WO2024133434A1 - Construction panel and method of manufacturing thereof - Google Patents
Construction panel and method of manufacturing thereof Download PDFInfo
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- WO2024133434A1 WO2024133434A1 PCT/EP2023/086906 EP2023086906W WO2024133434A1 WO 2024133434 A1 WO2024133434 A1 WO 2024133434A1 EP 2023086906 W EP2023086906 W EP 2023086906W WO 2024133434 A1 WO2024133434 A1 WO 2024133434A1
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- Prior art keywords
- composition
- construction panel
- cement
- cured
- dry weight
- Prior art date
Links
- 238000010276 construction Methods 0.000 title claims abstract description 32
- 238000004519 manufacturing process Methods 0.000 title claims description 12
- 239000004568 cement Substances 0.000 claims abstract description 62
- 239000000203 mixture Substances 0.000 claims abstract description 44
- 239000000843 powder Substances 0.000 claims abstract description 42
- 239000000835 fiber Substances 0.000 claims abstract description 36
- 239000011162 core material Substances 0.000 claims abstract description 27
- 230000002787 reinforcement Effects 0.000 claims abstract description 15
- 239000011230 binding agent Substances 0.000 claims abstract description 13
- 238000005266 casting Methods 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims abstract description 5
- 239000011148 porous material Substances 0.000 claims description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- 239000011398 Portland cement Substances 0.000 claims description 12
- 239000002657 fibrous material Substances 0.000 claims description 10
- 239000003365 glass fiber Substances 0.000 claims description 10
- 229920003086 cellulose ether Polymers 0.000 claims description 9
- 239000004088 foaming agent Substances 0.000 claims description 8
- 239000002245 particle Substances 0.000 claims description 6
- 238000009826 distribution Methods 0.000 claims description 5
- 239000002002 slurry Substances 0.000 claims description 5
- 229920001479 Hydroxyethyl methyl cellulose Polymers 0.000 claims description 4
- 239000003945 anionic surfactant Substances 0.000 claims description 3
- 238000007873 sieving Methods 0.000 claims description 3
- 239000011411 calcium sulfoaluminate cement Substances 0.000 claims description 2
- 238000012360 testing method Methods 0.000 description 7
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 235000019738 Limestone Nutrition 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000012512 characterization method Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000006260 foam Substances 0.000 description 3
- 239000006028 limestone Substances 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 239000010451 perlite Substances 0.000 description 3
- 235000019362 perlite Nutrition 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 235000012241 calcium silicate Nutrition 0.000 description 2
- 235000013339 cereals Nutrition 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 235000013312 flour Nutrition 0.000 description 2
- 238000010348 incorporation Methods 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- 238000012935 Averaging Methods 0.000 description 1
- 101100491335 Caenorhabditis elegans mat-2 gene Proteins 0.000 description 1
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- 206010037660 Pyrexia Diseases 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229920013820 alkyl cellulose Polymers 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- UGGQKDBXXFIWJD-UHFFFAOYSA-N calcium;dihydroxy(oxo)silane;hydrate Chemical compound O.[Ca].O[Si](O)=O UGGQKDBXXFIWJD-UHFFFAOYSA-N 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000004567 concrete Substances 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000009970 fire resistant effect Effects 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 238000013012 foaming technology Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 125000002768 hydroxyalkyl group Chemical group 0.000 description 1
- 229920013819 hydroxyethyl ethylcellulose Polymers 0.000 description 1
- 239000001866 hydroxypropyl methyl cellulose Substances 0.000 description 1
- 229920003088 hydroxypropyl methyl cellulose Polymers 0.000 description 1
- 235000010979 hydroxypropyl methyl cellulose Nutrition 0.000 description 1
- UFVKGYZPFZQRLF-UHFFFAOYSA-N hydroxypropyl methyl cellulose Chemical compound OC1C(O)C(OC)OC(CO)C1OC1C(O)C(O)C(OC2C(C(O)C(OC3C(C(O)C(O)C(CO)O3)O)C(CO)O2)O)C(CO)O1 UFVKGYZPFZQRLF-UHFFFAOYSA-N 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- MKTRXTLKNXLULX-UHFFFAOYSA-P pentacalcium;dioxido(oxo)silane;hydron;tetrahydrate Chemical compound [H+].[H+].O.O.O.O.[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-][Si]([O-])=O.[O-][Si]([O-])=O.[O-][Si]([O-])=O.[O-][Si]([O-])=O.[O-][Si]([O-])=O.[O-][Si]([O-])=O MKTRXTLKNXLULX-UHFFFAOYSA-P 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229920002545 silicone oil Polymers 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000010455 vermiculite Substances 0.000 description 1
- 235000019354 vermiculite Nutrition 0.000 description 1
- 229910052902 vermiculite Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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
- C04B28/02—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
- 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
- C04B28/06—Aluminous cements
- C04B28/065—Calcium aluminosulfate cements, e.g. cements hydrating into ettringite
-
- 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
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00612—Uses not provided for elsewhere in C04B2111/00 as one or more layers of a layered structure
Definitions
- the invention relates to a construction panel comprising: a core material provided with a composition comprising a set inorganic binder, and a fiber reinforcement, for instance in the form of a first and a second fiber mat.
- the invention further relates to a method of manufacturing such a construction panel.
- Such cement-based construction panels that are reinforced with fiber mats are known in the market, such as under the tradename Aquapanel®.
- the panels are known to be fire-resistant and insensitive for humidity. Typically, they are used outdoor behind a decorative panel or inside. As a consequence, the exposure to weather conditions is less, and hence the requirements on flexural strength and dimensional stability are not as high as those for fiber cement facade panels, such as for instance sold under the trade name Equitone®. This leads thereto that the density of the product is also lower.
- EP1981826B2 discloses a construction panel of the type mentioned in the opening paragraph.
- the core material herein comprises a lightweight component and a filler.
- the binder is Portland cement.
- the lightweight component is expanded perlite, in the form of grains embedded in the binder, which is furthermore hydrophobized with silicone oil.
- the filler is limestone flour.
- the first and second reinforcement are embedded in cover layers of Portland cement.
- the density of the resulting construction panel is in the range of 0.3 to 1.2 kg/dm 3 .
- the overall content of limestone flour is 60wt% based on dry weight (thus excluding any remaining humidity), Portland cement 27wt%, hydrophobized expanded perlite 12% and glass fiber mat 2%.
- the invention provides a construction panel comprising
- a porous cured core material having a density in the range of 0.75 to 0.95 kg/dm3 and provided with a composition comprising a set inorganic binder and cured cement powder, wherein the cured cement powder is present in an amount of at least 20wt% based on dry weight of the core material, and - a fiber reinforcement embedded in the core.
- the invention provides a method of manufacturing a construction panel having a density in the range of 0.75 to 0.95 kg/dm3, comprising the steps of:
- composition comprising an inorganic binder and cured cementitious powder and a foaming agent, wherein the cured cementitious powder is present in an amount of at least 20wt% based on dry weight of the core material, and
- the addition of cured cementitious powder in sufficient amount enabled embedding the fiber reinforcement into the same core material.
- the cured cement powder turns out to have a lower density than fresh cement and still may be integrated into the core material by virtue of reactions with fresh cement during curing.
- the resulting core material is moreover homogeneous, as visible with the human eye, and that the pores in the core material turn out to be of the closed cell-type.
- Preferably at least 80%, more preferably at least 90%, even more preferably at least 95% of the pores are closed cell pores.
- the amount of cured cement powder is at least 25wt% (i.e. weight per cent) based on dry weight of the core material. More preferably the amount of cured cementitious powder is in the range of 30 to 50 weight%. Good results were obtained with about 40wt%.
- composition referred to hereinabove and in the claims relates to the dry composition as specified prior to curing.
- Water will be added so as to enable curing.
- curing comprises hydration reactions to obtain certain calcium silicates, wherein water is adopted into the cement matrix.
- the cured cement powder comprises fibers and/or fibrous material.
- Such cured cement powder particularly originates from fiber cement products and is for instance based on waste generated during production and/or installation.
- the provision of fibrous material is deemed beneficial in view of its relatively low density, as compared to inorganic powders.
- the concentration of fibers and/or fibrous material is for instance in the range of 2-10 weight%, based on the dry weight of the cured cement powder. More preferably, the concentration is in the range of 2-6 wt%, such as 3-6 wt%, optionally 4-5 wt%.
- a higher concentration of fibrous material in the cured cement powder tends to decrease flowability and processability of the cured cement powder during production. Therewith, it limits the maximum amount of cured cementitious powder.
- the concentration of fibers and/or fibrous material in the cured cement powder may be limited by means of separation steps, especially in combination with grinding steps.
- the core material comprises a first cured cementitious powder comprising fibers and/or fibrous material and a second cured cementitious powder.
- the second cured cement powder may comprises fibers and/or fibrous material or may be free of fibers and/or fibrous material. Preferably it contains less fibers and/or fibrous material than the first cured cement powder.
- This second cured cementitious powder may further have a different cement composition than the first cured cement composition.
- such second cured cementitious powder may be a cured calcium silicate material, such as tobermorite, vermiculite, xonotlite.
- the cured cement powder has a particle size distribution with a d90-value of at most 100 pm as measured by air jet sieving, and a d25 value of at least 4 pm. Said particle size distribution is found appropriate for incorporation of the cured cement powder into the fresh cement matrix formed during curing.
- the porous core material has a porosity in the range of 10-20%, more preferably at least 11% by volume.
- a porosity is higher than porosities disclosed for other ways of forming porous cement particles, such as in WO2012/149421A1.
- a specific porosity of 9.2 % by volume is reported.
- a porosity of 13% was detected experimentally.
- the average pore radius is in the range of 100-140 pm, whereas the prior art specifies an average pore diameter between 20 and 60 pm. This distinct porosity and pore sizes leads to a significantly lower density with an enhanced flexural modulus (SMOR).
- SMOR enhanced flexural modulus
- the composition comprises cement as a binder in an amount in the range of 30-70wt%, preferably 40-60wt%, based on dry weight of the composition.
- the cement is preferably chosen from calcium sulfoaluminate cement and Portland cement, and more preferably is Portland cement.
- the use of cement as a binder in combination with cementitious cured powders was found beneficial.
- the composition and its weight percentages refer to the composition used for preparation of the core material, and hence prior to curing. In the curing reaction, hydratation of cement occurs and hence water is incorporated into the core material.
- the composition further comprises a cellulose ether, such as hydroxyethylmethylcellulose.
- a cellulose ether such as hydroxyethylmethylcellulose.
- Alternative cellulose ethers such as other hydroxyalkyl alkyl celluloses, wherein alkyl is preferably Ci-C 4 -alkyl and more preferably Ci-C 4 -n-alkyl are not excluded. Examples include hydroxymethylmethylcellulose, hydroxypropylmethylcellulose, hydroxyethylethylcellulose, hydroxyethylpropylcellulose, hydroxypropylpropylcellulose.
- Cellulose ethers are known to retain water and therewith in use to increase the viscosity.
- the beneficial results of the present technology may be facilitated by the use of the cellulose ether, in that the water retention leads to slower curing and hence extended incorporation of the cured cement powder into the fresh cement matrix.
- the cellulose ether is suitably present in an amount of at least 1.0 wt%, preferably at least 1.5 wt%, more preferably at least 2.0 wt% based on dry weight of the composition. This concentration is higher than amounts reported for dry construction mixes, such the maximum of 0.75 wt% reported in Yu. Kovalenko et al, Eastern- European Journal of Enterprise Technologies, 105(2020), 28-33.
- the present construction board is manufactured by using a foam technology.
- the composition comprises a foaming agent, such as an anionic surfactant.
- foaming agents such as an anionic surfactant.
- anionic surfactant a variety of foaming agents is known per se and furthermore discussed in WO2012/149421, which is incorporated by reference for that respect.
- water is used in an amount that exceeds the typical water/cement ratio known for hydratation.
- the water/cement ratio is in the range of 1 to 1.5.
- the ratio is a mass ratio.
- the mass of the cured fiber cement is not included in the cement mass.
- the curing of the core material occurs by means of air-curing.
- air-curing the need of transporting the casted uncured (i.e. green) panel to an autoclave, and the high- temperature treatment in the autoclave is avoided.
- autoclave-curing is not excluded, in which case the composition would include both cement and a source of silica such as quartz in appropriate ratios as known per se.
- the fiber reinforcement present in the construction panel is preferably a fiber matt. More preferably, use is made of a glass fiber matt, as known per se. More preferably, a first and a second fiber matt are present in the construction panel, so as to strengthen the panel on both outer sides. This use of fiber matts is deemed to provide an acceptable strengthening at an acceptable price. Nevertheless, it is not excluded that another type of fiber reinforcement is applied in the present technology.
- Fig. 1 is an optical microscopic picture of a cross-section through the porous core material of the present invention.
- the x- and y-axis indicate the dimensions of the sample.
- Fig. 2 is a histogram of the pore radius of the pores, as measured using a porosimeter.
- a test composition was prepared comprising cement, recycled and cured fiber cement powder, a foaming agent, a dispersing agent and a water retention compound.
- Portland cement (type I) was used as the cement.
- the cured fiber cement powder was an autoclave-cured fiber cement powder, comprising between 6 and 8 wt% of cellulose fiber. Additionally, the powder was a reaction product from a reaction of quartz with cement in a weight ratio of approximately 1:1, with some addition of aluminum oxide, such as kaolin.
- the cured fiber cement powder had a particle size entirely or at least substantially below 100 pm, as defined by sieving.
- the foaming agent is a mix of anionic surfactants, commercially available as a liquid air entrainer for concrete and other cement based systems, with recommended use level of 0.01- 0.5wt%.
- the dispersion agent is an admixture based on modified polycarboxylic ether (PCE) polymers, obtained from BASF as Masterglenium 51.
- the water retention compound was a cellulose ether.
- water was added in a ratio of water to Portland cement of 1.15.
- water was added in a ratio of water to Portland cement of 1.26.
- the dry test composition and the water were mixed to obtain a homogeneous slurry mixture.
- the resulting slurry was applied in a mould in which a first and a second glass fiber mat were provided on a top and a bottom side.
- the glass fiber mat was a glass-fiber mesh (scrim) supplied from Chomarat, type Rotatex G1100N.
- the scrims have a surface weight of 123 g/m 2 and a mesh size of 2.5mm x 3.0mm.
- a PVC coating 70 g/m 2
- the glass fiber matts were arranged in a manner that they are incorporated in the slurry, and at a distance of approximately 1 mm to the bottom and the top surface of the resulting plate.
- the mould had a top surface of 200 x 240 mm 2 .
- the composite After casting of the slurry into the mould with the glass fiber matts, the composite is post-compressed using an electrical mechanical press.
- the post-compression force is adapted to obtain a final sample thickness of ca. 12.5mm.
- the inner core comprises about 24 weight% of Portland cement, about 10 weight% of hydrophobated expanded perlite with a grain size in the range of 0.1-3 mm and about 50% calcium carbonate (limestone mehl), with remainder being humidity.
- the outer layer comprises Portland cement and calcium carbonate in a weight ratio of 1:3, with the remainder of the glass fiber matt and humidity.
- Ref 2 values are taken from WO2012/149421A1.
- a characterization on the microstructure was performed using a Keyence 3D Optical Profilometer KEYNCE VR-5000. Thereto, a sample as obtained from Example 1 was cut through to obtain a crosssection. Fig. 1 shows an optical image. The pores are of a closed-cell type, as far as identifiable visually and under a microscope. The pore distribution appears homogeneous, as a consequence of the manufacturing process using a foaming additive. The pore size in a bottom layer is substantially equal (i.e. not much smaller) than pore size of a top layer. This indicates that the foam was stable during manufacture, resulting in a stable mixture such that the foam bubbles did not coagulate and diffuse towards the top of the mixture. This implies that the foam mixture can be used in a casting process.
- Each of the areas had a size of 21x27.8 mm (583.8 mm 2 ).
- the total number of pores in the four areas was 6150.
- a threshold was set to -0.050 mm, which means that any feature with a depth of less than 50 microns was not included. Pores with a cross-sectional area of less than 0.003 mm 2 (3000 pm 2 ) were not included either. This setting reduces the noise considerably.
- Porosity was calculated as the sum of the cross-sectional areas measured for each pore divided by the total surface area of the four areas. Since the pore density is random and homogeneous, the porosity in the cutting plane can be assumed to be representative for the overall porosity.
- d max is chosen to be positive rather than negative. The calculation assumes spherical pores.
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- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
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- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The construction panel comprises a porous cured core material having a density in the range of 0.75 to 0.95 kg/dm3 and provided with a composition comprising a set inorganic binder and cured cement powder, wherein the cured cement powder is present in an amount of at least 20wt% based on dry weight of the composition, and a fiber reinforcement embedded in the core material. It is manufactured in a method comprising the steps of providing an aqueous composition and providing a fiber reinforcement, for instance in the form of a fiber mat; casting the composition into a mould, with the reinforcement being embedded therein; and curing the composition into a core material of the construction panel, for instance by means of air-curing.
Description
Construction panel and method of manufacturing thereof
FIELD OF THE INVENTION
The invention relates to a construction panel comprising: a core material provided with a composition comprising a set inorganic binder, and a fiber reinforcement, for instance in the form of a first and a second fiber mat. The invention further relates to a method of manufacturing such a construction panel.
BACKGROUND OF THE INVENTION
Such cement-based construction panels that are reinforced with fiber mats are known in the market, such as under the tradename Aquapanel®. The panels are known to be fire-resistant and insensitive for humidity. Typically, they are used outdoor behind a decorative panel or inside. As a consequence, the exposure to weather conditions is less, and hence the requirements on flexural strength and dimensional stability are not as high as those for fiber cement facade panels, such as for instance sold under the trade name Equitone®. This leads thereto that the density of the product is also lower.
EP1981826B2 discloses a construction panel of the type mentioned in the opening paragraph. The core material herein comprises a lightweight component and a filler. The binder is Portland cement. The lightweight component is expanded perlite, in the form of grains embedded in the binder, which is furthermore hydrophobized with silicone oil. The filler is limestone flour. The first and second reinforcement are embedded in cover layers of Portland cement. The density of the resulting construction panel is in the range of 0.3 to 1.2 kg/dm3. Based on the examples in the patent, the overall content of limestone flour is 60wt% based on dry weight (thus excluding any remaining humidity), Portland cement 27wt%, hydrophobized expanded perlite 12% and glass fiber mat 2%.
It is a disadvantage of the known construction panel that its mechanical properties are limited, while the density is still significant. Tests performed on commercially available Aquapanel-boards with a density of 1.06 kg/dm3 gave a flexural strength of 8.0 MPa and a bending strength of 1.2 J/m2. It would be desirous to provide construction panels with a lower density, with equal or higher flexural strength and improved bending strength. In fact, a lower density will result in lower transport cost and energy consumption. Typically, however, a decrease in density implies higher porosity or lower content of cement. The particle density of cement is about 3.2 kg/dm3, the bulk density around 1.5 kg/dm3. A reduction of the cement content will reduce the strength, as the cement is the binder that keeps the board together.
SUMMARY OF THE INVENTION
It is therefore a first object of the invention to provide a construction panel of the type mentioned in the opening paragraph, which has equal or better mechanical properties that existing construction panels on the market and still has lower density.
It is a further object of the invention to provide a manufacturing method for such panel.
According to a first aspect, the invention provides a construction panel comprising
- a porous cured core material having a density in the range of 0.75 to 0.95 kg/dm3 and provided with a composition comprising a set inorganic binder and cured cement powder, wherein the cured cement powder is present in an amount of at least 20wt% based on dry weight of the core material, and
- a fiber reinforcement embedded in the core.
According to a second aspect, the invention provides a method of manufacturing a construction panel having a density in the range of 0.75 to 0.95 kg/dm3, comprising the steps of:
- providing a composition comprising an inorganic binder and cured cementitious powder and a foaming agent, wherein the cured cementitious powder is present in an amount of at least 20wt% based on dry weight of the core material, and
- providing a fiber reinforcement, for instance in the form of a fiber mat;
- casting the composition into a mould, with the first and the second reinforcement being embedded therein;
- curing the composition into a core material.
It was found in experiments leading to the invention that the addition of cured cementitious powder in sufficient amount enabled embedding the fiber reinforcement into the same core material. Hence, there is no need anymore for separate outer layers. Moreover, the cured cement powder turns out to have a lower density than fresh cement and still may be integrated into the core material by virtue of reactions with fresh cement during curing. It was surprisingly found that the resulting core material is moreover homogeneous, as visible with the human eye, and that the pores in the core material turn out to be of the closed cell-type. Preferably at least 80%, more preferably at least 90%, even more preferably at least 95% of the pores are closed cell pores.
In one preferred embodiment, the amount of cured cement powder is at least 25wt% (i.e. weight per cent) based on dry weight of the core material. More preferably the amount of cured cementitious powder is in the range of 30 to 50 weight%. Good results were obtained with about 40wt%.
For sake of clarity, the composition referred to hereinabove and in the claims relates to the dry composition as specified prior to curing. Water will be added so as to enable curing. As known to the skilled person, such curing comprises hydration reactions to obtain certain calcium silicates, wherein water is adopted into the cement matrix.
In a further implementation, the cured cement powder comprises fibers and/or fibrous material. Such cured cement powder particularly originates from fiber cement products and is for instance based on waste generated during production and/or installation. The provision of fibrous material is deemed beneficial in view of its relatively low density, as compared to inorganic powders. The concentration of fibers and/or fibrous material is for instance in the range of 2-10 weight%, based on the dry weight of the cured cement powder. More preferably, the concentration is in the range of 2-6 wt%, such as 3-6 wt%, optionally 4-5 wt%. A higher concentration of fibrous material in the cured cement powder tends to decrease flowability and processability of the cured cement powder during production. Therewith, it limits the maximum amount of cured cementitious powder. The concentration of fibers and/or fibrous material in the cured cement powder may be limited by means of separation steps, especially in combination with grinding steps.
In an alternative or further embodiment, the core material comprises a first cured cementitious powder comprising fibers and/or fibrous material and a second cured cementitious powder. The second cured
cement powder may comprises fibers and/or fibrous material or may be free of fibers and/or fibrous material. Preferably it contains less fibers and/or fibrous material than the first cured cement powder. This second cured cementitious powder may further have a different cement composition than the first cured cement composition. In one further implementation, such second cured cementitious powder may be a cured calcium silicate material, such as tobermorite, vermiculite, xonotlite.
Preferably, the cured cement powder has a particle size distribution with a d90-value of at most 100 pm as measured by air jet sieving, and a d25 value of at least 4 pm. Said particle size distribution is found appropriate for incorporation of the cured cement powder into the fresh cement matrix formed during curing.
More preferably, the porous core material has a porosity in the range of 10-20%, more preferably at least 11% by volume. Such a porosity is higher than porosities disclosed for other ways of forming porous cement particles, such as in WO2012/149421A1. In the latter prior art, a specific porosity of 9.2 % by volume is reported. In the present technology, a porosity of 13% was detected experimentally. Furthermore, the average pore radius is in the range of 100-140 pm, whereas the prior art specifies an average pore diameter between 20 and 60 pm. This distinct porosity and pore sizes leads to a significantly lower density with an enhanced flexural modulus (SMOR).
In a suitable embodiment, the composition comprises cement as a binder in an amount in the range of 30-70wt%, preferably 40-60wt%, based on dry weight of the composition. The cement is preferably chosen from calcium sulfoaluminate cement and Portland cement, and more preferably is Portland cement. The use of cement as a binder in combination with cementitious cured powders was found beneficial. For sake of clarity, it is observed that the composition and its weight percentages refer to the composition used for preparation of the core material, and hence prior to curing. In the curing reaction, hydratation of cement occurs and hence water is incorporated into the core material.
According to an advantageous embodiment, the composition further comprises a cellulose ether, such as hydroxyethylmethylcellulose. Alternative cellulose ethers, such as other hydroxyalkyl alkyl celluloses, wherein alkyl is preferably Ci-C4-alkyl and more preferably Ci-C4-n-alkyl are not excluded. Examples include hydroxymethylmethylcellulose, hydroxypropylmethylcellulose, hydroxyethylethylcellulose, hydroxyethylpropylcellulose, hydroxypropylpropylcellulose. Cellulose ethers are known to retain water and therewith in use to increase the viscosity. The beneficial results of the present technology may be facilitated by the use of the cellulose ether, in that the water retention leads to slower curing and hence extended incorporation of the cured cement powder into the fresh cement matrix. The cellulose ether is suitably present in an amount of at least 1.0 wt%, preferably at least 1.5 wt%, more preferably at least 2.0 wt% based on dry weight of the composition. This concentration is higher than amounts reported for dry construction mixes, such the maximum of 0.75 wt% reported in Yu. Kovalenko et al, Eastern- European Journal of Enterprise Technologies, 105(2020), 28-33.
It is highly preferred that the present construction board is manufactured by using a foam technology. Thereto, the composition comprises a foaming agent, such as an anionic surfactant. A variety of foaming agents is known per se and furthermore discussed in WO2012/149421, which is incorporated by reference for that respect. In addition to a foaming agent, water is used in an amount that exceeds the
typical water/cement ratio known for hydratation. Preferably, the water/cement ratio is in the range of 1 to 1.5. Herein, the ratio is a mass ratio. Furthermore, the mass of the cured fiber cement is not included in the cement mass.
According to a further embodiment, the curing of the core material occurs by means of air-curing. Therewith, the need of transporting the casted uncured (i.e. green) panel to an autoclave, and the high- temperature treatment in the autoclave is avoided. However, autoclave-curing is not excluded, in which case the composition would include both cement and a source of silica such as quartz in appropriate ratios as known per se.
The fiber reinforcement present in the construction panel is preferably a fiber matt. More preferably, use is made of a glass fiber matt, as known per se. More preferably, a first and a second fiber matt are present in the construction panel, so as to strengthen the panel on both outer sides. This use of fiber matts is deemed to provide an acceptable strengthening at an acceptable price. Nevertheless, it is not excluded that another type of fiber reinforcement is applied in the present technology.
These and other aspects of the invention will be further elucidated with reference to the Examples and to the Figures. It is observed for clarity that any of the embodiments discussed hereinabove or hereinafter with respect to one aspect of the invention are also applicable to any other aspect of the invention.
In the Figures:
Fig. 1 is an optical microscopic picture of a cross-section through the porous core material of the present invention. The x- and y-axis indicate the dimensions of the sample.
Fig. 2 is a histogram of the pore radius of the pores, as measured using a porosimeter.
EXAMPLES
Example 1 - Manufacture
A test composition was prepared comprising cement, recycled and cured fiber cement powder, a foaming agent, a dispersing agent and a water retention compound. Portland cement (type I) was used as the cement. The cured fiber cement powder was an autoclave-cured fiber cement powder, comprising between 6 and 8 wt% of cellulose fiber. Additionally, the powder was a reaction product from a reaction of quartz with cement in a weight ratio of approximately 1:1, with some addition of aluminum oxide, such as kaolin. The cured fiber cement powder had a particle size entirely or at least substantially below 100 pm, as defined by sieving. 91.0 wt% passed a sieve with 90 pm sieve aperture, 85.2wt% passed a sieve with 63 pm sieve aperture, and 76.9 wt% passed a sieve with 40 pm sieve aperture. Median (50volume%) lies at 26 pm and the 10%-limit at 2.5 pm (check, 90% is in the graph of Kristof report at 200 pm, quite different from the report of Joyce). Bulk density of the fiber cement powder was 0.57 kg/dm3.1 The foaming agent is a mix of anionic surfactants, commercially available as a liquid air entrainer for concrete and other cement based systems, with recommended use level of 0.01- 0.5wt%. The dispersion agent is an admixture based on modified polycarboxylic ether (PCE) polymers, obtained from BASF as Masterglenium 51. The water retention compound was a cellulose ether. In this
1 Data from report R2019032959 annexes (J. Mareels)
example, use was made of a modified hydroxyethyl methyl cellulose (HEMC) obtained from Dow as Walocel with a viscosity of 50000 mPa.s and a neutral pH. The experimental composition is shown in Table 1.
Table 1; dry test composition.
In a first example, water was added in a ratio of water to Portland cement of 1.15. In a second example, water was added in a ratio of water to Portland cement of 1.26. The dry test composition and the water were mixed to obtain a homogeneous slurry mixture.
The resulting slurry was applied in a mould in which a first and a second glass fiber mat were provided on a top and a bottom side. The glass fiber mat was a glass-fiber mesh (scrim) supplied from Chomarat, type Rotatex G1100N. The scrims have a surface weight of 123 g/m2 and a mesh size of 2.5mm x 3.0mm. To make the scrims alkali resistant, a PVC coating (70 g/m2) is added to the glass fibre yarn (53 g/m2). The glass fiber matts were arranged in a manner that they are incorporated in the slurry, and at a distance of approximately 1 mm to the bottom and the top surface of the resulting plate. The mould had a top surface of 200 x 240 mm2.
After casting of the slurry into the mould with the glass fiber matts, the composite is post-compressed using an electrical mechanical press. The post-compression force is adapted to obtain a final sample thickness of ca. 12.5mm.
Example 2 characterization of mechanical properties
Tests were performed to identify mechanical properties of the plates manufactured in accordance with Example 1. Results thereof are listed in Table 2. For comparison, a commercially available fiber cement product sold as Aquapanel™ Interior by Knauf Aquapanel GmbH was tested (herein also referred to as Refl). This is a board made in accordance with a so-called semi-dry method and includes a core and two outer layers. The glass mesh is included in the outer layers. The fresh individual layers are herein board is then post-compressed to arrive at a thickness of approximately 12.5. Manufacturing method of such a board is disclosed in EP1981826B1. As mentioned therein, the inner core comprises about 24 weight% of Portland cement, about 10 weight% of hydrophobated expanded perlite with a grain size in the range of 0.1-3 mm and about 50% calcium carbonate (limestone mehl), with remainder being humidity. The outer layer comprises Portland cement and calcium carbonate in a weight ratio of 1:3, with the remainder of the glass fiber matt and humidity. As a further reference (herein referred to as Ref 2), values are taken from WO2012/149421A1.
The modulus of rupture (MOR, typically expressed in Pa = kg/m2.s) of each of the samples was measured by making use of a UTS/INSTRON apparatus (type 3345, cel = 5000N). The limit of elastic deformation (IMOR, J/m2) were measured by making use of a UTS/INSTRON apparatus (type 3345, cel = 5000N) with software Bluehill by Instron (Norm EN12467 and related norms). Table 2 specifies test results.
Table 2 - test results
Example 3 characterization of microstructure
A characterization on the microstructure was performed using a Keyence 3D Optical Profilometer KEYNCE VR-5000. Thereto, a sample as obtained from Example 1 was cut through to obtain a crosssection. Fig. 1 shows an optical image. The pores are of a closed-cell type, as far as identifiable visually and under a microscope. The pore distribution appears homogeneous, as a consequence of the manufacturing process using a foaming additive. The pore size in a bottom layer is substantially equal (i.e. not much smaller) than pore size of a top layer. This indicates that the foam was stable during manufacture, resulting in a stable mixture such that the foam bubbles did not coagulate and diffuse towards the top of the mixture. This implies that the foam mixture can be used in a casting process.
Four different areas of the surface created by cutting were analysed by the profilometer. Each of the areas had a size of 21x27.8 mm (583.8 mm2). The total number of pores in the four areas was 6150. A threshold was set to -0.050 mm, which means that any feature with a depth of less than 50 microns was not included. Pores with a cross-sectional area of less than 0.003 mm2 (3000 pm2) were not included either. This setting reduces the noise considerably.
Porosity was calculated as the sum of the cross-sectional areas measured for each pore divided by the total surface area of the four areas. Since the pore density is random and homogeneous, the porosity in the cutting plane can be assumed to be representative for the overall porosity.
Pore size distribution was calculated on the basis of the measured maximum pore depth (dmax) and the measured pore volume Vp. This was done for each pore separately. Use was made of the formula for the determination of the radius for a spherical cap: Vp = (l/3)n(3rb - dmax)dmax2, with R the radius, i.e. half the pore diameter. After reworking, this leads to rb = 1/3 * (3 * Vp / (n.dmax2) + dmax )• Herein, dmax is chosen to be positive rather than negative. The calculation assumes spherical pores.
Based hereon, a porosity of 13.2 % was found, and an average pore radius of 115 pm. Averaging of the horizontal feret generated by the software of the porosimeter, the average pore radius is 117 pm.
Claims
1. A construction panel comprising
- a porous cured core material having a density in the range of 0.75 to 0.95 kg/dm3 and provided with a composition comprising a set inorganic binder and cured cement powder, wherein the cured cement powder is present in an amount of at least 20wt% based on dry weight of the composition, and
- a fiber reinforcement embedded in the core material.
2. The construction panel as claimed in claim 1, wherein said cured cement powder has a particle size distribution with a d90-value of at most 100 pm as measured by air jet sieving, and a d25 value of at least 4 pm.
3. The construction panel as claimed in claim 1 or 2, wherein said cured cement powder comprises fibrous material in an amount of 2-10wt%, preferably 3-6 wt% based on dry weight of the cured cement powder.
4. The construction panel as claimed in any of the preceding claims, wherein said porous material has a porosity in the range of 10-20%.
5. The construction panel as claimed in claim 1-4, wherein said porous material has an average pore size in the range of 100-140 pm.
6. The construction panel as claimed in any of the preceding claims, wherein the composition comprises cement as a binder in an amount in the range of 30-70wt%, preferably 40-60wt%, based on dry weight of the composition, wherein the cement is preferably chosen from calcium sulfoaluminate cement and Portland cement, and more preferably is Portland cement.
7. The construction panel as claimed in any of the preceding claims, particularly claim 6, wherein the composition comprises cured cement powder in an amount of 30-50wt%, based on dry weight of the composition.
8. The construction panel as claimed in any of the preceding claims, further comprising a cellulose ether, such as hydroxyethylmethylcellulose.
9. The construction panel as claimed in claim 8, wherein the cellulose ether is present in an amount of at least 1.0 wt%, preferably at least 1.5 wt%, more preferably at least 2.0 wt% based on dry weight of the composition.
10. The construction panel as claimed in any of the preceding claims, wherein the core material is aircured.
11. The construction panel as claimed in any of the preceding claims, wherein the reinforcement is provided as at least one fiber mat, preferably comprising glass fibers.
12. Method of manufacturing a construction panel having a density in the range of 0.75 to 0.95 kg/dm3, comprising the steps of:
- providing an aqueous composition comprising an inorganic binder, such as cement, and cured cement powder and a foaming agent, wherein the cured cement powder is present in an amount of at least 20wt% based on dry weight of the composition, and
- providing a fiber reinforcement, for instance in the form of a fiber mat;
- casting the composition into a mould, with the fiber reinforcement being embedded therein;
- curing the composition into a core material of the construction panel, for instance by means of aircuring.
13. The method as claimed in claim 12, wherein the foaming agent is an anionic surfactant.
14. The method as claimed in claim 13, wherein water is present in the slurry in a ratio of water to inorganic binder in the range of 1 to 1.5.
15. The method as claimed in claim 12-14, wherein the composition further comprising cellulose ether, preferably in an amount of at least 1.0 wt% based on dry weight of the composition.
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EP22215366.0 | 2022-12-21 | ||
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