JP2021187731A - Fiber-reinforced concrete capable of recycling material, and recycling method thereof - Google Patents

Abstract

To provide a fiber-reinforced concrete capable of recycling a material capable of exhibiting material properties required as a housing material in service and of being separated and regenerated after the service.SOLUTION: A fiber-reinforced concrete 1 capable of recycling a material is made by putting a metallic fiber-reinforced material 3 having a low melting point into a hardened body 2 of a compound, the compound being formed by adding some or all of materials, such as a fine aggregate, a coarse aggregate and an admixture, to a binder agent comprising some or all of cement, an admixture and water. Preferably a metal fiber comprising an alloy or an element metal is used as the metallic fiber-reinforced material 3 having low melting point, the alloy mainly comprising aluminum, bismuth, cesium, mercury, potassium, lithium, sodium, lead, rubidium, tin, zinc, indium, gallium, cadmium, and their oxide. Moreover the fiber-reinforced concrete after service can be separated into a metal fiber and a cement-hardened body and be regenerated through low-temperature heating process or the like, and can thereby be recycled.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fiber reinforced concrete capable of recycling materials and a method for recycling the same.

As a fiber reinforced concrete mixed with a fiber reinforcing material, there is one disclosed in Patent Document 1. In the fiber reinforced concrete disclosed in Patent Document 1, stainless steel fibers and / or amorphous metal fibers are further mixed in a cured product of a formulation containing cement, pozzolanic fine powder, aggregate, water, and attenuating agent. It is concrete.

The fiber-reinforced concrete mixed with stainless steel fibers is a material that can enhance the structural performance of concrete by complementing the characteristic of concrete that it is weak in tensile force by the fiber cross-linking effect of steel fibers.

Japanese Unexamined Patent Publication No. 2001-253745

However, in the conventional fiber reinforced concrete, it is extremely difficult to separate the steel fiber and the cement hardened body due to its excellent properties, and the fiber reinforced concrete after the service has to be transported to the final disposal site and disposed of by landfill. Is the current situation. Further, since the resources of limestone, which is a raw material of cement (mortar), are limited, it is desired to develop a recycling technique for fiber reinforced concrete mixed with fiber reinforced concrete.

Therefore, the present invention has been made to solve the above-mentioned problems, and is a fiber reinforced concrete capable of recycling a material that can be separated and recycled after being in service while exhibiting material properties required as a building material during operation. And its recycling method.

The recyclable fiber reinforced concrete of the present invention is prepared by adding a part or all of materials such as fine aggregate, coarse aggregate and admixture to a binder consisting of cement, admixture, part or all of water. It is characterized in that a metal fiber reinforcing material having a lower melting point is further mixed into the cured product of the composition.

Further, the method for recycling fiber-reinforced concrete in which the material of the present invention can be recycled is a method for recycling a concrete structure made of fiber-reinforced concrete mixed with a metal fiber-reinforced material having a low melting point after it has been put into service. First, the fiber-reinforced concrete of the used concrete structure is disassembled, then the disassembled fiber-reinforced concrete is heat-treated at a low temperature to melt the metal fiber-reinforced material having a low melting point, and then the above-mentioned After crushing the fiber reinforced concrete heat-treated at a low temperature, the concrete material for regeneration and the metal for regeneration, which are the raw materials of the hardened cement, are separated and recovered, and then the recovered concrete for recycling is recovered. It is characterized in that a fiber reinforced concrete is manufactured again by mixing a recycled fiber reinforcing material made of the metal for regeneration with a recycled cement made of the material.

According to the present invention, it is possible to provide a fiber reinforced concrete and a recycling method thereof, which can recycle a material that can be separated and recycled after the service has been completed, while exhibiting the material properties required as a building material during the service.

It is a schematic perspective view which shows the fiber reinforced concrete which can recycle the material of 1st Embodiment of this invention. It is a graph comparing the characteristics of the said fiber reinforced concrete, reinforced concrete and unreinforced concrete. It is a schematic perspective view of the concrete structure made of the fiber reinforced concrete. (A) is a partially enlarged perspective view of a concrete structure made of reinforced concrete, and (b) is a partially enlarged perspective view of the concrete structure made of fiber reinforced concrete. It is a flowchart which shows the recycling process after the use of the concrete structure made of the fiber reinforced concrete. It is a schematic perspective view which shows the fiber reinforced concrete which can recycle the material of the 2nd Embodiment of this invention. It is a schematic perspective view which shows the fiber reinforced concrete which can recycle the material of the 3rd Embodiment of this invention. It is a graph which compares and shows the tensile property of a plurality of kinds of fiber reinforced concrete which can recycle the material of 1st, 2nd and 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic perspective view showing fibrous reinforced concrete in which the material of the first embodiment of the present invention can be recycled, FIG. 2 is a graph comparing the characteristics of fibrous reinforced concrete with reinforced concrete and unreinforced concrete, and FIG. 3 is fibrous reinforcing. Schematic perspective view of a concrete structure constructed of concrete, FIG. 4 (a) is a partially enlarged perspective view of a concrete structure made of reinforced concrete, and FIG. 4 (b) is a partially enlarged perspective view of a concrete structure made of fiber reinforced concrete. FIG. 5 is a flowchart showing a recycling process of a concrete structure made of fiber-reinforced concrete after it has been put into service.

As shown in FIG. 1, the fiber reinforced concrete 1 whose material can be recycled is composed of cement, an admixture material, a binder consisting of a part or all of water, sand (fine aggregate), gravel (coarse aggregate), and the like. A metal fiber reinforced concrete 3 having a low melting point is mixed in a cured product 2 of a compound composed by adding a part or all of a material such as an admixture material. The main material of the metal fiber reinforcing material 3 having a low melting point is aluminum, bismuth, cesium, mercury, potassium, lithium, sodium, lead, rubidium, tin, zinc, indium, gallium, cadmium, and oxides thereof. Metallic fibers made of alloys or elemental metals are used.

As shown in FIG. 2 showing the characteristics of the fiber reinforced concrete 1, the reinforced concrete, and the unreinforced concrete, it can be seen that the fiber reinforced concrete 1 has a lower peak load than the reinforced concrete, but has a higher energy absorption amount (deformation amount).

According to the fiber reinforced concrete 1 capable of recycling the material of the first embodiment, the fiber reinforced concrete 3 as a concrete reinforcing material includes aluminum, bismuth, cesium, mercury, potassium, lithium, sodium, which have a lower melting point than steel metal. By using metal fibers made of alloys containing lead, rubidium, tin, zinc, indium, gallium, cadmium and their oxides as main materials or single metals, high toughness is achieved due to the fiber cross-linking effect when used in a normal temperature environment. Can function as concrete with. That is, under normal temperature operation, a fiber strengthening effect equivalent to that of organic fibers can be obtained.

Further, the fiber reinforced concrete 1 capable of recycling the material is more suitable than the conventional reinforced concrete structure when used when constructing the tide embankment (concrete structure) 10 shown in FIG. 3 as an example.

In detail, the tide embankment installed in the coastal area is required to have high durability for long-term operation in a salt-damaged environment, and also exhibits toughness even after being severely damaged by unexpected wave force. However, performance such as continuing to block seawater in its original position is also required. Therefore, in general, as shown in FIG. 4A, a plurality of reinforcing bars 21 are arranged in the concrete 20 and a large cover thickness (the thickness thereof is indicated by reference numeral S in the figure) is set. Therefore, it is designed to be wide (the width is indicated by reference numeral H in the figure) so as to satisfy these requirements. However, since the concrete is cracked due to various factors, it is difficult to maintain the toughness by not corroding the reinforcing bar 21 for a long period of time. It is also known that the toughness does not improve with respect to the member thickness H because the cover portion having an excessive thickness S approaches the behavior as unreinforced concrete. Due to these factors, a normal reinforced concrete tide embankment may not be a stable infrastructure for a long period of time, and it is necessary to reconstruct everything including the reinforcing bar 21 using new materials.

Therefore, as shown in FIGS. 3 and 4B, when the tide embankment 10 is constructed of a fiber reinforced concrete 1 capable of recycling the material, the fiber reinforced concrete 1 is reinforced with a metal fiber reinforced concrete 3 having high corrosion resistance. Since the material itself has high toughness, it is possible to achieve both durability and toughness. This makes it possible to continue to dam the seawater in place even if it receives unexpected wave power.

Further, when the tide embankment 10 is constructed of the fiber reinforced concrete 1 whose material can be recycled, the cover portion of the reinforced concrete becomes unnecessary, so that the width H of the fiber reinforced concrete 1 can be reduced, and the width H of the fiber reinforced concrete 1 can be reduced accordingly. It is possible to reduce the cost. Further, the fiber reinforced concrete 1 and the shavings also suffer damage such as cracks after a long period of time, and the water blocking property is lowered due to the cracks or the like, so that they need to be replaced. At this time, as will be described later, in the fiber reinforced concrete 1, the concrete and the metal fiber can be separated and recovered by heat treatment and used as a recycled material, and the damaged tide prevention can be made by utilizing this characteristic. It is possible to reconstruct the embankment with recycled fiber reinforced concrete and use it for replacement.

Next, the recycling process after the service of the tide embankment 10 constructed of the fiber reinforced concrete 1 capable of recycling the material will be described with reference to the flowchart shown in FIG.

First, the fiber-reinforced concrete 1 of the used concrete structure 10 is disassembled and transported to the cement recycling factory (step S1).

Next, at a cement recycling factory, the disassembled fiber reinforced concrete 1 is heat-treated at a low temperature (for example, about 200 ° when containing tin fibers and about 600 ° when containing aluminum fibers) to crosslink the fibers. The effect is lost, and the metal fiber reinforcing material 3 having a low melting point is melted and liquefied (step S2).

Next, the fiber reinforced concrete 1 heat-treated at a low temperature is crushed into granules or powder (step S3).

Then, the crushed material is separated into a reclaimed concrete waste (concrete material) and a reclaimed liquid metal, which are raw materials for the hardened cement, and recovered by centrifugation or the like (step S4).

Next, the fiber-reinforced concrete 1 is manufactured again by mixing the recovered recycled cement, which is made of recycled concrete, with a recycled fiber reinforcing material made of a metal for recycling (step S5).

In this way, since aggregate suitable for regeneration is used as the raw material for concrete (mortar), it can be disassembled in the same way as ordinary concrete, and can be recycled by inputting relatively little energy by centrifugation or the like. It can be separated and recovered into concrete glass and metal for recycling, respectively, and the separated and recovered material can be used as it is as a raw material for recycling.

According to the first embodiment, the disassembled fiber reinforced concrete is heat-treated at a temperature higher than the melting point of the metal, but the heat treatment is performed at a temperature lower than the melting point to increase the rigidity of the metal fiber reinforced concrete. The fiber reinforced concrete may be disassembled at the point where it has fallen, and then heat-treated again to liquefy the metal.

Further, according to the first embodiment, the concrete glass for regeneration and the metal for regeneration are separated by centrifugation or the like, but they may be separated by natural separation by gravity, a filter or the like.

Further, according to the first embodiment, the aggregate used as the raw material of the hardened cement is limestone, so that the concrete portion is used as a recycled resource as it is, but limestone is not blended or powder other than limestone is used. It may be replaced by using a body or aggregate.

Further, according to the first embodiment, the tide embankment has been described as a concrete structure made of fiber reinforced concrete capable of recycling materials, but the concrete structure is not limited to the tide embankment, for example. Of course, it can be applied to other concrete structures such as precast concrete curtain walls used for outer walls of high-rise buildings and the like.

FIG. 6 is a schematic perspective view showing a fiber reinforced concrete in which the material of the second embodiment of the present invention can be recycled.

As shown in FIG. 6, the recyclable fiber reinforced concrete 1 of the second embodiment has cement, an admixture material, a binder consisting of a part or all of water, sand (fine aggregate), and gravel. An elliptical annular shape (so-called clip shape) made of aluminum as a fiber reinforced material made of metal with a low melting point is added to the cured body 2 of the compound composed by adding a part or all of materials such as (coarse aggregate) and an admixture material. It differs from that of the first embodiment in that a large number of fiber reinforcing materials 4 are mixed.

In the fiber reinforced concrete 1 in which the material of the second embodiment can be recycled, the fiber reinforced concrete 4 is made of aluminum and has an elliptical annular shape, so that the compound can be cured even with an easily meltable metal having low rigidity and low strength. It becomes possible to surely settle in the body 2. In the case of this elliptical annular shape, it is possible to suppress the fiber reinforcing members 4 from being entangled with each other and to ensure uniformity. Further, even if a weak point is generated at the fiber interface due to alkaline corrosion or the like, a large number of fiber reinforcing materials 4 are shaped to embrace the cured body 2 of the compound, so that a large number of fibers from the cured body 2 of the compound are used. The reinforcing material 4 does not easily come off. Further, as in the first embodiment, the fiber-reinforced concrete 1 after service can be recycled by being able to separate and regenerate the metal fiber and the hardened cement by low-temperature heat treatment or the like.

According to the second embodiment, the fiber reinforcing material is made of aluminum and has an elliptical annular shape. However, other than aluminum, a metal having a low melting point such as lead, rubidium, tin, and zinc is formed into an elliptical annular shape. May be used as a fiber reinforcing material.

FIG. 7 is a schematic perspective view showing a fiber reinforced concrete in which the material of the third embodiment of the present invention can be recycled.

As shown in FIG. 7, the recyclable fiber reinforced concrete 1 of the third embodiment has cement, an admixture material, a binder consisting of a part or all of water, sand (fine aggregate), and gravel. A twisted wire made of aluminum as a fiber reinforced material made of metal with a low melting point in a cured body 2 of a compound composed by adding a part or all of materials such as (coarse aggregate) and an admixture material (so-called twist shape). It is different from that of the first embodiment in that a large number of the fiber reinforcing materials 5 of the above are mixed.

In the fiber reinforced concrete 1 capable of recycling the material of the third embodiment, the fiber reinforced concrete 5 is made of aluminum and has a stranded wire shape, so that the same operations and effects as those of the second embodiment can be obtained.

According to the third embodiment, the fiber reinforcing material is made of aluminum and has a stranded wire shape. However, other than aluminum, a metal having a low melting point such as lead, rubidium, tin, and zinc is formed in the stranded wire shape. It may be used as a fiber reinforcing material.

FIG. 8 is a graph showing a comparison of the tensile properties of a plurality of types of fiber reinforced concrete capable of recycling the materials of the first, second and third embodiments of the present invention. In this graph, the aluminum fiber reinforced concrete without an oxide film and the linear fiber reinforced concrete, the aluminum-elliptical annular fiber reinforced concrete 4 of the second embodiment with and without the oxide film, and the third embodiment. Comparison of tensile properties of fiber reinforced concrete 1 made of aluminum and stranded wire-shaped fiber reinforced concrete 5 with and without oxide film, which can be recycled from 5 types of materials mixed in the cured body 2 of the compound. is doing.

In the fiber reinforced concrete 1 capable of recycling the materials of the first, second and third embodiments, sludge water (scoop or mixer used for kneading) is used to suppress alkaline corrosion that occurs when aluminum is used as the fiber reinforced material. (Highly alkaline water, which is a waste liquid discharged when washing etc.), or another high alkaline water other than the waste liquid, soaked an elliptical annular fiber reinforced concrete 4 made of aluminum in advance (made of aluminum and twisted). By forming an oxide film on the fiber surface in advance, the alkaline corrosion reaction after adding a large number of fiber reinforced concrete 4 to the cured body 2 of the compound can be carried out at low cost. Can be slowed down with. That is, during the curing of the recyclable fiber reinforced concrete 1, hydrogen is generated by a chemical reaction between the aluminum elliptical annular fiber reinforced material 4 and the cured body 2 of the compound, and the fiber reinforced material 4 and the compound are generated. A gap (gap) is created between the fiber and the hardened body 2, and the adhesion of the fiber reinforced material 4 is reduced. However, by causing alkaline corrosion in advance, as shown in FIG. 8, it is made of aluminum without an oxide film and has an elliptical ring shape. In the same way as when the fiber reinforced concrete 4 of the above is mixed in the cured body 2 of the compound, it is possible to recycle when the fiber reinforced concrete 4 made of aluminum with an oxide film and having an elliptical annular shape is mixed in the cured body 2 of the compound. It is possible to prevent the adhesion of the fiber reinforced concrete 4 from decreasing during the curing of the fiber reinforced concrete 1, and the reinforcing effect is higher than when a linear fiber reinforced concrete made of aluminum without an oxide film is mixed in the cured body 2 of the compound. Can be further enhanced.

Further, in the case of the aluminum-made stranded fiber reinforced concrete 5, by causing alkaline corrosion in advance, the cured body 2 of the compound and a large number of aluminum-made stranded fiber reinforced concrete 5 are kneaded. It is possible to further suppress the entanglement of the fiber reinforcing materials 5 at the time of mixing, and it is possible to expect uniform dispersion of a large number of fiber reinforcing materials 5. As a result, as shown in FIG. 8, when the stranded fiber reinforcing material 5 made of aluminum with an oxide film is mixed with the cured body 2 of the compound, it is made of aluminum without an oxide film and has a stranded wire shape. Compared with the case where the fiber reinforced concrete 5 of the above is mixed in the cured body 2 of the compound, it is possible to prevent the adhesion of the fiber reinforced concrete 5 from being lowered during the curing of the recyclable fiber reinforced concrete 1, and the reinforcing effect is further enhanced. be able to.

1 Recyclable fiber reinforced concrete 2 Cement, admixture material, binder consisting of part or all of water, sand (fine aggregate), gravel (coarse aggregate), part of the admixture material or Hardened compound made by adding all of them 3 Fiber reinforced concrete made of metal with low melting point 4 Fiber reinforced concrete made of aluminum and elliptical annular (Fiber reinforced concrete made of metal with low melting point and elliptical annular fiber)
5 Aluminum stranded fiber reinforced material (metal with low melting point and stranded fiber reinforced material)
10 Seawall (concrete structure)

Claims (8)

A cured product of a formulation composed by adding a part or all of materials such as fine aggregate, coarse aggregate, and admixture to a binder consisting of cement, admixture, part or all of water, and having a low melting point. Fiber reinforced concrete that can be recycled, which is characterized by being mixed with metal fiber reinforced concrete. It is a fiber reinforced concrete that can recycle the material according to claim 1.
The low melting point metal fiber reinforcing material is an alloy containing aluminum, bismuth, cesium, mercury, potassium, lithium, sodium, lead, rubidium, tin, zinc, indium, gallium, cadmium and their oxides as main materials. Alternatively, fiber reinforced concrete capable of recycling a material characterized by being a metal fiber made of a single metal. A fiber reinforced concrete capable of recycling the material according to claim 1 or 2.
The metal fiber reinforced concrete having a low melting point is a fiber reinforced concrete whose material is recyclable and is characterized by having an elliptical annular shape. A fiber reinforced concrete capable of recycling the material according to claim 1 or 2.
The metal fiber reinforced concrete having a low melting point is a fiber reinforced concrete that can be recycled as a material characterized by having a stranded wire shape. A fiber reinforced concrete capable of recycling the material according to claim 1, 3 or 4.
The fiber reinforced concrete made of metal having a low melting point is made of aluminum and is a reinforced concrete having an oxide film on the surface of the fiber, and the material can be recycled. A fiber reinforced concrete capable of recycling the material according to claim 5.
The oxide film on the surface of the fiber is a fiber reinforced concrete capable of recycling a material characterized by being composed of a chemical reaction of highly alkaline water. It is a recycling method after the service of a concrete structure made of fiber reinforced concrete mixed with a metal fiber reinforcing material having a low melting point.
First, the fiber-reinforced concrete of the used concrete structure is dismantled.
Next, the disassembled fiber reinforced concrete is heat-treated at a low temperature to melt the metal fiber reinforced concrete having a low melting point.
Next, after crushing the fiber-reinforced concrete heat-treated at a low temperature, the concrete material for regeneration and the metal for regeneration, which are the raw materials for the hardened cement, are separated and recovered.
Next, it is possible to recycle the material, which is characterized in that the recycled fiber reinforced concrete made of the recycled metal is mixed with the recycled cement made of the recovered recycled concrete material to remanufacture the fiber reinforced concrete. How to recycle fiber reinforced concrete. A method for recycling fiber reinforced concrete, wherein the material according to claim 7 can be recycled.
The low melting point metal fiber reinforcing material is an alloy containing aluminum, bismuth, cesium, mercury, potassium, lithium, sodium, lead, rubidium, tin, zinc, indium, gallium, cadmium and their oxides as main materials. Alternatively, a method for recycling fiber reinforced concrete, which is characterized by being a metal fiber made of a single metal and capable of recycling a material.

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