Reinforcement of 3D-printed concrete bodies

Abstract

A method for producing a component from hardenable material, wherein, in a first method step, at least one layer of the material is printed in a 3D printing process, in a second method step, multiple similar reinforcing elements are introduced into the layer(s) and the two method steps are cyclically repeated until the component is completed, characterized in that, with the exception of the two bottommost and the topmost layers, each reinforcing element extends over at least three layers, and the reinforcing elements are arranged in strands which extend through all the layers and have, in each layer, at least three reinforcing elements, the lateral distance (A) of these reinforcing elements from each other within a strand being a maximum of five times the largest lateral extent (D) of a reinforcing element.

Claims

1. A component made of hardenable material, comprising: a plurality of layers produced in a 3D printing method; and reinforcement elements connecting said plurality of layers, wherein, with the exception of two lowermost and uppermost layers, each reinforcement element extends over at least three layers, and the reinforcement elements are arranged in strands which extend through all the plurality of layers and comprise at least three reinforcement elements in each layer, the lateral spacing (A) between reinforcement elements within one strand is smaller than the greatest lateral extension (D) of a reinforcement element, wherein the reinforcement elements are designed as elongate loops.

2. The component according to claim 1, wherein the hardenable material is concrete.

3. The component according to claim 1, wherein the reinforcement elements consist of a rigid material.

4. The component according to claim 1, wherein the reinforcement elements consist of a flexible material.

5. The component according to claim 1, wherein the strands extend at right angles to the layers.

6. The component according to claim 1, wherein the strands extend at an angle of between 90° and 45° relative to the layers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Some embodiments of the invention are explained in greater detail in the following with reference to the accompanying drawings, in which:

(2) FIG. 1: is a cross section through a partially constructed component according to the claimed method in a first variant (a) and a second variant (b);

(3) FIG. 2: is an enlarged view of adjacent reinforcement elements with schematically shown force transmission; and

(4) FIG. 3: is a plan view of the reinforcement elements shown in FIG. 2 along the line Y-Y with schematically shown force transmission.

DETAILED DESCRIPTION

(5) For carrying out the method according to the invention, a 3D printer, e.g. in the form of a fully automatic gantry robot, is used, in this respect in a manner known per se, which robot can print a wall or a complete room module or other vertical units of a structure in successive layers. FIG. 1 shows a component as it is being produced, which consists of a plurality of layers of concrete that are printed one on top of the other, with two layers being provided with reference signs 2 and 3 by way of example and the uppermost layer shown still being in the process of being produced, i.e. during the printing process.

(6) FIG. 1 shows two variants of the insertion of reinforcement elements 4 into the layers 2 and 3 of the component 1.

(7) In both variants shown, the following method steps are repeated cyclically until the structure is complete. In a first method step, a layer 2 or 3 of the hardenable material, in this case concrete, is applied in a 3D printing method and, in a second method step, a plurality of similar reinforcement elements 4 are inserted into the layers 2 and 3. Both method steps are repeated cyclically until the component 1 is complete. Each reinforcement element 4 consists either of a rigid material, in particular metal, e.g. steel, and can be inserted into the not yet hardened layers 2 and/or 3 of the hardenable material once it has been printed, or, alternatively, each reinforcement element 4 consists of a flexible material, e.g. a high-tensile fiber, e.g. made of Kevlar, and is then inserted into the not yet hardened layers 2 and/or 3 of the hardenable material by means of a guide pin.

(8) Here, each reinforcement element 4 extends over at least three layers 2 and/or 3 and the reinforcement elements 4 are arranged in strands 5, with each strand extending through all the layers 2 and 3. Each strand 5 comprises at least three reinforcement elements 4 in each layer 2 and 3. In the embodiment shown, each reinforcement element 4 extends over three layers, with the strand 5 being formed such that the adjacent reinforcement element 4 extends over the three layers and the one indirectly positioned thereover, and the next reinforcement elements 4 extend over the next three layers that are positioned immediately thereabove. The strand 5 of reinforcement elements 4 thus comprises three adjacent reinforcement elements 4 in each layer 2 and 3.

(9) In the variant (a) shown on the left of FIG. 1, the strands (5) of reinforcement elements 4 extend perpendicularly to the layers 2 and 3, and in the variant (b) shown on the right in FIG. 1, the strands 5 of reinforcement elements 4 extend at an angle of approx. 60° to the layers 2 and 3. Other angles, preferably between 10° and 90°, are possible and are advantageous depending on the field of application.

(10) The precise arrangement of the reinforcement elements 4 forming a strand 5 is shown in FIGS. 2 and 3, with FIG. 3 being a cross section through the line Y-Y in FIG. 2. In both figures, the flow of force between the adjacent reinforcement elements 4 within a strand 5 is shown by shading and by dashed lines, respectively. The lateral spacing A between adjacent reinforcement elements 4 within a strand 5 is as small as possible and, in the embodiment shown, is considerably smaller than the diameter D of each reinforcement element 4. At most, it should be five times this diameter D, but ideally should have as low a value as possible in order to optimize the flow of force or force transmission. A dense arrangement of the reinforcement elements 4 within a strand 5, as shown in FIGS. 2 and 3, results in an improved flow of force or improved force transmission through the concrete therebetween, as shown by shading and dashed lines in FIGS. 2 and 3, respectively.

(11) The method according to the invention can be implemented both using rigid reinforcement elements and using flexible reinforcement elements, which are then inserted into the layers 2 and 3 by means of a guide pin.

(12) In an alternative embodiment (not shown), instead of the bar-shaped reinforcement elements 4, elongate loops can also be used which extend over a plurality of layers 2 and 3. These loops can also consist of a rigid material, e.g. metal, or a flexible material, e.g. Kevlar, and can be inserted both perpendicularly to the layers 2 and 3 and at an angle to the layers 2 and 3, similarly to variants (a) and (b) in FIG. 1.

(13) The method is also suitable for hardening materials other than concrete, in particular thixotropic materials.

(14) There are various variants for the approach to pushing in the reinforcement elements 4. The reinforcement elements 4 may be completely pushed into the layers 2 and/or 3 therebelow made of concrete before the next layer is applied by the print head. In this case, the print head can apply the next layer of concrete without being obstructed at all by protruding reinforcement elements. Alternatively, the reinforcement elements can only be guided through the uppermost layer or through the two uppermost layers or through a plurality of upper layers of concrete, with a part of the reinforcement elements then projecting upwards. In this case, a print head having a cut-out for the protruding reinforcement elements is preferably used in order not to damage or pull out said reinforcement elements.

(15) An alternative approach consists in manufacturing the reinforcement elements from a flexible, elastically yielding material if they protrude from the uppermost layer of the concrete when the next layer is being printed. In this case, the reinforcement elements can yield when the print head travels thereover and can elastically resiliently return to their initial position afterwards. A suitable material for corresponding reinforcement elements is spring steel, for example.

(16) The method according to the invention and the component manufactured thereby have the advantage of a considerably closer connection of the reinforcement elements and considerably stronger reinforcement, since the strands 5 made up of individual reinforcement elements 4 can achieve a similar effect to that achieved in conventional concrete casting by using a steel mat. By forming strands from individual reinforcement elements, as claimed according to the invention, even in 3D printing, in which a continuous steel mat cannot be used, it is possible to achieve the same or similar strength values as those achieved when using continuous structural steel mats in a concrete casting method.