WO2014086971A1

WO2014086971A1 - Building material comprising bamboo fibers and method for producing such a material

Info

Publication number: WO2014086971A1
Application number: PCT/EP2013/075795
Authority: WO
Inventors: Lothar Rauer; Gisela SCHROTH; Christoph Grieger
Original assignee: Lothar Rauer
Priority date: 2012-12-07
Filing date: 2013-12-06
Publication date: 2014-06-12

Abstract

The present invention relates to a building material including a mineral content, especially cement content, and a fiber content, wherein the fibers of the fiber content include bamboo fibers, wherein at least some, especially all, of the bamboo fibers have a fiber length l_fiber within a range from greater than or equal to 25 mm to less than or equal to 60 mm and an aspect ratio λ within a range of less than 100. The present invention further relates to a method for producing a construction material.

Description

BAUMATERIAL CONTAINING BAMBOO FIBERS AND METHOD FOR MANUFACTURING SUCH A

The invention relates to a building material and a method for producing a building material.

In the construction industry of modern times, the use of additional substances to hinder crack propagation in building materials or materials is currently geared primarily to loosely installed steel fibers and micro-steel fiber fabrics, which are offered as profiled wires, specially made chips or fine mesh fabrics from different manufacturers , The steel fibers are used for reinforced shotcrete walls in tunnel construction and for heavily loaded industrial floors. Steel wire meshes are said to be used, for example, in the manufacture of high performance ductile concrete, such as that known by the trade name DUCON. In addition, synthetic fibers, for example made of polyacrylonitrite with <1.5 vol .-%, especially in fine-grained mineral mixtures were used. In addition, with organic fibers or glass fibers in thin-walled concrete products to be prefabricated, important utility properties such as mechanical strength and flexural strength have been significantly improved instead of the asbestos fibers also used previously. This applies even more to the above-mentioned special concrete DUCON. In this case, purchase costs of> 1.50-2.00 € / kg, eg for short glass fibers and their not always sufficient resistance to alkalis or expensive special components such as micro-steel mesh, can limit the broad use of such materials. Bamboo particles as natural fiber aggregates for high strength concrete have not hitherto been used industrially for the above reinforcement tasks. However, document EP 1 151 972 A1 describes, for example, a process for the preparation of reaction resins and fiberized mineral mixtures, in particular concrete mixtures, wherein intended fillers, such as bamboo fibers, are particularly designed to have a property-improving effect in the mineral or concrete mixture.

With respect to a variety of properties of building materials, especially cementitious building materials, there is still room for improvement.

It is therefore the object of the present invention to provide a construction material which is improved in comparison with the building materials known from the prior art, in particular cement-containing construction material.

This object is achieved by a building material according to claim 1. This object is further achieved by a method for producing a building material according to claim 3. Preferred embodiments are specified in the subclaims. The embodiments and features described below can be combined as desired, unless clearly the opposite results from the context.

The present invention relates to a building material, comprising a mineral portion, in particular cement portion, and a fiber portion, wherein the fibers of the fiber portion comprise bamboo fibers, wherein the bamboo fibers at least partially, in particular completely, a fiber length 1ρ _α5εΓ in a range of greater than or equal to 25 mm less than or equal to 60 mm and a slenderness degree λ in a range of less than or equal to 100, for example less than or equal to 90, in particular less than or equal to 75, have.

By a building material according to the present invention, it becomes possible, the bamboo construction use especially after a special mechanical treatment with predominant decomposition into fibrous particles with adjustable high degree of slimming λ at λ <100 without or with subsequent process stages to improve the adhesion forces in the respective used mineral matrix such that the use of the particles and their disordered or ordered installation conditions for the transfer of tensile and / or bending loads, for hindering the formation of local cracks and to improve the impact or impact behavior including the energy dissipation and vibration propagation can be achieved.

The degree of slimming λ according to the present invention can be defined in particular as the ratio of length 1 of the fiber to the average thickness d: λ = 1 / d.

In addition, bamboo particles are referred to below as a generic term, wherein the bamboo particles may have specially shaped or configured bamboo fibers.

The invention thus relates to the technical field of the construction material use of bamboo occurring in a large variety of species to him after a mechanical treatment in particular comprising a decomposition into predominantly uniform fibrous particles with adjustable high degree of slimming λ at λ <100 without or with adjoining Process steps to improve the adhesion forces in the mineral matrix used in each case disorderly or orderly incorporated in this and thus conditions both for the transmission of tensile and / or bending loads, for hindering the formation of local cracks and to improve the shock or impact behavior Finally, the energy dissipation and vibration propagation to get. The solution according to the invention provides that the bamboo processed into fibers and / or fiber bundles, depending on the application with variable fiber bundle length and fiber bundle distribution and variable fiber or fiber bundle fractions, is either added to the respective matrix system during its production from various components it is further processed together and then comes in the form of a fiber-reinforced matrix as to be treated with traditional building technologies mounting mass on the site or in special prefabricated components for use. This can be realized in a targeted manner, for example, as a bed of loose fibers or in the form of prefabricated bamboo fiber nerves, as a two-dimensional thin sheet with random fiber and / or ordered structures, as network structures of different surface density or disordered. Further, the bamboo fibers may be incorporated in the matrix or added during incorporation of the mineral mixture. The high-strength, especially coarse-fiber bamboo _fiber particles proposed for the transmission of tensile and / or bending loads, for the prevention of the formation of local cracks and for the improvement of the impact behavior, including the energy dissipation and vibration propagation, can be used with d _fibers > 0.5 mm and lengths in the range 25-30 mm <1ρ _α5εΓ ^ 50-60 mm are used.

The extreme bending and tensile load properties of the bamboo straw with its exemplary fiber cell content <50% can also be used in individual bamboo fiber particles / bundles. This may be due to the fact that the bamboo fiber bundles used predominantly have tensile and flexural strength properties comparable to the structural steel, in particular because at least 100-150 individual fiber cells (with 0γζ 15-30 μιη, 1 mm 2) correspond to the above geometric criteria l pz ^ 3 mm) can be contained in the fiber bundle cross-section to be installed practically and, depending on the length of the fiber bundle, approximately 25-50 individual fiber cells can be strung together. Suitably, the fiber content of the bamboo fibers, in particular depending on the design of the bamboo fibers, in the building material, a proportion in a range of less than or equal to 70%, for example in a range of greater than or equal to 20% to less than or equal to 70%, approximately a range of less than or equal to 50%, with the volume duties being% by volume. In principle, the proportion should be selected such that a desired effect, in particular amplification effect, occurs.

Furthermore, it can be provided that the bamboo fibers have a reaction resin on their surface, in particular wherein a mineral substance is present on the surface of the reaction resin.

In this case, the reaction resins may be, in particular, those which are insensitive to moisture, ie in particular remain stable even in the presence of moisture. In addition, reaction resins can be understood as meaning, in particular, a solid or, in particular, liquid or liquefiable resin which can cure by itself or with reagents, such as a reaction accelerator or a hardener, preferably without elimination of volatile components by polymerization or polyaddition. In particular, an epoxy resin can be used. The resin may be further used in a ratio of 1 mass unit of the reaction resin to 3-10 mass units of bamboo particles. Furthermore, fine-grained, mineral substances such as rock flour, finely ground quartz sand, cement, lime and / or power plant filter ash can be dusted to cover the resin surfaces with fine-grained on the reaction resin surfaces to a maximum of 50% of its particle size, the ratio of finely divided covering substance to be added to the raw fibers can be <1.4-2.0 and the same surface treatment procedure can also be used for bamboo fibers of different thickness and length arranged in a planar manner in nonwovens or fabrics. With regard to further technical features and advantages of the building material according to the invention, reference is hereby explicitly made to the explanations in connection with the method according to the invention and the exemplary embodiments, wherein in the method and the embodiments mentioned features and advantages of the present invention are transferable to the described building material and vice versa, insofar not explicitly described otherwise.

The present invention further relates to a method for producing a particular cement-containing building material, wherein bamboo fibers after a preceding mechanical treatment, in particular comminution, a mineral constituents comprising matrix, in particular a cementitious matrix, are added, the bamboo fibers at least partially, in particular completely, a fiber length l have a _fiber in a range of greater than or equal to 25 mm to less than or equal to 60 mm and have a slenderness degree λ in a range of less than or equal to 100.

In this case, the fiber content of the bamboo fibers in a range of less than or equal to 70%, based on the building material, lie, wherein the above-described values are in particular% by volume. With regard to the bamboo fibers or bamboo particles used, these can be added in particular in the form of prefabricated thin unidirectional fiber scrims, as fiber webs, as a loose fiber bed of different thickness or as loose fiber particles of the mineral matrix. In addition, adding the bamboo particles or the bamboo fibers or bamboo fiber bundles to the particular cementitious matrix, in particular together with a mixing, in a completely or predominantly consisting of mineral constituents matrix both with the components before the mixing process and in the finished mixture. The above-described method is particularly suitable for the construction material use of fibers / fiber bundles made of bamboo, the fibers or fiber bundles after a preceding treatment with process stages such as multi-stage comminution with or without hydrothermal and biological pretreatment of the feed, fine crushing and classification and with or without an application-related surface treatment in a matrix consisting entirely or predominantly of mineral constituents to increase the ability to dissipate energy, to increase the resistance to impact and impact stress, to hinder cracking and to transfer tensile and / or bending loads across the edges of cracks In addition, the high-strength bamboo particles provided for use as reinforcements for bending, impact and / or tensile forces are arranged in the form of prefabricated thin unidirectional fiber scrims, as fiber webs with and / or without preferred layers of the nonwoven components, as a loose fiber bed of varying thickness with or without alignment of the fiber particles or as loose fiber particles in the mineral matrix ordered or randomly incorporated in the matrix.

In this case, a hydrothermal pretreatment can be understood as meaning, in particular, a cooking process for dissolving structures in the sense of improved comminution, and a biological pretreatment of the feed material can be understood as meaning, in particular, the use of enzymes with comparable technological goals. In this case, an optionally applicable pretreatment process can be chosen technologically and economically.

For coarse-fiber bamboo fiber particles, fiber fractions <6% by volume are particularly suitable for geometrical conditions such as _fiber > 0.5 mm and 1 _fiber <60, in particular <50 mm, which are> 75 masses. % in the fiber production process can have adjustable length / diameter ratios of, for example, greater than 50 to, for example, less than or equal to 80 or less than 100, and for two-dimensional fabrics and / or mesh fabrics. bamboo fiber contents are to be used in the mineral matrix to be reinforced <10% by mass, and that finely divided bamboo particles with length / diameter ratios < _20-50 and at proportions of _20-70 % by volume and dF _aser <0.5 mm and he <10 mm can be used as fillers and / or process fibers in each of the aforementioned bamboo fiber reinforcement options.

More preferably, the individual fibers or fibers present in flats or fabrics of the bamboo fibers can be pretreated to improve the adhesion between them and the surrounding mineral particles, in particular before the incorporation of a treatment to improve their adhesive properties by the mechanically processed, ie in particular crushed , and subjected to a treatment according to the subsite installation conditions moisture side adjusted fibers surface sealing and to improve the adhesion properties in the mineral matrix. Such a treatment is in particular a treatment with moisture-insensitive reaction resins, preferably an epoxy resin, in a ratio of 1 mass unit of reaction resin to 3-10 mass units of bamboo particles or bamboo fibers, wherein the bamboo fibers can be sprayed and / or mixed with the reaction resin. The fibers can then be dusted with fine-grained, fine-grained, mineral substances such as rock flour, in particular finely ground quartz sand, cement, lime and / or power plant filter ash, in particular on the reaction resin surfaces to cover at most 50% of their particle size, to cover the resin surfaces the finely divided covering substance to be added to the raw fibers should be <1.4-2.0. The same surface treatment procedure can accordingly be used for flat-layed bamboo fibers of varying thickness and length arranged in nonwovens or woven fabrics.

Preferably, it may be provided that in hydraulic-setting mineral matrix systems or cement-containing matrix systems to be reinforced with bamboo fibers. With regard to the mineral fraction of the building material, a limitation to a largest particle with a diameter of <16 mm takes place as well as the adjustment of the flour grain fraction of the mineral fraction with άκ <0.125 mm to 400 kg / m ³ and the fine grain fraction of flour meal and fine sand with άκ <0, 25 mm to 450 to 500 kg / m ^{3 is} made. The latter can be realized in a manner known to those skilled in the art by separate weighing and feeding, which can often already run programmatically in concrete mixing plants. It can be provided in particular that in particular in a bamboo fiber use in self-compacting concrete (SCC) and a higher flour meal and Feinstsandgehalt is possible, and that for concrete venting a sufficient flow path can be ensured. Furthermore, it should be possible for the bamboo fibers to align themselves in the direction of flow when the concrete flows. Regarding alignment, flowable systems such as concrete with energy-efficient added particles of a suitable degree of slimming occupy a position in the system that corresponds to the lowest flow loss so that alignment with sufficient flow can be easily adjustable, with a slenderness factor of less as 100 may already be enough. However, it is understandable to the person skilled in the art that, especially in the case of a bamboo fiber orientation justified by the above effect, the degree of slimming can be adapted to the corresponding properties of the building material. In concrete technology, all parts of the aggregate between 0 and 0.125 mm are referred to as flour meal. These include the fractions of ultrafine sand (0 to 0.25 mm), which are finer than 0.125, as well as the cement and any concrete admixtures (eg stone dust, fly ash, color pigments, etc.).

Further advantageously, it can be provided that the bamboo fibers or bamboo fiber bundles with proportions <30% by volume are used at dF _aser <0.5 mm and he <10 mm as process fibers, preferably for the production of fiber cement boards.

In a further embodiment, before being added to the hydraulically setting mineral matrix system, that is to say in particular to the cement matrix, a period of up to 50 hours may be included. - lo

Send water storage of bamboo fibers or bamboo fiber bundles can be connected upstream. In this way, an advantageously suitable moisture content can be adjusted, wherein already depending on the desired effect a brief immersion of the bamboo fibers in water can be sufficient.

In a further embodiment, the bamboo fibers or the bamboo fiber bundles in particular by several hours of storage, mixing, spraying or sprinkling in or with a basic, in particular adjusted to pH> 12 alkaline medium, in particular NaOH, as an aqueous solution, or with other chemicals such as water glass or maleic acid. Optionally, additional drying operations may be performed prior to fiber usage as reinforcing and / or reinforcing material. This embodiment can in particular serve the desired influencing of fiber surface properties and / or the capillary properties of the bamboo fibers or the bamboo fiber bundles.

Further advantageously, in the bamboo fiber production resulting finely divided dry bamboo particles (dpart <0.5 mm, t <0.5 mm, moisture content <12 - 13%) with cement and / or dry mortar in the mass ratio 1 to 2 to 1 to 6 mixed dry and then with the addition of finely divided water in a slowly rotating about its longitudinal axis, eg formed as a drum mixer of known type aggregate to more or less spherical granules with dependent on the application individual diameters of 3-4 mm to 8-10 mm. In this case, the small particles or the granules before being used as light granules can be subjected for at least 24 hours to a setting and drying process and a final classification process for the separation of insufficiently granulated fines.

In a further embodiment, finely divided dry fibers obtained in bamboo fiber production can be obtained

<0.5 mm, lpart <0.5 mm, moisture content <12 -13%) with longer fine particles Particle fibers (d _Part <0.5 mm, l _Part <10 - 12 mm, moisture content <12 - 13%) in proportions of 2 to 6 to 1 together the Leichtgranulatherstellung abandoned and processed and that the setting, drying and Classification process a surface treatment comprising a treatment with resin and optionally minerals, for example, as explained above in detail, be followed.

In a further embodiment, an alignment of bamboo fibers in the mineral matrix by their deliberate spreading in zugbeanspruchte cover layers, by applying bamboo fiber webs and / or textile bamboo fiber fabrics with subsequent covering with a mineral matrix layer with a thickness of "50 mm (in contrast for concrete use practice> 50 mm) or can be achieved by applying an electrostatic field with a turn-on voltage of <20 kV for a period of <60 seconds. It has been found that the bamboo particles in such an electrostatic field align themselves in the direction of the field lines and thus cause additional bending strength increase effects by the orientation.

In a further embodiment, for the bamboo fibers or bamboo fiber bundles equipped mineral matrix systems known aftertreatment steps such as microwave irradiation to accelerate Abbindevorgängen, the smoothing of surfaces analogous to the known procedures such as in fiberless concrete and / or sealing measures are classified.

For example, in the bamboo fiber production resulting first particles having a fiber thickness d _Part <0.5 mm, a fiber length l _Part <0.5 mm, a moisture content <12 -13% with second particles with a fiber thickness d _Part <0.5 mm one Fiber length l _Part <10 - 12 mm and a moisture content <12 - 13% in an amount ratios of 2 to 6 of the first particles to 1 of the second particles are added together with the bamboo fibers added, in particular wherein a prescribed surface treatment comprising the Application of a reaction resin and mineral substances can be carried out accordingly for the bamboo particles.

Considering the above, the method thus relates to the technical field of the construction material use of bamboo to him after a special mechanical treatment with predominant decomposition into fibrous particles with adjustable high degree of slimming λ at λ <100 without or with subsequent process steps to improve the To incorporate adhesion forces in the mineral matrix used in each case disorderly or ordered in this and thus to obtain conditions for both the transmission of tensile and / or bending loads, for hindering the formation of local cracks and to improve the impact or impact behavior including energy dissipation and vibration propagation ,

The high-strength, especially coarse-fiber bamboo fibers proposed for the transmission of tensile and / or bending loads, for the prevention of the formation of local cracks and for the improvement of the impact behavior, including the energy dissipation and vibration propagation, can be used with d _fiber > 0.5 mm and lengths in the range 25-30 mm <l _fiber <50-60 mm are used. The solution according to the invention provides that the raw bamboo processed into fibers and / or fiber bundles, depending on the application with matched fiber bundle length and fiber bundle thickness distribution and variable fiber or fiber bundle fractions with or without pretreatment of the fiber components for influencing their surface properties of the respective matrix system in shape prefabricated thin unidirectional fiber fabric, as fiber webs with and / or without preferred layers of the nonwoven components, as a loose fiber bed of different thickness with or without alignment of the fiber particles or as loose fiber particles in the mineral matrix are installed. To achieve depending on the particular application of additional input properties of bamboo fiber fleeces and / or bamboo fibers or bamboo fiber bundles special pretreatment stages such as impregnation for influencing the Schwindverhaltens, chemical and / or physical treatment of the fibers for influencing Faseroberflächen- and deformation properties as well as additional drying operations are provided.

Likewise, for the fiber-reinforced matrix systems as a further embodiment features of the invention, after-treatment steps such as special measures for fiber orientation, surface treatment and / or sealing measures can be classified.

Further refinement features of the invention may be special pretreatment stages for the chemical and / or physical treatment of the fibers, for fiber orientation and for influencing fiber surface and other material properties.

EXAMPLES

The following conditions may apply to products from the abovementioned system variants that are to be taken into account in the yield assessment:

The following experimental, operational and exemplary embodiments illustrate the invention in more detail without the invention being restricted to the following examples:

First embodiment

As an application test of untreated bamboo fibers for previously steel fiber-reinforced industrial floors, the attempt should be made to ensure the same parameters for steel fiber substitution with bamboo fibers as for steel fiber concrete, in particular with regard to compressive and flexural strength. Steel fibers to be used in accordance with the technology were used Bamboo fibers of variable thickness with άρ _α5εΓ ^ 2 mm and length 1ρ _α5εΓ <30 mm in proportions of 2.5 kg / m ³ , 3.0 kg / m ³ and 3.5 kg / m ³ replaced. The addition of the bamboo fibers was carried out during the dry metering of the aggregates in order to ensure the greatest possible mixing time of the bamboo fiber mineral mixture.

For the pressure test (after 7 and 28 days) cubes were made with 15 cm edge length; The determination of the 28-day bending tensile strength was carried out with the aid of prisms (70 cm × 15 cm × 15 cm and 110 cm × 30 cm × 15 cm). For the evaluation of the tests prepared and carried out according to DIN 1048 as well as for the evaluation of the achieved test results, the assessment bases valid for industrial floors made of steel fiber concrete were used. The pressure test according to DIN 1048 gave the following values:

37-38 N / mm ² after 7 days,

- 51.5-53.5 N / mm ² after 28 days.

The determination of the bending tensile strength ß _ß z was carried out mathematically after carrying out bending tensile tests according to DIN 1048. ß _ß z values between 3.6 and 4.2 N / mm were determined. It should be noted that no noteworthy fiber cracks in the fracture zone can be seen from the fracture pattern of the destroyed samples with the bamboo fibers evenly distributed in the concrete. It should be noted that it has been possible with a relatively small amount of fiber (2.5-3.5 kg / m ³ corresponding to 1-2 M.) in the industrial experiment to achieve mechanical properties of the fiber concrete as they with the addition of 25 kg steel fibers / m ³ can be achieved.

Remarkable is the stronger hardening of the test specimens compared to steel fiber reinforcements, which is accompanied by the delay of the rate of hydration of the cement by the o.g. Bamboo fiber components is explainable.

The comparison of the test results with the average values from the technology monitoring at the sample processor (a ₇ d pressure = 23.65 N / mm ² , a ₂ 8d pressure = 31.5 N / mm ² ) shows that the objective of comparable mechanical properties at bamboo-reinforced concrete (on the example of concrete quality B 25) clearly outbid has been. Values for Ö7d pressure and for Ö28d pressure are 55-65% higher than the reference values.

Second embodiment

For the economic production of surface-treated bamboo fibers with high bond strengths in the concrete matrix, 3 aggregates connected in series were used. In the first unit designed as a continuous or batch mixer, 3-10 kg of bamboo fibers per 1 kg of synthetic resin coating material were added and mixed, depending on the viscosity of the synthetic resin, until a uniform wetting of the fiber surfaces or a complete synthetic resin film formation was ensured on them , Necessary mixing times of 10-12 minutes, e.g. with a resin having the viscosity of 400 mPas, could be significantly shortened by spraying the resin over the one or more pulse addition. In the downstream second unit, which was also designed as a continuous or batch-type mixer, cement was added in excess to the bamboo fibers wetted with resin in the form of a surface, and the cement process achieved complete coverage of the resin surfaces with cement.

The only condition for the permanent close-to-surface incorporation of the cement particles in the synthetic resin film is that the residence time of the bamboo fibers in the first two aggregates does not exceed the pot life that is different for individual synthetic resins.

The technical applicability of the surface-treated bamboo fibers above was ensured by separating the cement surplus by sieving in the third unit designed as a screening machine. In the absence of water, the coated particles were then storable and could be used as an additive in the sense of the effective fiber reinforcement of cement-bound concrete, taking into account the applicability limits of the cement used. Third embodiment

In the experimental evaluation of the application results of untreated and treated bamboo fibers with different types of concrete, it was found that the incorporability of the fibers with mass fractions of, for example, <5% of the amount of cement used is particularly problematic and that the fresh concrete properties as well as mechanical properties (compressive strength, modulus of elasticity uam) are not adversely affected.

Fourth embodiment

The use of surface-treated bamboo fibers in normal concrete was carried out with a cement insert (CEM I 32.5 R) of 330 kg / m ³ concrete at 720 kg / m ³ sand 0/2, 360 kg / m ³ gravel 4/8 and 720 kg / m ³ gravel 8/16 tested at a fiber use of about 1% of the cement amount. The fiber installation was carried out both as an unoriented layer and in the aligned state in each case in the tensile zone of the test specimens for the modulus of elasticity, bending and splitting tensile strength test. It was found that with approximately constant compressive and tensile strength, the splitting tensile strength increased by up to 5% compared to the blank sample and that the elastic properties improved by the fiber additives, so that the use of corresponding surface-treated bamboo fibers for the production of fiber-reinforced thick-walled concrete pipes was recommended. Fifth embodiment

When using surface-treated bamboo fibers to reinforce sprayed concrete with fiber additions of 3 and 6 kg / m ³ , it was found that with a slight increase in compressive strength (2%) due to the blended epoxy resin and cement pretreated fibers, the 28-day bending tensile strength would be around increased to 7.5% and that the water penetration depth is reduced by 36% compared to the blank sample, so that all examined samples are classified as water-impermeable. In addition, it was found that, in contrast to steel fiber additions from the spray, almost no bamboo particles precipitated during the application process, and that these were preferably located parallel to the wall in the tensile strength. Spraying zone deposited. In conclusion, it was deduced that predominantly surface-treated bamboo fibers should be used instead of steel fibers for work with shotcrete and for the technologically comparable centrifugally cast production of thin-walled concrete pipes.

Sixth embodiment

The use of surface-treated bamboo fibers to reinforce high-strength concrete was achieved using cement (CEM 1 42.5 R) of 453 kg / m ³ concrete at 514 kg / m ³ sand 0/1, approx. 125 kg / m ³ sand 0/4 , 413 kg / m ³ gravel 2/8 and 780 kg / m ³ gravel 8/16 with a fiber use of about 0.64-1.2% of the cement quantity and simultaneous use of microsilica (about 36 kg / m ³ ) tested. It was found that the use of fibers to increase the strength only makes sense if restricted to the compressive strength range <50 N / mm ² .

The splitting tensile strength increased by up to 13% in the case of fibers incorporated in layers compared to the blank sample. Other properties, such as water penetration depths and freeze-thaw resistance, were well below the applicable limits for bamboo fibers randomly distributed in concrete. In addition, it was found that the impact strength compared to zero concrete in the investigated fiber content range increased significantly and improved overall by the surface treatment compared to the use of untreated bamboo fibers. Apart from the modulus of elasticity, especially in the case of bamboo fibers installed in the train area, especially the 7-day values increased strongly, eg the bending tensile strength by 26% compared to the zero sample. With the experimental installation of a longitudinally oriented thin layer according to the procedure of Example 2 pretreated slender bamboo particles (dfiber> 0.5 mm and he <50-60 mm) in a provided as a patch repair layer matrix of the above high-strength concrete could be shown that, compared to the traditional technology with steel mesh reinforcement with comparable strength properties, significant cost reductions of approximately 12-15% can be achieved. Seventh embodiment

In the production of fiber cement boards in the thickness range between 4 and 12 mm relatively thin and slender bamboo fibers were used with dpaser ^ 0.5 mm. It was found that fiber cement boards with the finest-divided fiber version achieved the highest flexural strength. The reached upper limit of strength is 16 N / mm ² . In comparative measurements, it was found that the replacement of expensive synthetic fibers such as dolanite previously used for fiber cement boards with comparable bamboo fibers resulted in comparable flexural strength values and a 20% higher modulus of elasticity. Furthermore, it was found that the replacement of 25% cellulose fibers with finely divided bamboo fibers with dFiber 0,5 0.5 mm, which was additionally carried out in another test series, led to comparable values with respect to modulus of elasticity and flexural strength compared to the standard formulation. This could significantly reduce the cost of manufacturing bamboo fiber-containing fiber cement boards compared to expensive polyamide fibers used after asbestos substitution. As a result of weathering tests, the long-term stability (test validity 5 years) of the used bamboo fibers in the alkaline medium with pH> 12 has been confirmed.

Eighth embodiment

Fine-particle dry bamboo particles (dpart <0.5 mm, t <0.5 mm, moisture content <12-13%) were widely mixed in bamboo fiber production and dry-mixed with different proportions of cement and / or dry mortar Granulated addition of water in a drum slowly rotating about its longitudinal axis. In this case, predominantly spherical light granules formed after the hydraulic setting of the cement and / or lime content and time-delayed drying to be very dimensionally stable, resistant to abrasion and despite a bamboo content of about 50 masses. -% proved to be very flame retardant or flammable. These light granules also have good thermal insulation properties. Their use as an aggregate instead of appropriate gravel and / or grit additives can lead to significant mass reductions in lightweight concrete products to be produced therewith. Another novel building material production and application variant can be deduced from the requirements of fire protection of steel supporting structures in industrial and social construction. From mixtures of the above-mentioned small-particle light granules with cement and fine-grained aggregates, later-installable fire protection linings for any statically and / or dynamically loaded steel profiles and tubes or as spray-on single or multi-layer protective layers can be produced in appropriate forms.

Ninth embodiment

Very favorable purchase and sales opportunities are expected for reinforcing and reinforcing fibers made of bamboo in mineral composites (fiberboard, fiber-reinforced concrete as well as various fittings and tubes made of fiber concrete).

By orientation to light granules according to Example No. 8 in combination with surface-treated long fibers, it is possible, e.g. to produce much lighter water and sewage pipes than in the orientation to heavy concrete and thereby steel reinforcements to be used. Measured reductions of <4-25% are considered realistic. Tenth embodiment

To evaluate the long-term behavior of bamboo fiber concrete samples, the water impermeability test as well as the freeze-thaw and the freeze-thaw test were carried out. In addition, the elongation behavior of specimens with different bamboo fiber content and the impact strength of specimens was evaluated. The bamboo fiber content was 6, 9 and 12 kg / m ^{3 of} fresh concrete. The fiber bundle lengths were adjusted to 25 mm, the fiber bundle diameter was d fiber 2 mm.

To test the freeze-thaw resistance standard test specimens with the above-mentioned different bamboo fiber contents were cured after curing (28 d) 50 times the cycle: 8 h - Frozen at 20 ° C and then thawed at 20 ° C for 4 hours. All fibrous samples had better results than the blank sample at all load changes. The best freeze-thaw resistance was found at 6 kg / m ³ fiber fractions at approximately 300% compared to the blank sample.

The water penetration depths were below the permissible upper limit for all fiber contents, so that the conclusion of the manufacturability of the "waterproof bamboo fiber reinforced concrete" is permissible.

The elongation behavior of bamboo fiber-containing concrete parts is more favorable than that of bamboo fiber-reinforced concrete.

- The impact strength and toughness of concrete with untreated bamboo fibers exceeds the values of unreinforced concrete at low dynamic loads (load changes <50); At higher dynamic loads (load changes> 50) concrete with pretreated bamboo fiber additive delivers significantly better results.

Claims

claims

A building material comprising a mineral component, in particular a cement component, and a fiber component, the fibers of the fiber component comprising bamboo fibers, the bamboo fibers at least partially, in particular completely, having a fiber length 1ρ _α5εΓ in a range from greater than or equal to 25 mm to less than or equal to 60 mm and have a slenderness λ in a range of less than 100.

2. Building material according to claim 1, characterized in that the bamboo fibers have on their surface a reaction resin, in particular wherein on the surface of the

Reaction resin is a mineral substance.

3. A method for producing a particular cementitious building material, wherein bamboo fibers after a preceding mechanical processing, in particular crushing, a mineral constituents comprising matrix, in particular a cementitious matrix, are added, the bamboo fibers at least partially, in particular completely, a fiber length 1ρ _α5εΓ in a range of greater than or equal to 25 mm to less than or equal to 60 mm and have a slenderness degree λ in a range of less than or equal to 100

4. The method according to claim 3, characterized in that the bamboo fibers are provided before adding to the cement content with a reaction resin, in particular selected from an epoxy resin, in particular wherein a mineral substance is applied to the reaction resin surface.

5. The method according to any one of claims 3 or 4, characterized in that the application of the bamboo fibers are limited to a mineral largest grain in the mineral content in the total mixture in a range of <16 mm and that the adjustment of the flour grain fraction with d _K <0.125 mm to 400 kg / m ³ and the fine grain fraction of flour meal and fine sand with άκ <0.25 mm to 450 to 500 kg / m ^{3 are} set.

6. The method according to any one of claims 3 to 5, characterized in that the bamboo fibers are used with proportions <30 vol .-% at d _fiber <0.5 mm and he <10 mm for the production of fiber cement boards.

7. The method according to any one of claims 3 to 6, characterized in that prior to adding the fibers to the matrix, the fibers are subjected to storage in water for a period of less than or equal to 50 h.

8. The method according to any one of claims 3 to 7, characterized in that prior to adding the fibers to the matrix, the fibers are pretreated with a basic medium.

9. The method according to any one of claims 3 to 8, characterized in that the building material bamboo particles having a thickness d _part of less than or equal to 0.5 mm, a length lpart of <0.5 mm and a moisture content of <12% and optionally bamboo particles a thickness dpart of less than or equal to 0.5 mm, a length t of> 0.5 mm to <10 mm and a moisture content of <12% are added.

10. The method according to any one of claims 3 to 9, characterized in that the bamboo fibers are aligned in the material matrix, in particular wherein the orientation is realized by targeted scattering in zugbeanspruchte cover layers, by applying bamboo fiber webs and / or textile bamboo fiber fabric with subsequent overlap with a mineral matrix layer, in particular with a thickness of "50 mm, or by a limited to a period of <60 seconds applying an electrostatic field, in particular with a turn-on voltage of <20 kV.