JP3877639B2 - Test method to evaluate material separation resistance of high fluidity concrete - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a test method for evaluating material separation resistance when freshly flowing high fluid concrete.
[0002]
[Prior art]
The most commonly used method for evaluating the workability of high-fluidity concrete is the slump flow test. The slump flow test is standardized as JIS A 1150 (2001) (a concrete slump flow test method).
In this test method, a slump cone formed as a truncated cone-shaped container having a height of 30 cm is placed on a flat base plate, the slump cone is filled with a concrete sample, and the top surface is slumped. After aligning with the upper end of the cone, immediately pulling up the slump cone continuously in the vertical direction, the concrete sample flows out from the lower end of the slump cone onto the base plate.
Then, after the movement of the flowing concrete sample stops, the diameter (passing dimension) of the concrete sample that spreads on the base plate (that is, slump flow) and the diameter in the direction orthogonal thereto are measured, The average value of both diameters is the slump flow value.
This test method is widely used in both the test room and the field because the equipment used and the test work are extremely simple and have the accuracy that is usually required.
[0003]
Japanese Patent Application No. 08-059337 discloses a test method for a barrier slump flow test in which a slump flow test is performed using a barrier. In this test method, when a slump cone is placed on the base plate and the concrete sample is filled in the slump cone, a barrier is then placed on the base plate so as to surround the periphery of the slump cone. Put. Thereafter, when the slump cone is lifted and removed, a part of the concrete sample that has flowed out onto the base plate passes through the barrier and flows to the outside of the barrier, thereby forming a slump flow. The barrier provides mechanical resistance to the concrete sample flowing through the barrier. Subsequently, samples are collected from the area inside the barrier and the area outside the barrier of the slump flow formed as described above, and the degree of material separation of the collected samples inside and outside the barrier is compared.
[0004]
High fluidity concrete with excellent workability must have good fluidity and high separation resistance.
The slump flow value obtained by a normal slump flow test is an index mainly representing the fluidity of concrete, whereas the barrier slump flow test can evaluate both the fluidity and separation resistance of concrete. .
Other tests for evaluating the separation resistance of concrete include sieving tests using flow tables and standard sieves (1.2 mm to 20 mm) used in cement physical testing methods, and dropping concrete. There is a drop separation test that evaluates the separation resistance from the expanded state.
However, a simple test method for evaluating the material separation resistance when freshly flowing high-fluidity concrete has not been established so far.
[0005]
For example, “Section 18: High-fluidity concrete” and “Section 19: High-strength concrete” in “The Architectural Institute of Japan, Building Construction Standard Specification / Description, JASS5, Reinforced Concrete Construction” (1997) Although there is a “material separation” item in the quality control test items, it is described as “not separated by visual inspection”, and a quantitative evaluation method has not been established. It is.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and the object of the present invention is not to require a large-scale test apparatus, and besides simple instruments used for normal slump flow tests and barrier slump flow tests, simple circles are used. A high-fluidity concrete that can be easily implemented in both the laboratory and the construction site by using a ring-shaped sample dividing member, and that enables quantitative characterization of the material separation resistance of concrete. An object of the present invention is to provide a test method for evaluating the material separation resistance when fresh.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a test method according to the present invention is a test method for evaluating material separation resistance when freshly flowing high-fluidity concrete, and a base plate and a slump cone for a slump flow test are prepared, Preparing a plurality of sample-splitting members in an annular shape having different diameters to divide the concrete sample of the slump flow into a plurality of regions by inserting into the concrete sample of the slump flow formed on the base plate, The slump cone is placed on the base plate and filled with the concrete sample, and the slump cone is lifted and removed to form a slump flow of the concrete sample on the base plate, A plurality of sample dividing members are positioned substantially concentrically with respect to the center of the slump flow on the base plate. The concrete sample of the slump flow is divided into a plurality of substantially concentric areas, and the concrete samples are collected from each of the plurality of areas. The slump is obtained by obtaining a coarse aggregate mass ratio or coarse aggregate particle size distribution for each of the plurality of collected samples, and comparing the obtained coarse aggregate mass ratio or coarse aggregate particle size distribution of the plurality of collected samples. It is characterized by evaluating the material separation resistance of the whole concrete sample filled in the cone .
In addition, the test method according to the present invention is a test method for evaluating material separation resistance when freshly flowing high-fluidity concrete, and a base plate and a slump cone for a slump flow test are prepared, and for a barrier slump flow test. A plurality of toroidal shapes having different diameters to divide the concrete sample of the slump flow into a plurality of regions by being inserted into the concrete sample of the slump flow formed on the base plate. A sample dividing member is prepared, the slump cone is placed on the base plate, the concrete sample is filled in the slump cone, and the barrier is provided on the base plate so as to surround the slump cone. Placing the slump cone on the base plate by removing the slump cone. A slump flow of the sample is formed, and a part of the concrete sample that forms the slump flow is allowed to flow through the barrier, and after the barrier is removed, the plurality of sample dividing members are mounted on the table. By inserting the slump flow concrete sample into the concrete sample of the slump flow so as to be in a substantially concentric positional relationship with respect to the center of the slump flow on the plate, a plurality of regions that are substantially concentric. A concrete sample is collected from each of the plurality of regions, a coarse aggregate mass ratio or a coarse aggregate particle size distribution is obtained for each of the plurality of collected samples, and the coarse samples of the obtained collected samples are obtained. by comparing the bone material weight ratio or coarse aggregate particle size distribution, commentary material separation resistance of the entire concrete sample filled in the slump cone Characterized in that it.
[0008]
According to the test method for evaluating the material separation resistance when freshly flowing high fluid concrete according to the present invention, a large-scale test apparatus is not required, and other than the equipment used for normal slump flow test and barrier slump flow test. Can be carried out easily in both the test room and the construction site by using a simple ring-shaped sample dividing member, and quantitative characteristic evaluation of material material separation resistance is possible. It is.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
1A to 1D are schematic views showing the work procedure of the test method according to the first embodiment of the present invention, and FIGS. 2A and 2B are steel rings inserted into a concrete sample of slump flow. FIG. 3A to FIG. 3D are schematic views illustrating the work procedure of the test method according to the second embodiment of the present invention.
[0010]
The test method for evaluating the material separation resistance when freshly flowing high-fluidity concrete according to the present invention is performed together with the concrete slump flow test defined in JIS A 1150 (2001). Such an embodiment is shown in FIGS. 1a to 1d.
In addition, the test method according to the present invention may be performed together with the barrier slump flow test method disclosed in Japanese Patent Application No. 08-059337. Are shown in FIG. However, the test method according to the present invention can be performed together with other concrete tests, and can be performed independently of other concrete tests.
[0011]
In the test method according to the embodiment shown in FIG. 1, first, for a general slump flow test, such as a base plate for a slump flow test, a slump cone, a cone funnel, and a slump flow measurement scale. Prepare the equipment.
Since the slump flow test is a test that is widely performed in many test rooms and construction sites, the test room and the construction site that handle concrete are usually equipped with these instruments. However, in order to carry out the present invention, not all of the above-exemplified instruments are necessary, and essential instruments are the base plate 10 and the slump cone 12 for the slump flow test shown in FIG.
The base plate 10 is prepared to have a size of 70 cm square or more, and preferably about 80 cm square.
The slump cone 12 is defined in JIS. Specifically, the slump cone 12 is formed as a frustoconical container having a height of 30 cm and an open top and bottom. The upper end has a diameter of 10 cm and the lower end has a diameter. Is 20 cm.
[0012]
Furthermore, in this test method, by inserting into the concrete sample of the slump flow formed on the base plate 10, an annular shape having different diameters for dividing the concrete sample of the slump flow into a plurality of regions. A plurality of sample dividing members 14 are prepared.
These sample dividing members 14 are conveniently formed, for example, as a steel ring by rolling a steel strip having a width of 50 mm into an annular shape and welding both ends.
Further, when the sample dividing member 14 is formed as such a steel ring, for example, as shown in FIG. 2 b, the diameter is set in increments of 100 mm within a range of 200 to 600 mm, that is, 200 mm, 300 mm. , 400 mm, 500 mm, and 600 mm, the combination of five steel rings 14 a to 14 e is convenient. However, the shape, size, and number of the sample dividing members 14 to be used are not limited to this, and other shapes, sizes, and numbers may be used.
[0013]
Furthermore, it is desirable to prepare a mixer, a kneading board, etc., so that the test work can be carried out quickly and easily, and the test work is started when the equipment and apparatus to be used are prepared. .
First, after a concrete sample is kneaded with a mixer, it is discharged onto a kneading plate and further sufficiently stirred.
When stirring is completed, measure the air volume of the concrete sample as necessary, and execute the slump flow test.
The slump flow test may be performed in accordance with what is defined in JIS A 1150 (2001). That is, the slump cone 12 is placed on the base plate 10, and the concrete sample is filled in the slump cone 12 (a in FIG. 1).
Then, after the top surface of the filled concrete sample is aligned with the upper end of the slump cone 12, the concrete sample flows out from the lower end of the slump cone 12 onto the base plate 10 by removing the slump cone 12. Thereby, a slump flow FL of the concrete sample is formed on the base plate 10 (b in FIG. 1).
After the flow of the concrete sample that has flowed out, measure the maximum possible diameter (passing dimension) and the diameter in the direction perpendicular to the slump flow FL formed from the concrete sample. Is the slump flow value.
[0014]
Even in the case of high fluidity concrete, when the fluidity of the concrete sample is relatively small, the diameter of the slump flow formed on the base plate 10 may be less than 50 cm.
In such a case, the slump flow on the base plate 10 is further expanded by applying vibration or repetitive impact to the base plate 10 by hitting the base plate 10 with a stick or a mallet. It is preferable to be within a range of 50 to 70 cm.
[0015]
In order to increase the slump flow on the base plate 10, the base plate 10 may be placed on an appropriate vibration machine in advance, and the vibration machine may be operated to increase the slump flow.
However, when expanding the slump flow, it is desirable that the concrete sample of the slump flow be spread in a circular shape as uniformly as possible in all directions. It is preferable to apply vibrations and repetitive impacts manually using a scissors or the like because fine adjustment to obtain uniformity is possible.
Above all, it is an advantage that a large-scale vibration machine is not required when performing manually using a stick or a mallet.
[0016]
Subsequently, the above-described plurality of steel rings (sample dividing members) 14 are arranged in a concentric position with respect to the center of the slump flow FL on the base plate 10 to form a concrete sample of the slump flow FL. By inserting, the concrete sample of the slump flow FL is divided into a plurality of substantially concentric regions (c in FIG. 1).
The state in which the steel rings 14 are so inserted is clearly shown in front and plan views in a and b of FIG. 2 (however, in FIG. 2, the reference numerals 14 a to 14 e are attached to the steel rings 14. ).
In particular, in the illustrated embodiment, when the steel rings 14 a to 14 e are inserted into the concrete sample of the slump flow FL, one (lower) side edge of the steel rings 14 a to 14 e is on the upper surface of the base plate 10. In this state, the other (upper) side edges of the steel rings 14a to 14e protrude sufficiently upward from the surface of the concrete sample. Thus, the concrete sample of the slump flow FL is completely divided into a plurality of regions by the steel rings 14a to 14e.
[0017]
Subsequently, a concrete sample is taken from each of a plurality of substantially concentric regions divided by the plurality of steel rings 14 (d in FIG. 1), and the concrete material is collected for each of the plurality of collected samples. Evaluate the separation resistance. When collecting a sample, if the sample is collected along the steel ring by using a hand scoop or the like sequentially from the outer peripheral side of the slump flow FL, the collecting operation can be performed well.
[0018]
Various methods can be adopted as an evaluation method for evaluating the material separation resistance of concrete for each of the collected samples.
A suitable example thereof is to determine the coarse aggregate mass ratio of the collected sample. In this case, for example, if a concrete sample is collected from each region divided by the plurality of steel rings 14, the mass of the collected sample is immediately measured, and then wet screening is performed using a 5 mm sieve. The material other than the coarse aggregate is washed away from the collected sample to extract the coarse aggregate, and the mass of the extracted coarse aggregate is measured.
Then, the coarse aggregate mass ratio may be obtained by dividing the coarse aggregate mass by the collected sample mass. In this way, the coarse aggregate mass ratio is obtained for each of the plurality of regions having the concentric positional relationship, and the obtained values are compared with each other.
As a result, if there is no significant difference in the coarse aggregate mass ratio between the plurality of regions, it can be determined that the concrete is excellent in workability with high material separation resistance.
[0019]
Another example of an evaluation method for evaluating the material separation resistance of concrete for each of the collected samples is to extract the coarse aggregate from the sample, dry the extracted coarse aggregate, and the dried coarse aggregate By performing sieving, the coarse aggregate particle size distribution of the collected sample is obtained.
In this case, for example, the coarse aggregate is extracted by performing wet screening using a 5 mm sieve, the extracted coarse aggregate is dried in a drying furnace set at about 105 ° C. for 24 hours, and then dried. The coarse aggregate may be screened using 25 mm, 20 mm, 15 mm, 10 mm, 5 mm, and 2.5 mm sieves to obtain the particle size distribution.
In this way, the coarse aggregate particle size distribution is obtained for each of a plurality of regions having a concentric positional relationship, and the obtained coarse aggregate particle size distributions are compared with each other.
As a result, if there is no significant difference in the coarse aggregate particle size distribution among the plurality of regions, it can be determined that the concrete is excellent in workability with high material separation resistance.
[0020]
Furthermore, by collecting a portion of the concrete sample to be tested from now, extracting the coarse aggregate from it, drying the extracted coarse aggregate, and screening the dried coarse aggregate, The coarse aggregate particle size distribution of the concrete sample may be obtained in advance.
Then, the coarse aggregate particle size distribution of each of the collected samples collected from the plurality of regions is compared with the coarse aggregate particle size distribution of the concrete sample obtained in advance.
As a result, if the difference between the coarse aggregate particle size distributions is within a predetermined range, it can be determined that the concrete is excellent in workability with high material separation resistance.
[0021]
Next, the test method of the embodiment shown in FIG. 3 will be described.
In this test method, a base plate 10 and a slump cone 12 for a slump flow test are prepared, and a barrier 16 for a barrier slump flow test is prepared. The barrier 16 in the illustrated example has a plurality of rods prepared by cutting a steel strip having a width of 30 mm and a thickness of 3 mm into a ring shape 20 having an inner diameter of 300 mm and a round steel having a diameter of 10 mm cut to a length of 130 mm. It is formed by welding materials at regular intervals.
When the barrier 16 is placed on the base plate 10, the slump cone is positioned at the center of the barrier 16, and the barrier 16 is placed with the band ring on the top.
The plurality of bars of the barrier 16 provide mechanical resistance to the concrete sample when the concrete sample flows between the bars. Note that the test method of FIG. 3 can be carried out using barriers having other shapes and dimensions. For example, various barriers disclosed in Japanese Patent Application No. 2001-299078 can be used. it can.
[0022]
In the test method of the embodiment of FIG. 3, in addition to the above, the same instruments and devices as those used in the test method of the embodiment of FIG. 1 are used.
Therefore, also in the test method of FIG. 3, a plurality of sample dividing members 14 (14a to 14e) as shown in FIGS. 1 and 2 are prepared. It is also desirable to prepare a mixer, a kneading board, and the like. Regarding the test work procedure, the test method of FIG. 3 and the test method of FIG. 1 are the same in many parts, and therefore only the differences between them will be described in detail in the following description.
[0023]
In the test method of FIG. 3, the same operation procedure as that of the test method of FIG. 1 may be performed until the slump cone 12 is placed on the base plate 10 and the concrete sample is filled in the slump cone 12. .
However, in the test method of FIG. 3, the barrier 16 is further placed on the base plate 10 so as to surround the periphery of the slump cone 12 (a in FIG. 3), and at this time, the slump cone 12 is centered on the barrier 16. To be located. Moreover, normally, the stabilizing protrusions provided in the vicinity of the lower end of the slump cone 12 so as to project to the left and right may interfere with the barrier 16 and are preferably removed.
[0024]
Subsequently, the slump cone 12 is pulled up and removed, thereby forming a slump flow FL of the concrete sample on the base plate 10. At this time, a part of the concrete sample forming the slump flow FL forms the barrier 16. Let it flow through (b in FIG. 3).
After the flow of the concrete sample that has flowed out, measure the maximum possible diameter (passing dimension) and the diameter in the direction perpendicular to the slump flow FL formed from the concrete sample. Is the barrier slump flow value.
As already described in connection with the description of the test method in FIG. 1, even if the fluidity of the concrete sample is relatively small, the slump flow formed on the base plate 10 is high. The diameter may be less than 50 cm. In such a case, the slump flow on the base plate 10 is further expanded by applying vibration or repeated impact to the base plate 10, and the diameter is in the range of 50 to 70 cm. It is better to be inside.
[0025]
Subsequently, after the barrier 16 is removed from the base plate 10 (however, the removal of the barrier 16 may be performed before measuring the diameter of the slump flow FL), the plurality of steel rings 14 are attached to the base plate 10. By inserting the concrete sample of the slump flow FL into the concrete sample of the slump flow FL so as to be in a substantially concentric positional relationship with the center of the upper slump flow FL, a plurality of regions which are substantially concentric (C in FIG. 3). The work of inserting the steel ring 14 may be performed in the same manner as the test method of FIG.
[0026]
Subsequently, a concrete sample is taken from each of a plurality of substantially concentric regions divided by the plurality of steel rings 14 (d in FIG. 3), and the concrete material is collected for each of the plurality of collected samples. Evaluate the separation resistance. These sample collection operations and evaluation operations of the material separation resistance of the sample sample concrete can be performed in the same manner as the test method of FIG.
[0027]
【Example】
FIGS. 4a and 4b are graphs showing the coarse aggregate mass ratio for each region, obtained by conducting the test by the test method according to the present invention for four types of concrete samples. 2 represents the test result by the test method (slump flow test), and b represents the test result by the test method (barrier slump flow test) in FIG. G060, G080, G100, and G120 in the graph are formulation numbers.
In either test method, the coarse aggregate mass ratio of the sample collected from the region exceeding the diameter of 600 mm at the outermost peripheral part of the slump flow is 10 to 20% higher than the coarse aggregate mass ratio of the sample collected from the region inside. The degree is decreasing. Except for this, in the test method (slump flow test) in FIG. 1, the coarse aggregate mass ratio in any region is almost the same value and the variation is small, and it is judged that any concrete sample has good workability. Is done.
In the test method (barrier slump flow test) in FIG. 3, the coarse aggregate mass ratio of the sample taken from the region between the steel ring with a diameter of 200 mm and the steel ring with a diameter of 300 mm shows a particularly high value. Indicates that the coarse aggregate of the concrete sample that flowed out of the slump cone was somewhat retained in this region due to resistance by the barrier 16. Even if the barrier 16 is present, if the variation in the coarse aggregate mass ratio falls within this level, it is determined that the barrier 16 has good workability.
[0028]
【The invention's effect】
As is clear from the above description, according to the test method of the present invention, a large-scale test apparatus is not required, and a simple annular ring can be used in addition to the equipment used for the normal slump flow test and barrier slump flow test. Fresh fluidized high-fluidity concrete that can be easily implemented both in the laboratory and on the construction site, using a sample-cutting member in the shape, and capable of quantitative characterization of the material's material separation resistance Tests to evaluate material separation resistance over time are possible.
[Brief description of the drawings]
FIGS. 1A to 1D are schematic views showing work procedures of a test method according to a first embodiment of the present invention.
FIGS. 2a and 2b are a front view and a plan view showing a steel ring inserted into a concrete sample of slump flow.
FIGS. 3A to 3D are schematic views showing work procedures of a test method according to a second embodiment of the present invention. FIGS.
FIGS. 4A and 4B are graphs showing test results obtained by the test method according to the present invention.
[Explanation of symbols]
10 Base plate 12 Slump cone 14 Steel ring (sample dividing member)
16 Barrier FL Slump Flow

Claims (6)

In the test method for evaluating material separation resistance when freshly flowing high fluid concrete,
Prepare a base plate and slump cone for slump flow test,
Prepare a plurality of annularly-shaped sample dividing members having different diameters for dividing the slump flow concrete sample into a plurality of regions by inserting the slump flow concrete sample formed on the base plate. ,
Placing the slump cone on the base plate and filling the slump cone with a concrete sample,
By lifting and removing the slump cone, a slump flow of the concrete sample is formed on the base plate,
By inserting the plurality of sample dividing members into the concrete sample of the slump flow so as to be in a substantially concentric positional relationship with respect to the center of the slump flow on the base plate, the concrete sample of the slump flow Is divided into multiple areas that are roughly concentric,
A concrete sample is collected from each of the plurality of regions, a coarse aggregate mass ratio or a coarse aggregate particle size distribution is obtained for each of the multiple collected samples, and the obtained coarse aggregate mass ratio of the plurality of collected samples. Or, by comparing the coarse aggregate particle size distribution, the material separation resistance of the whole concrete sample filled in the slump cone is evaluated,
A test method characterized by the above. In the test method for evaluating material separation resistance when freshly flowing high fluid concrete,
While preparing the base plate and slump cone for the slump flow test, prepare the barrier for the barrier slump flow test,
Prepare a plurality of annularly-shaped sample dividing members having different diameters for dividing the slump flow concrete sample into a plurality of regions by inserting the slump flow concrete sample formed on the base plate. ,
The slump cone is placed on the base plate and filled with the concrete sample, and the barrier is placed on the base plate so as to surround the slump cone.
By lifting and removing the slump cone, a slump flow of the concrete sample is formed on the base plate, and at this time, a part of the concrete sample forming the slump flow flows through the barrier. West,
After removing the barrier, the plurality of sample dividing members are inserted into the concrete sample of the slump flow so as to be substantially concentric with the center of the slump flow on the base plate. , Dividing the concrete sample of the slump flow into a plurality of substantially concentric areas,
A concrete sample is collected from each of the plurality of regions, a coarse aggregate mass ratio or a coarse aggregate particle size distribution is obtained for each of the multiple collected samples, and the obtained coarse aggregate mass ratio of the plurality of collected samples. Or, by comparing the coarse aggregate particle size distribution, the material separation resistance of the whole concrete sample filled in the slump cone is evaluated,
A test method characterized by the above.   The test method according to claim 1 or 2, wherein the sample dividing member is a steel ring formed by rolling a steel strip.   The test method according to claim 1, wherein a diameter of the sample dividing member is 200 to 600 mm. Determined each for coarse aggregate particle size distribution of the plurality of sample taken, whereby a plurality of each pressurizing et coarse aggregate sample taken was extracted, the extracted coarse aggregate dried, coarse aggregate was dried any one method of testing according to claim 1 to 4, characterized in that to perform the screening of wood. By extracting the coarse aggregate from the concrete sample to be tested, drying the extracted coarse aggregate, and screening the dried coarse aggregate, the coarse aggregate particle size distribution of the concrete sample is obtained in advance. Every
6. The test method according to claim 5, wherein the coarse aggregate particle size distribution obtained for each of the plurality of sampling samples is compared with the coarse aggregate particle size distribution of a concrete sample obtained in advance.

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