a slurry of a relatively low consistency. Subsequently the formation of the sheets takes place by a dewatering process, where the excess water are drained off, so that the concentration of solids is increased heavily. A number of processes for practically carrying out the mentioned increase in solids concentration is known.
Examples of this is the so-called Hatschek-process, which for example is described in AT patent no 5970, and the Magnani-process, among other places described in Heribert Hiendl "Asbestzementmaschinen" page 42, 1964, and filterpressing, where the slurry is dewatered in a press, where either the press-table or the piston, or both are provided with holes, a net or similar arrangements, that allows the excess water to be drained off, when the slurry is put under pressure.
Alternatively the sheets can be manufactured by a dry or semi-dry method. According to this, the included dry material, for exampl e cement , l i me , f l y-ash and dry product i s mixed with the likewise dry fibres. The mixed, dry mass is continuously laid out in a constant thickness on a conveyer belt. After this the dry product is wetted in a special unit, possibly while air is sucked off. Finally the wetted material is compacted, either in a press, that is synchronised to follow the belt during the compression, a continuously belt-press, or by means of a roller or another suitable compaction unit.
Regardless of the formation method being used, the subsequent steps in the manufacturing process are by and large identical. The sheets are after the formation stored, possibly supported by stable templates, in a period of 1 to 24 hours, preferably 2 to 24 hours, and in particular 2 to 20 hours, at a temperature of 15 to 80 ºC, preferably 20 to 60 ºC, and in particular 30 to 50 ºC. During this storing a development of the strength will occur, resulting in that the sheets gain stability, and thus if necessary can be stripped and stacked.
The sheets must subsequently be cured in an autoclave in an atmosphere of saturated steam of high pressure and high temperature. The autoclaving temperature snail be within the interval 120-210 ºC, preferably 140-210 ºC, and in particular 160-210 ºC. The autoclaving process should proceed for a period of 3-24 hours, preferably 3-16 hours, and in particular 3-14 hours.
Following the autoclaving process, further treatment of the sheets can take place, such as drying, cutting out in sizes, sanding, and surface treatment.
The special characteristics of the sheets, manufactured according to this invention, is the combination of raw materials, combined with the autoclave treatment. The characteristic raw materials are the following. Raw materials.
Cement: Hydraulic cement , for example Portland cement, trass cement, blast furnace slag cement, fly-ash cement, and pozzolan cement. Portland cement is a preferred type.
The proportion of cement in the sheets is 5- 60 percent by wei ght , preferabl y 8-40 percent by weight, and in particular 10-30 percent by weight. The proportion of cement can partly or totally be substituted by lime as described below.
Lime: Quicklime with the chemical formula CaO, and/or slaked lime, also called hydrated lime, which in chemical terms is designated as Ca(OH)2.
Fly-ash: Waste product, which is separated from flue- gas from combustion plants, in particular plants where the fuel is coal or oil. The fly-ash mainly consists of ball-formed particles of a size of 2-200 μm. The main ingredients of the particles are typically 30-75% SiO2, 15-25% Al2O3, 3-10% Fe2O3, and
0-8% CaO.
The proportion of fly-ash in the sheets is
20-60 percent by weight, preferably 30-60 percent by weight, and in particular 40-60 percent by weight,
Dry product: The by-product from the so-called atomization-absorption-desulphurization process, which is used for eliminating especially SO2 from the flue-gas in combustion plants, in particular plants where the fuel is oil or coal. The dry product consists of particles, often scale-formed, in the size field of 0.1-50 μm. The chemical composition of the particles are typically 40-70% CaSO3, 5-12%
CaSO4, 5-10% Ca(OH)2, and 5-10% CaCO3.
Depending on the construction of desulphurization plant the dry product will in practice be mixed with a varied amount of fly-ash, as mentioned above. When the name "dry product" is used in the following without additional comments, the clean dry product without the content of fly-ash is considered.
The proportion of dry product in the sheets is 10-50 percent by weight, preferably 12- 40 percent by weight, and in particular 15- 35 percent by weight.
Fibres: The fibre material contributes particularly to reinforce the sheet, and to make it more tough. A number of different fibre types can be used for this purpose, both organic an inorganic fibres. The characteristic of suitable fibres are, that the ratio between their typical length and diameter must be at least 10:1, and preferably at least 50:1, that their typical diameter should be in the interval of 1-200 μm, preferably 5-100 μm, and in particular 10-50 μm, and that they must be durable in an alkaline environment. Suitable fibres are for example asbestos, glassfibers, and mineral wool fibres, in particular fibres with good alkaline resistance, steel fibres, cellulose fibres from plants, polymer-based fibres, in particular such fibres that can stand the high temperature during autoclaving.
In a preferred embodiment the fibres for reinforcement are cellulose fibres from plants, for example cellulose fibres from pine, flax, elephant grass, abaca hemp and coir, which all are relatively long fibres, and for example cellulose fibres from birch, straw, and eucalyptus, which are relatively short fibres. In a particularly preferred embodiment cellulose fibres from paperwaste, such as office wastepaper, paperbag-waste, plus second hand newspapers and magazines, are used.
It can furthermore be advantageous to use reinforcement fibres, which is composed of a mix of two or more of the types of fibres, mentioned above.
In those cases where cellulose fibres are used, and particularly where also the thinslurry technique is used, it can be advantageous to fibril late the fibres, among other things to improve the filtration properties. The fibrillation can also result in tnat the fipres are better anchored in the matrix-material, and thus contributes to an improved reinforcing effect. Such a fibrillation can be obtained by grinding the fibres in a so-called cellulose-refiner. The degree of grinding can be measured in a so- called Schopper-Riegler device, and is indicated in the unit °SR. A suitable degree of grinding is 20-80 °SR, in particular 30-65 ºSR.
The proportion of fibre-mass in the sheets is 2-25 percent by weight, preferably 5-25 percent by weight, and in particular 10-20 percent by weight.
The weight ratio between the components containing silicate, and the lime-equivalent components (cement, lime) is determined from a wish to develop the strongest and most stable calcium-silicate-hydrates during the autocla tain this the molar ratio between equivalent CaO and SiO2 is chosen to 0.5-1.1, in particular 0.8-0.9, as the reaction depth in the individual particles is taken into consideration. In addition to the main components of raw-materials mentioned above, it can according to the invention be suitable to use some materials, such as dispersants, that contributes to a better mixing of the raw materials; flocculants, that can boost the dewatering of slurry for the above-mentioned thin-slurry production process; compounds, that influences the hydration process, for example by accelerating or retarding it; fillers, that changes certain properties, for example improves the properties with respect to fire, or which increases or reduces the stiffness of the material.
The invention is further illustrated by the following examples:
Example 1. A set of test sheets was manufactured with the following composition:
Component Dry matter in percent by weight
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Rapid hardening 20 22.5 18 18 17 Portland cement
Fly-ash 35 45 27 27 26
By-product 35 22.5 45 45 44 from coal-fired power-plant )
Fibres from news- 10 10 10 10 10 papers and magazines
Mineral wool fibres
Mole ratio CaO:SιO2 0.88 0.90 0.88 0.88 0.88 1 ) The oy-product consisted of approx. 75% dry product and approx. 25% fly-ash.
The fibres were disintegrated in water in the ratio 1:50 (fibres:water), and the mixture was worked intensively in a turbine-mixer, until the fibres were separated. Then the rest of the dry matter was added to the fibre-watermixture, and the intense working was continued until the slurry had a homogenous consistency. From the slurry sheets were manufactured in the following way:
A measured quantity of slurry was poured in a box-formed container, of which the bottom was formed like a sievesheet, covered with a fine-meshed wire-mesh. A funnelformed extension to the container was positioned under the sieve-sheet, and this was connected to a vacuum-pump, so that a vacuum in the size of 0.02 MN/m2 couId be established. under the influence of the gravitation and the applied vacuum the excess water was drained out of the slurry, by means of which the slurry was converted to a partly dewatered filter-cake. In order to further remove the excess water, and increase the density of the filtercake, this was transferred to a filterpress, and pressed with different pressure levels.
The pressed sheets was stored, wrapped in plastic film, for 18 hours at a temperature of 25ºC. Afterwards they were placed in an autoclave, and autoclaved for 12 hours at a temperature of 180ºC and with an equivalent steam pressure of approx. 1 MN/m2.
After the autoclaving, the sheets were conditioned for three weeks at room climate, approx. 20ºC and 50% relative humidity, after which the density and the bending strength was recorded. The following values was recorded: Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5
Su rface pressure 0. 7 0. 7 0. 7 1 . 5 0. 7 i n the press MN/m2
Density kg/m3 1020 950 940 1220 960
Modulus of rupture 7.0 5.5 6.2 9.5 7.1 MN/m2
Example 2.
This example illustrates the importance of autoclaving for the properties of the sheets.
A sheet, identical in composition to sheet no 4 from example 1, was made following the same procedure as described in example 1, but with the modification, that the sheet was not autoclaved. Instead, immediately after being pressed with a surface pressure o* 1.5 MN/m2, it was wrapped in plastic film, and stored at 25"C for four weeks. Then the plastic film was removed, and the sheet was conditioned for three weeks at room climate, approx. 20ºC and 50% relative humidity.
After this the density and the modulus of rupture was recorded:
Density: 1210 kg/m3
Modulus of rupture: 4.3 MN/m2 In order to examine possible differences in water-proofness, a sample was cut out from sheet no 4 in example 1 and the sheet from example 2. The two samples were stored for 2 weeks in a vessel filled with water. Afterwards they were taken out of the water and examined. Sheet no 4 from example 1 was visually assessed to be completely intact, and still possessed good strength and solidness. The sheet from example 2 was partly disintegrated, and had very little strength and cohesion.
Example 3.
This example illustrates lime as a binder in a sheet, A, which is compared with sheets B and C, where the binder is rapid hardening Portland cement, which sheets A, B, and C were made as the sheets 1, 2, 3, and 5 from example 1.
These sheets had the following composition:
Component Dry matter composition in percent by weight
Sheet A Sheet B Sheet C
Rapid hardening 0 30 7 Portland cement
Quicklime 10 0 0
Fly-ash 45 30 45
By-product 35 30 38 from coal-fired power-plant )
Fibres from news10 10 10 papers and magazines
Mole ratio CaO:SiO2 0.S2 1.22 0.46 1) The by-product consisted of approx. 75% dry product and approx. 25% fly-ash.
After this the density and the modulus of rupture was recorded, the results being:
Sheet A Sheet B Sheet C
Surface pressure 0.7 0.7 0.7 in the press MN/m2
Density kg/m3 980 1020 940
modulus of rupture MN/m2 6.7 3.3 2.7

Claims

C L A I M S
1. Process for manufacturing sheets, in particular building sheets, which process comprise of steps Deginning with making a matrix by dry, semidry, or aqueous mixing of hydraulic cement or lime, fly-ash and dry product from desulphurization of flue gas; forming the matrix into sheets; compacting the sheets and setting plus precuring them, which matrix based on dry-weight contains:
5-60%, preferably 8-40%, and in particular 10-30% hydraulic cement, preferably Portland-cement, or lime in the form of quicklime or hydrated lime, or any mixture of cement and lime;
20-60%, preferably 30-60%, and in particular 40-60% fly-ash;
plus 10-50%, preferably 12-40%, and in particular 15- 35% dry product, which is produced by a reaction between the S02 content in a flue-gas and a finegrained spray of milk of lime in an atomizationabsorption-type flue-gas-desulphurization plant, and which main ingredient is calcium-sulphite.
c h a r a c t e r i z e d in,
that the matrix additionally contains 2-25%, preferably 5-25%, and in particular 10-20% fibre-formed material, and that
the precured sheets go through a final curing by autocla ving.
2. Process according to claim 1, c h a r a c t e r iz e d in, that there as fibre-formed material is used fibres, where the ratio between length and diameter is at least 10:1, and preferably 50:1, plus that the diameter of the fibres is in the interval 1-200 μm, preferably 5-100 μm, and in particular 10-50 μm.
3. Process according to claims 1-2, c h a r a c t e r iz e d in, that the fibre-formed material consist of asbestos, fibre glass, mineral wool fibres, steel fibres, aramid fibres, and cellulose fibres from plants, preferably cellulose fibres of pine, flax, elephant grass, and eucalyptus, and in particular fibres extracted from paperwaste, newspapers and magazines.
4. Process according to claims 1 to 3, and where cellulose fibres are used, c h a r a c t e r i z e d in, that the cellulose fibres are fibri Hated by grinding the fibres in a cellulose-refiner to a freeness, that measured according to the Schopper-Riegler method is in the interval of 20-80 °SR, preferably 30-56 °SR.
5. Process according to any of the claims 1 to 4, c h ar a c t e r i z e d in, that the composition of the matrix is determined in the way that the molar ratio between equivalent CaO and SiO2 has a value between 0.5 and
1.1, and preferably a value between 0.8 and 0.9.
6. Process according to any of the claims 1 to 5, c h ar a c t e r i z e d in, that the autoclaving is carried out at temperatures between 120-210°C, preferably within the interval 160-210°C.
PCT/DK1989/000093 1988-04-25 1989-04-24 Process for manufacture of plates, especially for construction use WO1989010333A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK223888A DK223888A (en) 1988-04-25 1988-04-25 PROCEDURE FOR THE MANUFACTURE OF AUTOCLAVATED, FIBER ARMED BUILDING PLATES
DK2238/88 1988-04-25

Publications (1)

Publication Number Publication Date
WO1989010333A1 true WO1989010333A1 (en) 1989-11-02

Family

ID=8110995

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK1989/000093 WO1989010333A1 (en) 1988-04-25 1989-04-24 Process for manufacture of plates, especially for construction use

Country Status (3)

Country Link
AU (1) AU3447589A (en)
DK (1) DK223888A (en)
WO (1) WO1989010333A1 (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3942244A1 (en) * 1989-12-21 1991-06-27 Fulgurit Baustoffe Gmbh Fibre reinforced calcium silicate building material contg. anhydrite - to reduce expansion, shrinkage and weathering, used esp. for facade panel
ES2068733A1 (en) * 1992-07-15 1995-04-16 Cia Sevillana De Electricidad Procedure for preparing ceramic material of different qualities from fly ash
WO1998001404A1 (en) * 1996-07-09 1998-01-15 Pittsburgh Mineral & Environmental Technology, Inc. Method of making building blocks from coal combustion waste and related products
EP0858480A1 (en) * 1995-11-03 1998-08-19 Building Materials Corporation Of America Sheet felt
AT504072B1 (en) * 2006-08-09 2008-09-15 Gipsbergbau Preinsfeld Ges M B DEPONABLE MATERIAL FOR THE EVALUATION OR DEPOSITION OF SMOKE-GAS SPINNING PRODUCTS
CN102248590A (en) * 2011-05-24 2011-11-23 欧阳忠贞 Method for manufacturing honeycomb bottom plates
RU2496738C1 (en) * 2012-07-03 2013-10-27 Юлия Алексеевна Щепочкина Crude mixture for making brick
CN108035445A (en) * 2017-12-18 2018-05-15 上海理工大学 A kind of construction method of graphite oxide alkenyl thermal insulation mortar
CN115572130A (en) * 2022-10-14 2023-01-06 安徽工业大学 Composite high-strength low-shrinkage cement-based material and preparation method thereof
EP4342866A1 (en) * 2022-09-22 2024-03-27 Etex Services NV Fiber cement product and method of manufacturing thereof

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3785840A (en) * 1972-06-05 1974-01-15 Corson G & W H Lime-fly ash-sulfite mixtures
DE3518410A1 (en) * 1985-05-22 1986-11-27 Gebr. Knauf Westdeutsche Gipswerke KG, 8715 Iphofen Compact commercial product, process for its manufacture and its use

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3785840A (en) * 1972-06-05 1974-01-15 Corson G & W H Lime-fly ash-sulfite mixtures
DE3518410A1 (en) * 1985-05-22 1986-11-27 Gebr. Knauf Westdeutsche Gipswerke KG, 8715 Iphofen Compact commercial product, process for its manufacture and its use

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3942244A1 (en) * 1989-12-21 1991-06-27 Fulgurit Baustoffe Gmbh Fibre reinforced calcium silicate building material contg. anhydrite - to reduce expansion, shrinkage and weathering, used esp. for facade panel
ES2068733A1 (en) * 1992-07-15 1995-04-16 Cia Sevillana De Electricidad Procedure for preparing ceramic material of different qualities from fly ash
EP0858480A1 (en) * 1995-11-03 1998-08-19 Building Materials Corporation Of America Sheet felt
EP0858480A4 (en) * 1995-11-03 2004-12-22 Gaf Building Materials Sheet felt
WO1998001404A1 (en) * 1996-07-09 1998-01-15 Pittsburgh Mineral & Environmental Technology, Inc. Method of making building blocks from coal combustion waste and related products
US6068803A (en) * 1996-07-09 2000-05-30 Pittsburgh Mineral And Enviromental Technology, Inc. Method of making building blocks from coal combustion waste and related products
AT504072B1 (en) * 2006-08-09 2008-09-15 Gipsbergbau Preinsfeld Ges M B DEPONABLE MATERIAL FOR THE EVALUATION OR DEPOSITION OF SMOKE-GAS SPINNING PRODUCTS
CN102248590A (en) * 2011-05-24 2011-11-23 欧阳忠贞 Method for manufacturing honeycomb bottom plates
RU2496738C1 (en) * 2012-07-03 2013-10-27 Юлия Алексеевна Щепочкина Crude mixture for making brick
CN108035445A (en) * 2017-12-18 2018-05-15 上海理工大学 A kind of construction method of graphite oxide alkenyl thermal insulation mortar
EP4342866A1 (en) * 2022-09-22 2024-03-27 Etex Services NV Fiber cement product and method of manufacturing thereof
WO2024062039A1 (en) * 2022-09-22 2024-03-28 Etex Services Nv Fiber cement product and method of manufacturing thereof
CN115572130A (en) * 2022-10-14 2023-01-06 安徽工业大学 Composite high-strength low-shrinkage cement-based material and preparation method thereof

Also Published As

Publication number Publication date
DK223888A (en) 1989-07-17
AU3447589A (en) 1989-11-24
DK223888D0 (en) 1988-04-25

Similar Documents

Publication Publication Date Title
US6506248B1 (en) Building products
CN1022403C (en) Lightweight insulating boards and process for manufacturing same
KR850001173B1 (en) Method of producing a building element
US4132555A (en) Building board
EP0263723B1 (en) A process for manufacture of fibre-reinforced shaped articles
US4680059A (en) Building material
EP0127960B1 (en) A process for the manufacture of autoclaved fibre-reinforced shaped articles
US6875503B1 (en) Cementitious product in panel form and manufacturing process
MXPA03002711A (en) Fiber cement composite materials using cellulose fibers loaded with inorganic and/or organic substances.
NO161907B (en) PROCEDURE FOR THE MANUFACTURE OF ASBESTOUS CORRUGATED PLATES, SPECIFIC BUILDING PLATES.
US5350549A (en) Synthetic aggregate compositions derived from spent bed materials from fluidized bed combustion and fly ash
WO1989010333A1 (en) Process for manufacture of plates, especially for construction use
RU2753546C2 (en) Methods for producing air-cured fiber cement products
DK160484B (en) FIBER MIXTURE FOR STRENGTHENING HYDRAULIC BINDING MATERIALS, THE USE OF THE MIXTURE AND BENEFITS PREPARED IN USING THE MIXTURE.
EP0199728B1 (en) Adjustment method for the properties of concrete
Singh et al. Fibre reinforced gypsum binder composite, its microstructure and durability
AU723626B2 (en) Building products
IE57230B1 (en) Process for the manufacture of shaped products
Raut et al. Bond strength of waste-create bricks
JP2659806B2 (en) Manufacturing method of inorganic plate
CZ61898A3 (en) Mixture pro producing mortars and compacted building materials and process of treating thereof
CHANDRAN Agricultural Wastes Based Fibrous Pozzolanic Concrete as a Green Construction Material
Basta et al. Lignocellulosic materials in building elements. Part II. Cement light-weight building bricks
JPH05221699A (en) Fiber-reinforced cement board
DK149882B (en) PROCEDURE FOR THE MANUFACTURE OF AUTOCLAVATED FIBER PREPARED PRODUCTS

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AT AU BB BG BR CH DE DK FI GB HU JP KP KR LK LU MC MG MW NL NO RO SD SE SU US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE BF BJ CF CG CH CM DE FR GA GB IT LU ML MR NL SE SN TD TG

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642