Microfiber-reinforced high-strength concrete

Abstract

A method is provided for producing a microfiber-reinforced high-strength concrete, comprising a cement matrix with a microfiber addition. The fiber elements have a shape-memory alloy. The method has at least the following steps: training a fiber shape of the fiber elements at a temperature above a transition temperature, wherein the fiber shape allows the fiber elements to latch; cooling the trained fiber elements; plastically deforming the fiber elements from the trained fiber shape into an intermediate form by means of which the fiber elements are prevented from latching; introducing the fiber elements into the cement matrix in order to form a fresh concrete; and casting the fresh concrete and heating the fresh concrete to the transition temperature such that the fiber elements reform into the fiber shape, thereby latching the fiber elements. The invention additionally relates to a microfiber-reinforced concrete which is produced using such a method.

Claims

1. A method of manufacturing a microfiber-reinforced concrete comprising a cement matrix in which a microfiber additive of fiber elements is introduced and wherein the fiber elements have a shape memory alloy, with the method comprising at least the following steps: training a fiber shape of the fiber elements at a temperature above a transition temperature, with the fiber shape making an interlocking of the fiber elements possible; cooling the trained fiber elements; plastic deformation of the fiber elements from the trained fiber shape into an intermediate shape by which an interlocking of the fiber elements is prevented, wherein, to form the intermediate shape, the fiber elements are brought into a compacted form; the compacted form further comprises a curled form, a ball form, or a wound form, whereby an interlocking of the fiber elements is prevented; introducing the fiber elements into the cement matrix to form a fresh concrete; casting the fresh concrete; and heating the fresh concrete to the transition temperature so that the fiber elements return to the fiber shape while interlocking the fiber elements.

2. The method in accordance with claim 1, wherein the training of the fiber shape of the fiber elements takes place at a temperature of 300° C. to 400° C. and/or at a temperature of 340° C. to 360° C.

3. The method in accordance with claim 1, wherein the fiber elements have a straight extent prior to the training of the fiber shape.

4. The method in accordance with claim 1, wherein the training of the fiber shape is performed by means of a shaping of the fiber elements supplied in a straight shape.

5. The method in accordance with claim 4, wherein the trained fiber shape is at least formed by end hooks shaped into the fiber elements at the fiber ends.

6. The method in accordance with claim 1, wherein the transition temperature is selected at a value of 40° C. to 50° C.

7. The method in accordance with claim 1, wherein the fiber elements are introduced into the cement matrix at more than 2 vol %.

8. The method in accordance with claim 1, wherein the fiber elements are added into the cement matrix with a length of 5 mm to 50 mm and/or with a diameter of 0.1 mm to 2 mm.

Description

PREFERRED EMBODIMENT OF THE INVENTION

(1) Further measures improving the invention will be shown in more detail below together with the description of a preferred embodiment of the invention with reference to the only FIGURE. There is shown:

(2) The FIGURE is a schematic sequence of the steps of the method in accordance with the invention of manufacturing a microfiber-reinforced concrete.

DETAILED DESCRIPTION OF THE DRAWING

(3) The FIGURE shows a sequence of a plurality of method steps 101 to 107 that describe a method in accordance with the invention of manufacturing a microfiber-reinforced concrete 1.

(4) The method begins with the provision 101 of fiber elements 11 and the heating of the fiber elements 11 to a temperature above a transition temperature. The transition temperature of the fiber elements 11 from a shape memory alloy is the temperature above which the shape memory alloy remembers an originally trained geometrical shape in that the component composed of the shape memory alloy returns into this remembered shape.

(5) The next step of the method in accordance with the invention is formed by a training 102 into a fiber shape, with the fiber elements 11, for example, being changed by a shaping process or by another plastic deformation process into the desired shape that should be remembered by the shape memory alloy on a reaching of the transition temperature. In a further step, the cooling 103 of the trained fiber elements 11 from a temperature T1 subsequently takes place to train the fiber shape to a room temperature, for example.

(6) In a further step 104, a plastic deformation of the fiber elements takes place into an intermediate shape 13 that is formed such that an interlocking of the fiber elements among one another and also with a cement matrix is suppressed.

(7) The introduction 105 of the fiber elements to the intermediate shape 13 into the cement matrix 10 and the casting of the fresh concrete follows this. Once the fresh concrete has been cast, the heating 106 of the fresh concrete to a transition temperature T2 takes place so that the obtaining 107 of the microfiber-reinforced subsequently takes place. In method step 107, the fiber elements 11 are again present in the trained shape for the casting of the concrete so that the strength enhancing effect of the fiber elements 11 in the cement matrix 10 can be fully exploited despite a simple preceding casting of the fresh concrete.

(8) The fiber elements 11 that have a rod shape are shown in step 101 here. A heating by a heat input, shown by an arrow, to, for example, a temperature of 350° C. takes place from step 101 to step 102. The shaping of the fiber elements 11 into a fiber shape 12 in which they have end hooks 15 of the fiber elements 11 forming a form fit takes place in step 102.

(9) Following step 102, the cooling 103 takes place from the temperature T1 for training the fiber shape 12, for example back to room temperature.

(10) A curled shape of the fiber elements that corresponds to the intermediate shape 13 is shown in step 104. The fiber elements 11 in the intermediate shape 13 are introduced into the cement matrix 10 in step 105, whereby the fresh concrete 14 is provided. The heating to the temperature T2, that describes the transition temperature, subsequently takes place so that the curled intermediate shape 13 of the fiber elements 11 return from step 105 into the fiber shape 12 that was originally trained in step 102.

(11) A substantially larger number of fiber elements 11 per volume unit of the cement matrix 10 can be introduced in the microfiber-reinforced concrete 1, whereby the tensile and/or compressive strength of the microfiber-reinforced concrete 1 is considerably increased. The proportion of the fiber elements 11 in the cement matrix 10 is, for example, considerably above 2 vol %, with the rheological properties of the concrete 1 for processing being promoted despite the increased fiber proportion since the rheological step of casting the fresh concrete takes place with fiber elements 11 that are present in the intermediate shape 13.

(12) The invention is not restricted in its design to the preferred embodiment specified above. A number of variants is rather conceivable that also makes use of the solution shown with generally differently designed embodiments. All the features and/or advantages, including any construction details or spatial arrangements, originating from the claims, the description, or the drawings can be essential to the invention both per se and in the most varied combinations.

REFERENCE NUMERAL LIST

(13) 1 microfiber-reinforced concrete 10 cement matrix 11 fiber element 12 fiber shape 13 intermediate shape 14 fresh concrete 15 end hook 101 providing fiber elements and heating the fiber elements to a temperature above a transition temperature 102 training a fiber shape 103 cooling the trained fiber elements 104 plastic deformation of the fiber elements 105 introducing the fiber elements into the cement matrix and casting of the fresh concrete 106 heating the fresh concrete to a transition temperature 107 obtaining a microfiber-reinforced concrete T1 temperature to train a fiber shape T2 transition temperature