JP2006322288A - Construction method for grating crib - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method for a grating crib, which enables a grating-crib constructing material to be stably conveyed over a long distance, and which is excellent in filling properties. <P>SOLUTION: In the wet grating-crib constructing material, a 0.001-0.5 wt.% surfactant and 0.5-5.0 wt.% sepiolite, based on the amount of cement, are added and mixed into a compounding material mainly composed of mortar or concrete, and a slump value within 120 minutes before pumping is in the range of 15-27 cm. The wet grating-crib constructing material is sprayed in a state in which a slump value within one minute after the ejection of the material from the spray nozzle is set to be in the range of 5-11 cm. The sepiolite is obtained by roughly crushing a raw ore, and finely crushing this roughly crushed matter at a grading at which particulates with a diameter smaller than 45 μm occupy 95% or more, in the presence of 200-600 wt.% water based on the amount of the roughly crushed matter. The amount of the charge of the surfactant and the sepiolite is adjusted on the basis of a torque value from a torque detector which is provided in an agitating shaft of the mixer installed on a spraying site. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for constructing a frame for stabilizing a slope such as a slope.

The frame construction method represented by the so-called free frame method has been widely adopted.
In this free frame method, cement, sand (fine aggregate) and, if necessary, gravel (coarse aggregate) are mixed with water in the tank of the spray gun body, and air is transferred by an air gun provided on the tank outlet side. Pressure is fed into the hose by force, and sprayed as mortar or concrete on the target surface from the spray nozzle connected to the tip of the hose. In this case, the molds are arranged in parallel along the natural ground, and are connected by spacers between them to be self-supported. For example, the molds are assembled in a lattice shape and sprayed into the adjacent side molds. The material is sprayed to build a legal framework. Further, reinforcing bars are arranged in adjacent side molds.

  As a spray material, in the case of mortar spraying, the weight ratio of cement: sand is basically 1: 4, and in the case of concrete spraying, the weight ratio of cement: sand: gravel is 1: 4: Based on 1-2. Furthermore, since a crimp wire mesh is used as a formwork, the slump value specified in JIS A 1101 is 0 cm due to low rigidity, a material transport distance of 50 m as a maximum height, and a horizontal distance of approximately 100 m. It is based on being.

However, in the case of this type of conventional frame-frame spraying method, the following problems remain despite the fact that there are many achievements.
(1) The weight ratio of cement (C): sand (S) is 1: 4, and the spraying method is poorly blended (small amount of unit cement), so the strength is not sufficient.
(2) When a poorly blended material is blown into the formwork together with air, a large amount of reband loss occurs. If this is not eliminated, a nest is formed, resulting in a decrease in strength.
(3) When a non-fluid material having a slump value of 0 cm is used, it is difficult to go around the back side of the reinforcing bar, and a gap or nest is formed, resulting in a decrease in strength.
In view of this, a method has been developed in which a general-purpose (normally blended) ready-mixed concrete material is used in a form that completely surrounds the cross section and the material is filled in the form.

However, the so-called pumping method frame method also has the following problems.
(B) When the material is pumped through a normally used 2.5 inch hose, the worker holding the tip of the hose and the spray nozzle is subjected to a load of about 20 kg. It is difficult to drive while holding the ground and moving along the ground and the formwork.For this purpose, the boom is extended to the shoulder with a concrete pump car and is placed along the boom. It is necessary to drive through the installed pipe line, and it is not suitable for construction in mountainous areas where the concrete pump truck cannot be carried to the vicinity of the installation site or the movement of the boom is spatially restricted.
(B) In order to spread the material throughout the formwork or to maintain its quality, it is necessary to vibrate the material with a vibrator. Also inferior.
(C) It is extremely difficult to spread the material placed from the shoulder over the entire formwork, and it is particularly difficult to fill the transverse formwork. Furthermore, specifically, an unfilled space part will arise in the shoulder top part of the horizontal frame. As a result, it is limited to the construction of a small area range legal framework.
(D) Insufficient vibration of the vibrator causes variations in the quality of the completed frame.

On the other hand, the present applicant has previously described a “wet method frame construction material mainly composed of mortar or concrete, having a cement: sand weight ratio of 1: 1 to less than 4 and a slump value of 8 to 27 cm. Pumped through a pipe line by a pump, and sprayed from a spray nozzle at the tip of the pipe line into a mold fixed to a natural ground, and in the middle of a pipe line between the pump and the spray nozzle At a position 5 to 40 m away from the nozzle, air is blown in an amount of 2 to 10 Nm ³ / min, and the wet method frame construction material is blown from the spray nozzle in a state where the air is entrained. The construction method was proposed "(Patent Document 1).
It was also proposed to add sepiolite ("Milcon SP" manufactured by Showa Mining Co., Ltd.) in addition to a water reducing agent as a material for constructing a legal framework (Patent Document 2).
Japanese Patent No. 3003751 JP-A-6-264449

  The present applicant has proved that such a construction method is a practically superior method by accumulating construction results. However, even after that, the present inventor can stably transport the frame construction material over a long distance (especially, a long distance of 100 m or more) and spray it into a side mold frame with an opening ratio of 70% or more. In this case, the inventors have eagerly continued to search for a material with excellent filling properties while reliably preventing the so-called “sag” from flowing out of the opening. As a result, it has been found that this can be achieved by using a sepiolite to be added which is special to a normal one.

  However, it has been found that the special sepiolite is slightly dispersible with respect to the blended material, and that the transportability and the material properties after spraying deteriorate when transported with poor dispersibility.

  Therefore, the problem of the present invention is that when the frame construction material can be stably transported over a particularly long distance (especially a long distance of 100 m or more) and is blown and filled into a side mold frame having an opening ratio of 70% or more, An object of the present invention is to provide a method for constructing a method frame that is excellent in filling properties while reliably preventing so-called “sag” from flowing out of the opening.

The present invention that has solved the above problems is as follows.
<Invention of Claim 1>
For blended materials with mortar or concrete as the main component, water-to-cement ratio W / C of 40-60%, unit cement amount of 430 kg / m ³ or more for mortar, and 380 kg / m ³ or more for concrete The surfactant is added in an amount of 0.001 to 0.5% by weight and the sepiolite in an amount of 0.5 to 5.0% by weight with respect to the cement amount. Wet method frame construction material with a slump value within 15 to 27 cm within minutes,
In a state where the slump value within 1 minute after discharge of the material discharged from the spray nozzle is 5 to 11 cm from the spray nozzle at the tip of the pipe by pumping through the conduit, Blowing and filling into the side mold frame where the opening ratio is fixed and the reinforcing bars are arranged is 70% or more,
The wet method frame is blown with air in an amount of 2 to 10 Nm ³ / min only in one blowing position that is in the middle of a pipe line between the pump and the blowing nozzle and is separated from the blowing nozzle by 7 to 40 m. While blowing the construction material from the spray nozzle in the state of entraining the air, and without any rapid setting agent added to the wet method frame construction material in any process,
The sepiolite is obtained by crushing a raw mineral ore, and crushing the crushed material into a particle size of 95% or more under 45 μm under the presence of 200 to 600% by weight of water,
The blended material is transported to a spraying site by a ready-mixed concrete car in advance as a ready mixed material, and the blended material is charged into a mixer installed at the spraying site, and the sepiolite and the surfactant are charged into the mixer. To disperse the material,
Based on the torque value from the torque detector provided on the stirring shaft of the mixer, the input amount of the surfactant and sepiolite is adjusted, and the slump value within 120 minutes before the pumping is adjusted to 15 to 27 cm.
A legal framework construction method characterized by that.
Here, the slump value is measured based on JIS A 1101 (1998).

(Function and effect)
Sepiolite, which is an additive proposed by the present applicant, is “Milcon SP” manufactured by Showa Mining Co., Ltd. (see Patent Document 2).

  On the other hand, the sepiolite used in the present invention crushes a raw mineral ore, and the crushed material is under 45 μm in the presence of 200 to 600% by weight (more preferably 250 to 450% by weight) of water. Is pulverized to a particle size of 95% or more (more desirably 97% or more). Table 1 shows the difference between the sepiolite used in the present invention and that used in Patent Document 2. All of these are crushed ores from Spain and are sold by Showa Mining Co., Ltd., all of which are trade names.

  As is apparent from Table 1, “Mircon SP” of wet pulverization is finely divided with respect to “Mircon P” of dry pulverization, but “RSA agent” as an example used in the present invention has bulk specific gravity and particle size. It is a fine powder as can be seen from the structure (particle size distribution). Moreover, the viscosity is high and the viscosity ratio of 6 rpm / 60 rpm is as high as 8.3.

  Because of the sepiolite having such characteristics, when the sepiolite of the present invention is used, a material having a slump value of 15 to 27 cm within 120 minutes after the kneading of the material is discharged from the spray nozzle for 1 minute after the discharge. It was also found that the slump value was within 5 to 11 cm. The amount of change in the slump value is at least 5 cm, usually 8 cm or more. Although the slump value is reduced by blowing air in the middle of the pipeline, it is about 2 cm at maximum with no addition of sepiolite. Even when conventional sepiolite is added, the slump value is reduced to some extent, but the reduction amount is small. When the sepiolite of the present invention is used, the amount of change in the slump value is 5 cm or more, usually 8 cm or more.

  Materials that cause such a change in slump value offer significant advantages. That is, since a soft material having a slump value of 15 to 27 cm can be used, the material can be stably conveyed over a long distance of 100 m or more (from the kneading site to the spraying site). In the stage where the side mold is sprayed and filled, a small slump value is obtained, that is, the material can be filled with a hard material, so that the so-called “sagging” of the material flowing out from the opening of the side mold can be reliably prevented.

  On the other hand, based on the results shown in Table 3 showing the results of the experimental examples described later, the sepiolite of the present invention can be seen from the fact that only the slump value reduction rate (decrease amount) does not correspond to the evaluation one-to-one. Since the properties and behavior are different from the conventional products, it was found that high evaluation could be obtained.

  It has been found that the sepiolite actually used conventionally and the sepiolite of the present invention show completely different behaviors. FIG. 1 shows a double-cylinder rotating clay in the case of adding conventional sepiolite to the concrete material of cement: sand: coarse aggregate = 1: 3: 1 and the case of adding the sepiolite of the present invention. After filling concrete with a gap between the inner cylinder 51 (φ150 mm) and the outer cylinder 52 (φ200 mm) having the dimensions shown in FIG. 5, the outer cylinder 52 is gradually rotated, and the torque generated in the inner cylinder 51 in the rotation is torqued. The relationship between the shear rate and the shear stress is shown based on the rotational speed measured by the total 53 and the rotational speed measured by the rotational speed meter 54.

  As can be seen from FIG. 1, the concrete added with the sepiolite mineral increases the shear rate when the shear rate is increased (increases the rotational speed of the viscometer), but the sepiolite of the present invention is compared with the case where the conventional sepiolite is added. Has higher shear stress. Furthermore, when the shear rate is decreased, the shear stress is higher than that of the conventional product, and the area of the hysteresis curve is increased. That is, when a low shear rate is applied, the structure recovers and the viscosity increases. From a rheological point of view, this property is called a rheopexy. When the shear rate is finally reduced to zero, it can be seen that the yield stress is higher than that of the conventional product. Thus, when the shear rate is zero, the yield stress (yield value) is higher than that of the conventional product. The mortar is in the stage where the side mold is sprayed and filled (the shear rate is zero). Or it means that the fluidity of the concrete is lowered, which means that the so-called “sagging” of the material flowing out from the opening of the side mold can be surely prevented. In this regard, the viscosity change will be described in Experimental Example 3 below.

  The above-mentioned “Milcon SP” is obtained by kneading a coarsely crushed product with 100% by weight of water, extruding it into pellets, and drying it. Then, it grind | pulverizes with a pin mill. On the other hand, when the example of the manufacturing method of the sepiolite "RSA agent" of this invention is demonstrated, the mineral ore from Spain is crushed and this crushed material is 200-600 weight% with respect to this (normally 300-400 weight%) In the presence of water, it can be obtained by crushing to a particle size of 95% or more with a 45 μm under, for example, with a mortar colloid mill. Since there is a large amount of water and a colloid mill is used, it becomes a fine and highly viscous sepiolite.

  On the other hand, in the past, when the compounded material was transported to the spraying site by a ready-mixed concrete car, a predetermined amount of sepiolite and surfactant was put into the ready-mixed car tank, and the high-speed agitator in the tank was used for about 3 minutes. Sufficient dispersibility was obtained only by stirring. The slump value could be adjusted within the target range.

  On the other hand, as described above, the sepiolite of the present invention has poor dispersibility with respect to the blended material, and the slump value is also unstable. Therefore, according to the present invention, the blended material is conveyed as a ready mixed material to the spraying site by a ready-mixed concrete vehicle in advance, and the blended material is charged into a mixer installed at the spraying site, and sepiolite and a surfactant are charged into the mixer. Dispersion of the compounding material can improve dispersibility as compared with dispersion in a ready-mixed concrete vehicle. And the slump value within 120 minutes before pumping is adjusted to 15-27 cm by adjusting the input amount of the surfactant and sepiolite based on the torque value from the torque detector provided on the stirring shaft of the mixer. It becomes easy.

<Invention of Claim 2>
The mixer has at least two dispersion tanks, and the blended material is introduced into one dispersion tank from the chute of the ready-mixed concrete car, and the sepiolite and the surfactant are introduced to disperse the blended material. A first step, and then a second step in which the chute is moved and the compounded material is charged into the other dispersion tank, and the sepiolite and the surfactant are charged to disperse the compounded material. The method for constructing a frame according to claim 1, which is performed alternately.

(Function and effect)
As described above, by alternately performing the first process and the second process, smooth dispersion can be performed, and continuous spraying from the spray nozzle is possible.

The present invention will be further described below.
In the present invention, the main component is mortar or concrete, the water cement ratio W / C is 40 to 60%, and the unit cement amount (here, a value not considering the air amount. In the blending design, the air amount is 4 to 6). It is often calculated assuming that it is a percentage (it may be assumed that it is assumed to be 10% in some cases), so it means that the amount of air is not taken into account. 430 kg / m ³ or more in the case of concrete, 380 kg / m ³ or more in the case of concrete, 0.001 to 0.5 wt% of the surfactant and 0.5 to 5.0 wt. Of sepiolite with respect to the cement amount. %, And a wet method frame construction material having a slump value of 15 to 27 cm (especially 18 to 26 cm is optimal) within 120 minutes after kneading is passed through a pipe line by a (concrete) pump. To pump.

The construction mode of the present invention will be described in detail with reference to the drawings.
FIG. 2 is an overall view of concrete spraying. Concrete mixed in a predetermined manner is received from the ready-mixed concrete car 1 into the mixer 2, and the surfactant Y and sepiolite X are introduced into the mixer 2 and well dispersed. The wet method frame construction material Z that has been dispersed is put into a concrete pumping pump 3, and is then pumped to the spray nozzle 6 through the pumping line 5.

  On the other hand, the compressor 7 introduces air into the wet material from the Y-shaped tube 9 provided in the middle of the pressure feeding line 5 via the air pressure feeding line 8. As a result, air is entrained in the wet material and discharged from the spray nozzle 6. Reference numeral 10 denotes an air flow meter, which adjusts the amount of air according to the composition of the material and the state of spraying.

  As the pump 3, an appropriate one such as a squeeze pump or a piston pump can be used. Here, it is preferable that the pressure feed line 5 is basically composed of a metal pipe up to the Y-shaped pipe 9 and a flexible pressure-resistant hose up to the spray nozzle 6. Instead, a high-pressure hose can be used. The position of the Y-shaped tube 9 for entraining air is 7 to 40 m from the spray nozzle 6 according to the present invention, and 10 to 30 m is particularly preferable.

  If the air input position (entrainment start position) is close to the spray nozzle 6, the transport distance in a state where the air is entrained is short, and the material discharge from the spray nozzle is not stable. Furthermore, it becomes difficult for the worker to move while holding the spray nozzle, resulting in a decrease in workability. On the other hand, if the distance is excessively large, there is a possibility that material may be separated during transportation. In order to stabilize the flow of the discharged material, it is preferable that the pressure feed pump 3 is at least 5 m away. The characteristics regarding the air input position based on the spray nozzle 6 reference will be described later.

  As shown in FIG. 4, the mold is set up in a lattice shape, for example, by sidely adjoining side molds 21 made of a steel net (such as a crimp wire mesh or a punching metal). In this case, the adjacent side molds 21 and 21 are connected to each other by a connecting member 22 such as a steel bar or a steel wire, and the reinforcing bars 23 are fixed to the connecting member 22 in the longitudinal direction by a number wire or the like. Furthermore, an anchor pin is driven into the ground at a necessary place, for example, an intersection. The opening ratio of the side mold 21 is 70% or more according to the present invention. If the aperture ratio is small, there is a problem that the integrity with the material is not sufficient, and that the material becomes heavier when carried into a stationary site.

  At the time of spraying, an operator sprays material in a state where the spray nozzle 6 is directed between the side molds 21 and 21 while carrying a hose. At that time, the worker can work while observing the filling state of the material into the side molds 21 and 21. In the area surrounded by the legal framework that was finally constructed, vegetation sandbags can be piled, vegetation bases can be created, and mortar sprayed. In addition, a wire mesh or the like can be laid on the target slope in advance. For steep slopes, you can drive a full-fledged anchor at the intersection.

  As a spray nozzle, in addition to a general cone-shaped nozzle, a nozzle having an appropriate shape and structure can be used.

  As described above, the opening ratio of the side mold is 70% or more, but 95%, particularly 90%, can be used as long as the bending strength is not hindered.

In the present invention, air is entrained with respect to the rich material. In the case of improving the pumpability by air, the inner diameter can be increased stepwise as the pipe line goes to the tip, and air can be blown into the stepped portions of the increased portions. In any case, the total amount of air entrained is preferably 2 to 10 Nm ³ / min, particularly 2 to 7 Nm ³ / min. The discharge pressure is preferably ² to 10 kg / cm ² , particularly 5 to 8 kg / cm ² . The air entrainment amount and the discharge pressure can be adjusted sequentially or in advance in response to the communication from the worker, depending on the spraying situation. The inner diameter of the hose described above is preferably 35 to 60 mm, particularly 40 to 50 mm, and the inner diameter of the discharge part of the spray nozzle 6 is preferably 40 to 60 mm. If the flow rate of air is less than 2 Nm ³ / min and the pressure is less than 2 kg / cm ² , the material discharge force is weak, and the formability of the mold is reduced. On the other hand, if the flow rate exceeds 10 Nm ³ / min and the pressure exceeds 10 kg / cm ² , the material is separated and a large amount of rebound loss occurs, resulting in a reduction in quality.

As the frame material of the present invention, mortar or concrete is used. The unit cement amount is 430 kg / m ³ or more in the case of mortar, and 380 kg / m ³ or more in the case of concrete. If it is less than this, the strength becomes insufficient. Incidentally, the blending ratio is shown in Table 2.

In any case, the weight ratio of cement (C): sand (S) is set to less than 1: 1 to 4. If C: S is less than 1: 1, it becomes uneconomical and cracks easily occur. When C: S is 1: 4 or more, the strength is insufficient and the pumpability is impaired. In the case of concrete, the weight ratio of cement: sand: coarse aggregate is less than 1: 1 to less than 4: <2. The particle size of the coarse aggregate is preferably 25 mm or less, particularly 15 mm or less. As the coarse aggregate, gravel, slag (slowly cooled slag), and the like can be used. Further, in these materials, in addition to the additive of the present invention, a water reducing agent, a foaming agent, a thickener and the like are added in a range of 3% by weight or less with respect to the cement, and hydraulic slag fine powder, charcoal cal, A mixed material such as fly ash can be added in an amount of 50% by weight or less based on the cement. The amount of water added is preferably 40 to 60% as W / C. The discharge amount of the frame material from the spray nozzle is preferably 2 to 10 Nm ³ / hour.

  In the present invention, no quick setting agent is used. This is the difference from the NATM method for tunnel lining, which requires the use of a quick setting agent. The proposal by the present applicant of Patent Document 1 has become a major issue, and a similar construction method has been developed, and a construction method using a quick setting agent has also been adopted. However, even if the droop can be suppressed by using the quick setting agent, the present inventor has found that a long-term decrease in strength is caused. The addition of air is also suitable only at one location described above. It has been found that the conveyance is not stable when there are two or more places.

  In the present invention, the slump value within 1 minute after the discharge of the material discharged from the spray nozzle is adjusted to 5 to 11 cm (especially 7.5 to 10 cm is optimal). This adjustment can be achieved mainly by selecting the addition amount of the surfactant and sepiolite and the air blowing position.

  When the slump value is less than 5 cm, the filling property is poor, and particularly the wraparound property to the back of the reinforcing bar is deteriorated. If it exceeds 11 cm, problems such as sagging from the side mold will occur. These points will be described later together with experimental examples.

  JP-A-61-28670 is partially in common with the configuration of the present invention. However, this is not only based on the NATM method, but also has a slump value of 6 to 10 cm at the conveyance source, which is clearly different from that of the present invention. Moreover, this method is intended to mix air and add a quick setting agent to the one having a slump value of 6 to 10 cm, and within 1 minute after discharging the material discharged from the spray nozzle. The slump value of is unknown. According to our experiments, the slump value is greatly lowered by the mixing of air, particularly the addition of the quick setting agent, and the slump value itself cannot be measured due to gelation, and the actual value should be 0 cm. Actually, in the general-purpose NATM method, the slump value of the conveyance source is usually 8 cm, and air is mixed and the quick setting agent is added to this. it is obvious. In the construction of the legal framework targeted by the present invention, it is necessary not to focus on adhesion to the target surface and to prevent the generation of dust, but to improve the wraparound property to the back of the reinforcing bar and to have excellent filling properties. Yes, and the purpose is clearly different.

By the way, the water cement ratio W / C is 55% in all cases, and in the case where the unit cement amount is 420 kg / m ³ , when the quick setting agent is added 5.0%, the concrete 28-day strength is 27N. / mm is ² whereas, 28 days strength without addition of quick-setting admixture strength that is high has been found by not adding 32N / mm ^2. Therefore, the quick-setting admixture.

  As described above, when the slump value within 1 minute after the discharge of the material discharged from the spray nozzle is adjusted to 5 to 11 cm, the dominant factors are the slump value of the transport source and the addition amount of the sepiolite of the present invention. And the state of kneading / dispersing.

  In the case of concrete, it is difficult to say that the concrete received from the ready-mixed concrete vehicle 1 is homogeneous over time. Further, the sepiolite of the present invention has a slightly lower dispersibility than the conventional product. Therefore, conventionally, the surfactant and sepiolite have only to be put into the tank of the arrived ready-mixed concrete vehicle 1 and stirred, whereas the ready-mixed concrete vehicle 1 and the pump 3 as shown in FIG. It is necessary to install the mixer 2 between the receiving port and the surfactant Y and sepiolite X into the mixer 2 and disperse well. The mixer 2 is preferably a plurality of dispersion tanks (dispersion tanks 2A and 2B in the illustrated example), and the concrete from the ready-mixed concrete vehicle 1 is introduced into one dispersion tank via a chute 1a (see FIG. 2). In the process of dispersing, it is desirable to adopt an alternate receiving / dispersing method in which the other dispersing tank accepts the subsequent concrete.

  In the embodiment, it has been found that a dispersion tank provided with stirring blades 2b and 2b on the two shafts 2a and 2a has excellent dispersibility. The at least one stirring blade 2b is preferably a flat plate having a surface substantially parallel to the rotation axis. Under this configuration, the shaft 2a, 2a or one of the shafts 2a is provided with a torque detector 2C, the shear resistance value is obtained from the detected torque value, and the sepiolite of the present invention is within a predetermined shear resistance value range. By adjusting the addition amount, the slump value of the conveyance source can also be adjusted.

  The presence / absence and amount of addition of the surfactant also improve the fluidity because fine air is mixed, and the slump value becomes soft. Usable surfactants include soap, sulfate ester, sulfonate, phosphate ester, nonionic surfactant, ether type, ester ether type, amphoteric surfactant betaine, imidazoline betaine. The above-mentioned anionic surfactants are preferable. In the surfactant of the present invention, the generated fine bubbles reduce the pumping resistance in the pumping line. If the amount is less than 0.001% by weight with respect to the amount of cement, the effect is inferior. On the other hand, if the amount is excessive, the effect is saturated. A more preferred upper limit is 0.1% by weight.

  The amount of sepiolite added is less than 0.5% by weight with respect to the amount of cement.

[Experimental example]
The effects of the present invention will be clarified by showing experimental examples.
(Experimental example 1)
Under the above-mentioned apparatus configuration, the slump value of the spray material, the air charging position (the distance from the Y-tube spray nozzle), and the type of sepiolite were changed in various ways to observe the spraying situation and to build the method The physical properties of the frame were examined. The air pressure (original pressure) was 6.5 kg / cm ² , the air flow rate was constant at 4 Nm ³ / min, and a straight nozzle type was used as the spray nozzle.
The concrete spray material used was cement: sand: hydraulic slag fine powder: coarse aggregate = 1: 3: 0.2: 1, the unit cement amount was 402 kg / m ³ , and the water cement ratio W / C was 55%. The surfactant was fixed at 0.005% by weight with respect to the cement amount.
What was used for the experiment was “Mircon SP” manufactured by Showa Mining Co., Ltd. as the conventional product sepiolite shown in Table 1 above, and “RSA Agent” manufactured by Showa Mining Co., Ltd. as the sepiolite of the present invention.
The slump value was changed by using the amount of sepiolite added and the dispersion time to obtain the shear resistance value from the torque value detected by the torque detector described above and using the predetermined shear resistance value as an index. The addition amount of sepiolite was able to cope with the change within the range of 1.0 to 2.5% by weight with respect to the cement amount.
As the side mold, a crimp wire net having an opening ratio of 82% was used. The inner diameter of the tip hose from the Y-shaped tube was 45 mm.
In addition, the slump value of the conveying material and the slump value of the material discharged from the spray nozzle were measured. The transportability mainly depends on whether or not the discharge status from the spray nozzle is stable. The spray status is evaluated by five experimenters on the rebound loss status, the cut section status of the legal frame, and the appearance status of the sampling core. Judgment was made based on variation in average and evaluation. This situation observation evaluation also includes the situation of “su” generation, the situation of turning around the reinforcing bars, and the like. Furthermore, it was set as another evaluation item especially about sagging. The results are shown in Table 3. The fine aggregate was from Kinugawa and has a coarse grain ratio of 2.9. The 28-day strength of the method frame constructed with the material of the present invention was 35 to 39 N / mm ² .

(Experimental example 2)
The same experiment as Experimental Example 1 was performed in place of the mortar spray material. The material was cement: sand = 1: 3, and the unit cement amount was 495 kg / m ³ . Since the result is substantially the same as the result of Table 3, the description is omitted.

(Experimental example 3)
Based on the above experimental results, a significant difference in effect was observed between the conventional sepiolite and the sepiolite of the present invention.
(1) Weigh 180 g of water at room temperature, 20 g of sepiolite (“RSA agent”) of the present invention and sepiolite (“Mircon SP”) obtained from Showa Mining Co., Ltd.
(2) After each material is put into water, it is stirred for 3 minutes at a rotational speed of 550 rpm by a chemical mixer to prepare a 10% suspension.
(3) The viscosity of the prepared 10% suspension is measured with a vibratory viscometer. In order to know the tendency of viscosity development of each material, the change with time is also examined.
The time course of the viscosity of each sepiolite is shown in FIG.
The measurement was performed until 3 hours later. The viscosity of the “RSA agent” of the present invention immediately after preparation of the suspension is 84.1 mPa · s, and continues to increase from this, 360.0 mPa · s after 60 minutes, 591.6 mPa · s after 120 minutes, and 783 after 180 minutes. It was 3 mPa · s. That is, the viscosity increased 9.3 times after 3 hours. On the other hand, the viscosity immediately after the suspension of “Milcon SP” was 12.4 mPa · s, followed by a slight increase of 13.1 mPa · s in 60 minutes and 13.8 mPa · s in 180 minutes.
From this experimental result, the “RSA agent” was significantly different from “Milcon SP” in terms of viscosity development. The “RSA agent” showed a large value immediately after kneading, and showed a tendency for the viscosity to further increase with time. On the other hand, “Milcon SP” has a viscosity of about 1/7 of that immediately after kneading and immediately after kneading of “RSA agent”. The difference is seen.
It will be apparent from the results shown in FIG. 6 that the sepiolite “RSA agent” according to the present invention will behave differently from conventional products.

(Experimental example 4)
The mixer was equipped with a torque detector, and the correlation between the detected torque value and the slump value was studied at the laboratory stage.
Torque wrench manufactured by Tohnichi Manufacturing Co., Ltd. “FTD100CN2-S” The shaft tip of the four stirring blades shown in FIG. As a result of investigating the correlation, as shown in FIG. 7, a result having a very high correlation over the entire region was obtained. The torque value in the experiment here means the shear resistance value of the vane with respect to the material. It is clear that this is also effective for managing the slump value on the conveyance source side, and in accordance with the present invention, the surfactant and sepiolite are charged based on the torque value from the torque detector provided on the stirring shaft of the mixer. It turned out that the method of adjusting the amount and adjusting the slump value within 120 minutes before pumping to 15 to 27 cm is effective. In addition, the upper limit 11 cm of the slump value within 1 minute after discharging the material discharged from the spray nozzle is 1.2 kgN / m ² as the shear resistance value of the vane.

It is a graph which shows the hysteresis curve of sepiolite addition concrete. It is explanatory drawing which shows the pressure feeding system of material and air. It is a schematic diagram of a mixer. It is a general | schematic perspective view of the example of a legal frame. It is a front view of the instrument of a shear test. It is a graph of an experimental result. It is a graph of another experimental result. It is a graph of the result of the rotor used for experiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Ready-mixed concrete car, 2 ... Mixer, 3 ... Pump, 5 ... Pressure feeding line, 6 ... Spray nozzle, 7 ... Compressor, 8 ... Air pressure feeding pipe, 9 ... Y-shaped pipe, X ... Sepiolite, Y ... Surfactant , Z: Leg frame construction material.

Claims (2)

For blended materials with mortar or concrete as the main component, water-to-cement ratio W / C of 40-60%, unit cement amount of 430 kg / m ³ or more for mortar, and 380 kg / m ³ or more for concrete The surfactant is added in an amount of 0.001 to 0.5% by weight and the sepiolite in an amount of 0.5 to 5.0% by weight with respect to the cement amount. Wet method frame construction material with a slump value within 15 to 27 cm within minutes,
In a state where the slump value within 1 minute after discharge of the material discharged from the spray nozzle is 5 to 11 cm from the spray nozzle at the tip of the pipe by pumping through the conduit, Blowing and filling into the side mold frame where the opening ratio is fixed and the reinforcing bars are arranged is 70% or more,
The wet method frame is blown with air in an amount of 2 to 10 Nm ³ / min only in one blowing position that is in the middle of a pipe line between the pump and the blowing nozzle and is separated from the blowing nozzle by 7 to 40 m. While blowing the construction material from the spray nozzle in the state of entraining the air, and without any rapid setting agent added to the wet method frame construction material in any process,
The sepiolite is obtained by crushing a raw mineral ore, and crushing the crushed material into a particle size of 95% or more under 45 μm under the presence of 200 to 600% by weight of water,
The blended material is transported to a spraying site by a ready-mixed concrete car in advance as a ready mixed material, and the blended material is charged into a mixer installed at the spraying site, and the sepiolite and the surfactant are charged into the mixer. To disperse the material,
Based on the torque value from the torque detector provided on the stirring shaft of the mixer, the input amount of the surfactant and sepiolite is adjusted, and the slump value within 120 minutes before the pumping is adjusted to 15 to 27 cm.
A legal framework construction method characterized by that.
Here, the slump value is measured based on JIS A 1101 (1998).   The mixer has at least two dispersion tanks, and the blended material is introduced into one dispersion tank from the chute of the ready-mixed concrete car, and the sepiolite and the surfactant are introduced to disperse the blended material. A first step, and then a second step in which the chute is moved and the compounded material is charged into the other dispersion tank, and the sepiolite and the surfactant are charged to disperse the compounded material. The method for constructing a frame according to claim 1, which is performed alternately.

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