Sound-absorbing elements made of reed cob

Abstract

The invention relates to loam elements based on a compacted reed cob mass with reed stalks of different lengths arranged non-directionally therein as acoustically active, worked-in fibre material, wherein a plurality of reed stalks are cut in or through by means of a shape-imparting cutting, sawing or milling operation on the compacted loam material and as a result outwardly open cavities and channels of different shapes, sizes, lengths and orientation are produced in the cut surfaces of the loam elements, which provide the loam elements with a sound-absorbing functionality. The invention further relates to the production and the use of the loam elements in building construction, infrastructure construction and landscaping.

Description

[0001] Sound-absorbing elements made of reed and wave clay

[0002] TECHNICAL AREA

[0003] The present invention lies in the field of construction and relates to the production of fiber-reinforced clay elements with sound-absorbing surfaces, primarily for use in ecologically sustainable infrastructure and landscape construction as well as in building construction.

[0004] STATE OF THE ART

[0005] In Germany, "Wellerlehm" typically refers to a historical building material made from a mass of clay, usually excavated soil, mixed with straw for reinforcement. For centuries, Wellerlehm was traditionally used to construct houses and barns by hand, without formwork, in layers. When semi-dried, it was then "cut" with a sharp spade to level the surface, resulting in solid, load-bearing clay walls made from a single piece.

[0006] The production of wattle and daub for modern applications, however, must be mechanized to be competitive. For example, EP 3929169A1 discloses a method in which a ready-mixed wattle and daub mass is compacted to a desired strength using a hydraulic press, pneumatic press, vibrating press, or vibration, and load-bearing elements made of wattle and daub are prefabricated from it.

[0007] For noise barriers – one of the intended applications of modernized corrugated clay – a sound-absorbing surface is required. Traditional corrugated clay elements, whether manufactured in formwork or by pressing, have a largely sound-hard surface that reflects sound. While such corrugated clay elements do offer some sound insulation due to their mass and density, they do not qualify as noise barriers with a significant acoustic effect. Building elements with a claimed sound insulation effect must also be sound-absorbing, meaning they reflect as little sound as possible.

[0008] Sound absorption, i.e., a reduction of sound energy, is achieved, among other things, through pores and open cavities in the surface of a building element, such as a wall. In these cavities, the sound waves are essentially "trapped" and reflected back and forth multiple times, potentially forming vortices. In the process, a significant portion of their original sound energy is lost, both through the resulting increase in the sound path length and through dissipation, i.e., energy transfer in the form of frictional heat to the surrounding material. Such cavities and pores can be created, for example, by plant stems embedded in concrete or clay walls. These stems are hollow and possess a certain degree of mechanical compressive and tensile strength, such as reeds or bamboo stalks.

[0009] US 5,322,738 discloses clay bricks which may contain reed stems arranged in one or more layers on top of each other and aligned parallel to each other, extending over the entire length or width of the clay brick.

[0010] DE 19825440 A1 discloses a lightweight clay brick in which the clay mass is fiber-reinforced by chopped reeds.

[0011] DE 1020181 16426 A discloses a building element made of clay and straw or reed stalks, in particular a clay brick in which the straw or reed stalks are aligned parallel to each other, similar to US 5,322,738, and extend over the entire width of the clay brick.

[0012] Wellerlehm is a composite material made of clay, typically excavated soil below the humus layer, and long-fibered plant components, usually straw from grain cultivation in Germany. Since farmers now mostly plow under and reintroduce straw into the soil after the grain harvest, alternative long-fibered plant components are needed as potential reinforcement for clay masses, preferably those that are currently underutilized or not used at all.

[0013] For the commercial, and especially industrial, large-scale application of modified clay aggregate (i.e., clay with straw substitute), consistent quality over many years and reliable availability in large quantities are crucial. Providing a defined quality is particularly important for the formulation of fiber-reinforced clay material when specific requirements and minimum parameters of relevant standards and building regulations for structural and infrastructure construction must be met. From both an ecological and economic perspective, the availability of raw materials, ideally from regional sources, is also of particular importance.

[0014] All these circumstances are taken into account by the present invention.

[0015] BRIEF DESCRIPTION OF THE INVENTION

[0016] Reed, also known as thatch, is a material traditionally used for roofing in northern Germany. Moorland, marshland, and lake shores produce large quantities of reed annually, which can be harvested and used, thereby further promoting the preservation of certain landscapes and ecosystems.

[0017] With regard to an alternative, modernized production of corrugated clay, reed is advantageous as an essential plant-based reinforcing fiber material due to several properties:

[0018] • It has greater hardness and higher tensile strength than straw;

[0019] • has a high silicate content;

[0020] • has a comparatively stable hollow tube, which is a necessary and essential property for sound absorption;

[0021] • It can be harvested annually on a large scale;

[0022] • It exhibits largely consistent structural, chemical, and mechanical material properties;

[0023] • Like straw or any other plant material, it binds carbon as its basic material, which is removed from the atmosphere in oxidized form as a component of the greenhouse gas CO2. The resulting CO2-reducing effect lasts for the lifespan of the material, ideally for hundreds of years.

[0024] Another advantage of using reeds is that, as part of nature conservation and climate measures, renaturalized and preserved moor and marsh areas can yield income as agricultural land for farmers and as part of a value chain for the production of modified loam, whereas reeds are practically unused in Germany today. FIGURE DESCRIPTION

[0025] Fig. 1 shows the manufacturing principle of an embodiment of the clay elements according to the invention by means of a continuously operating processing device, e.g., a formwork chamber, pressure chamber, or press, followed by cutting or sawing transversely to the direction of travel of the resulting continuous strand (a) of compacted clay reinforced with reed and optionally additional fiber material (= reed clay) into individual elements (b) of the desired thickness / wall thickness and a substantially rectangular cross-section. Subsequently, the cut or sawn clay elements can, for example, be joined end-to-end and assembled into a larger structure (c), e.g., a noise barrier.

[0026] Fig. 2 shows the sawn surface of a reed-well clay specimen produced according to the invention, with countless open pores, cavities and channels of various sizes, shapes, lengths and orientations.

[0027] DETAILED DESCRIPTION OF THE INVENTION

[0028] The machine production of highly compacted corrugated clay in a press, as described in EP 3929169A1, produces an almost perfectly smooth surface that is sound-reflecting and therefore unsuitable for effective sound insulation. According to the invention, this significant acoustic disadvantage has been successfully overcome by the following measures: a) by using reed as the main reinforcing material for the clay mass:

[0029] Measurements on test specimens produced according to the invention using an impedance tube have shown that open reed ends, visually recognizable as pores, holes, or channels in the surface of the clay element according to the invention, significantly increase the sound absorption capacity of the clay surface. Furthermore, these tests demonstrated that the length of the reeds influences the absorbable sound frequencies due to resonance effects. Clay with a high density and chaotically arranged reeds of varying lengths, and a surface configured in this way, meets the standard structural engineering requirements for noise barriers. The cut reeds shown in Fig.The clay blocks shown in Figure 1 (b, c) are not only highly effective acoustically, but also fulfill the important function of erosion control, preventing premature weathering of the clay elements' surfaces when used outdoors, for example as noise barriers, especially in the form of noise barriers along busy roads, as sound-absorbing exterior walls or facades of buildings, as privacy screens, art objects, or as part of landscaping projects with noise-reducing properties. In such outdoor applications, a further welcome side effect arises from the fact that the open reed ends on the surface of the material form cavities that are readily used by various insects, such as solitary bee species, as breeding grounds, thus these clay elements also contribute to biodiversity.The cavities enclosed within the material also have a positive effect on the thermal insulation properties of the reed-reinforced clay elements according to the invention, hereinafter referred to as reed-reinforced clay elements. b) by a non-directional, quasi-“chaotic”, random arrangement of the reed stalks:.

[0030] The highest stability, cost-effectiveness in production, and the broadest spectrum of absorbed sound frequencies are achieved through a chaotic, non-directional, purely random arrangement and through varying lengths of the reed stems used. Preferred reed stem lengths range from approximately 1 cm to approximately 50 cm, particularly from approximately 3 cm to approximately 50 cm.25 cm; a largely parallel arrangement of reed stems of numerous different lengths would indeed also produce certain sound-absorbing effects, especially in combination with supplementary, chaotically distributed fiber material without its own acoustic contribution; however, such an embodiment of reed clay elements is not preferred due to the increased labor costs and the comparatively lower stability and strength of the resulting clay elements; and c) by cutting reed clay elements in cuboid form of desired length and / or thickness from a pre-formed elongated strand of compacted reed clay and / or by treating at least one surface of a reed clay element of any length by a cutting, sawing or milling process to produce cut surfaces with an open-pored, sound-absorbing surface structure.

[0031] For the sake of simplicity, the term "cut surfaces" in this context should include not only surfaces produced by a cutting process, but also those produced by sawing or milling.

[0032] The terms "reed," "reed," and "reed cane" used herein are to be understood as synonyms and refer to a plurality of reed stems which, in their natural growth state, typically have an upper, slender part and a lower, thicker, and more lignified part. The reed stems suitable for the present invention have an internal cavity whose diameter typically increases from the stem tip to the stem base, depending on the stem length. Furthermore, it is essential for the present invention that the reed stems, for example in bundles, are sawn or cut to the desired lengths of approximately 1–50 cm, in particular 3–25 cm, so that the individual stem pieces remain essentially intact and have the shape of open-ended tubes of varying lengths.

[0033] Chopped reed material is not suitable for use as a sound-absorbing and erosion-inhibiting base element within the framework and for the purposes of the present invention, as it lacks the necessary cavities and substantially intact tubular structures required for the formation of the open-pored surface structure essential to the invention. However, it could be used as a supplementary fiber material to increase the mechanical strength of the reed-reed clay elements according to the invention.

[0034] For the industrial-scale production of reed-weave clay elements according to the invention, a continuous process variant is preferred. For example, in a processing device designed as a continuous press, a continuous strand of reed-weave clay according to the invention can be provided in a formwork channel with a preferably rectangular cross-section, compacted, and conveyed from the formwork channel to a cutting or sawing device by means of a conveying device. There, the compacted continuous strand can be cut or sawn transversely to its direction of travel or conveying into individual elements, typically into cuboid blocks with a rectangular or square cross-section and any desired thickness (Fig. 1). The thickness is determined by the positioning of the saw or cutting device and essentially corresponds to the desired wall thickness of the produced clay element.The resulting cuboid blocks are installed vertically or horizontally in such a way that the cut or sawn surfaces form the wall surfaces facing the sound. A schematic diagram of this process is shown in Fig. 1.

[0035] The production of such building elements from reed mat clay is, in principle, also possible on-site, either through traditional, manual layering or in a formwork, possibly a mobile formwork or slipform, using pneumatic compaction and / or vibratory compaction. In this case as well, subsequent sawing, cutting, or milling of the potentially many-meter-long, pre-formed strand of compacted reed mat clay is carried out, depending on the dimensions and geometry of the pre-formed strand, either parallel to the formwork direction or to the longitudinal direction of the resulting elongated strand, or perpendicular to it.

[0036] According to another embodiment of the manufacturing process, formwork panels are placed parallel to each other at a horizontal distance, for example, 1 to 5 m apart, with a height of, for example, 1 to 3 m. These panels are filled with reed clay, which is then mechanically compacted. In this case, after removing the formwork – analogous to Fig. 1 – large clay blocks, e.g., wall elements, are produced by sawing off sections perpendicular to the longitudinal direction of the resulting compacted, elongated strand of reed clay. The pre-selected thickness of these blocks, produced by the sawing process, corresponds to the desired wall thickness or thickness of the respective clay block or wall element. The surfaces produced by the sawing process already exhibit the sound-absorbing open-pore structure according to the invention and do not require any further sawing or milling.

[0037] A formwork method is particularly suitable for the on-site construction of reed-weave clay walls. In this method, the formwork panels are positioned vertically at horizontal intervals, similar to how formwork is typically used in masonry construction. The thickness of the resulting clay wall is determined by the spacing of the formwork panels. Using mobile or slipforming systems, this method allows for the production of continuous reed-weave clay walls, which, depending on the intended use, can subsequently be cut or sawn into sections of the desired length, for example, as wall panels, perpendicular to their longitudinal direction.

[0038] In order to achieve the inventive, sound-absorbing open porosity of the side surfaces of such reed-well clay elements or walls - which are mostly freestanding in their intended use - these are processed superficially parallel to their longitudinal direction, at least on one of the two outer sides, by a layer-removing cutting, sawing or milling process in order to expose the desired openings and cavities.

[0039] This layer-removing surface treatment involves removing a layer several centimeters thick, e.g., 1-5 cm, from at least one of the two freestanding side surfaces or outer surfaces of a clay wall element produced according to the invention, using a suitable cutting, sawing, or milling tool. This is done to cut and open the enclosed, randomly arranged reed stems at various angles and, if necessary, to straighten the wall surfaces. The resulting reed-clay elements according to the invention, for example, in the form of wall or ceiling panels with a sound-absorbing surface, are installed in practical applications such that the at least one treated, open-pored, sound-absorbing surface faces the sound source, which is usually disruptive or unwanted.

[0040] EXAMPLE

[0041] To produce comparable test specimens, the respective clay mass was compacted in molds of a fixed size (40 x 20 x 20 cm), removed from the mold, and immediately afterward, while still moist, sawn into two equal pieces (20 x 20 x 20 cm). It was found that when the reed stalks were arranged parallel to each other and perpendicular to the future wall surface, the resulting reed-clay structures were less stable because the tensile forces within the material were only directed in one direction, namely along the essentially parallel fibers. Conversely, it was also shown that a disordered, undirected, and as chaotic as possible arrangement of the reed stalks in the clay material resulted in increased stability, so that the produced test specimens could be sawn immediately after removal from the mold without deformation.

[0042] The mechanical strength, particularly compressive, tensile, and / or flexural strength, of the reed-reed clay elements with a chaotic (isotropic) arrangement of the reed material is unexpectedly high. An optional addition of further plant or animal reinforcing fibers to the clay encasing the reed stems, for example in the form of hemp fibers and / or wool fibers, especially sheep's wool, can further increase the mechanical stability of the material—particularly when the reed stems are arranged in a partially or predominantly directional manner.

[0043] To achieve the desired sound absorption by ensuring sufficient open reed ends, the mixture of moist, fiber-reinforced reed clay was optimized by increasing the proportion of reeds by weight relative to the clay. The clay, with a relatively high water content of, for example, 15 to 30 wt.%, and especially 20 to 28 wt.%, was added to the fiber material containing the reed stems in a creamy, or even flowable, consistency. This allowed the clay to effectively encase the reed stems and penetrate all the spaces between them even before compaction, leaving virtually no unwanted gaps.The water content is adjusted as needed depending on the intended use of the clay elements and can be set to a desired value after the cutting or sawing process of the compacted and pre-formed reed-well clay mass by natural or artificially accelerated drying.

[0044] Mixing reed pieces of varying lengths with the clay mixture has proven particularly effective in achieving high strength and good sound absorption. Depending on the dimensions of the formwork or the desired wall thickness of the final clay elements, a reed-reed clay mixture according to the invention therefore contains a mixture of reed stalks of varying lengths, preferably from approximately 1 cm to approximately 50 cm, and in particular from approximately 3 to approximately 25 cm in length. For example, this mixture may include reed stalks with lengths in the range of 3, 5, 10, 15, 20, and / or 25 cm, and optionally, for specific applications, even longer reed stalks in the range of, for example, 30, 35, 40, 45, and / or up to 50 cm.

[0045] The base material, clay, should preferably have a minimum binding capacity of 50 to 60 g / cm³. 2Lean clay with lower cohesiveness can be made richer by adding clay or highly cohesive clay; highly cohesive clay can be made leaner by adding sand if required by the specific application. The composition of the material mixture is usually determined by weight, as the material volumes are generally too imprecise for determination due to sometimes considerable differences in density and consistency.

[0046] When processing excavated soil, the initial moisture content is first determined, and then the amount of water that may need to be added is adjusted accordingly. Furthermore, the excavated soil is preferably sieved before use to remove larger stones, and then, if necessary, crushed to further reduce the particle size of the excavated material.

[0047] The following describes a general procedure for the production of reed-weave clay elements according to the invention, which can be varied as needed and carried out with different tools and aids without deviating from the spirit of the present invention: a) For excavated soil: determine the clay cohesion; b) determine the base moisture content. For this purpose, a sample of moist clay can be weighed, then dried and weighed again. The difference in weight gives the water content; c) sieve the excavated soil and remove stones, breaking it up if necessary; d) increase the cohesion if necessary by adding clay or decrease it with sand; e) mix the clay by adding water to achieve the desired water content, resulting in a homogeneous, lump-free mass, preferably of a creamy and / or sprayable consistency; f) optionally mix the clay mass with optional organic non-reed components such as, for example,Thoroughly mix hemp fibers, sheep's wool, and / or other suitable, preferably regionally sourced, fiber material and allow to soak for 24 hours; g) Cut or saw the reeds into pieces, never shred them. The pieces should be of varying lengths from 1 to 50 cm, particularly from approximately 3 to approximately 25 cm. Reed bundles can be cut or sawed, for example, using a circular saw, band saw, or other saws, or using a cut-off saw or other cutting tool.Cutting the reeds to different lengths serves, among other purposes, to achieve a higher reed density in the chaotic, directionless arrangement within the clay mixture (comparable to the particle size distribution in concrete construction); h) carefully mixing the reed stalks of varying lengths; i) combining the mixture of reed stalks with the preferably creamy and optionally sprayable clay mixture, preferably by adding the clay mixture to the reed mixture. On an industrial scale, this can be accomplished, for example, by injecting the clay mixture into a mixing container containing the reed mixture using a mortar pump; the quantity of reed determines the quantity of clay to be added, or conversely, the quantity of clay determines the quantity of reed material to be used.The proportions of the components of the reed-well clay mass according to the invention are preferably (in weight percent) depending on the properties of the raw clay and the desired properties of the final product:.

[0048] - Clay approx. 60-83%

[0049] - Water approx. 15-30%

[0050] - Reed approx. 2-20% j) Transferring the ready-mixed reed-weave clay mixture into a formwork or a processing device – preferably a continuously operating one – such as a compaction channel or a press chamber. The length or width and the height of the cuboid clay elements to be produced are predetermined by the dimensions of the formwork, compaction channel, or press chamber. The thickness of the resulting clay elements, e.g., clay wall panels, is determined only after the compacted, elongated clay strand emerges from the compaction channel or press chamber by a cutting or sawing operation transverse to the direction of travel of the emerging clay strand, or, in the formwork method, after removal of the formwork by a cutting, sawing, or milling operation transversely or parallel to the formwork, depending on the dimensions of the horizontal distance between the formwork walls.It is identical to the desired wall thickness of the clay element obtained in this way; k) Compaction: in a typical embodiment of the process, the reed clay mixture is filled into the press chamber, compaction channel, or formwork in layers preferably approximately 10 to 50 cm high or thick, and finally compacted in a single operation so that the reed stalks are not crushed as much as possible. This is advantageously supported by a creamy and preferably sprayable clay mass, which coats the reed stalks well even before compaction and thus mechanically stabilizes them; l) the compacted reed clay mass produced in this way can be demolded or removed directly after compaction.In automated continuous production, the pre-formed, continuous strand is conveyed from the processing device, for example, a press chamber or a compaction channel, whereupon individual "discs" or cuboids of the desired thickness are separated from the continuous strand of compacted, pre-formed reed clay mass, i.e., cut or sawn off using a cutting or sawing device. During the cutting or sawing process, countless long and short, crisscrossing and oriented reed stems are cut or severed at different angles, creating open pores, holes, and channels of varying diameters, geometric shapes, lengths, and orientations on the cut surfaces, as can be seen in part in Fig. 2.

[0051] For elements produced on-site using formwork, after stripping (removing the formwork), at least one of the lateral surfaces created by the formwork is processed by sawing, cutting, or milling. This means that a surface layer approximately 3–5 cm thick is removed by sawing or milling to expose the desired pore structure. This side represents the acoustically effective side of the finished thatched clay element.

[0052] The cut or removed clay elements are then assembled into vertical walls or surface elements in such a way that the surfaces created by the cutting or sawing process form the respective freestanding wall surfaces, which, when used as intended, face the sound sources. Typically, the clay elements are placed end-to-end, i.e., rotated at a 90° angle to the cutting or sawing direction, and joined together – for example, using clay mortar and other adhesives – to construct, for instance, a sound-absorbing load-bearing or non-load-bearing clay wall in a building or a noise barrier along a busy highway or railway line. However, non-linear arrangements of individual clay elements into composite elements are also possible without impairing the sound-absorbing properties of the surfaces.

[0053] It is essential that as many cut or severed reed stems as possible appear open as holes, pores, and channels on the sawn, cut, or milled surfaces (Fig. 2), thereby making the surfaces sound-absorbing. At the same time, the cut reed stems also act as erosion barriers, preventing or reducing the weathering of the clay elements' surfaces when used outdoors. Conversely, the uncut reed stems enclosed within the clay elements, with their closed cavities, enhance the thermal insulation properties of these clay elements and the walls and other surfaces constructed from them.

[0054] The clay elements can be cut to size using a circular saw, band saw, or other suitable cutting or sawing device; m) subsequent drying of the clay elements according to the invention can be accelerated by natural or artificial ventilation. The drying process causes the clay elements to shrink slightly, but this does not impair their suitability for the intended applications; n) any pores, holes, and / or channels in the surface of the compacted clay elements that may be clogged with clay, caused by sawing or cutting the compacted clay mass, can be subsequently reopened using compressed air or other suitable methods, so that full sound absorption functionality is immediately restored. This is not strictly necessary when the clay elements are used outdoors, as this occurs naturally over the long term through natural "sandblasting" by dust, wind, and rain.However, supplementary tests have shown that particularly good sawing results, i.e. clean cut surfaces without or largely without smearing of the pores, can be achieved by moving the saw blade of a suitable masonry circular saw slowly through the block while rotating very quickly.

[0055] This method can also be applied analogously to traditionally hand-stacked strands of compacted reed clay. In this case, compaction can be achieved solely through the weight of the reed clay mass or through additional manual or mechanical tamping or vibrating of the successively stacked layers of reed clay. The surface treatment required to create the open-pore structure according to the invention can also be carried out here – in the longitudinal direction of the strand of stacked, compacted reed clay – by cutting, sawing, or milling. An additional benefit is the smoothing or straightening of the treated side(s) of the reed clay strand, which is typically constructed in the form of a clay wall, resulting from the cutting, sawing, or milling process.

[0056] The reed-well clay elements produced according to the invention possess a high degree of sound absorption capacity and achieve a sound absorption, measured with the impedance tube, of at least 10%, in particular of 30 to 80%, across the entire frequency spectrum relevant to road traffic.

[0057] The compressive, tensile, and flexural strengths of the reed-weave clay elements according to the invention can be adjusted, among other things, by the moisture content of the clay, the quantity and quality of plant-based reinforcing material, and the degree of compaction. For use as load-bearing elements in building construction, compressive strengths in the range of, for example, at least 1 N / mm² can be achieved through high compaction. 2 up to 5 N / mm 2The required values, as stipulated by building standards and regulations, are achieved. However, increasing density leads to a decrease in sound absorption capacity because, depending on their inner diameter and wall thickness, the reed stalks are increasingly compressed beyond a certain tipping point, thus also compressing or completely closing the pores on the surfaces of the sawn, final clay elements. For non-load-bearing or purely self-supporting applications, e.g., as part or filling of cavities, compressive strengths of 0.5 N / mm² are possible. 2 and that should be sufficient.

[0058] The advantages and quality features associated with the invention enable the use of Reetweller clay elements produced according to the invention for the construction of sound-absorbing load-bearing and non-load-bearing walls in building construction, especially in residential construction, including acoustically effective, climate-regulating walls or wall elements in interiors, as well as for the construction of heat-insulating, sound-absorbing interior wall coverings, exterior walls, exterior facades and facade coverings.Another area of ​​application is ecologically and economically advantageous, sound-absorbing noise barriers and sustainably designed, noise-reducing boundaries for sensitive infrastructures such as kindergartens, schools, hospitals or residential areas, whereby these applications also contribute to biodiversity in the insect world, because the outwardly open cavities on the surface of the installed clay elements are readily accepted as breeding cavities by numerous smaller insect species, such as solitary bees.

Claims

PATENT CLAIMS 1. A method for producing sound-absorbing, fiber-reinforced clay elements from reed clay, characterized in that it comprises the following steps: a) providing clay with a minimum binding density of 50 g / cm³ 2 preferably of at least 60 g / cm² 2b) Providing a mixture of sawn or cut, substantially intact and hollow reed stems of varying lengths in a range of 1 to 50 cm, preferably 3 to 25 cm; c) Adjusting the water content of the clay to achieve a creamy, preferably sprayable consistency, and optionally adding plant and / or animal non-reed fiber material to produce a fiber-reinforced clay mass; d) Mixing the reed stems with the creamy and preferably sprayable, optionally fiber-reinforced, clay mass to form reed matting clay with reed stems of varying lengths arranged randomly and in a crisscross pattern; e) Transferring the reed matting clay into a formwork, optionally a slipform, or into a processing device – preferably a continuously operating one – or manually stacking the reed matting clay to the desired height and width;f) Compacting the reed clay to produce a pre-formed, elongated strand of compacted reed clay with a preferably substantially rectangular cross-section; g) Removing the formwork or conveying the pre-formed elongated strand of compacted reed clay from the processing device to a cutting or sawing device; and h) Performing at least one cutting, sawing, or milling operation on the pre-formed elongated strand of compacted reed clay, whereby reed stalks are cut or pierced at various angles, so that open cavities and channels of different sizes, shapes, lengths, and orientations with sound-absorbing properties are formed on the cut surfaces of the resulting clay elements.

2. Method according to claim 1, characterized in that the creamy, and preferably sprayable, clay mass according to paragraph (c) is mixed with hemp fibers and / or animal fiber material, in particular sheep's wool.

3. Method according to claim 1 or 2, characterized in that the reed clay mass contains 60 - 83 wt.% clay, 2 - 20 wt.% reed stems, and 15 - 30 wt.% water.

4. Method according to one of claims 1 to 3, characterized in that the preformed elongated strand of compacted reed clay is cut into individual clay elements by means of a cutting or sawing device transversely to the formwork or transversely to its longitudinal direction, wherein cavities and channels of different size, shape, length and orientation with sound-absorbing properties are formed on the resulting cut surfaces of the clay elements open to the outside.

5. Method according to one of claims 1 to 3, characterized in that the elongated strand of compacted reed clay, pre-formed by means of formwork and compaction, optionally directly on site, is subjected to a layer-removing surface treatment by cutting, sawing or milling on at least one of the lateral outer surfaces formed during production, by cutting, sawing or milling, whereby cavities and channels of different size, shape, length and orientation with sound-absorbing properties are formed on the resulting cut surfaces of the clay elements.

6. Method according to one of claims 1 to 3, characterized in that the elongated strand of compacted reed clay, pre-formed by manual layering, is subjected to a layer-removing surface treatment by cutting, sawing or milling on at least one of the lateral outer surfaces produced during the layering and compaction, whereby cavities and channels of different sizes, shapes, lengths and orientations with sound-absorbing properties are formed on the resulting cut surface, open to the outside, and wherein optionally - 1 8 - a straightening of the preformed strand of compacted reed clay is carried out on the side of the surface treatment performed.

7. Method according to claim 5 or 6, characterized in that the surface treatment comprises cutting, sawing or milling off a layer typically 3 - 5 cm thick from a lateral outer surface of a preformed clay element made of compacted reed clay.

8. Sound-absorbing, preferably cuboid, clay element based on a compacted reed clay mass with a preferred minimum clay cohesion of at least 50 g / cm³ 2 , preferably at least 60 g / cm² 2, characterized in that it contains cut or sawn, substantially intact and hollow reed stems and optionally additional non-reed fiber material, in particular hemp fibers and / or animal wool fibers as reinforcing material, wherein the reed stems have different lengths in a range of 1 to 50 cm, in particular 3 to 25 cm, and are arranged randomly and crisscross in the clay mass, and wherein the sound-absorbing clay element has at least one surface produced by cutting, sawing or milling, which has a plurality of outwardly open cavities and channels of different shape, size, length and orientation, formed by reed stems cut or through at different angles.

9. Sound-absorbing clay element according to claim 8, characterized in that in its moist raw state it contains 60 - 83 wt.% clay, 15 - 30 wt.% water and 2 - 20 wt.% reed stems.

10. Sound-absorbing clay element according to claim 8 or 9, characterized in that it has a sound absorption capacity, measured with the impedance tube, of at least 10%, in particular of 30 to 80%, over the entire frequency spectrum relevant to road traffic. 1 1 . Use of a sound-absorbing clay element made of compacted reed clay as defined in one of claims 8 to 10, as a functional and / or aesthetic element in ecologically sustainable infrastructure, landscape and / or building construction. - 1 9 - 12. Use according to claim 1 1 , for the construction of acoustically effective, load-bearing or non-load-bearing, climate-regulating walls or wall elements in buildings, for the production of sound-absorbing, heat-insulating interior wall coverings, exterior walls, exterior facades and facade coverings in building construction, as well as for ecological, noise-reducing landscaping, for the construction of noise barriers, in particular along busy transport routes, and for the sustainable design of optical and / or acoustic boundaries of sensitive infrastructures such as kindergartens, schools, hospitals or residential areas.

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