JP2007062263A - Controlling method of concrete setting time and constructing and reinforcing method of concrete structure by using controlling method of concrete setting time - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling a setting time of concrete for improving construction quality by adding an activating agent before setting a concrete (mortar) and controlling the setting time of the concrete (mortar). <P>SOLUTION: The method for controlling the setting time of concrete and method for constructing and reinforcing of the concrete construction comprises (S1) adding a setting retarder to concrete(mortar) and (S2) kneading the concrete (mortar) to which the setting retarder is added in a stirring unit or the like. Next (S3,S4) carrying the kneaded concrete (mortar) to a construction site and then (S5,S6) after standing or holding it, adding an activating agent, (S7) regulating a flow property of the concrete (mortar) by adding an SP agent or the like and (S8) constructing or mending the concrete structure by applying the concrete (mortar) finally. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

In the present invention, a concrete (mortar) is prepared by adding an activator immediately before use or before placing concrete into a concrete (mortar) which is blended with a setting retarder so as not to be set for a long time. The present invention relates to a method for constructing or reinforcing a concrete structure such as a tunnel lining, a railway pier, or a viaduct using the concrete (mortar) in which the setting time is controlled.

Conventionally, as an example of this type of conventional technology, for example, as a method of constructing a tunnel that is a concrete structure, a shield is pushed into the ground to prevent the collapse of earth and sand and to safely excavate and cover the inside. There is a shield method that performs the work and constructs the tunnel. This shield method is a so-called ECL (Extruded Concrete Lining) method, in which fresh concrete is cast at the tail of the shield without using a lining segment, and the lining is directly constructed with a face.
For example, when the ECL method is cycle driving as shown in FIG. 11 and the reinforcing bar 1 is used, the rebar and the inner mold 2 are assembled as shown in FIG. As shown in FIG. 11 (b), the rebar interior formwork is assembled, and the concrete 3 is placed as shown in FIG. 11 (c). Furthermore, as shown in FIG. 11 (d), for example, the configuration example shown in FIG. 12 is completed as the entire structure of the concrete structure constructed by pressing the concrete 3 with the press jack 4 and digging with the shield jack 5. .
As a method of reinforcing concrete structures, a high-toughness mat formed of polyvinyl alcohol fibers in a mat shape is attached to the surface of existing concrete, and a board reinforced with polyvinyl alcohol fibers is attached to the mat surface as an embedded mold frame. There is a method (REDEEM method) for forming a cement-based fiber reinforced mortar plate having excellent toughness by injecting mortar or grout into the mat portion.

As another example of the prior art, there is a setting retarder disclosed in JP-A-6-263498 and a method for constructing fast-hardening concrete using the same. To explain this, a set retarder for concrete containing no slaked lime-containing substance and organic acids as an active ingredient is used, and the set retarder is mixed with concrete, and immediately before the concrete is used. It is a construction method for fast-curing concrete that is mixed with a binder. Therefore, the slaked lime-containing material is a carbide soot produced when acetylene is generated from slaked lime or calcium carbide, for example, and uses a large amount of organic acid or the like so that the concrete containing no rapid setting material does not condense and harden for a long time. Then, even when the curing time is shorter than the planned curing time, it has a function of being able to quickly cure and cure by using the rapid setting material together. The organic acids are various water-soluble carboxylic acids such as citric acid, gluconic acid, tartaric acid and malic acid, and are controlled so that the setting time is increased in direct proportion to the amount of use. And at the time of spray construction, the said quick setting material is mixed with the concrete which mixed the said setting retarder.
Japanese Patent Laid-Open No. 6-263498 Japanese Patent Laid-Open No. 4-214058

One example in the prior art has been the use of common high fluidity concrete for the ECL method, but if the open time increases, such as when rock strength is high and excavation takes time, the fresh properties of the concrete Construction troubles such as deterioration and inducing blockage of the concrete placement opening occurred. As a result, there are problems such as defective filling of concrete, defects of concrete such as concrete joints, and accompanying water leakage.
In mountain tunnel construction, there are many cases where an agitator can run and transport in an already built mine. In urban tunnels, there are many cases where an agitator cannot travel and transport unlike mountain tunnels. It is necessary to pump concrete for a long distance by piping. In this case, the length of the pipe may be several kilometers, and there is a problem that the pipe is blocked due to deterioration of the fluidity of the concrete being pumped.
Normally, raw concrete plants stop shipping around 6:00 pm, and there are many plants that cannot be shipped until tomorrow. The ECL method is characterized by the fact that concrete can be placed at all times by placing concrete simultaneously with the excavation of the shield. However, when concrete is placed during night construction, the raw concrete plant does not operate at night. However, there are problems such as being economically disadvantageous when making an on-site plant. In addition, there are many situations where it is difficult to install a site plant in an urban tunnel, and there has been a demand for concrete that can maintain fluidity until the time required by the construction site.
Conventionally, after injecting mortar or grout (hereinafter referred to as “mortar etc.”) into a single injection location, it is necessary to discard the mortar remaining inside the injection hose and to clean the inside of the injection hose. However, there are problems such as labor complexity and economical disadvantage.
When using ready-mixed concrete, it is absolutely necessary that there is a facility for manufacturing ready-mixed concrete near the site. If there was no ready-mixed concrete plant near the site, it was necessary to install a plant on the site. When a small amount of concrete or special concrete is used, there is a problem that it is economically disadvantageous or difficult to obtain a stable quality in the field plant.

Another example in the prior art is a technique for construction of fast-curing concrete using a setting retarder or a quick setting material, but it is not a technique of adding an activator after placing concrete, but a technique for concrete. There was a problem that the setting time could not be controlled and the construction quality was not stable.

A concrete setting time control method and a concrete structure construction / reinforcement method using the concrete setting time control method according to the present invention include adding a setting retarder to concrete containing no activator (mortar), A concrete (mortar) in which the setting time is controlled by post-adding the activator before using concrete, and is a construction method for constructing and reinforcing a concrete structure, which is constituted by the following constitution and means.

The concrete setting time control method and the concrete structure building / reinforcing method using the concrete setting time control method according to the present invention have the following effects because they have the above-described configuration.
That is, by adding a setting retarder to concrete, it is possible to maintain good fresh properties for 24 hours or more after the concrete is mixed. Furthermore, by adding the activator immediately before the concrete is placed, there is an effect that after the concrete is placed, the setting is promoted to ensure good strength development. In addition, when tunnel lining concrete is cast by the ECL method, it is possible to cast concrete with good fresh properties even when it takes a long time for excavation work by using the concrete. Thus, there is an effect that it is possible to block the concrete placement opening and prevent the occurrence of concrete filling defects, concrete defects such as cold joints, and the accompanying water leakage.
In addition, in order to maintain good fresh properties for 24 hours or more after the concrete is mixed, it can be pumped over a long distance by piping, and the ECL method can be applied to an urban tunnel.
Furthermore, by using the setting time control in the injection method of mortar and grout (hereinafter referred to as “mortar etc.”) used in the REDEEM method, the problem of the REDEEM method is solved and a setting retarder is added to the mortar. Since it is possible to maintain good fresh properties for 24 hours or more after mixing, after the completion of one injection, leave the mortar remaining inside the injection hose without discarding it. Can be used at the next injection. Therefore, the disposal of the mortar and the like inside the injection hose and the cleaning operation inside the injection hose, which are necessary every time the injection point is moved, are unnecessary, and there is an advantage that it is economically advantageous.
In addition, by adding an activator immediately before the injection of mortar, etc., it is possible to secure good strength development by promoting the setting after the injection. When placing nearby concrete (mortar, etc.) at a factory, if it is not possible to use a nearby plant, it can be transported over a long distance from a remote raw plant, and it is not necessary to install an on-site plant. There are various effects such as being advantageous.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a concrete setting time control method and a concrete structure building / reinforcing method using the concrete setting time control method according to the present invention will be described below in detail with reference to FIGS.

The setting retarder and activator used in the present invention are not particularly limited, and the set retarder developed to make effective use of the residual concrete and return concrete generated in the concrete production of the ready-mixed concrete factory. An activator or a setting modifier generally used for sprayed concrete can be used.
Here, the setting retarder is a setting retarder for concrete (mortar) containing, for example, slaked lime-containing substances and organic acids as active ingredients, and is a material added to the concrete (mortar). The slaked lime-containing substance has a function of being able to quickly set and harden even in a shorter time than the planned hardening time when a large amount of organic acid or the like is used so that the concrete (mortar) does not harden and harden for a long time. Specific examples include slaked lime and carbide soot produced as a by-product when acetylene is generated from calcium carbide. In addition, alkylaminophosphonic acid is used as an active ingredient. Among them, the use of carbide soot is more preferable from the viewpoint of the best strength development after mixing with the quick-setting material and being inexpensive and economical because it is a by-product. The particle size of the slaked lime-containing substance is not particularly limited, but is preferably 100 μ to 60 μ. The organic acids can be used singly or in combination of various water-soluble carboxylic acids such as citric acid, gluconic acid, tartaric acid, and malic acid, or salts thereof. Of these, use of citric acid is more preferable from the viewpoint that the setting time is increased in direct proportion to the amount used and easy to control.

It was experimentally verified whether the setting time could be controlled by a method of delaying the setting time of concrete (mortar) with a setting retarder and then activating from the setting stop state with an activator. For setting retarded concrete, the target value of time during which setting can be controlled was set to 24 hours. After 24 hours, an activator, a high-performance AE water reducing agent and an air amount adjusting agent were added so that the required fresh properties were obtained, and the properties of the concrete were confirmed.

FIG. 1 shows a control flow of the setting time of concrete (mortar).
To explain this, first, when acetylene is generated from slaked lime or calcium carbide in concrete (mortar) material, a slaked lime-containing substance consisting of by-product carbide soot and organic acids such as citric acid and gluconic acid are added. A setting retarder as an active ingredient is added (step 1). In addition, alkylaminophosphonic acid is used as an active ingredient. Then, the concrete (mortar) to which the setting retarder is added is kneaded with a stirrer or the like (step 2). Next, the kneaded concrete (mortar) is mounted on a special vehicle and transported to the site of a concrete structure to be built or repaired (steps 3 and 4). And after standing still and waiting for this, the activator mentioned above is post-added (step 5, step 6). Further, a fluidizing agent or the like is added to adjust the fluidity of the concrete (mortar) (step 7). Finally, concrete (mortar) is placed to construct or repair the concrete structure (step 8).

In general high-fluidity concrete, the slump flow is reduced by about 15 cm as shown in FIG. 2 and FIG. 3 after 2 hours of mixing, but the setting delay concrete with the target value of the standing time set to 24 hours. Even after standing for 24 hours after kneading, the slump flow decreases only by about 10 cm as shown in FIG. 2, and the setting can be suppressed by the action of the setting retarder. FIG. 2 shows the change over time in the slump flow after the target standing time has elapsed and the activator has been added. With regard to setting retarded concrete, good fresh properties can be maintained even after the addition of the activator, and the slump flow is reduced only by about 10 cm even after 2 hours have elapsed after the addition of the activator. FIG. 4 shows the compressive strength properties of 7 day and 28 day concrete. It is possible to adjust the fluidity of the concrete as shown in the characteristic diagram of FIG.

Next, a time-dependent change characteristic diagram of the slump flow shown in FIGS. 6 and 7 created based on the experimental results will be described.
As shown in Fig. 6, the slump flow is reduced by about 15 cm after 2 hours of mixing with general high-fluidity concrete, but the setting delay concrete with the target value of setting control time set to 24 hours is mixed. Even after 24 hours of standing, the slump flow is only reduced by about 10 cm, and the setting can be controlled by the action of the setting retarder.

FIG. 7 shows the change over time in the slump flow after the target standing time has elapsed and the activator and high-performance AE water reducing agent have been added. The setting retarded concrete can maintain good fresh properties even after the addition of the activator, and the slump flow is reduced only by about 10 cm even after 2 hours have passed since the addition of the activator.

FIG. 8 shows the results of compressive strength tests of concrete at 7 and 28 days of age. As a result of comparing general high-fluidity concrete with setting retarded concrete, there is no significant difference in the compressive strength of the concrete, and even if the setting time of the concrete is controlled by setting retarder and activator, the strength development is affected. Was found not to be affected.

Based on the knowledge obtained from the above experiment, the setting time of the concrete (mortar) is delayed by the setting retarder, and the setting time of the concrete (mortar) is activated by the addition of the activator. Control is possible.

By the way, when general high-fluidity concrete in the prior art is used, the slump flow decreases by about 17 cm as shown in FIG. 6 after 2 to 3 hours from the mixing shown in Step 2 above. Yes.
Note that FIG. 2 also clearly shows the state in the conventional technique.

Here, the slump flow test method of the concrete 9 for deriving the characteristic diagram of FIG. 6 will be described.
As shown in FIGS. 9 (a) and 9 (b), the test instrument performs design specifications with the following members and conditions. That is, the slump cone 7 is defined in JIS A 1101. The thrust rod shall be specified in JIS A 1101. The flat plate 8 is made of steel having sufficient water tightness and rigidity, and has a size of 0.8 m × 0.8 m or more and a smooth surface. When attaching the handle, place it at a position that does not interfere with the slump flow measurement. The caliper or measure can be read up to 1 mm. The auxiliary instrument 6 for measurement shall be used for the measurement of a slump flow as shown to FIG. 6 (a), (b). The receiving container is a bucket having a capacity of about 12 L, and is prepared as necessary. The stopwatch can measure up to 0.1 seconds.

And as a test method,
a. Regarding the installation of the slump cone 7 and the flat plate 8, the slump cone 7 and the flat plate 8 are wiped on the inner surface and the surface with a compress. The slump cone 7 is placed on a flat plate 8 installed horizontally.
b. The sample is packed carefully so as not to cause separation of the material, and the time from the start of packing into the slump cone 7 to the end of packing is within 2 minutes. In the case of the underwater non-separable concrete 9, it is better to divide it into three layers and poke it uniformly with 25 rams for each layer.
c. The slump flow is measured after the top surface of the concrete 9 packed in the slump cone 7 is aligned with the upper end of the slump cone 7, and then immediately after the slump cone 7 is pulled up continuously in the vertical direction, the concrete 9 stops moving. Measure the diameter that seems to be the largest and the diameter in the direction perpendicular to it. Note that the number of measurements is one.
d. When obtaining the 50 cm flow arrival time, the time from when the slump cone 7 starts to be pulled until the first time when the spread reaches the 50 cm diameter circle drawn on the flat plate 8 is measured by a stopwatch in units of 0.1 second. .
e. When determining the flow stop time of the flow, the time from when the slump cone 7 starts to be pulled until the stop is visually confirmed is measured by a stop watch in units of 0.1 second. As a result, the slump flow is displayed by rounding the average value of both diameters to the nearest 0.5 cm.

The concrete compressive strength test method for deriving the characteristic diagram of FIG. 8 will be described.
This test method is
a. The specimen is prepared according to JIS A 1132.
b. The diameter and height are measured to 0.1 mm and 1 mm, respectively. The diameter is measured in two directions orthogonal to each other at the center of the specimen height.
c. If there is damage or defect and it appears to affect the test results, do not test or record the contents.
d. The mass is measured with a scale having a scale of 0.25% or less of the mass. The mass is measured after all the excess water of the specimen has been removed.
e. The specimen should be able to be tested in a state immediately after the prescribed curing is finished.

The apparatus for performing the compressive strength test of concrete is as follows.
The compression tester is JIS B 7733 6. It shall be 1st grade or higher as specified in (Testing Machine Grade). In addition, the maximum load during the test is used in the range from 1/5 to the maximum capacity. When the weighing capacity can be changed with the same testing machine, each weighing capacity is regarded as a separate weighing capacity, and the size of the upper and lower pressure plates is not less than the diameter of the specimen and the thickness is not less than 25 mm. The compression surface of the pressure plate is polished, its flatness is within 0.02 mm per 100 mm, and its Shore hardness is 70 HS or more.

The test method for the compressive strength test of concrete is as follows.
The upper and lower end surfaces of the specimen and the compression surfaces of the upper and lower pressure plates are cleaned, and the specimen is placed so that its central axis coincides with the center of the pressure plate with an error within 1% of the specimen diameter. In addition, the pressure plate of the testing machine and the end face of the specimen should be in direct contact with each other, and no cushion material should be put between them. However, the case of unbonded capping is excluded. Further, a load is applied at a uniform speed so as not to give an impact to the specimen, and the speed at which the load is applied is set so that the increase in the degree of compressive stress is 0.6 ± 0.4 N / mm ² per second. Then, after the specimen begins to suddenly deform, the adjustment of the speed at which the load is applied is stopped, the load is continuously applied, and the maximum load indicated by the testing machine is 3 digits before the specimen breaks. I shall read.

In the present invention, by adding an activator immediately before injection of mortar or the like, it is possible to ensure good strength development by promoting the setting after injection, and during nighttime construction and large-scale disasters. When placing concrete (mortar, etc.) on time and on a remote island, if a nearby factory cannot be used, it can be transported over a long distance with a special vehicle 10 from a raw plant plant of a remote factory P as shown in FIG. Since there is no need to install the on-site plant R, it is advantageous in terms of economy and quality.

It is a control flow of the setting time of the concrete (mortar) in the construction / reinforcement method of the concrete structure using the setting time control method of the concrete according to the present invention and the setting time control method of the concrete. The method for controlling the setting time of concrete according to the present invention and the change over time in the slump flow after mixing of the concrete (mortar) in the construction / reinforcement method of the concrete structure using the setting method of the setting time of the concrete It is a characteristic figure of typical high fluidity concrete and setting retarded concrete. It is a characteristic view which shows a time-dependent change of the slump flow after kneading of the general high fluidity concrete in a prior art. It is a characteristic view which shows the compressive strength expression of the setting retarded concrete in the construction / reinforcement construction method of the concrete structure which uses the setting time control method of the concrete which concerns on this invention, and this setting time control method of this concrete. Properties showing the time-dependent change (including flow adjustment) of slump flow of setting retarded concrete in the concrete construction / reinforcement method using the concrete setting time control method and concrete setting time control method according to the present invention FIG. Characteristics of the method for controlling the setting time of concrete according to the present invention and the change over time of the slump flow after mixing of the concrete (mortar) in the construction / reinforcing method of the concrete structure using the setting time control method of the concrete It is a figure (experiment result). Method of controlling setting time of concrete according to the present invention and change with time of slump flow after adjusting the flow of concrete (mortar) in concrete construction and reinforcement method using the setting method of setting time of concrete (experimental result) FIG. It is a characteristic view which shows the compressive strength expression (experimental result) of the concrete (mortar) in the construction / reinforcement construction method of the concrete structure using the setting time control method of the concrete according to the present invention and the setting time control method of the concrete. . The concrete setting time control method according to the present invention and the concrete slump flow test method in the construction / reinforcement method of a concrete structure using the concrete setting time control method are shown, (a) is a plan view, (B) is the side view seen from the arrow AA line direction of (a). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram for transporting concrete (mortar) for a long time in a concrete setting time control method and a concrete structure construction / reinforcement method using the concrete setting time control method according to the present invention. It is a block diagram which shows the cycle placement method of the concrete in a prior art, (a) shows assembly setup of a rebar internal formwork, (b) shows rebar internal formwork assembly, (c) is concrete. (D) is each figure for pressurizing concrete and performing excavation. It is a sectional view showing the whole structure of a concrete structure in the prior art.

Explanation of symbols

6 Measuring aid 7 Slump cone 8 Flat plate 9 Concrete 10 Special vehicle P Distant factory R Field plant

Claims (3)

Setting time of concrete or mortar is controlled by adding and retarding a setting retarder to concrete or mortar containing no activator, and adding the activator immediately before placing the concrete or mortar. Control method. A concrete structure using this control method, which controls the setting time of concrete or mortar by adding and retarding a setting retarder to concrete or mortar, and adding an activator before placing the concrete or mortar. Construction and reinforcement method. A first step of adding a setting retarder to the concrete or mortar material, a second step of kneading the concrete or mortar from the first step with a stirrer or the like, and the concrete or mortar from the second step to a special vehicle 3rd and 4th steps for transporting the concrete structure to be built or repaired to the site, 4th step, and 5th after adding the activator after standing or waiting for the concrete or mortar from the 4th step, Adding a SP agent to the concrete or mortar from the sixth step, and adjusting the fluidity of the concrete or mortar, and placing the concrete or mortar from the seventh step; And the final step of building or repairing concrete structures Construction and reinforcement method of the concrete structure using the coagulation time method of controlling setting time control method and the concrete.

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