JP7456679B1 - Spraying method - Google Patents

Abstract

[Problem] To provide a spraying method that can bring out the color that would normally be obtained by a pigment. [Solution] This spraying method involves spraying a spraying material whose main component is cement onto a construction target ST, and is configured to include a first spraying step in which a first spraying material 11, which is a spraying material, is sprayed onto the construction target ST to form a first spraying material layer FS1, and a second spraying step in which a second spraying material 12, which is a spraying material different from the first spraying material 11 and contains no aggregate but a pigment, is sprayed onto the first spraying material layer FS1 to form a second spraying material layer FS2. [Selected Figure] Figure 1

Description

The present invention relates to a spraying method in which a spraying material whose main component is cement is sprayed onto a construction target.

Conventionally, as disclosed in Patent Document 1, a spraying method is known in which a spraying material (mortar or concrete) containing cement as a main component is sprayed onto the construction object to form a spraying material layer made of the spraying material on the construction object. It is being The spraying method can be applied to construction targets such as slopes and slopes, and the sprayed material layer that is formed prevents weathering of the construction target, erosion and collapse due to penetration of rainwater, etc., and small-scale rockfalls. can do.

In addition, with the spraying method, by mixing pigments with the spraying material, the color of the spraying material layer made of the spraying material can be changed, and the construction target can be indirectly colored, so construction that takes design into consideration is possible. It is possible.

On the other hand, the spraying method has a problem in that a portion of the sprayed material bounces back and does not properly settle on the construction target, the so-called rebound problem. Due to the rebound of the sprayed material, a portion of the sprayed material is wasted (rebound loss), and the required amount of sprayed material increases, which increases construction costs.

Moreover, the problem of rebound is not limited to an increase in construction costs. As mentioned above, the spraying method can indirectly color the construction target by mixing pigments with the spraying material, but rebound may worsen the color development of the spraying material layer, causing the color originally obtained by the spraying material to change. The problem arises that it is not expressed. The mechanism by which this problem occurs is as follows.

(1) The rebounded spray material causes material separation due to the impact when it is sprayed. (2) When the spray material that has undergone material separation adheres to the surface of the appropriately formed spray material layer, the separated aggregate (sand or gravel) is exposed on the surface of the spray material layer. (3) The color of the aggregate exposed on the surface of the spray material layer has a strong influence on the color development of the spray material layer, and the color originally obtained by the spray material no longer appears.

At this time, for example, if the color of the aggregate is dark such as black or gray, the color of the sprayed material layer appears to the human eye as a color with lower saturation (dull color) than the color originally obtained. Become recognized.

To address this rebound issue, Patent Document 1 discloses a technique for suppressing rebound by keeping the pressure of the gas transporting the spray material within a specified range. Use of this technique is believed to reduce rebound loss and therefore prevent increases in construction costs.

However, the technique disclosed in Patent Document 1 cannot completely eliminate rebound, and therefore cannot solve the problem of color development.

Japanese Patent Application Publication No. 2022-128071

The present invention has been made in view of this conventional situation. One of the objects of the present invention is to provide a spraying method that can bring out the color originally obtained by spraying material.

Means for solving the problem and effects of the invention

The spraying method according to the first aspect of the present invention is a spraying method in which a spraying material is sprayed onto a construction target, and the spraying material is sprayed onto the construction target, the first spraying material being a spraying material containing cement as a main component and containing aggregate. a first spraying step of spraying to form a first spraying material layer, and spraying a second spraying material that is a spraying material that mainly contains cement, does not contain aggregate, and contains pigment on the first spraying material layer. , and a second spraying step of forming a second spraying material layer. According to the above configuration, spraying can be performed in two stages: a first spraying process in which the first spraying material is sprayed, and a first spraying process in which the second spraying material is sprayed, and the second spraying process is performed while ignoring the influence of rebound. The color originally obtained by the second spraying material can be made to appear on the material layer.

Moreover, the spraying method according to the second aspect of the present invention can be configured such that the pigment includes titanium oxide. According to the configuration, the effect of titanium oxide as a photocatalyst can be imparted to the construction target.

Moreover, the spraying method according to the third aspect of the present invention can be configured such that the second spraying step is performed three days after the first spraying step. According to the above configuration, it is possible to prevent strength problems from occurring due to insufficient curing of the first spray material layer FS1 .

Moreover, the spraying method according to the fourth aspect of the present invention can be configured such that the second spraying step is performed within seven days after the first spraying step. According to the configuration, the first spray material layer FS1 and the second spray material layer FS2 have poor bite due to the increased probability that impurities such as dust will adhere to the surface of the first spray material layer FS1. This can prevent the second spray material layer FS2 from peeling off.

Further, the spraying method according to the fifth aspect of the present invention can be configured such that the second spraying material layer has a thickness of 0.5 mm or more. According to the above configuration, it is possible to increase the possibility of completely covering the rebounded first spray material 11 (particularly aggregate) on the surface of the first spray material layer FS1.

Further, the spraying method according to the sixth aspect of the present invention can be configured such that the second spraying material layer has a thickness of 1.0 mm or less. According to the configuration, it is possible to prevent cracks from occurring in the second spray material layer FS2.

It is a flow chart explaining the spraying method concerning the present invention. It is a schematic diagram explaining a first spraying step. It is a schematic diagram explaining a second spraying process. It is a photograph for comparing the spraying method according to the present invention and the conventional spraying method. It is a photograph for comparing the spraying method according to the present invention and the conventional spraying method. 1 is a photograph for comparing the spraying method according to the present invention with a conventional spraying method. It is a photograph for comparing the spraying method according to the present invention and the conventional spraying method.

Hereinafter, the embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below are merely examples for embodying the technical idea of the present invention, and the present invention is not limited to the following. In addition, this specification never specifies the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, and relative positions of the components described in the embodiments are merely explanatory examples, and are not intended to limit the scope of the present invention, unless otherwise specified. Note that the size and positional relationship of the members shown in each drawing may be exaggerated to clarify the explanation. Furthermore, in the following explanation, the same names and symbols indicate the same or similar members, and detailed explanations will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured as a form in which multiple elements are composed of the same member, and one member serves multiple elements, or conversely, the function of one member can be shared by multiple members.
[Spraying method according to the present invention]

As shown in the flowchart of FIG. 1, the spraying method according to the present invention includes a cleaning process ST101, a lath tensioning process ST102, a first spraying process ST103, a curing process ST104, a first spraying material layer cleaning process ST105, and a second spraying process ST106. Consists of.

Each step will be explained below.
<Cleaning process ST101>

The cleaning process ST101 is a process for cleaning the construction target ST to remove loose stones, loose soil lumps, and other objects that may impede the implementation of subsequent processes.

Note that the mode of the cleaning step ST101 is not particularly limited, and for example, cleaning may be performed using a high-pressure washer. Further, the cleaning step ST101 does not necessarily need to be performed and may be omitted.
<Las tension process ST102>

The lath laying process ST102 is a process for fixing lath LT (not shown) to the construction target ST, which can prevent peeling and cracking of the first sprayed material layer FS1 and the second sprayed material layer FS2 (not shown; details will be described later).

Specifically, a lath LT, which is a diamond-shaped wire mesh made of galvanized iron wire with a diameter of 2.0 mm and a mesh size (the length of the side of the diamond) of 50 mm, is stretched so as to follow the shape of the ST to be constructed, and then anchored. Drive it in and fix it.

When adding laths LT, they are expanded so that at least two rows of meshes of adjacent laths LT overlap.

Two types of anchors are used: a main anchor with a diameter of 16 mm and a length of 400 mm, and a sub-anchor with a diameter of 9 mm and a length of 200 mm. At this time, it should be noted that 30 or more main anchors are driven per ^100m2 , and 150 or more sub-anchors are driven per ^100m2 .

Furthermore, when driving the main anchor and sub-anchor, a rock drill or hammer drill may be used depending on the situation.

Note that the mode of the lath stretching step ST102 is not particularly limited, and the types of laths LT and anchors used, the method of stretching the laths LT, etc. can be changed as appropriate. Further, the lath stretching step ST102 does not necessarily need to be performed and may be omitted.
<First spraying process ST103>

The first spraying step ST103 is a step of spraying the first spraying material 11 (details will be described later) onto the construction target ST to form a first spraying material layer FS1.

Specifically, in the first spraying step ST103, as shown in FIG. 2, the first spraying material 11 accommodated in the spraying material storage section FS is fed under pressure through the hose HS using compressed air from an air compressor KA. , the first spraying material 11 is sprayed from the nozzle NZ to the construction target ST in order from the top to the bottom.

In addition, if the first spray material 11 rebounds in the first spraying step ST103, it is removed using wind pressure before the first spray material layer FS1 hardens. Specifically, by stopping the pressure-feeding of the first spray material 11, the nozzle NZ will spray only air, which is used to remove the rebound. The purpose of removing the rebounded first spray material 11 here is to level the surface of the first spray material layer FS1, and is not to solve the coloring problem, so it is sufficient if the rebounded first spray material 11 is removed to a certain extent. On the other hand, if a strong wind is applied for a long time in an attempt to completely remove the rebounded first spray material 11 at this stage, the first spray material 11 of the first spray material layer FS1 will separate into materials, and the surface strength of the first spray material layer FS1 will decrease when it hardens.
First spray material 11

The first spray material 11 is a spray material used in the first spray step ST103. The first spray material 11 is a mixture of cement, aggregate, and water, and the composition thereof can be designed as follows.
(Setting design conditions for first spray material 11)

First, design conditions are set. Here, as an example, the unit amount of cement C ₁ (weight of cement included in 1 m ³ of first spray material 11) is 420 kg/m ³ and the water to cement ratio W ₁ /C ₁ is 55%. do. Further, ordinary Portland cement (density cp ₁ =3160 kg/m ³ ) manufactured by Tokuyama Cement Co., Ltd. is used as the cement, and sea sand (density sp ₁ =2570 kg/m ³ ) is used as the aggregate. Further, the density of water wp is calculated as 1000 kg/m ³ .

The above design conditions are summarized in Table 1.

(Determination of unit water volume W ₁ )

Next, the unit water amount W ₁ (weight of water contained in 1 m ³ of first spray material 11) is determined. The unit water amount W ₁ can be determined using Equation 1 below. When the above-mentioned design conditions are applied to Equation 1, the unit water volume W ₁ becomes 231 kg/m ³ .

(Determination of unit aggregate amount _S1 )

Next, the unit aggregate amount S ₁ (weight of aggregate contained in 1 m ³ of first spray material 11) is determined.

In order to obtain the unit aggregate amount S ₁ , first, the unit aggregate ratio sr ₁ (ratio of aggregate included in 1 m ³ of first spray material 11) is obtained using the following formula 2. When the above-mentioned design conditions are applied to Equation 2, the unit aggregate ratio _sr1 becomes 63.61%.

Next, by applying the above-mentioned design conditions and the unit aggregate ratio sr ₁ to the following equation 3, the unit aggregate amount S ₁ can be determined. The unit aggregate amount S ₁ under the present design conditions is 1635 kg/m ³ .

(Composition of first spray material 11)

The composition of the first spraying material 11 (weight per 1 ^m3 ) obtained above and the composition converted into a value per batch are summarized in Table 2. The composition converted into a value per batch is based on 50 kg of cement (two bags of bagged cement).

(Surface water percentage of aggregate)

Furthermore, when making the first spray material 11, it is necessary to make adjustments based on the water content (surface water) of the aggregate, rather than simply blending as shown in Table 2.

In the spraying method according to the present invention, for example, the surface water percentage of the aggregate is measured twice in the morning and afternoon on the day when the first spray material 11 is carried out, and the amount of aggregate and the amount of water are determined based on the surface water percentage. Adjust amount.

Note that the aspect of the first spraying step ST103 is not particularly limited, and the method of spraying the first spraying material 11, the composition of the first spraying material 11, the cement and aggregate used, etc. can be changed as appropriate.
<Curing process ST104>

The curing step ST104 is a step in which cracks that occur when the first spray material layer FS1 formed in the first spraying step ST103 is cured are investigated and repaired as necessary.

Note that the aspect of the curing step ST104 is not particularly limited. Furthermore, the curing step ST104 does not necessarily need to be performed and may be omitted.
<First spray material layer cleaning step ST105>

The first spray material layer cleaning process ST105 is a process in which dust and sand accumulated on the first spray material layer FS1 and fragile layers of the first spray material layer FS1 are removed using a high-pressure washer (at a pressure of about 30 MPa) prior to the second spray material layer ST106 described below. This process improves the adhesion between the first spray material layer FS1 and the second spray material layer FS2, preventing the second spray material layer FS2 from peeling off.

Note that the mode of the first spray material layer cleaning step ST105 is not particularly limited. Further, the first spray material layer cleaning step ST105 does not necessarily need to be performed and may be omitted.
<Second spraying process ST106>

The second spraying step ST106 is a step of spraying the second spraying material 12 (not shown; details will be described later) onto the first spraying material layer FS1 to form a second spraying material layer FS2.

Specifically, in the second spraying step ST106, as shown in FIG. 3, the second spraying material 12 accommodated in the spraying material storage section FS is pressure-fed by the squeeze pump SP, and the second spraying material 12 is fed under pressure by the squeeze pump SP, and the second spraying material 12 is fed to the air compressor KA at the tip of the hose HS. The second spraying material 12 is mixed with air and injected from the nozzle NZ, thereby spraying the second spraying material 12 onto the construction target ST in order from the top to the bottom.

Moreover, it is preferable that the second spraying step ST106 is carried out three days after the first spraying step ST103. This is because if the second spraying step ST106 is performed within two days after the first spraying step ST103, problems in strength are likely to occur because the first spraying material layer FS1 is insufficiently cured.

Moreover, it is preferable that the second spraying step ST106 is carried out within 7 days after the first spraying step ST103. If the second spraying step ST106 is performed 8 days or later after the first spraying step ST103, the probability that impurities such as dust will adhere to the surface of the first spraying material layer FS1 increases, and the first spraying material layer FS1 and the second spraying material layer FS1 are This is because the bite with the material layer FS2 becomes poor, causing the second spray material layer FS2 to peel off.

Further, in the second spraying step ST106, it is preferable that the second spraying material 12 is sprayed so that the thickness of the second spraying material layer FS2 immediately after spraying the second spraying material 12 is 0.5 mm or more. By setting the thickness of the second spray material layer FS2 to 0.5 mm or more, it is possible to increase the possibility of completely covering the first spray material 11 (especially aggregate) that has rebounded on the surface of the first spray material layer FS1. .

Further, in the second spraying step ST106, it is preferable that the second spraying material 12 is sprayed so that the thickness of the second spraying material layer FS2 immediately after spraying the second spraying material 12 is 1.0 mm or less. This is because if the thickness of the second spray material layer FS2 is made thicker than 1.0 mm, cracks are likely to occur in the second spray material layer FS2.

Note that as a tool for carrying out the second spraying step ST106, for example, a ricing gun used in the construction field can also be used. However, since the present invention is in the field of construction, where slopes, slopes, etc. are assumed to be the main construction targets, the range of spraying with a ricing gun is narrow and is not practical. In other words, it is difficult to practically implement the present invention using a combination of existing technologies. Therefore, the applicant of the present application is currently actively developing a tool for implementing the second spraying step ST106 of the present invention.
《Second spray material 12》

The second spray material 12 is a spray material used in the second spray process ST106. The second spray material 12 is a mixture of cement, water, and pigment, and does not contain aggregate.

Although the pigment used for the second spray material 12 is not particularly limited, for example, by using titanium oxide, the object to be applied can be colored white (the original color of titanium oxide). In addition, in the conventional spraying method, when titanium oxide is mixed with the spraying material, it cannot be colored to the original color of titanium oxide, and the whiteness becomes lower than the original color.

Moreover, when titanium oxide is used as the pigment of the second spray material 12, the effect of titanium oxide as a photocatalyst can be imparted to the construction target ST.

The design of the formulation of the second spray material 12 will be described below.
(Setting design conditions for second spray material 12)

First, design conditions are set. Here, as an example, the unit amount of cement C ₂ (weight of cement included in the first spraying material 11 of one batch) is 20 kg, the ratio of water to cement W ₂ /C ₂ is 70%, and the pigment and cement are 20 kg. Let the ratio A ₂ /C ₂ be 10%. In addition, white cement manufactured by Taiheiyo Cement Co., Ltd. will be used as the cement, and titanium white (titanium oxide pigment) manufactured by LANXESS Co., Ltd. will be used as the pigment.

The above design conditions are summarized in Table 3.

(Determination of unit water volume _W2 )

Next, the unit water amount W ₂ (weight of water contained in 1 m ³ of second spray material 12) is determined. The unit water amount W ₂ can be determined by the following equation 4. When the above-mentioned design conditions are applied to Equation 4, the unit water amount W ₂ becomes 14 kg.

(Determination of Unit Pigment Addition _A2 )

Next, the unit pigment addition amount A ₂ (weight of pigment added to one batch of first spray material 11) is determined. The unit pigment addition amount _A2 can be determined by the following equation 5. When the above-mentioned design conditions are applied to Equation 5, the unit pigment addition amount _A2 becomes 2 kg.

(Composition of second spray material 12)

The formulations of the second spray material 12 determined above are summarized in Table 4.

Note that the aspect of the second spraying step ST106 is not particularly limited, and the method of spraying the second spraying material 12, the composition of the second spraying material 12, the cement and pigment used, etc. can be changed as appropriate.
[experiment]
<Comparison experiment with conventional technology>

In order to compare the spraying method according to the present invention with the conventional spraying method, an experiment was conducted in which the pigment was titanium oxide and the whiteness of test pieces prepared by each method was measured.

Specifically, first, as a test piece corresponding to the construction target to which the spraying method according to the present invention is applied, a flat plate with a thickness of about 7 cm (corresponding to the first spraying material layer FS1) made of mortar of a general composition was used. ) and sprayed with the second spraying material 12 containing the pigment shown in Table 5, test pieces A to D are prepared.

Next, as a test piece corresponding to a construction target to which the conventional spraying method was applied, a test piece E is prepared by spraying a spray material containing the pigment shown in Table 6 into mortar of a general composition.

After storing the test specimens A to E outdoors for about 7 days (this assumes the actual construction target environment), using a whiteness meter (OSK 97BX216 from Ogawa Seiki Co., Ltd.), Measure their whiteness.

The results of the experiment are shown in Table 7, and the test specimens A to D produced by the spraying method according to the present invention had a higher degree of whiteness than the test specimen E produced by the conventional spraying method, and were colored whiter. I know that there is. In particular, test pieces A and C have a higher degree of whiteness than test piece E, even though they contain less pigment.

This result is also visually clear, as shown in FIGS. 4-7.
<Experiments related to the transition of white color>

In addition, an experiment was conducted to determine whether the color development achieved by the spraying method according to the present invention would deteriorate over time.

As an experimental method, the above-mentioned test pieces A to D are further stored outdoors and the change in whiteness is measured.

The results of the experiment are shown in Table 8. After 21 days and 36 days, the whiteness did not decrease significantly, and it can be said that the color of test pieces A to D produced by the spraying method according to the present invention did not deteriorate significantly.

[Effects of the spraying method according to the present invention]

As explained above, the spraying method according to the present invention is a method in which the spraying process is divided into two stages, the first spraying process ST103 and the second spraying process ST106, thereby solving the problem of color development caused by rebound. This is a construction method that can completely nullify the color and bring out the color originally obtained by the second spray material 12.

Specifically, as shown in FIG. 3, the surface of the first spray material layer FS1 is covered by the second spray material layer FS2 formed in the second spray process ST106, so the effect of rebound occurring in the first spray process ST103 can be ignored. In addition, since the second spray material 12 does not contain any material (aggregate) that affects the color development, the effect of rebound occurring in the second spray process ST106 can also be ignored.

Furthermore, it is also possible to cover cracks that occur in the first spray material layer FS1.

11...First spraying material 12...Second spraying material ST...Construction target LT...Rath FS1...First spraying material layer FS2...Second spraying material layer FS...Shotting material storage section KA...Air compressor HS...Hose NZ...Nozzle SP…Squeeze pump

Claims (5)

A spraying method that sprays spraying material onto the construction target, and is not intended to repair slopes,
a first spraying step of spraying a first spraying material, which is a spraying material containing cement as a main component and aggregate, onto the construction target to form a first spraying material layer;
A second spraying material, which is a spraying material mainly composed of cement other than polymer cement, containing no aggregate, and containing a pigment containing titanium oxide, is sprayed onto the first spraying material layer to form a second spraying material layer. a second spraying step,
Spraying method including. The spraying method according to claim 1,
The spraying method is characterized in that the second spraying step is carried out three days after the first spraying step. The spraying method according to claim 1,
The spraying method is characterized in that the second spraying step is carried out within 7 days after the first spraying step. The spraying method according to claim 1,
A spraying method characterized in that the second spraying material layer has a thickness of 0.5 mm or more. The spraying method according to claim 1,
A spraying method characterized in that the second spraying material layer has a thickness of 1.0 mm or less.