JP2021038610A - Biodegradability block, structure and dismantling method - Google Patents

Abstract

To provide a biodegradable block that does not collapse when ready-mixed concrete is cast around and can maintain excellent strength for a desired period of time, and provide a structure and a demolition method.SOLUTION: Provided are: a biodegradable block (11) including a binder (12) in which aggregates are bonded to each other with a binding agent and a coating body (13) that covers the entire binder (12), wherein the binding agent contains at least one selected kind from the group consisting of aliphatic polyesters and water-soluble polymers, and the coating body (13) is waterproof; and a structure and a dismantling method.SELECTED DRAWING: Figure 1

Description

The present invention relates to biodegradable blocks, structures and dismantling methods.

The block demolition method is a type of environmentally friendly demolition method for buildings, in which a flat saw, wire saw, etc. are used according to the part of the building to separate the building frame, transport it to a place that does not affect the surrounding environment, and crush it. Is. The size and weight of the skeleton to be cut is determined by the lifting weight and the capacity of the truck, and the entire building will be cut to a considerable length. In this method, the cutting process of the reinforced concrete (RC) skeleton requires a lot of time (30 to 40% of the time from cutting to lifting), and improvement of cutting efficiency of RC members is required. There is.

In Patent Document 1, as a method of placing an easily dismantled concrete structure in which it is necessary to remove an appropriate amount of concrete once placed, the inside of the form is divided into multiple floors by a horizontal partition and formed by this partition. The space on each floor is divided into multiple rooms by vertical partitions, and each room on the multiple floors is provided with a communication hole leading to the corresponding room on the upper floor. A method for placing an easily dismantleable concrete structure is described, which comprises injecting concrete and filling each room on each floor with ready-mixed concrete from below through the above-mentioned communication holes.
However, although the concrete structure cast by the casting method described in Patent Document 1 is suitable as a structure utilizing the mass of concrete for ballast use of ships, dead weight use of railway vehicles, etc., it is a building. The strength is not enough and it is not suitable.

On the other hand, there is a technique for improving the cutability of the building frame at the time of dismantling by designing the allocation of the block dismantling at the time of new construction and incorporating an element for improving the cutability in advance in the part of the RC member scheduled to be cut. The characteristic of the element is that it is a material that has the required strength and loses its function and performance under certain conditions.

As such an element, a biodegradable block formed by molding a material that collapses upon contact with water described in Patent Documents 2 to 4 can be considered.

Special Publication No. 56-38437 Japanese Unexamined Patent Publication No. 2017-218337 JP-A-2017-218482 JP-A-2017-218336

However, when ready-mixed concrete is placed around the biodegradable block formed from the materials described in Patent Documents 2 to 4, the biodegradable block starts to collapse due to contact with water contained in the ready-mixed concrete. The desired strength could not be maintained for a desired period of time, such as the biodegradable block collapsing during the placement of the concrete, and the strength of the structure may decrease.

Therefore, it is an object of the present invention to provide a biodegradable block, a structure and a dismantling method which can maintain excellent strength for a desired period without collapsing even when ready-mixed concrete is cast around.

The above problem is solved by the following configuration.
[1] A binder obtained by binding aggregates to each other with a binder and a coating body covering the entire of the binder are provided, and the binder is selected from the group consisting of an aliphatic polyester and a water-soluble polymer. A biodegradable block comprising at least one, said covering having waterproof properties.
[2] The biodegradable block according to [1], wherein the coating is a plastic film.
[3] A structure including the biodegradable block according to [1] or [2] and concrete surrounding the biodegradable block.
[4] A structure according to the method for dismantling a structure according to [3], wherein a through hole is formed in the concrete and water is injected into a composite body in which aggregates inside the biodegradable block are bonded with a binder. How to dismantle things.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a biodegradable block, a structure and a dismantling method which can maintain excellent strength for a desired period without collapsing even when ready-mixed concrete is cast around.

Further, in the demolition work by the block demolition method of the RC building, the cutting efficiency of the members can be improved, the entire construction period can be shortened, and the cost can be reduced.

FIG. 1 is a diagram illustrating an embodiment of a biodegradable block of the present invention. FIG. 1 (A) shows the appearance of the biodegradable block. FIG. 1 (B) shows a cross section cut at the plane connecting the PQRS of the biodegradable block of FIG. 1 (A). FIG. 2 is a diagram illustrating an embodiment of the structure of the present invention.

In the present specification, the numerical range represented by using "~" shall include the numerical values on both sides of "~" in the range.
As used herein, the term "biodegradable" is intended to mean that the binder that binds the aggregates to each other is decomposed by an external factor. Specifically, hydrolyzable, biologically degradable, photodegradable, oxidatively degradable and the like are included. Of these, it is preferably hydrolyzable or degradable by biological action.
As used herein, the term "water-soluble" is intended to mean that contact with water causes dissolution of a binder that binds aggregates to each other.
As used herein, the term "disintegration rate" refers to the rate at which the weight of the binder is reduced due to the breakdown of the binder due to the decomposition or dissolution of the binder and the resulting separation of a part of the aggregate from the binder. Intended. The faster the decay rate, the shorter the time it takes for the conjugate to completely collapse. In other words, in the case of a bond having the same shape including the dimensions, if the time until the bond completely collapses is short, it can be said that the collapse rate is high.

[Biodegradable block]
The biodegradable block of the present invention comprises a conjugate and a cladding.
FIG. 1 shows an embodiment of the biodegradable block of the present invention. As shown in FIG. 1 (A), the binder 12 is completely covered with the covering 13, and the coupling 12 is not exposed to the outside. FIG. 1 (B) is a cross-sectional view taken along a plane including the PQRS of FIG. 1 (A). As shown in FIG. 1 (B), the conjugate 12 is coated with the cladding 13.

<Conjoined twins>
The binder is made of a material in which aggregates are bonded to each other with a binder.

(aggregate)
The aggregate constitutes the main component of the conjugate.
As the aggregate, coarse aggregate and fine aggregate generally used for building materials can be used. Examples of the coarse aggregate include crushed stone, land gravel and river gravel. Examples of the fine aggregate include river sand, sea sand, mountain sand, crushed sand and silica sand. These aggregates may be used alone or in combination of two or more.
In addition to the natural aggregates described above, artificial aggregates such as waste glass, glass beads, ceramics and plastics may be included. However, from the viewpoint of suppressing the burden on the environment after the collapse of building materials, it is preferable not to use artificial aggregate.

(Binder)
The binder binds aggregates to each other and contains at least one selected from the group consisting of aliphatic polyesters and water-soluble polymers.
The binder can be biodegradable by containing at least one selected from the group consisting of aliphatic polyesters and water-soluble polymers.

Examples of the aliphatic polyester include polyglycolic acid, glycolic acid or a copolymer of glycolide and another hydroxycarboxylic acid, polylactic acid, a copolymer of lactic acid and another hydroxycarboxylic acid, polybutylene succinate, and polybutylene. Examples include adipates, polycaprolactones, and copolymers of caprolactone with other hydroxycarboxylic acids. Among them, polyglycolic acid, polylactic acid and polycaprolactone are preferable, and polyglycolic acid is more preferable. The aliphatic polyester may contain low molecular weight substances which are unreacted products when the aliphatic polyester is produced. The low molecular weight substance may be a monomer which is a raw material of an aliphatic polyester, an oligomer thereof, or the like, which will be described later. The binder may also include a catalyst for polymerizing the raw material of the aliphatic polyester, a molecular weight modifier, and the like as its composition.

Examples of the water-soluble polymer include polysaccharides (for example, starches, alginic acid derivatives, natural gums, simple polysaccharides, complex polysaccharides, and mucopolysaccharides) and synthetic polymers. More specifically, but not limited to, sodium alginate, propylene glycol alginate, carmellose, carmellose calcium, ghatti gum, carrageenan, carboxyvinyl polymer, carboxymethyl ethyl cellulose, sodium carboxymethyl starch, sodium carboxymethyl cellulose, sodium carmellose, Xanthan gum, guar gum, quince seed gum, glucomannan, copolyvidone, gellan gum, gelatin, tamarind gum, tara gum, dextrin, starch, corn starch, tragant, potato starch, sodium hyaluronate, hydroxyethyl cellulose, hydroxypropyl starch, hydroxypropyl cellulose, hydroxy Propylmethylcellulose, hydroxymethylcellulose, hypromerose, purulan, polyvinylpyrrolidone, polyethylene oxide, polyvinylalcohol, polyvinylalcohol-acrylic acid-methylmethacrylate copolymer, macrogol 6000, ethylcellulose, methylcellulose, phosphoric acid cross-linked starch, locust bean gum, agar , Cold plum flour, fully pregelatinized starch, crystalline cellulose carmellose sodium, oxidized starch, low-substituted hydroxypropyl cellulose and partially pregelatinized starch. Among them, purulan, starch, hydroxypropyl cellulose, hydroxypropyl methyl cellulose and polyvinyl alcohol are preferable, purulan, starch, hydroxymethyl cellulose, hydroxypropyl methyl cellulose and polyvinyl alcohol are more preferable, and purulan and hydroxypropyl methyl cellulose are further preferable.

When the binder contains at least one selected from the group consisting of aliphatic polyesters and water-soluble polymers, decomposition of the binder proceeds by hydrolysis and decomposition by biological action, and the aggregates are bonded to each other. The function of causing is lost, or the binder disappears. As a result, the aggregates fall apart and the biodegradable block collapses.

(Content ratio of aggregate and binder)
The content ratio of the aggregate and the binder in the above-mentioned conjugate is not particularly limited, and may be appropriately set according to the purpose, use, period of use and environment of use of the biodegradable block, the type of aggregate, the type of binder, and the like. Just do it. For example, the amount of aggregate in the conjugate can be 70-90% by weight, 90-95% by weight or 95-98% by weight. Further, when the whole body is 100, the ratio (volume ratio) of the aggregate can be, for example, 65 to 90, 90 to 95, 95 to 98.

The conjugate may have air bubbles or air gaps that communicate with each other, but it is preferable that the conjugate does not contain these. In addition, when it is said that "there are no bubbles", it does not exclude those having minute bubbles that are unintentionally generated in the manufacturing process.

(Nuclear lamina and coating layer)
The bond has a two-layer structure of a nuclear layer and a coating layer, and each of the nuclear layer and the coating layer may be formed by binding the above-mentioned aggregates to each other with a binder.
In this case, the coating layer covers the entire nuclear layer. That is, there is a coating layer on the outside that is in contact with a factor that decomposes or dissolves the binder (hereinafter referred to as "decomposition factor"), for example, water or microorganisms, and a nuclear layer on the inside. Therefore, the decay of the outer coating layer that the decomposition factor touches progresses, and the progress of the collapse of the nuclear layer begins only when the decomposition factor comes into contact with the inner nuclear layer.
In the above-mentioned bond, each layer is configured so that the decay rate of the nuclear layer and the decay rate of the coating layer are different. Specifically, the decay rate of the nuclear layer is faster than the decay rate of the covering layer.
Since the decay rate of the nuclear layer is faster than the decay rate of the coating layer, when the decay of the coating layer progresses and the decomposition factor comes into contact with the nuclear layer, the decay rate of the building material as a whole increases.
The means for making the disintegration rate different between the nuclear layer and the coating layer is not particularly limited, and for example, the disintegration rate can be made different by changing the type of binder, the type of aggregate, or the amount of the binder used. ..
When changing the type of the binder, for example, it is preferable to use a water-soluble polymer for the core layer and an aliphatic polyester resin for the coating layer.
The thickness and shape of the core layer and the coating layer can be appropriately set depending on the strength required for the building material and the period of use of the building material.

(Other ingredients)
The biodegradable block conjugate of the present invention may contain components other than the aggregate and the binder. Examples of the components that can be contained include antifoaming agents, inorganic fibers, organic fibers and the like.

(Manufacturing method of conjugate)
The above-mentioned conjugate can be produced based on a conventional method for producing a molded body using an aggregate and a binder.
For example, in the case of an aliphatic polyester, a binder can be obtained by mixing a binder and an aggregate in a predetermined ratio, molding the mixture, heating and melting the binder, and then cooling and solidifying the binder. In the case of a water-soluble polymer, a binder can be obtained by mixing a powdery binder, water and an aggregate in a predetermined ratio, molding the mixture, heating or drying the binder to solidify the binder. it can. Specific conditions may be appropriately set according to the binder to be used and the expected environment in which the biodegradable block is used.

<Cover>
The covering body covers the entire body and has waterproof property.

The covering body covers the entire of the binding body to prevent contact between the bonding body and water.
Further, the covering body is preferably one that can withstand the state at the time of placing concrete.
Further, the covering body is preferably one having durability that can prevent the contact between the combined body and water during the service period of the structure.
By preventing the contact between the binder and water, the hydrolysis of the binder contained in the binder is suppressed and the hardening of the mortar is not inhibited.

The covering body is preferably a waterproof coating film formed on the entire surface of the bonded body or a waterproof film covering the entire surface of the bonded body.
Both the coating film and the film may have a laminated structure in which two or more layers are laminated. Further, two or more kinds of coating films and films may be used in combination.

(Waterproof coating film)
Examples of the waterproof coating film include coating films such as urethane resin, acrylic resin, epoxy resin, and acrylic silicone resin formed by a non-water-based waterproof paint.
The same type of coating film may be laminated, or different types of coating films may be laminated.
The thickness of the coating film is not particularly limited, but is preferably 1.0 to 2.0 mm, and about 1.5 mm is preferable in terms of waterproofness and a balance between durability and productivity.

(Waterproof film)
Examples of the waterproof film include a plastic film.
Examples of the material of the plastic film include polyvinyl chloride, polyvinylidene chloride, polyethylene, polypropylene, polyethylene terephthalate and the like.
The same type of film may be laminated, or different types of films may be laminated.
The thickness of the film is not particularly limited, but may be 20 to 100 μm, and the coating is preferably 75 μm or more.

<Shape of biodegradable block>
The shape of the biodegradable block of the present invention is not particularly limited, and any shape that can be molded can be used depending on the intended purpose. Examples of the shape of the biodegradable block include a cube, a rectangular parallelepiped, a panel, a cylinder, a cylinder, a gutter, a rod, a cone, a pyramid, a sphere, and a frame.

<Use of biodegradable blocks>
The use of the biodegradable block of the present invention is not particularly limited, but in particular, an element for improving cutability, which is designed up to the allocation of block dismantling at the time of new construction and incorporated in advance in the part of the RC member to be cut. It is preferable to use as.
In addition, regarding the part of the building where the biodegradable block is placed, as an application other than the separation position of the member assuming the dismantling of the building in the future, the part of the reinforced concrete member that is expected to open at the time of extension or renovation, temporary construction When changing the structure due to the boundary between the concrete member and the skeleton, the temporary support member until the seismic isolation device is installed or replaced, the temporary support member of the structure damaged by the disaster, etc. There are basics such as temporary support members and equipment books that are supposed to be used temporarily (for a fixed period).

<Manufacturing method of biodegradable block>
The biodegradable block of the present invention can be produced by producing a conjugate by the above-mentioned method for producing a conjugate and then covering the entire conjugate with a coating.
The method of covering the entire bond with the coating material is not particularly limited.
When the coating film is a coating film, the entire surface of the bonded body can be covered with the coating film by applying a non-aqueous waterproof paint to the entire surface of the bonded body and curing the coating body. The application of the paint is not limited to one time, and a plurality of times of repeated coating may be applied. The type of paint to be applied multiple times may be the same or different.
When the covering body is a film, it is preferable to cover the entire surface of the bonded body with a film and seal the edges of the film with a heat seal or the like. Vacuum packaging is also preferred. The number of films is not limited to one, and a plurality of films may be stacked. The type of film when a plurality of sheets are stacked may be the same or different.

[Structure]
The structure of the present invention includes the biodegradable block described above and the concrete surrounding the biodegradable block.

The biodegradable block is preferably placed at the site to be cut at the time of disassembly.
In addition to concrete, components such as reinforcing bars that can be included in ordinary reinforced concrete may also be included.
FIG. 2 is a diagram illustrating an embodiment of the structure of the present invention.
As a method of manufacturing the structure of the present invention, for example, a method of arranging a reinforcing bar 23 and a biodegradable block 21 and placing ready-mixed concrete to form a concrete 22 surrounding the biodegradable block 21 can be mentioned. Be done. In the biodegradable block 21, the joint that decomposes by contact with water is covered with a waterproof covering, so that the internal joint comes into contact with the water contained in the ready-mixed concrete when the ready-mixed concrete is placed. However, the strength of the conjugate and even the biodegradable block is maintained.
Needless to say, the shapes and arrangements of the biodegradable blocks, concrete, and reinforcing bars are not limited to those shown in FIG. 2, and various modifications are possible as long as they do not deviate from the gist of the present invention.

[Disassembly method]
The dismantling method of the present invention is the above-mentioned dismantling method of a structure, which is a method of dismantling a structure in which a through hole is made in concrete and water is injected into a joint inside a biodegradable block.
As described above, the structure of the present invention includes a biodegradable block and concrete surrounding the biodegradable block, and a hole is made in the concrete and water is injected into the joint inside the biodegradable block. By doing so, the biodegradable block collapses within a few hours to a few days, so that cutting with a flat saw, a wire saw, or the like becomes easy.
In particular, if a biodegradable block is placed at a site to be cut at the time of dismantling, the convenience of dismantling as scheduled is enhanced.
According to the dismantling method of the present invention, the cutting efficiency of the member is improved, the entire construction period can be shortened, and the cost can be reduced.
The cutability can be determined from the power consumption, cutting time, noise, etc. of cutting tools such as slab saws and wire saws at the time of cutting.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the examples described below, and various modifications can be made without departing from the gist of the present invention. ..

[Example 1]
A resin concrete composition was prepared by mixing a fine aggregate with a polyglycolic acid resin powder (manufactured by Kureha Corporation). The content of the polyglycolic acid resin in the resin concrete composition was 16% by mass.
The prepared resin concrete composition was injected into a mold and heated to obtain a rectangular parallelepiped composite having a size of 40 mm × 40 mm × 80 mm.
A coating film made of urethane resin was formed on the surface of the obtained block-shaped composite body to make it waterproof.
A test structure (H = 300 mm, L = 300 mm, H = 150 mm) in which six manufactured biodegradable blocks were placed in a reinforcing bar enclosure as shown in FIG. 1 and ready-mixed concrete was poured and hardened. And, a test structure having no biodegradable block of the same size for comparison was manufactured.
The remaining one of the test structures was perforated in concrete, water was poured into the biodegradable block, and then kept warm at 80 ° C. for 24 hours. After that, when the structure was cut, it was confirmed that the biodegradable block had collapsed.
In a cutting experiment using a slab saw with a constant output, the cutting time was shortened by 27% and the noise was reduced by 25% in the test structure in which the biodegradable block was disintegrated, as compared with the test structure having no biodegradable block. It was confirmed that the cuttability was improved by reducing the percentage.

Biodegradability that is waterproofed by using a coating film made of urethane resin or a film using PVDC (polyvinylidene chloride) in the test piece (φ100 mm, L = 200 mm) for checking the concrete strength of the test structure. One block (40 mm × 40 mm × 80 mm) was prepared, and the effect of the coating material and the influence of the presence or absence of biodegradation of the biodegradable block on the concrete strength were confirmed.

The biodegradable block, structure and disassembly method of the present invention can improve the cutting efficiency of members in the dismantling work by the block dismantling method of the structure, and can achieve shortening of the entire construction period and cost reduction.

11 Biodegradable block 12 Joined 13 Cover 21 Biodegradable block 22 Concrete 23 Reinforcing bar

Claims (4)

A binder obtained by binding aggregates to each other with a binder and a covering covering the entire aggregate are provided.
The binder comprises at least one selected from the group consisting of aliphatic polyesters and water-soluble polymers.
The covering is waterproof.
Biodegradable block. The biodegradable block according to claim 1, wherein the coating is a plastic film. A structure comprising the biodegradable block according to claim 1 or 2 and concrete surrounding the biodegradable block. The method for dismantling a structure according to claim 3, wherein a through hole is formed in the concrete and water is injected into a bond in which aggregates inside the biodegradable block are bonded with a binder. Method.

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