JP2017194356A - Expansive coefficient measurement method of expansive mortar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an expansive coefficient measurement method of an expansive mortar capable of simply and accurately measuring an expansive coefficient of an expansive mortar without being limited in measurement location.SOLUTION: An expansive coefficient measurement method includes: a casting step of casting an expansive mortar inside a mold form 2 whose top surface is opened; and a measurement step of obtaining an expansive coefficient of the expansive mortar M. The casting step includes: a mold form setting work for installing the mold form 2 inside a container 3; a water injection work for injecting water W into the container 3; and a sealing work for sealing the container 3. A narrow tube 5 is disposed extending above the top surface of the container 3 from the inside of the container 3. In the water injection work, the water is injected until a water level inside the container 3 becomes higher than the top surface of the mold form 2 and the lower end of the narrow tube 5. In a water sealing work, the container 3 is sealed except for the narrow tube 5 only. In the measurement step, a change Δh of the water level of the small tube 5 is measured.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for measuring an expansion rate of expanded mortar.

  In the case of installing a shear reinforcement member by post-installation, or in the reinforcement work of post-installation anchors, etc., after drilling a reinforcement member insertion hole in an existing structure, this expansion member insertion hole is filled with expansion mortar together with the reinforcement member There is. Since it is necessary to fill the expansion mortar so that an unfilled portion is not formed, when the expansion mortar is used, it is necessary to grasp the expansion rate of the expansion mortar in advance. Therefore, many methods for measuring the expansion rate of expanded mortar have been proposed.

For example, the so-called ASTM method (ASTM C827-01a “Standard Test Method for Change in Height at Early Ages of Cylindrical Spectral Mice” This is a method of measuring the amount of expansion by irradiating the indicator ball with light in an embedded state and projecting it on a chart paper several meters away.
The so-called Architectural Institute method (JASS 5T-701) is a method in which 800 cc of mortar is put into a 1000 cc graduated cylinder and the upper surface of the mortar and the water level of bleeding water are measured.
Further, in Non-Patent Document 1, after the mortar is put into the mold, silicon oil is poured onto the upper surface of the mortar, and the distance to the upper surface of the silicon oil is measured by a depth measuring micrometer to expand the mortar. A method of measuring is disclosed.

Tatsuo Suenaga and three others, "Proposal of an early mortar expansion measurement method", Proceedings of the annual lecture on concrete engineering (2), Japan Concrete Institute, 1980, p. 145-p. 148

The ASTM method affects the measurement result when the indicator ball sinks due to vibration or the like. In addition, it is difficult to work on site, and it is necessary to secure a space (distance) for enlarging and projecting the indicator ball. Furthermore, since the indicator ball moves in the process of hardening the specimen, it takes time to focus.
In addition, the Architectural Institute method directly measures the surface height of mortar and the water surface height of bleeding water, so it was difficult to measure a small amount of expansion.
Furthermore, since the method of Non-Patent Document 1 also directly measures the surface of silicon oil, it is difficult to measure a small amount of expansion.
From such a point of view, the present invention has an object to propose a method for measuring the expansion rate of an expanded mortar that does not require a wide space and enables the expansion rate of the expanded mortar to be easily and accurately measured. To do.

In order to solve the above-mentioned problems, the present invention provides an expansion rate measurement of an expanded mortar comprising a placing step of placing an expanded mortar in a mold having an open upper surface, and a measuring step for obtaining an expansion rate of the expanded mortar. In the method, the placing step includes a mold installation operation for installing the mold in a container, a water injection operation for injecting water into the container, and a sealing operation for sealing the container. A thin tube extending upward from the upper surface of the container from the inside of the container is piped, and in the water injection operation, water is poured until the water level in the container is higher than the upper surface of the mold and the lower end of the thin tube, In the sealing operation, the container is sealed except for only the thin tube, and in the measurement step, the change in the water level of the thin tube is measured.
According to the method for measuring the expansion rate of the expanded mortar, since the amount of expansion of the mortar is simply measured by the change in the water level amplified by the thin tube, it can be measured with high accuracy even when the expansion rate is small. . Moreover, since it can measure with a simple instrument, it does not require a large space and can be measured on site. In addition, since the expansion rate of the mortar immediately after driving can be measured, the displacement after the elapse of a predetermined period from immediately after driving can be measured with high accuracy.

In the measurement step, the expansion coefficient may be calculated using Equation 1.
α = (Δh × A) / V × 100 Equation 1
α: Expansion rate (%)
Δh: Amount of change in water level A: Inner hollow cross-sectional area of capillary tube V: Volume of mortar Further, in the placing step, if the water surface in the capillary tube is water-insoluble and liquid specific gravity is less than 1, Water evaporation is prevented, and more accurate measurement is possible.

  According to the method for measuring the expansion rate of the expansion mortar of the present invention, the expansion rate of the expansion mortar can be measured easily and accurately without being limited to the measurement location.

It is a flowchart which shows the expansion coefficient measuring method of the expansion mortar which concerns on embodiment of this invention. It is a schematic diagram which shows an example of the expansion coefficient measuring apparatus used for the expansion coefficient measuring method of expansion mortar. It is a schematic diagram which shows the expansion coefficient measuring apparatus after predetermined time progress.

In the present embodiment, a method for measuring an expansion rate of an expanded mortar used when a shear reinforcement member is installed by post-installation on an existing structure will be described.
The shear reinforcement member is inserted into a reinforcement member insertion hole formed in the existing structure. The reinforcing member insertion hole is filled with mortar together with the shear reinforcing member.
As the mortar, an expanded mortar is used so that no void is formed in the reinforcing member insertion hole. The composition of the expanded mortar is appropriately determined.
In this embodiment, the presence or absence of quality fluctuations in the field environment is confirmed by confirming the expansion rate of the expanded mortar.

The expansion rate of the expanded mortar is confirmed by carrying out the expansion rate measurement method for the expanded mortar on site. As shown in FIG. 1, the expansion mortar expansion rate measuring method of the present embodiment includes a placing step S1 and a measuring step S2.
In this embodiment, the expansion coefficient of the expansion mortar M is measured using the expansion coefficient measuring device 1. As shown in FIG. 2, the expansion coefficient measuring apparatus 1 includes a mold 2 for placing an expansion mortar, a container 3 for housing the mold 2, a lid member 4 for shielding the upper surface of the container 3, and a lid member 4. Are provided with a thin tube 5 and a water injection tube 6. In addition, the structure of the expansion coefficient measuring apparatus 1 is not limited.
The expansion rate measuring device 1 ensures the same temperature environment as that at the time of construction by storing it at the site for half a day or more, preferably for one day or more before performing the placing process.

The placing step S1 is a step for placing the expanded mortar M in the mold 2 (see FIG. 2).
The placement step S1 includes a placement operation S11, a formwork installation operation S12, a water injection operation S13, a sealing operation S14, and a water head covering operation S15.
In the placement operation S11, the expansion mortar M is placed in the mold 2 having a known volume. As the mold 2, as shown in FIG. 2, one having an open upper surface is used. In addition, the mold 2 has a smooth inner surface (a contact surface with the expansion mortar). Furthermore, the mold 2 is formed in a shape (for example, a cylindrical shape) that does not excessively restrain the expansion and contraction of the expansion mortar M. The mold 2 is preferably as large as possible from the viewpoint of increasing measurement sensitivity.
In the present embodiment, the expansion mortar M is placed so that the upper end of the mold 2 and the upper surface of the expansion mortar M immediately after placement are flush with each other.

In the mold installation operation S12, the mold 2 is installed in the container 3 as shown in FIG.
A container 3 having a shape capable of accommodating the mold 2 and capable of being sealed with the lid member 4 is used. The order of the placement work S11 and the formwork installation work S12 is not limited. That is, the mold 2 on which the expansion mortar M is placed may be installed in the container 3, or the empty mold 2 is installed in the container 3, and the expansion mortar M is placed on the mold 2 in the container 3. You may cast it.
When the mold 2 on which the expanded mortar M is placed is placed in the container 3, the upper surface of the container 3 is covered with the lid material 4. The periphery of the lid 4 is brought into close contact with the periphery of the container 3.

In the water injection operation S13, water W is injected into the container 3.
The water W is poured into the container 3 from the bottom of the container 3 using the water injection pipe 6. The water injection pipe 6 penetrates the lid member 4. The water inlet (lower end) of the water injection pipe 6 is disposed between the mold 2 and the container 3 and in the vicinity of the bottom of the container 3. The other end of the water injection pipe 6 (the end opposite to the water injection port) is connected to the water storage tank 7. Further, the water injection pipe 6 is provided with an on-off valve 8 between the water storage tank 7 and the lid member 4. The water storage tank 7 of the present embodiment is disposed so that the water level in the water storage tank 7 is always higher than the upper end of the container 3. The water temperature of the water W is the same as the air temperature.

When water W is poured into the container 3, the on-off valve 8 is opened and the water in the water storage tank 7 is poured. Since the water injection port of the water injection pipe 6 is disposed near the bottom of the container 3, the expansion mortar M is not disturbed by the flow of the water W discharged from the water injection pipe 6. In addition, the position of the water injection port of the water injection pipe 6 is not limited as long as it is a position sufficiently away from the upper end (expansion mortar M) of the mold 2 or a sufficiently low position.
The water W is poured until the water level becomes higher than the upper surface of the mold 2 on which the expansion mortar M is placed and the lower end of the thin tube 5.
The thin tube 5 is a straight tube having a constant cross section penetrating the lid member 4, the lower end is located in the container 3, and the upper end is higher than the water surface of the water storage tank 7 (the upper surface of the container 2). It is piped to become.

In the sealing operation S14, the container 3 is sealed except for the thin tube 5.
In this embodiment, the container 3 is sealed by closing the on-off valve 8. At this time, the height of the water surface of the narrow tube 5 and the water surface of the water storage tank 7 are the same.

In the water head covering operation S15, a non-water-soluble and liquid specific gravity smaller than 1 is injected from the upper end of the thin tube 5 and a non-volatile liquid is injected to cover the water surface in the thin tube 5 with the liquid. The liquid is not limited, but kerosene is used in this embodiment. Further, a colored liquid may be used.
The water head covering operation S15 may be performed before the sealing operation S14, or may be performed after the sealing operation S14.

The measurement step S2 is a step for obtaining the expansion coefficient of the expanded mortar M.
As shown in FIG. 1, the measurement step S2 of the present embodiment includes a water level measurement operation S21 and an expansion rate calculation operation S22.
In the water level measurement operation S21, the amount of change in the water level of the narrow tube 5 for each elapsed time is measured. In the present embodiment, the water level is measured until a material age of 7 days every predetermined time. The water level may be measured visually by a measurer or automatically by a video camera or a data logger.

First, the water level (initial value) is measured immediately after the sealing operation S14. When using a thin tube 5 with a scale, the scale may be read as an initial value. On the other hand, when the fine tube is not graduated, the thin tube is marked as an initial value. Next, after a predetermined time has elapsed, the change in the water level relative to the initial value is measured, and the amount of change Δh in the water level for each elapsed time is recorded.
When the expanded mortar M expands, the expanded mortar M protrudes from the mold 2 as shown in FIG. Accordingly, the water level in the container 3 rises. However, since the container 3 is sealed, the air pressure in the container prevents the water level from rising in the container 3. As a result, the water level in the narrow tube 5 rises.

In the expansion rate calculating operation S22, the expansion rate α of the expanded mortar M is calculated based on the measurement result of the change amount Δh of the water level.
In the present embodiment, the expansion coefficient is calculated using Equation 1.
α = (Δh × A) / V × 100 Equation 1
A = π × φ ² ÷ 4
α: Expansion rate (%)
Δh: Amount of change in water level A: Inner hollow cross-sectional area of capillary tube V: Volume of mortar φ: Inner diameter of capillary tube

According to the method for measuring the expansion rate of the expansion mortar of the present embodiment, the water level fluctuation is amplified because the water level of the narrow tube 5 having an inner diameter smaller than that of the container 3 is measured. Changes in water level can be accurately measured.
Moreover, since the expansion coefficient measuring apparatus 1 having a simple configuration is used, the influence (measurement error) exerted on the accuracy by the apparatus or the instrument is small. Moreover, since the expansion coefficient measuring apparatus 1 is economical, it can be expected to be used generally. Also, the measurement error by the measurer is small.

Moreover, since the expansion rate of a mortar can be measured by the same environmental temperature as the mortar utilized for this construction, construction with high reliability is possible.
Since the non-water-soluble and liquid specific gravity is smaller than 1 and a non-volatile liquid is injected into the water surface of the thin tube 5, water does not evaporate in the thin tube 5. Moreover, if a colored liquid is used, the water level can be measured more easily.
Since the measurement can be started only by placing the expansion mortar M, pouring water W into the container 3 and operating the on-off valve 8, the expansion rate of the mortar M immediately after the injection can be measured.
Further, the measurement sensitivity can be adjusted by the volume of the container 3 and the inner diameter of the thin tube 5. The smaller the inner diameter of the narrow tube 5 with respect to the mortar volume (volume of the mold 2) V, the higher the water level is amplified, so that measurement becomes easier.

In addition, the measurement accuracy β of the expansion coefficient and the inner diameter φ of the thin tube 5 corresponding to the volume of the mortar (volume of the mold 2) V can be calculated by Equation 2. The method for determining the inner diameter φ of the thin tube 5 is not limited.
Table 1 shows the relationship between the volume of the mold 2 and the inner diameter φ of the narrow tube 5 when the measurement accuracy β calculated by Equation 2 is 0.01% and the amount of change Δh in the water level is 1 mm (the minimum scale of the ruler). Show.

The embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and the above-described components can be appropriately changed without departing from the spirit of the present invention.
In the above embodiment, the case of measuring the expansion rate of the expansion mortar used when installing the shear reinforcement member in the existing structure has been described. However, the use of the expansion mortar is not limited. It may be used for construction.
Note that the length (upper end position) and the initial water level of the narrow tube 5 are appropriately determined according to the expected expansion rate so as not to leak from the upper end of the narrow tube 5. For example, when the measurement accuracy is 0.01% (the 1 mm water level rises when the expansion rate is 0.01%), and the expansion rate at the age of 7 days is 0.38%, a scale of 38 mm is secured for the thin tube 5. There is a need to.

DESCRIPTION OF SYMBOLS 1 Expansion coefficient measuring device 2 Form 3 Container 4 Cover material 5 Narrow pipe 6 Water injection pipe 7 Water storage tank 8 On-off valve M Expansion mortar W Water S1 Placing process S11 Placing work S12 Forming work S13 Water filling work S14 Sealing work S15 Water head Covering operation S2 Measuring process S21 Water level measuring operation S22 Expansion rate calculating operation

Claims (3)

An expansion rate measurement method for an expansion mortar comprising: a placing step of placing an expansion mortar in a mold having an open upper surface; and a measurement step for obtaining an expansion rate of the expansion mortar,
The placing process includes
Formwork installation work for installing the formwork in a container;
A water injection operation for injecting water into the container;
A sealing operation for sealing the container,
A thin tube extending upward from the upper surface of the container from the inside of the container is piped,
In the water pouring operation, water is poured until the water level in the container is higher than the upper surface of the mold and the lower end of the narrow tube,
In the sealing operation, the container is sealed except for only the thin tube,
In the measurement step, the expansion rate measurement method for the expanded mortar, wherein the change in the water level of the capillary tube is measured. 2. The method for measuring an expansion rate of an expanded mortar according to claim 1, wherein the expansion rate is calculated using Equation 1 in the measurement step.
α = (Δh × A) / V × 100 Equation 1
α: Expansion rate (%)
Δh: Amount of change in water level A: Inner hollow cross-sectional area of capillary tube V: Volume of mortar   3. The expansion according to claim 1, wherein in the placing step, an operation of covering the water surface in the narrow tube with a liquid that is insoluble in water and has a liquid specific gravity of less than 1 is performed. Method for measuring expansion rate of mortar.

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