JP2002129897A - Spray device, quick-setting cement-concrete, and spray method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spray device capable of spraying stably over a long time while providing better strength developability, based on the fact that pipelines will not be clogged by the setting of quick-setting cement-concrete. SOLUTION: The spray device for the quick-setting cement-concrete comprises a pipeline A for transporting cement-concrete and a pipeline B for transporting a set accelerating agent. The crossing angle with which the axes of the lines A and B cross is 0 to 90 degrees.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spraying device, a quick-setting cement concrete, and a spraying method, which are performed, for example, for reinforcing a ground or stabilizing an excavated surface in tunnel excavation work. In the present invention, paste, mortar, and concrete are collectively called cement concrete.

[0002]

2. Description of the Related Art Conventionally, a method of spraying quick-setting cement concrete, which is a mixture of cement concrete and a quick-setting agent, has been used in order to prevent the excavation surface from falling off or collapse due to spring water when excavating a tunnel.

[0003] The method of spraying quick-setting cement concrete is roughly classified into a dry method and a wet method. In the dry method, a mixture containing cement, aggregate, quick-setting agent, etc. is transported in a pipe together with compressed air, and water is added from another pipe at the rear end of the spray nozzle, mixed, and the quick-setting cement concrete is mixed. Is prepared and sprayed. In the wet method, cement concrete in which water and a material other than the quick-setting agent are mixed is transported through the pipe by compressed air or a piston pump, and a quick-setting agent is added from another pipe at the rear end of the spray nozzle, resulting in quick setting. It is a method of preparing and spraying cement concrete.

Each method is characterized in that a joining pipe is provided at the rear end of the spray nozzle, two pipes are connected, and the respective materials are joined and mixed with the joining pipe to prepare a quick-setting cement concrete and spray it. I have. That is, in the dry method, a mixture containing cement, aggregate, a quick setting agent, etc., and containing no water is transported from one of the confluence pipes, and water is transported from the other of the confluence pipes to the confluence pipe. Are mixed and mixed to prepare a quick-setting cement concrete. In the wet method, cement concrete made of a material containing water other than the quick-setting agent is transported from one of the joining pipes, the quick-setting agent is transported to the joining pipe from the other of the joining pipes, and the two are merged, mixed, and then rapidly mixed. This is a method for preparing cement cement.

[0005] In ordinary spraying of quick-setting cement concrete, compressed air is transported to pipes, and the quick-setting cement concrete is sprayed with the compressed air to fix the quick-setting cement concrete on a target ground. . At that time, some quick-setting cement concrete floats around as dust, deteriorating the working environment. Even if it reaches the ground, it does not settle and rebounds, causing a loss called rebound. These dusts and rebounds are due to the fact that the quick setting cement concrete is not evenly mixed or
It is thought to be caused by the fact that the amount of compressed air used for spraying has not been optimized.

That is, it is considered that dust is generated due to insufficient mixing of fine-grained cement and fine aggregate at the tip of the merging pipe, or insufficient mixing of the powder quick-setting agent and water.
In addition, the rebound is not sufficiently mixed with coarse aggregate such as gravel and cement paste, or because the quick-setting agent is not uniformly distributed in the quick-setting cement concrete, cement concrete in which the quick-setting agent is not dispersed is used. It is thought to be caused by falling without fixing on the ground.

[0007] In order to reduce such dust and rebound, it is necessary to uniformly mix the quick-setting agent with cement concrete at a position ahead of the confluence pipe. Conventionally, a pipe of several meters is provided between the confluence pipe and the spray nozzle. Or a method of mixing the quick-setting agent and cement concrete at the end of a merging pipe by connecting the nozzles or squeezing the tip of a spray nozzle.

[0008]

However, when a pipe of several meters is connected between the merging pipe and the spray nozzle or the tip of the spray nozzle is narrowed, the quick-setting cement concrete hardens in the pipe. Therefore, there is a problem that the piping may be clogged. In addition, when the quick-setting cement concrete is sprayed for a long time, there is a problem that the quick-setting cement concrete gradually adheres to the inside of a pipe or a spray nozzle, and the pipe is easily clogged. The present inventor has conducted various studies to solve the above-described problems, and as a result, has obtained a finding that can solve the above-described problems by using a spraying device having a specific structure without using a confluent pipe as in the related art. It was completed.

[0009]

That is, the present invention comprises a pipe A in which cement concrete is transported and a pipe B in which a quick-setting agent is transported, and an intersection angle at which the central axes of the pipe A and the pipe B intersect. Is between 0 and 90 degrees,
A quick-setting cement concrete spraying device, wherein the quick-setting agent is a slurry quick-setting agent, and the quick-setting agent is a liquid quick-setting agent. Then, the intersection angle at which the central axis of the pipe A for transporting the cement concrete and the pipe B for transporting the quick-setting agent intersects from 0 to 90.
It is a quick setting cement concrete by setting the temperature and injecting the cement setting agent and the quick setting agent and joining them.
Further, there is provided a spraying method using the quick-setting cement concrete.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The present invention comprises a pipe A for transporting cement concrete and a pipe B for transporting a quick-setting agent. It consists of a pipe A to which cement concrete has been transported and a pipe B to which quick-setting agent has been transported. When the cement concrete and quick-setting agent are sprayed, the intersection angle at which the center axis of the pipe A tip and the center axis of the pipe B tip intersect. Is set to 0 to 90 degrees with respect to the spraying direction, so that the cement concrete and the quick-setting agent merge after being sprayed, and are sprayed as a quick-setting cement concrete on the spraying surface.

The material and the shape of the pipe A and the pipe B are not particularly limited. However, since the blowing material is blown by compressed air, a pressure-resistant rubber or a steel pipe is preferable, and the crossing angle and the blowing distance are appropriately changed near the blowing surface. Since it is necessary to adjust the pressure, a pressure-resistant rubber that can be moved back and forth and right and left is more preferable. The size of the pipe depends on the amount of the spraying material.
Is preferably 80 mm, and the inner diameter of the pipe B is 25 to 50 mm.
Is preferred. Alternatively, another pipe called a nozzle may be connected to the end of the pipe to reduce the inner diameter of the pipe and increase the spraying speed of the spray material.

In the present invention, the intersection angle between the center axis of the pipe A and the center axis of the pipe B is 0 to 60 degrees, preferably 20 to 6 degrees.
Set to 0 degrees. If the crossing angle exceeds 60 degrees, the cement concrete and the quick-setting agent reach the spraying surface without being mixed after the spraying, and the rebound rate increases, and the strength development is undesirably reduced.

In the present invention, in order to reduce the rebound rate and improve the workability, the cement concrete injected from the pipe A is prevented from colliding with the pipe B, and the quick-setting agent injected from the pipe B is prevented. Preferably does not collide with the pipe B.

Further, in the present invention, in order to reduce the rebound rate and increase the strength development, the cement concrete and the quick-setting agent may be mixed at a location before the spraying surface of the quick-setting cement concrete. Preferably, the angle of the tip of the pipe A with respect to the spray surface is set to 70 to 110 degrees, and the distance from the central axis of the pipe A to the spray surface is set to 1 to 5 m.

The quick-setting agent of the present invention includes a slurry quick-setting agent and a liquid quick-setting agent containing a powder quick-setting agent and water (hereinafter referred to as slurry water). Among these, a slurry quick-setting agent is preferred because of its long-term strength development.

Examples of the powder quick-setting admixture include calcium aluminates, alkali metal aluminates, aluminum sulfate, and combinations of these with alkali metal sulfates such as sodium sulfate.

Here, calcium aluminates are
A raw material containing calcia and a raw material containing alumina are mixed, and calcined in a kiln, or obtained by heat treatment such as melting in an electric furnace, and CaO and Al ₂ O ₃ as main components.
It is a general term for substances having hydration activity, and a part of CaO and / or Al ₂ O ₃ is alkali metal oxide, alkaline earth metal oxide, silicon oxide, titanium oxide, iron oxide, alkali metal halide, Alkaline earth metal halides,
It is a compound obtained by dissolving a small amount of a compound substituted with an alkali metal sulfate, an alkaline earth metal sulfate, or the like, or a compound containing CaO and Al ₂ O ₃ as main components. The mineral form may be either crystalline or amorphous.

In order to improve the properties of cement concrete, a dust reducing agent and a coagulant may be dissolved in water mixed with the powder quick-setting agent, and a setting retarder, a thickener and an ultrafine powder are mixed. May be.

The amount of the slurry water used is preferably 30 to 600 parts by mass based on 100 parts by mass of the powder quick-setting binder. If the amount is less than 30 parts by mass, the powder quick-setting agent and the slurry water are insufficiently mixed at the time of spraying, and the powder quick-setting agent becomes dust, which may deteriorate the working environment. May be reduced.

Examples of the liquid quick setting agent include potassium aluminate, a mixture of potassium aluminate and an alkali metal carbonate such as sodium carbonate, and a solution of sodium silicate, silica sol, alumina sol, and aluminum sulfate. . Among these, aluminum sulfate is the main component because it contains almost no alkali component, does not reduce the long-term strength development of quick-setting cement concrete, has a good working environment, and has no adverse effects such as soil pollution. Is preferred.

In the present invention, the used material is transported mainly by pneumatic feeding. The transport speed of cement concrete is not particularly limited, but is preferably 1 to 20 m ³ / hr. 1
If it is less than m ³ / hr, it takes a long time for spraying, and the working efficiency may be reduced. If it exceeds 20 m ³ / hr, it may be difficult to finish the spray surface uniformly. The transport speed of the quick setting agent is determined by the composition of the cement concrete and the type and amount of the quick setting agent.

The material used for the cement concrete of the present invention is not particularly limited.

As the cement, there can be used ordinary cements, for example, various portland cements such as ordinary and early strength, and various mixed cements obtained by mixing these portland cements with fly ash and the like.

An aggregate can be used if necessary. The aggregate is not particularly limited as long as it is used in the cement concrete field, and fine aggregates such as silica sand and natural sand and coarse aggregates such as gravel can be used.

In the present invention, if necessary, fibrous substances such as glass fibers, carbon fibers, and steel fibers; insoluble admixtures in water such as methyl cellulose; setting regulators; AE agents; water reducing agents; Superplasticizers, thickeners, water retention agents, waterproofing agents, foaming agents, foaming agents, rust inhibitors, coloring agents, high molecular polymer emulsions, blast furnace slag, fly ash, and silica fume do not interfere with the object of the present invention. Can be used together within the range.

[0027]

The present invention will be described below in detail with reference to examples.

(Experimental Example 1) The following spraying apparatus was manufactured and evaluated. Pipe A for pumping cement concrete has an inner diameter of 65
A urethane rubber nozzle having a length of 40 cm and capable of narrowing the inner diameter to 50 to 65 mm was attached to the discharge port of the pipe A using a pressure-resistant rubber of mm. The pipe B for pressure-feeding the quick-setting agent was made of pressure-resistant rubber having an inner diameter of 25 mm. A Y-tube is installed at the rear end of the pipe B 15 cm from the front end, a mixture of compressed air and a powder quick-setting agent is pumped from one of the Y-tubes, and slurry water is pumped from the other of the Y-tubes. The powder quick-setting admixture and the slurry water were mixed at the tip to become a slurry quick-setting admixture. A pressure-resistant hose having an inner diameter of 13 mm was used as a pipe for feeding the slurry water, and a chip and a check valve were attached to the Y-shaped pipe for adding the slurry water at a high pressure. The ends of the pipe A and the pipe B are set so as to secure a position of 100 cm from the point where the center axes of both the pipes intersect, and the intersection angle between the pipe A and the pipe B is set to the angle shown in Table 1. Set. Further, the angle of the pipe A with respect to the spray surface was set to 90 degrees, and the distance from the center axis of the tip of the pipe A to the spray surface was set to 3 m. For the concrete used for spraying, the unit amount of each material was cemented at 450k.
g / m ³ , water 203 kg / m ³ , fine aggregate 1164 kg / m
³ and 503 kg / m ^{3 of} coarse aggregate, and further 1 part by mass of a high-performance water reducing agent was added to 100 parts by mass of cement. For transporting concrete, piston type concrete pump "BSA1002" (Maruya Kogyo)
And the concrete was transported at a speed of 10 m ³ / hr. Compressed air required for concrete transport Compressors "PDS390S" (Hokuetsukogyo manufactured, the discharge amount 10 m ³⁾
Supplied using two units connected in parallel. A Y-tube is installed at the end of the concrete pump, and 10
After supplying compressed air at m ³ / min, a mixture of concrete and compressed air was pumped to piping A. Incidentally, the pumping of the powder quick-setting admixture is quick-addition device "Natomukurito PAC250" used after connecting the compressor "PDS390S" (discharge amount 10 m ³⁾ 2 units in parallel to the (Chiyoda Seisakusho), 4m ³ / Min compressed air. 10 parts by mass of powder quick-setting admixture as a quick-setting admixture, 100 parts by mass of cement in concrete, and pressure-pumped from one of the Y-tubes to 100 parts by mass of powder quick-setting admixture from the other Y-tube. On the other hand, 60 parts by mass of the slurry water is supplied to a plunger pump “TA-3DX” (manufactured by Arikko Industry Co., Ltd., maximum capacity 21 l / m
In), the powder quick-setting agent and the slurry water were mixed to form a slurry quick-setting agent, which was pressure-fed to the pipe B.
Quick-setting concrete 1 using the above spray equipment and spray material
m ³ was sprayed on the wall of the simulated tunnel for 6 minutes, and the rebound rate and strength development were evaluated. Table 1 shows the results.

(Materials used) Cement α: Commercial product, ordinary Portland cement, specific gravity 3.15 Fine aggregate: river sand from Himekawa, Niigata prefecture, specific gravity 2.62, FM 2.8
2 Coarse aggregate: crushed stone from Himekawa, Niigata Prefecture, specific gravity 2.64, FM 6.8
9 High-performance water reducing agent: Commercial product, polyethylene glycol polymer compound Powder quick-setting agent: Commercial product, containing calcium aluminates as the main component

(Evaluation method) Rebound rate: 1 m ³ of concrete was sprayed into a simulated tunnel having a height of 4.5 m, a width of 5.5 m, and a length of 20 m. The mass of the concrete dropped on the ground was measured and divided by the mass of the sprayed concrete. Strength development: Three-hour and one-day strengths are based on JSCE standards.
It was evaluated by the drawing method described in SCE-G561. The 28-day-old strength is 50 cm wide, 50 cm long, and 20 c deep according to the method described in JSCE-F561 of the Japan Society of Civil Engineers.
After the concrete was sprayed on the m mold, a test specimen having a diameter of 5 cm and a height of 10 cm was cut out, and the compressive strength was measured by the method described in JIS-A1108.

[0031]

[Table 1]

(Experimental Example 2) Table 2 shows the intersection angle between pipe A and pipe B using cement β, 10 parts by mass of a liquid quick-setting agent as a quick-setting agent for 100 parts by mass of cement in concrete. The procedure was carried out in the same manner as in Experimental Example 1 except that the angle was set and the method for adding the quick setting agent was as follows. Table 2 shows the results. Quick-setting additive "L pump"
(Yamada Kosan Co., Ltd., the maximum capacity of 2.6 l / min) is used to feed the liquid quick-setting agent, and then the liquid quick-setting agent is supplied to one of the Y-shaped tubes provided at the end of the quick-setting agent adding device. Compressed air is supplied to the other side of the Y-shaped pipe by connecting two compressors “PDS390S” (manufactured by Hokuetsu Kogyo Co., Ltd., discharge amount 10 m ³ ) in parallel at a pressure of 4 m ³ / min, and is supplied with a liquid quick-setting agent. And compressed air were fed to the pipe B under pressure.

(Materials used) Cement β: Commercial product, early-strength Portland cement, specific gravity 3.17 Liquid quick-setting agent: Commercial product, aqueous solution containing aluminum sulfate as a main component

[0034]

[Table 2]

[0035]

According to the spraying device of the present invention, the pipe is not clogged due to the hardening of the quick-setting cement concrete.
By using the spraying apparatus of the present invention, stable spraying can be performed for a long time, and the strength expression can be improved.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2D055 DB03 KA00 4D075 AA02 AA85 BB64X EA25 4F033 QB03Y QB05 QB12X QB15Y QB20 QD25 QE14 QE23 QF08X QF08Y QH05

Claims (5)

[Claims] 1. A pipe A in which cement concrete is transported and a pipe B in which a quick-setting agent is transported, wherein a crossing angle at which the central axes of the pipe A and the pipe B intersect is 0 to 90 degrees. A quick setting cement concrete spraying device. 2. The quick setting agent according to claim 1, wherein said quick setting agent is a slurry quick setting agent.
A spraying device as described. 3. The spraying device according to claim 1, wherein the quick-setting agent is a liquid quick-setting agent. 4. The cement concrete and the quick-setting admixture are set by setting the crossing angle at which the center axis of the pipe A where the cement concrete is transported and the pipe B where the quick-setting agent is transported intersects at 0 to 90 degrees. Quick setting cement concrete by injection and merging. 5. A spraying method comprising using the quick-setting cement concrete according to claim 4.