LV15331B - Bio-fiber and magnesium oxychloride cement multi-layer construction panel and manufacturing method thereof - Google Patents

Description

The present invention relates to the field of construction, in particular to load-bearing structures, thermal insulation and finishing materials, which are classified as a single building element and to methods of making them.

BACKGROUND OF THE INVENTION [0002] There are known bio-fiber cement blocks and panels of biological origin for use in construction. Bio-fibers are plant-based fibers such as hemp shoots, flax shoots, bamboo, reed, etc. stems. Organic fibers in the composite provide the functions of both lightweight aggregates and reinforcing elements, while the cement binder interconnects the fibers to form a matrix and provide the product with mechanical and functional properties. In order to prepare the binder mortar, it is first necessary to prepare an aqueous solution consisting of 36% by weight of MgO, 10% by weight of MgCl ₂ and 54% by weight of water. Add the prepared solution to the dry mixture of organic fibers following the prescribed procedure and mix mechanically (1).

Mineral-based binders (Portland cement, lime binder, or a mixture thereof) are predominantly used in the manufacture of biofiber composites for use in construction. These binders are available on the market, have a low cost, and do not contain volatile organic compounds (VOCs). Since the lightweight aggregate used in biocomposites is of organic origin, its curing under hydrothermal conditions is limited to 200 ° C.

[004] Curing of magnesium oxychloride cement (MOC) is related to the reaction of MgO and MgCl _{2 in the} aqueous medium [2J:

3MgO + MgCl ₂ + 11H ₂ O 3Mg (OH) ₂ MgCl ₂ · 8H ₂ O,

5MgO + MgCl ₂ + 13H ₂ O 5Mg (OH) ₂ MgCl ₂ 8H ₂ O.

[005] These reaction products are first mentioned in the 1866 patent for the production of Sorel cement [3] and later widely described in a publication in 1867 [4]. The ability of magnesium cements to cure and bind aggregates of various origins relatively quickly, from rocks of different origins (eg granite) to biological fibers (eg sawdust), to form composite materials with high compression and tensile strength, promoted the use of cement binder in various construction used in the manufacture of products. The use of magnesium cements has varied over time, ranging from decorative products (ivory, billiard balls, door handles) to structural elements (flooring, plasterboard [5] and polishing rails [6]). Magnesium cement products were widely used in the manufacture of ship decks between 1900 and 1950 due to the need for materials with high fire resistance and soundproofing properties [7, 8]. The widespread use of magnesium cements in the middle of the last century is largely due to the possibility of obtaining products with high compressive strength, which in some cases can reach 120 MPa [9] or even 140 MPa [2].

Nowadays, the application areas of magnesium oxychloride cement (MOC) have changed, being less used as flooring and plastering material, but increasingly being used as a binder for the production of building boards, which are successfully replacing traditional gypsum board sheets. This is based on the fact that MOC construction sheets have a high fire resistance because they require a large amount of energy to release chemically bound water under fire conditions.

[007] The ability of MOCs to interconnect bio-based aggregates is used to produce panels that are similar in appearance and properties to particle board and also exhibit increased fire resistance [10, 11]. Products of equivalent quality are available on the market and are made of MOC, perlite and particle board [12-14].

[008] Various binders (lime, cement and others) can be used to bind the fibers of biological origin [1]. Unlike lime-based binders, magnesium oxychloride cement (MOC) binders are more compatible with lightweight aggregates of biological origin, since their curing is much less affected by organic curing retardants, which are released in the basic environment from biological fillers.

[009] There is known a binder composition [15] in which the magnesium oxychloride cement composition is supplemented with mild volcanic ash. The disadvantage is the limited distribution and availability of this lightweight filler.

[010] The composition and method of making low-thermal conductivity magnesium oxychloride cement panel are known [16]. Microspheres, polystyrene foam granules or perlite have been used as light fillers for the production of these boards. The plate making process involves three basic steps: 1) MOC paste making; 2) adding light fillers to the MOC paste to form a mixture; 3) building a panel. This panel and its method of manufacture are accepted as a prototype. The disadvantages are as follows: the material has a relatively high density (over

I000 kg / m ³ ), which results in a relatively high thermal conductivity for the slabs and a high consumption of fillers and binders compared to the thermal insulation materials.

OBJECTIVE AND SUMMARY OF THE INVENTION The object of the invention is to provide a refractory construction panel with low density of biological fibers and a method of making it.

[012] To overcome the drawbacks of the prototype, it is proposed to form a panel of multiple layers of various densities consisting of widely available organic fiber-containing materials (hemp shives, reeds, etc.). The invention differs from the prototype in that the use of organic fibers as lightweight aggregates significantly reduces the density of the building panel and, thus, the thermal conductivity.

[013] Using different biofibre / mortar weight ratios and different applied pressures during the extrusion process, a multilayer construction panel is obtained with properties (apparent density, thermal conductivity, compressive strength) that vary from one layer to another (Fig. 3). ). Such a building panel has cover, decorative, heat insulating and thermoregulatory functions and can be installed vertically. Thanks to the multilayer panel structure, the product has both load-bearing structural features (provided by a barrier / outer layer with an apparent density of 400 to 450 kgnr ³ and a thermal conductivity of 0.09 to 0.10 W m '-K' ¹ ) (Fig. 2). ) and heat-insulating functions (provided by panel inner layers with apparent densities of 200 to 250 kgnr ³ and thermal conductivity from 0.058 to 0.065 Wnr ^L K ') (Figure 2). The fire resistance of the panel is provided by magnesium oxychloride cement, which can be raised by a refractory coating layer containing a hollow ceramic microsphere, as described in one embodiment.

[014] The multilayer panel is made by filling the binder and filler mixture in a layered form and pressing. Table 1 shows the layer thicknesses and the compression pressures used to make the panel-forming layers.

[015] The multilayer panel consists of at least three layers (Fig. 3): two outer layers (7) and one inner layer (6). Preparation of outer layers (7): Magnesium oxide is added to the mix, moistened with hemp or flax, bamboo, reed or other stems, sprayed with a solution of magnesium chloride salts. The resulting mixture is filled into pre-prepared molds and pressed. The molds (Fig. 1) consist of vertical (1) and horizontal (2) parts - molds.

Table 1

Parameters of the manufacturing process of the panels forming the panel

Layer thickness before pressing, cm Thickness of the layer after pressing, cm Pressing pressure, MPa Outer layer 2-20 1-10 0.05-0.50 Inner layer 7-35 5-20 0.01-0.10 Refractory coating 1-4 * * * - No additional pressure is used

[016] Preparation of Inner Layer (6): Magnesium oxide is added to the stirred, moistened hemp or flax spatula, bamboo, reed or other stem, and sprayed with a solution of magnesium chloride salts. The resulting mixture is filled into a mold and pressed at a lower pressure than the outer layer.

[017] Preparation of Refractory Coating (8) (Fig. 4): After hardening of the panel, a mortar / ceramic hollow microspheres mixture is applied to it within 24 hours. Ceramic hollow microspheres at the same time have low thermal conductivity and high thermal stability (up to 1100 ° C), high softening temperature and low linear expansion coefficient, their use provides high thermal stability and low thermal conductivity of the coating.

The present invention provides a multilayer construction panel with improved fire resistance and physico-mechanical properties (apparent density, thermal conductivity, compressive strength), which change step by step from one layer to the next, as shown in Figure 4.

[019] The invention is explained by the following drawings:

Fig. 1 Form of production of organic aggregates and MOC multilayer building panel (3) consisting of vertical (1) and horizontal (2) molds.

Fig. 2 Dependence of hemp fiber and magnesium oxychloride cement composite compression strength (MPa, left vertical axis) and thermal conductivity (W m 'K' ¹ , right vertical axis) on hemp spatula dimensions.

Fig. 3 Schematic representation of the bio-based aggregates and MOC multilayer building panel (above): bio-fiber / lightweight aggregates (4); MOC binder (5); an inner layer (6); outer layer (7). The relative stepwise changes in the physical properties of the individual layers of the multilayer panel are shown in the diagram (bottom): outer layer properties (i), inner layer properties (ii). The 'x' axis is the cross-section of the sample and the 'y' axis the physical properties (apparent density, thermal conductivity and l / compression strength or Ф ' ¹ ).

Fig. 4 Schematic representation of bio-based aggregates and MOC multilayer construction panel with refractory coating (top): bio-fiber / lightweight aggregates (4); MOC binder (5); an inner layer (6); an outer layer (7); refractory coating (8); Ceramic hollow microspheres (9). The relative stepwise changes in the physical properties of the individual layers of the multilayer panel are shown in the diagram (bottom): outer layer properties (i), inner layer properties (ii), and refractory coating properties (iii). The x-axis represents the sample cross-sectional length and the y-axis the physical properties (apparent density, thermal conductivity, l / compressive strength or Ф ' ¹ ).

Fig. 5 Schematic representation of the bio-based aggregate and MOC multilayer building panel with refractory coating and density gradient (above): bio-fiber / lightweight aggregate (4); MOC binder (5); an inner layer (6); an outer layer (7); refractory coating (8); Ceramic hollow microspheres (9). The relative stepwise changes in the physical properties of the individual layers of the multilayer panel are shown in the diagram (bottom): outer layer properties (i), inner layer properties (ii), and refractory coating properties (iii). The x-axis shows the cross-sectional length of the sample and the y-axis the physical properties (apparent density, thermal conductivity, l / compressive strength or Ф ¹ ).

EXAMPLES FOR CARRYING OUT THE INVENTION Example 1: The method of obtaining a lightweight aggregate and MOC multilayer building panel of biological origin comprises making an outer (7) and inner (6) layer which differ in density and thermal conductivity (Fig. 3). To obtain layers with different properties, the biofibre MOC mass is pressed at different pressures or a different biofibre MOC mass ratio is used (Fig. 2). The outer layer is obtained by pouring 21% (w / w) of a biological filler, hemp spools with a fiber length of 2 to 20 mm (hereinafter referred to as "bio-fiber") into a forced mixer and agitating at 50-60 rpm. 26% by weight of water is sprayed evenly on the spatulas within 30 seconds. After adding water, the shakes are stirred for another 60 seconds. Without stirring, add 32% by weight of magnesium oxide over a period of 20 seconds. Stir the mass for another 60 seconds. Spray a mass of 21% (w / w) of a 23% (w / w) MgCl2 solution in water over a period of 30 seconds, from a single sprayer on a single mass sprayer. Stir the mass for another 60 seconds. The resulting mixture is filled into a mold in a layer 2 to 20 cm thick and pressed at 0.05-0.50 MPa. The inner layer is obtained as follows: 29% by weight of the bio-fiber is poured into the forced mixer. In a mixer operating at 50-60 rpm, 37% by weight of water is sprayed onto the presses evenly for 30 seconds. After adding water, the shakes are stirred for another 60 seconds. Without stirring, add 15% by weight of magnesium oxide in powder form with a particle size of d9o = O2 mm for 20 seconds. Mass stir for 60 sec undes. Within a period of 30 seconds, 19% by weight of an aqueous solution of magnesium chloride (11.5% by weight of MgCl 2) is sprayed uniformly onto the surface of the individual sprayer. Stir the mass for another 60 seconds. The resulting mixture is filled into a mold over the outer layer in layers 7 to 35 cm thick and pressed at 0.01 to 0.10 MPa pressure until the desired layer thickness is 5 to 20 cm. Then another (sealing) outer layer is applied over the inner layer using the outer layer fabrication technology described above. After the cement mass has hardened within 24 hours, it is rendered from both vertical and horizontal molds (Fig. 1). The multi-layer panel so manufactured cannot have a size greater than 49.5 x 25.0 cm and a thickness between 20 and 60 cm.

[021] Example 2: The multi-layer construction panel is made analogous to Example 1, in that, after the MOC hardens, the panel is rendered only from horizontal molds (Fig. 1), leaving the vertical molds. The multilayer panel thus made has dimensions from 49.5 x 25.0 cm to 300 x 250 cm, and its thickness ranges from 20 to 60 cm.

[022] Example 3: The multi-layer construction panel is made analogously to Example 1, being different from making the inner layer - that is, with 30% less binder content: 33% by weight of bio-fiber is poured into the forced mixer. In a mixer operating at 50-60 rpm, 41% by weight of water is sprayed onto the presses evenly for 30 seconds. After adding water, the shakes are stirred for another 60 seconds. Without stirring, add 11% by weight of magnesium oxide over a period of 20 seconds. Stir the mass for another 60 seconds. 15% by weight of an aqueous solution of magnesium chloride (with a MgCl2 concentration of 11,5% by mass) is uniformly sprayed over a mass on a single sprayer over a period of 30 seconds. Stir the mass for another 60 seconds. The resulting mixture is filled into panel frames on top of the outer layer in layers of 7-15 cm and pressed at 0.05-0.50 MPa until the desired layer thickness is achieved. Then apply another outer layer according to the method described above. After the cement mass has hardened, it is formed from both vertical and horizontal forms within 24 hours. The multi-layer panel so manufactured cannot have a size greater than 49.5 x 25.0 cm and a thickness between 20 and 60 cm.

[023J Example 4: The multilayer building panel is made analogous to Example 3, in that after the MOC has cured, the panel is rendered. The multilayer panel thus made can be up to 49.5 x 25.0 cm in size and 20 to 60 cm in thickness.

[024] Example 5: The multilayer panel is made analogously to any one of l. up to Example 4, characterized in that an additional layer of ceramic hollow microspheres / MOC mortar, with a microspheres content of 20 to 60% by volume (Fig. 4) with a thickness of 1-4 cm, is added to the outer layer, thereby forming one refractory coating (covering the panel from the outer layer) or two refractory coatings (8) (Figure 4), covering the panel on both sides. The size of the ceramic hollow microspheres is between 50 and 150 pm. Ceramic hollow microspheres at the same time have low thermal conductivity and high (up to 1100 ° C) thermal stability (high softening temperature and low linear expansion coefficient). The result is a multilayer construction panel with increased fire resistance and improved physical-mechanical properties (apparent density, thermal conductivity, l / compressive strength), which change in leaps and bounds from layer to layer (Fig. 4).

[025] Example 6: The multilayer panel is made in analogy to any one of l. for example 4, characterized in that the ceramic hollow microspheres have a size of 20 to 300 µm, thus forming one or two refractory coatings (8) (Figure 5) with different densities.

[026] Example 7: The multilayer panel is made analogously to any one of l. for example 6, different in that the inner layer is made with less pressure. After forming the outer layer as described in l. or In Example 2, the spatula mortar mixture is filled into panel substrates on top of the outer layer in 5 to 10 cm thick layers and pressed at 0.01 to 0.03 MPa pressure until the desired layer thickness is achieved. Then apply another outer layer according to the method described above.

[027] A mixture (biocomposite) is obtained from bio-fibers (such as hemp spikes), which are considered as agricultural waste, and magnesium oxychloride cement, which can be used for the production of low-thermal conductivity wall insulation material. Compressing the molded biofibre MOC at a certain pressure across the layers yields ready-made wall panels with good thermal properties that can be used in both low-rise and high-rise construction. The increased fire resistance of the panel is provided by the binder used (magnesium oxychloride cement) and the refractory coating containing ceramic hollow microspheres.

[028] Biofiber and Magnesium Oxychloride Cement (MOC) multilayer panel combines the best properties of the raw materials used: the porosity and pore size of the biofiber filler (such as hemp spatula) provide low thermal conductivity and high humidity buffering, thereby ensuring optimal indoor comfort for the individual. temperature and humidity. In contrast, the high strength and good adhesion of magnesium oxychloride cement to biofibres provide the necessary strength for the biocomposite functionality. The panel fabrication technique allows optimization of layer density and thickness: more mechanically and denser layers of material are placed on the outside of the panel, while less dense layers are placed inside the panel and vary the thickness of the layers (5 to 20 cm). physical properties) and consumption, but also significantly improve the thermal performance of the panel.

Sources of Information Used [J.G. Berg and R. Smith-Johannsen, "Water and Fire Resistant Building Material," EP0241103 Al, 1987.

[2] B. Xu, H. Ma, C. Hu, S. Yang, and Z. Li, "Influence of curing regimes on mechanical properties of magnesium oxychloride cement-based composites," Construction and Building Materials, vol. 102, p. 613-619, 2016.

[3] S. Soeel, "Stanislas soeel," US53092 A, 1866.

[4] S. Sorel, "Sur and Nouveau Ciment Magnesien," by C. R. Hebd. Sed nces Acad. Sci., Vol. 65, p. 102-104, 1867.

[5] J. B. Shawl and G. A. Bole, "NEW DEVELOPMENTS IN OXYCHLORIDE STUCCO AND FLOORING 1," Journal of the American Ceramic Society, vol. 5, no. 6, p. 311-321, Jun. 1922

[6] S. Malkin and C. Guo, Grinding Technology: Theory and Applications of Machining with Abrasives. Industrial Press: New York, 2008.

[7] J. H. Paterson, "Magnesium oxychloride cement," Journal of the Chemical Industry, vol. 43, no. 9, p. 215-218, Feb. 1924

[8] E. F. Greenleaf, "Rubber deck covering used on ships," Bur. Ships, J., vol. 1, no. 3, p. 26-29, 1952.

[9] Y. Li, H. Yu, L. Zheng, J. Wen, C. Wu, and Y. Tan, "Compressive strength of fly ash magnesium oxychloride cement containing granite wastes," Construction and Building Materials, vol. 38, p. 1-7, 2013.

[10] F. Prymelski and V. Zur, "Xylolith Building Boards and Sheets," US 3788870 A, 1974.

[11] F. Prymelski, "Building Materials in the Form of Woodstone Panels or Sheets and Processes for Their Production", US 4150185 A, 1979.

[12] Magnesium Oxide Board Corporation, “Magnesium Oxide Board Corporation Product

Range, ”2017. http://mgoboard.com.au/product-ranges/. [Viewed 04/01/2017] [13] Euroform, Euroform product range, 2017. http://www.euroform.co.uk/abouteuroform-products-limited/. [Viewed 04/01/2017] [14] Μ. E. Feigin and T. S. Choi, "Magnesium Oxide-Based Construction Board," US 7998547 B2, 2011.

[15] G. E. Caine and C. W. Ellis, "Magnesium Oxychloride Cement," WO2008063904 A2, 2008.

[16] J. Gillman, "Magnesium Based Cement Board Composition to Lower Thermal Conductivity," US20160304401 Al, 2016.

Claims (6)

1. Magnesium oxychloride cement (MOC) multilayer panel consisting of at least three layers: first and second outer layers having a higher density and one inner layer having a lower density disposed therein, characterized in that said layers contain biofibres with a length from 2 to 20 mm. The multilayer panel according to claim 1, further comprising a refractory coating having a thickness of 1 to 4 cm applied to one or both outer layers and containing a ceramic hollow microsphere / MOC mortar with a microsphere content of 20 up to 60% by volume. A method of making a multilayer panel according to claim 1 or 2, comprising the following sequential steps: (i) making the first outer layer by mixing 21% by weight of bio-fiber and adding 26% by weight of water while stirring, then adding 32% by weight of powdered magnesium oxide with a particle size d9o = O2 mm without stirring and mixing from a separate nebulizer to the resulting mass surfaces are sprayed with 21% by weight of an aqueous solution of magnesium chloride (23% by weight of MgCE), the resulting mixture is uniformly filled in a form having a thickness of between 2 and 20 cm and a pressure of 0.050.50 MPa; (ii) Preparation of the inner layer: 29% by weight of bio-fiber is added to the mixer, 37% by weight of water is sprayed, then without stirring, 15% by weight of powdered magnesium oxide with a particle size d9o = O2 mm is sprayed. of the magnesium chloride salt solution (at a concentration of 11.5% by weight), the resulting mixture is filled into a mold over the outer layer in layers of 7 to 35 cm thick and pressed at 0.01 to 0.10 MPa pressure until the desired layer thickness is 5 up to 20 cm; (iii) making the second outer layer: the layer is made analogous to step (i), then, after the cement mass has cured within 24 hours, the panel is rendered. A process according to claim 3, characterized in that in step (ii), 33% by weight of said biofibre is mixed with 41% by weight of water to form an inner layer and 11% by weight of powdered magnesium oxide is added with stirring, 15% chloride saline (11.5% w / w) and stir for an additional 1 minute. Process according to claim 3 or 4, characterized in that in step (ii), the mixture obtained for the production of the inner layer is pressed at a pressure of 0.01-0.03 MPa. ll A method according to any one of claims 3 to 5, characterized in that, after curing the cement mass, the panel is rendered within 24 hours from horizontal molds and optionally from vertical molds.