JPH0126752B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spraying method for concrete, etc.

Conventionally, when constructing concrete or mortar in tunnels, shafts, guide shafts, slopes, etc.,
A mixture consisting of aggregate (sand, gravel, reinforcing fibers), cement, and admixtures as necessary, or a mixture with a predetermined amount of water added to this, is charged into a spraying machine and compressed all at once. The air was discharged from the spray machine to the nozzle on the machine side, and then passed through the hose to the spray nozzle at the tip for spraying.

However, in this method of mixing aggregate and cement in the spraying machine and spraying under pressure, the moisture contained in the aggregate itself (5 to 10%) and the cement come into contact with each other, which causes problems in the capacity of the spraying machine. The hydration reaction progresses to form a paste during stirring and mixing before being charged into the storage section or before spraying after being charged into the storage section. Materials tend to adhere to the conveyance hose and cause problems such as clogging or blockage, which worsens work efficiency, reduces construction efficiency due to time loss during disassembly and cleaning, and effectively limits the conveyance distance. There was a problem. These problems are particularly likely to occur when fast-reacting cements such as jet cement and early-strengthening cement are used, and this becomes one of the bottlenecks, resulting in the problem of not being able to effectively perform winter construction work or construction work at spring water points. I was letting it happen.

Furthermore, with the above spraying method, the mixture is fixed by the amount that is put into the spraying machine, so you can freely and quickly change the mixture depending on the situation at the site, such as when spring water suddenly occurs during spraying work. I had the inconvenience of not being able to change.

The present invention solves the above-mentioned problems with conventional spraying methods for concrete, etc., and eliminates equipment troubles even when using aggregate with a high water content or rapid reaction cement such as jet cement. The purpose of the present invention is to provide a method for spraying concrete, etc., which enables smooth and highly efficient spraying construction, and which allows flexible and quick control of the composition in response to on-site conditions.

In order to achieve this objective, the present invention has changed the concept of conventional techniques in which concrete and mortar are sprayed by adjusting the mixture to include cement from the beginning, then blowing and spraying the mixture. Only the material or a mixture of water and admixtures added to it is blown from a spraying machine using compressed air, and before this mixture reaches the spray nozzle, cement powder blown from a separate system is added to the mixture. and mix in an air stream,
This method uses a spray nozzle to spray onto the construction surface.

The present invention will be explained below based on the accompanying drawings.

Fig. 1 shows an embodiment of the spraying method for concrete, etc. according to the present invention, in which 1 is a spraying machine, 2 is a machine side nozzle (discharge part) provided in the spraying machine 1, and 3 is a conveyance hose ( (main hose), 4 is a spray nozzle connected to the tip of the conveyance hose, and 5 is a water addition part interposed and connected to the conveyance hose in front of the spray nozzle. The spraying machine 1 includes a material storage section 6, an air blowing section 7 for discharging a fixed amount of the material stored therein to a conveyance hose 3 through a machine side nozzle 2, and blowing the material toward a spray nozzle 4. 7', but there are no other restrictions. In this embodiment, a rotor 8 having a large number of pockets 9, 9 is rotated under the storage part 6, and when the pockets reach a fixed position, compressed air from the air blowing parts 7, 7' is used to blow the machine side nozzle. 2, but a pressure vessel type sprayer may be used instead. When performing wet spraying, a type with a built-in kneading mechanism is recommended.

Conventionally, when spraying, cement and aggregate, cement, aggregate, and admixture, or a combination of these and water is charged into the storage section 6 of the spraying machine, and the air pipes 10, 10 are filled with water. The compressed air introduced from '
However, this method is not used in the present invention, and the spraying machine 1 uses a mixture A excluding cement.
This mixture A is quantitatively blown from the machine side nozzle 2 to the transfer hose 3, while cement powder B is blown from a separate system, and this cement powder B is sent from the machine side nozzle 2. A fixed amount is continuously blown into the conveying hose 3 at the tip and before the spray nozzle 4.

Here, mix A excluding cement refers to fine aggregate,
Refers to aggregates such as coarse aggregates and reinforcing fibers, or aggregates to which admixtures such as quick-setting agents and water-reducing agents have been added, or those to which a certain amount of water has been added. (without adding water), add an appropriate amount of water at the machine side nozzle 2 or spray nozzle 4, or at the water addition section 5 before it, and mix A with a wet type (intentionally). (with water added thereto), as a general rule, it is directly sprayed onto the construction surface C from the spray nozzle 4 without adding water.

Next, a concrete example of the cement powder blowing mechanism featured in the present invention described above is as shown in FIG. That is, an addition pipe 11 having a main passage 12 and a communication port 13 thereto is connected to the conveying hose 3 between the machine nozzle 2 and the water addition part 5, and a cement storage part 15 is connected separately from the spraying machine 1.
, a fixed amount cutting mechanism 21 like a rotor, and a discharge section 1
6 and a pressure-feeding air blowing section 17, an air conveying type fixed-quantity cutting device 14 is provided, and the discharge section 16 of the fixed-quantity cutting-out device 14 is connected to the communication port 13 with a hose 18, and the pressure-feeding air blowing device An air pipe 19 that is independent of or branched from the air pipes 10, 10' of the spray machine 1 is connected to the recess 17 via a regulating valve 20.

When spraying, the cement powder B is charged into the quantitative cut-out device 14, and at the same time as the spray machine 1 starts blowing the mixture A, the air blowing section 17 for pressure feeding is started.
Compressed air is sent to the container, and the compressed air and quantitative cut-out mechanism 21 are used to discharge the cement powder B in the container, and the air flow is conveyed to the communication port 13 by the hose 18. At this time, the cement powder addition pressure, that is, the compressed air in the hose, should be equal to or slightly lower than the blending and conveying air pressure. The reason is that if the internal pressure of the hose is too high, the main passage 1 in the axial direction of the conduit
This is because an air curtain is formed in the container 2, which tends to cause pulsations in the feeding of the mixture within the conveying hose.
This pressure adjustment is carried out by detecting the pressure in the air pipes 10, 19, and manually or mechanically or electrically adjusting the regulating valve 20.
All you have to do is control the opening.

In addition, formulation A excluding cement powder and cement powder B
performs fixed amount cutting by controlling the rotation speed of the rotor 8 and fixed amount cutting mechanism 21 of the spraying machine 1 and the fixed amount cutting device 14, respectively, and both air blowing sections 7, 7' and pressure feeding air blowing section 17. This is to quantitatively control the air flow rate. This allows mixing and spraying at an optimal solid-gas ratio.

In any case, if the mixture A excluding cement is discharged quantitatively and blown by the conveying hose 3, and at the same time, the cement powder B is blown quantitatively by the conveying hose 3 and the hose 18 which is separate from the system. As shown in Fig. 2, the cement powder B becomes dispersed cement powder B and is continuously introduced from the communication port 13 into the main passage 12. Since the blended grains a are passing through, the compressed air blown from the conduit port 13 as described above creates turbulent flow in the main passage, and as a result, the cement powder b in the compressed air flows into the conveying hose. is vigorously stirred with the blended grains a passing through, and this is repeated many times while passing through the conveyance hose in front. In this way, formulation A is discharged in a fixed amount and is in a dispersed floating state.
By adding cement powder B, which has also been discharged in a fixed amount and in a dispersed state, and by using the dynamic energy of compressed air, which is the transport medium of the cement powder, the cement powder is locally too small or too large. The mixture passes through the conveyor hose in a uniformly mixed state without being distributed over the air. Then, due to the turbulent flow and stirring action mentioned earlier, the cement powder b comes into vigorous contact with the mixed grains a, so that the cement powder adheres around the mixed grains a due to the adsorption phenomenon due to the moisture contained in the mixed grains a. The paste becomes a solid paste, and in this state it is sprayed from the spray nozzle 4. In addition, when formulation A is of the dry type, following adhesion due to the moisture retained in the blended grains a, a fixed amount of water is added in the next water addition section 5, so that the shell-forming action rapidly progresses. It is sprayed from the spray nozzle 4.

The present inventor also tried adding cement powder B to the water addition section 5 and the spray nozzle 4, but in both cases, a uniform mixing state could not be obtained, resulting in problems in terms of strength and dust generation. I didn't like it.

Next, concrete implementation results of the present invention will be shown.

Example (2) Concrete was sprayed onto the vertical surface of a tunnel using the spraying machine and quantitative cutting device shown in FIG. This spraying is done using mixed jet cement.
360Kg/m ³ , fine aggregate 997Kg/m ³ , coarse aggregate 662Kg/
^m3 , S/a 60%, and W/C 45-50%.
The moisture content of the aggregate was approximately 8%.

() Inner diameter 65φ and inner diameter as cement powder addition part
Using a 25φ Y-shaped branch metal fitting, this is connected to a conveyance hose (inner diameter 65φ) located 20m forward from the machine side nozzle of the spraying machine and 24m backward from the spraying nozzle, and connected to the cement powder addition section and quantitative cutting device. The space between them was connected with a 25φ, 20m hose.

Then, the mixture excluding the cement powder is blown from a spraying machine at a spraying volume of 5 m ³ /hγ and a spraying pressure of 3 to 4 kg/cm ² , while cement powder is sprayed at a discharge volume of 1800 kg/hγ and a spraying pressure of 2. A fixed amount of ~3Kg/cm ² was discharged, and water was added and sprayed at the water addition section.

In order to compare this, we used the conventional method to mix and charge cement powder and aggregate of the above composition into the spray machine without installing a cement addition section, and sprayed with the same spray volume and spray pressure. .

() As a result, in the case of the present invention, even though the quick-reacting jet cement was used and the moisture content of the aggregate was high, the entire amount could be sprayed without variation within a predetermined time, whereas in the case of the conventional method, Approximately 30 minutes after spraying started, a blockage occurred around the pocket of the spray machine and inside the nozzle on the machine side, forcing spraying to be stopped. When samples were taken from the sprayed surface and tested for compressive strength, the present invention was comparable to that of the conventional method.

According to the present invention as described above, the conventional idea of mixing the sprayed material in advance and blowing it is changed, and the sprayed material is divided into cement and other mixtures and each is blown with compressed air. By conveying airflow through separate hoses and merging them at the hose section behind the spray nozzle, the mixture is stirred and mixed using the air in the conveyance medium, and a mixture for spraying is created in the process of passing through the conveyance hoses. Since the spray is sprayed from the spray nozzle onto the construction site, it is possible to carry out extremely smooth and highly efficient spraying without clogging the various parts of the spraying equipment or the transfer hose, and it is also possible to mix materials easily. Because it is reliable, there is less rebound loss and dust generation.
Moreover, a uniform coating layer with good strength can be formed.
Furthermore, there is no need to mix the entire spraying material in advance, which simplifies the mixing process and equipment, simplifies the adjustment of aggregate moisture content, and eliminates the need for complicated disassembly and assembly of equipment due to clogging, which improves work efficiency. It becomes possible to greatly improve the In addition, it has become easier to use fast-curing cement such as jet cement, allowing its properties to be fully demonstrated, and the degree of freedom in the amount of cement in the mix has increased, allowing the addition or reduction of the amount to be added at any time, making it possible to adjust the amount of cement to suit the conditions of the site. Since spraying can be carried out in a timely manner, it is possible to effectively carry out construction works at spring water locations and during winter or rainy seasons.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the spraying method for concrete, etc. according to the present invention, and FIG. 2 is a sectional view showing the state of the cement powder addition section in FIG. 1. DESCRIPTION OF SYMBOLS 1... Spraying machine, 3... Transfer hose, 4... Spraying nozzle, 11... Cement addition part, 13... Conduction port, 1
4...Quantitative cutting device, 18...Hose, A...Composition excluding cement, B...Cement powder.

Claims (1)

[Claims] 1. While blowing the mixture excluding cement from the spray machine using compressed air as a conveying medium to the spray nozzle via the main hose, the cement powder is blown from another system using compressed air as a conveying medium from a quantitative cutting device. By adding cement powder to the mixture passing through the main hose behind the spray nozzle, the mixture is mixed and stirred until it reaches the spray nozzle, and then sprayed from the spray nozzle to the construction site. Characteristic spraying method for concrete, etc.