JP7436263B2 - Conductive static crushing agent and static crushing method using the same - Google Patents

Description

The present invention relates to a conductive static crushing agent used for demolishing or removing concrete structures or rocks.

Mainly in the construction and civil engineering fields, when demolishing or removing concrete structures or rocks, the surrounding environment is taken into consideration, and instead of using dynamic means such as blasting or impact, the expansion is done by filling multiple small holes hollowed out. Static fracturing means to create cracks may be employed. It has been proposed that after a hole is drilled in a concrete structure or rock to be crushed using a static crushing agent that has hydration reaction expansion properties, the static crushing agent mixed with water is filled into the hole. ing. That is, rocks and reinforced concrete structures are crushed by the expansion phenomenon caused by the hydration reaction of the static crushing agent filled in the holes (Patent Document 1).
However, in the above method, the estimated crack initiation time for general static crushing agents ranges from 12 to 24 hours, while for fast-acting agents it ranges from 1 to 3 hours, making it difficult to control the process and making it difficult to use in low-temperature environments (approximately 5 degrees Celsius). Problems include the delay in crushing with static crushing agents and the difficulty in selecting the number during the off-season period.
In order to solve this problem, Patent Document 2 proposes heating the kneaded material filled in the holes of the crushed material from the opening side of the holes (heating source: calcium oxide, aluminate, calcined dolomite, or other hydrated material). A construction method has been proposed that uses one or more of the following: a substance that generates heat through a reaction, heat generated from a gas burner, a torch burner, an electric heating wire, a bonfire, etc.
Further, in Patent Document 3, a cylinder or a hollow polygon made of a material having heat insulating properties is placed in the hole, a kneaded material is filled in the cylinder, and the reaction heat of the kneaded material is generated to promote the reaction, A crushing method using a heat insulating material has been proposed, which is characterized by crushing non-destructible materials.
Furthermore, in Patent Document 4, a temperature adjustment tube that allows fluid to flow inside is installed in the center of the hole provided in the object to be crushed, and a static crushing agent is filled around the temperature adjustment tube, A construction method has been proposed in which the reaction time of the static crushing agent is controlled by circulating a fluid around the temperature regulating pipe.

Japanese Patent Application Publication No. 2014-141387 Japanese Unexamined Patent Publication No. 161751/1986 Japanese Unexamined Patent Publication No. 164595/1983 Japanese Unexamined Patent Publication No. 17673/1983

However, in the case of Patent Document 2, the heating range is only the part that is in contact with the opening of the hole, and the entire kneaded material is heated only from the top surface, so that the kneaded material inside the hole is not uniform. There is a problem in that it takes time for the material to be heated, and it is difficult to adjust the temperature or crush the material to be crushed at an arbitrary timing. Further, in the case of Patent Document 3, there is a problem that it takes time to heat the kneaded material only by keeping it warm, and it is difficult to adjust the temperature or crush the material to be crushed at an arbitrary timing. Furthermore, in the case of Patent Document 4, in order to circulate cold water and hot water, large-scale preparations such as piping, pumps, compressors, etc. are required. Furthermore, since the circular tube is buried in the static crushing agent filling hole, there is a problem that the amount of static crushing agent filled decreases and the crushing effect is reduced.

In order to solve the above-mentioned problems, the present invention has been made after various studies, and it has been discovered that it is possible to make the static crushing agent generate heat by adding a conductive substance to the static crushing agent and applying electricity. As a result, we have obtained knowledge that can solve the above-mentioned problems, and have completed the present invention.
That is, the present invention is as follows.
[1] A conductive static crushing agent containing free quicklime, carbon-based conductive particles, and an electrolyte , wherein the content of the carbon-based conductive particles in the conductive static crushing agent is 0.1 to 3. 0% by mass and an electrolyte content of 0.05 to 3.0% by mass .
[2] The conductive static crushing of [1], wherein the electrolyte is one or more selected from alkali metal carbonates, percarbonates, sulfates, sulfites, nitrates, nitrites, and chlorides. agent.
[3] A method for crushing an object to be crushed using a conductive static crushing agent, in which a hole is provided in the object to be crushed, and an electrode and the conductive static of [1] or [2] are placed inside the hole. A crushing method characterized in that the electrically conductive static crushing agent self-heats by supplying electricity to the electrode in a state where the static crushing agent is placed.

By using the conductive static crushing agent of the present invention, objects to be crushed such as concrete can be destroyed within a predetermined time regardless of the temperature environment, specifically even in a low temperature environment.

FIG. 1 is a conceptual diagram showing a crushing method according to the present invention. FIG. 3 is a diagram showing the relationship between kneaded material temperature and mold strain-time in Examples. FIG. 3 is a diagram showing the relationship between formwork strain and time in Examples and Comparative Examples.

The conductive static crushing agent in the present invention contains free quicklime, carbon-based conductive particles, and an electrolyte. Embodiments of the present invention will be described in detail below.

<Conductive static crushing agent>
The conductive static crushing agent of the present invention contains free quicklime as an active ingredient. Free quicklime is crystalline CaO. The content of free quicklime is not particularly limited, as long as it can exhibit an expansion force that causes expansion cracks in the hardened concrete. Preferably, the free quicklime content in the conductive static crushing agent is preferably 65% by mass or more, more preferably 70% by mass or more, and 75% by mass or more, since it is possible to stably express higher expansion force. % or more is more preferable.

Free quicklime used in the present invention is obtained by calcining calcareous raw materials such as limestone. Alternatively, the calcareous material is mainly composed of a calcareous raw material, and one or more of a siliceous raw material, an alumina raw material, a ferrite raw material, a gypsum raw material, etc. are mixed therein and fired. After calcination, clinker is obtained as a clinker whose main component is free quicklime, and granules obtained by crushing and classifying this are used.

Examples of the carbon-based conductive particles in the present invention include carbon black (furnace black, Ketjen black, acetylene black, etc.), graphite, carbon nanotubes, graphene, fullerene, carbon fiber, etc., and one or more types may be used. Can be done. In particular, a configuration containing two or more types of particles such as graphite and fine particles such as Ketjen black and nanocarbon in combination is preferable from the viewpoint of heat generation efficiency. The content of carbon-based conductive particles in the conductive static crushing agent is preferably 0.1 to 3.0% by mass, more preferably 0.5 to 1.5% by mass.

In the present invention, an electrolyte is included together with the carbon-based conductive particles. As a result, a conductive static crushing agent with good current conduction efficiency and good heat generation efficiency can be obtained. The electrolyte in the present invention may be any substance that dissolves in water and ionizes to produce anions and cations, and is not particularly limited, but includes, for example, alkali metal carbonates, percarbonates, and sulfates. , sulfites, nitrates, nitrites, and chlorides, and it is preferable to use one or more selected from these. Specific examples include sodium chloride, potassium chloride, calcium chloride, sodium sulfate, iron sulfate, sodium nitrate, calcium nitrate, magnesium nitrate, iron nitrate, and the like. The content of the electrolyte in the conductive static crushing agent is preferably 0.05 to 3.0% by mass, more preferably 0.1 to 2.0% by mass, and 0.2 to 1.5% by mass. More preferred.

<Static crushing method>
First, holes are provided in the object to be crushed. The object to be crushed is not particularly limited as long as it is a brittle object that can generally be crushed by a static crushing method, and examples thereof include concrete structures, rocks, bedrock, and the like.

The hole size and hole spacing are appropriately selected depending on the rock quality of the object to be crushed, the joints, the amount of reinforcing steel, and the condition of the free surface. Generally, the pore diameter is 30 to 80 mm and the pore spacing is often about 30 to 60 cm, but this can be determined by conducting test crushing as necessary. The method for forming the holes is not particularly limited, but generally a core drill or the like is used.

Then, an electrode and a conductive static crushing agent are placed inside the provided hole. Generally, an electrode is inserted into the hole, and the excess space within the hole is filled with a conductive static crushing agent. At this time, the electrode is preferably inserted to the vicinity of the tip of the hole so that the conductive static crushing agent filled in the hole can be efficiently heated. Further, it is preferable that the conductive static crushing agent be filled so that the holes are completely filled, but rather that they slightly overflow.

The electrode used here is not particularly limited as long as it is a commonly used electrode material. Examples include iron, copper, zinc, etc. Copper is preferable as the electrode used in the present invention. Since the electrode is inserted into the hole, it is preferably rod-shaped or band-shaped. The electrodes are placed within the hole, with the anode and the negative electrode spaced apart from each other by a certain distance. The electrodes are connected to an external power supply via wiring.

The conductive static crushing agent used in the static crushing method of the present invention is a conductive static crushing agent containing the above-mentioned free quicklime, carbon-based conductive particles, and electrolyte. When the conductive static crushing agent is filled into the holes provided in the object to be crushed, it is filled in a state where it is mixed with water (kneaded material). The amount of water blended is preferably 15 to 35 parts by weight, more preferably 18 to 32 parts by weight, per 100 parts by weight of the conductive static crushing agent. The kneading can be done by hand or using a hand mixer, and is preferably completed within 2 minutes.

According to the method of the present invention, after the electrode and the conductive static crushing agent are placed in the holes of the object to be crushed, the conductive static crushing agent itself can be made to generate heat by energizing the electrode. Thereby, hydration of the conductive static crushing agent can be promoted, and expansion pressure due to the hydration reaction can be developed at an early stage. Thereby, the object to be crushed can be crushed in a short time. Further, even in a low-temperature environment, it can be crushed quickly without being affected by the environmental temperature. Furthermore, by adjusting the timing of energization, it is also possible to crush the object at a desired time.

The present invention is characterized in that the conductive static crushing agent itself generates heat when energized. Compared to conventional heating methods using gas burners, heating wires, etc., the conductive static crushing agent itself can be uniformly and efficiently heated, and the expansion pressure of the conductive static crushing agent can be quickly, uniformly and efficiently reduced. It has the effect of making it possible to express.

Next, the present invention will be explained in more detail with reference to Examples. Note that the present invention is not limited to the following examples.

<Preparation of conductive static crushing agent>
First, a mixed powder of 95 parts by weight of quicklime, 4 parts by weight of clay, and 1 part by weight of gypsum was calcined at 1450° C. for 1 hour to obtain clinker containing 80% by mass of free quicklime. This clinker was coarsely crushed using an impeller breaker and further crushed using a mill. 100 parts by mass of this pulverized clinker, 1.25 parts by mass of graphite (manufactured by Fujifilm Wako) as carbon-based conductive particles, and Ketjenblack ECP (manufactured by Lion Specialty Chemicals, particle size) as carbon-based conductive fine particles. A conductive static crushing agent was prepared by blending 0.05 parts by mass of 39.5 nm) and 0.5 parts by mass of iron (II) sulfate heptahydrate (manufactured by Kanto Kagaku Co., Ltd.) as an electrolyte. Therefore, the present conductive static crushing agent contains 1.28% by mass of carbon-based conductive particles and 0.49% by mass of iron(II) sulfate heptahydrate (0.49% by mass in terms of anhydride). 27% by mass).

<Crushing test using conductive static crushing agent>
A crushing test was conducted using the above conductive static crushing agent. A cylindrical concrete specimen (φ150×300 mm) was prepared as an object to be crushed. A hole (filling hole) of φ42 x 250 mm is opened in a cylindrical concrete specimen, and filled with a conductive static crushing agent kneaded mixture in which 20 parts by mass of water is added to 100 parts by mass of the above conductive static crushing agent, A thermocouple was installed in the hole to measure the temperature of the kneaded material. In addition, strain gauges were installed in the formwork of the cylindrical concrete specimen.
A conductive static crushing agent kneaded material is filled into the hole, a copper rod is inserted into the hole as an electrode, and 15 minutes after filling, a constant voltage of 20 V is applied.
FIG. 2 shows a graph of the kneaded material temperature-time relationship and mold strain-time relationship obtained from the crushing test results of a conductive static crushing agent. As a comparative example, a crushing test was conducted using Taiheiyo Power Blaster (manufactured by Taiheiyo Materials Co., Ltd.), which is a commercially available static crushing agent. In the case of the conductive static crushing agent, it was confirmed that the temperature rise of the warmed material was large after energization. Furthermore, when looking at the strain in the formwork, it was confirmed that the strain value rapidly increased approximately 45 minutes after filling (the concrete specimen was crushed). In the case of the comparative example, the strain in the formwork increased more slowly than in the example, and it took about 80 minutes until the concrete specimen was crushed. That is, it was confirmed that the crushing effect of the conductive static crushing agent was improved by heating the conductive static crushing agent.

1 Object to be crushed 2 Conductive static crushing agent 3 Electrode 4 Power supply device 5 Wiring

Claims (3)

A conductive static crushing agent containing free quicklime, carbon-based conductive particles, and an electrolyte , wherein the content of carbon-based conductive particles in the conductive static crushing agent is 0.1 to 3.0% by mass. A conductive static crushing agent having an electrolyte content of 0.05 to 3.0% by mass . The conductive static crushing agent according to claim 1, wherein the electrolyte is one or more selected from alkali metal carbonates, percarbonates, sulfates, sulfites, nitrates, nitrites, and chlorides. . A method for statically crushing an object to be crushed using a conductive static crushing agent, the method comprising:
A hole is provided in the object to be crushed, and an electrode and the conductive static crushing agent according to claim 1 or 2 are arranged inside the hole, and the conductive static crushing agent is energized by supplying electricity to the electrode. A crushing method characterized by self-heating of the crushing agent.

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