JP7457188B2 - Separation resistance evaluation container - Google Patents

Description

The present invention relates to a container for evaluating separation resistance.

The mix of concrete is designed so that it not only exhibits the necessary strength after hardening, but also ensures the necessary workability during construction. The workability of fresh concrete is evaluated by a slump test to evaluate the consistency of concrete.
However, even if concrete has the same slump value, there may be differences in material separation resistance. The material separation resistance of concrete has a significant impact on concrete compaction, pumping, etc. On the other hand, there is no method to quantitatively evaluate the material separation resistance of concrete, and at present, it is common to judge whether separation has occurred by visually checking the degree of sinking of concrete aggregates.
Patent Document 1 discloses a test method that utilizes a concrete sample after a slump flow test as a test method for evaluating the material separation resistance of concrete. In this test method, a concrete sample is divided into multiple areas in the radial direction by placing multiple steel rings with different diameters in a concentric position on the base plate after the slump flow test, and each Material separation resistance is evaluated by measuring the coarse aggregate mass ratio in the area.
However, in the test method of Patent Document 1, it is necessary to calculate the coarse aggregate mass ratio for each region, which is time-consuming. That is, it is necessary to measure the mass of the sample collected for each region and the mass of coarse aggregate contained in the sample, and use the measurement results to calculate the coarse aggregate mass ratio.

Japanese Patent Application Publication No. 2003-322602

An object of the present invention is to propose a separation resistance evaluation container that makes it possible to easily evaluate the separation resistance of fresh concrete.

A separation resistance evaluation container of the present invention for solving the above problems includes a bottom plate, a plurality of cylinders stacked vertically on the upper surface of the bottom plate, and a receiving material provided around the outer surface of the cylinders. The cylindrical body includes an engagement member that protrudes from the upper end or the lower end of the cylindrical body and is inserted into another adjacent cylindrical body. It is preferable that the engagement member is a cylindrical member having an outer diameter equivalent to an inner diameter of the cylindrical body.
According to such a separation resistance evaluation container, since the plurality of cylinders can be separated, a certain amount of fresh concrete can be collected by removing the uppermost cylinder. Since the cylindrical bodies are engaged with each other via the engaging member, fresh concrete is prevented from flowing out from between the cylindrical bodies.

Furthermore, since a receiving material is further provided around the outer surface of the cylindrical body, the fresh concrete that overflows when the uppermost cylindrical body is removed remains on the receiving material, making it easy to collect fresh concrete. It is. This receiving material includes a bottom portion that is annular in plan view, and an inner wall portion and an outer wall portion that are erected on the upper surface of the bottom portion, and the volume of the space surrounded by the bottom portion, the inner wall portion, and the outer wall portion is: It is desirable to use one whose volume is larger than the inner volume of one of the cylindrical bodies.

According to the separation resistance evaluation container of the present invention, it becomes possible to easily evaluate the separation resistance of fresh concrete.

FIG. 2 is a front view of the separation resistance evaluation container according to the present embodiment. FIG. (a) is a plan view of the cylindrical body, and (b) is a sectional view of the cylindrical body. (a) is a plan view of the receiving material, and (b) is a sectional view of the receiving material. It is a flowchart which shows the procedure of a concrete evaluation method. (a) and (b) are graphs showing the results of experiments conducted on concrete evaluation methods. It is a graph for explaining a method of setting compaction time using a separation resistance evaluation container.

In this embodiment, a concrete evaluation method for evaluating separation resistance of concrete will be described. FIG. 1 shows a separation resistance evaluation container 1 used in the concrete evaluation method of this embodiment. As shown in FIG. 1, the separation resistance evaluation container 1 includes a bottom plate 2, a plurality of cylindrical bodies 3, and a receiving material 4.
The bottom plate 2 has a square shape with one side of 360 mm and is made of a steel plate with a thickness of 5 mm. Note that the bottom plate 2 is not limited as long as it has a larger shape than the outer shape of the cylindrical body 3; for example, it may have a rectangular shape (square shape), such as a circle with a larger diameter than the outer shape of the cylindrical body 3. It doesn't have to be. Further, the bottom plate 2 is not limited to a steel plate, and may be, for example, a synthetic resin plate or a glass plate.

The plurality of cylindrical bodies 3 are stacked vertically on the upper surface of the bottom plate 2. In this embodiment, seven cylindrical bodies 3 (cylindrical bodies 31 to 37) are stacked on the bottom plate 2. The cylindrical body 3 of this embodiment is made of a vinyl chloride pipe with an inner diameter of 250 mm, an outer diameter of 267 mm, and a height of 50 mm. Note that the material constituting the cylindrical body 3 is not limited. Further, the shape and dimensions of the cylindrical body 3 are not limited, and the inner diameter may be set to 200 mm or 300 mm, for example.
Engagement members 5 are attached to the cylinders 3 other than the bottom cylinder 31 (the second to seventh cylinders 32 to 37 from the bottom). The engagement member 5 protrudes from the lower end of the cylindrical body 3 and is inserted into the cylindrical body 3 directly below. The engagement member 5 is a cylindrical member having an outer diameter equivalent to the inner diameter of the cylindrical body 3 . By inserting the engaging member 5 of the cylinder 3 into the cylinder 3 immediately below, the upper and lower cylinders 3 engage with each other. The length of the engagement member 5 protruding from the lower end of the cylindrical body 3 is not limited, and may be appropriately determined to a size that allows engagement with the lower cylindrical body 3. Note that the configuration of the engaging member 5 is not limited, and for example, a plurality of plate-shaped engaging members 5 may be arranged at intervals in the circumferential direction of the cylindrical body 3, It may cover the outer periphery of the butt portion of the upper and lower cylinders 3.

The receiving material 4 is provided around the outer surface of the cylindrical body 3. The receiving member 4 is made of plastic resin and includes a bottom portion 41 that is annular in plan view, and an inner wall portion 42 and an outer wall portion 43 that are erected on the upper surface of the bottom portion 41 . An opening 44 having an opening diameter equivalent to the outer diameter of the cylindrical body 3 (268 mm in this embodiment) is formed in the center of the bottom portion 41 . The inner wall portion 42 is erected along the inner edge of the bottom portion 41 (the edge of the opening 44). Further, the outer wall portion 43 is erected along the outer edge of the bottom portion 41 . The height of the inner wall portion 42 and the outer wall portion 43 is 50 mm. Although the shape and dimensions of the receiving member 4 are not limited, in this embodiment, the volume of the space surrounded by the bottom 41, the inner wall 42, and the outer wall 43 is equal to the inner space of one cylinder 3. It is larger than the volume. The receiving material 4 of this embodiment is attached to the outer surface of the cylinder 3 (cylindrical body 36) in the second stage from the top. Note that a jig may be used when attaching the receiving material 4 to the outer surface of the cylindrical body 3.

Next, a concrete evaluation method using the separation resistance evaluation container 1 will be explained. As shown in FIG. 5, the concrete evaluation method includes a container preparation step S1, a filling step S2, a compaction step S3, a concrete sampling step S4, an aggregate amount measurement step S5, and an evaluation step S6.
The container preparation step S1 is a step of preparing a container 1 for evaluation of separation resistance. The separation resistance evaluation container 1 is formed by vertically arranging a plurality of cylindrical bodies 3, . . . on the bottom plate 2 (see FIG. 1). At this time, the receiving material 4 is attached to the outer periphery of the second cylindrical body 35 from the top. In this embodiment, four separation resistance evaluation containers 1 are prepared. Note that the number of separation resistance evaluation containers 1 assembled in the container preparation step S1 is not limited.

The filling step S2 is a step of filling fresh concrete into the separation resistance evaluation container 1. Fresh concrete is poured into the separation resistance evaluation container 1 from above. The upper surface of the fresh concrete is made to coincide with the upper end surface of the separation resistance evaluation container 1. The mix of concrete will be determined as appropriate.

The compaction step S3 is a step of compacting the fresh concrete filled in the separation resistance evaluation container 1. In the compaction step S3, the compaction time is varied for each container. In this embodiment, the vibration times applied to the four separation resistance evaluation containers 1 are 5 seconds, 10 seconds, and 20 seconds, respectively. Compaction of the fresh concrete is performed using an internal vibrator inserted into the separation resistance evaluation container 1. In addition, compaction of fresh concrete may be performed by applying vibration from the outer surface of the separation resistance evaluation container 1 or by shaking the separation resistance evaluation container 1. Moreover, the vibration time of the container is not limited to the above-mentioned one, and may be determined as appropriate.

The concrete collection step S4 is a step of collecting fresh concrete from the upper part of the separation resistance evaluation container 1. Fresh concrete is collected by removing the uppermost cylinder 3 (cylindrical body 37). The uppermost cylindrical body 37 is removed by pulling it upward. When the uppermost cylindrical body 37 is removed, fresh concrete corresponding to the volume (certain amount) of the cylindrical body 37 overflows. Since the overflowing fresh concrete flows into the receiving material 4 attached to the outer periphery of the cylinder 36 in the second stage from the top, the fresh concrete that has flowed into the receiving material 4 is collected. Note that fresh concrete is collected immediately after compaction and in a fluid state before hardening.

The aggregate amount measurement process S5 is a process for measuring the mass of the coarse aggregate in the collected fresh concrete. First, coarse aggregate is collected from the collected fresh concrete, and the cement paste adhering to the coarse aggregate is washed off. The coarse aggregate can be collected by sieving the fresh concrete collected from the receiving material 4 and rinsing it with water on the sieve. Next, the mass of the collected coarse aggregate is measured. The coarse aggregate may be washed using a container separate from the sieve.

Evaluation step S6 is a step of evaluating the material separation resistance of fresh concrete based on the mass of coarse aggregate. In evaluating the material separation resistance, first, the mass of the coarse aggregate is divided by the volume of the cylinder 3 to calculate the unit coarse aggregate amount. Then, by comparing the calculated unit coarse aggregate amount (measurement unit coarse aggregate amount) with the unit coarse aggregate amount during mixing (mixing unit coarse aggregate amount), the tendency of material separation in concrete is determined. do.
In this embodiment, the material separation resistance of fresh concrete is evaluated based on the relationship between the mass of coarse aggregate and compaction time. In the evaluation step S6 of this embodiment, if the ratio of the measurement unit coarse aggregate amount to the mixing unit coarse aggregate amount is equal to or higher than a threshold value (for example, 95%), it is determined that separation is not achieved. Note that the size of the threshold value may be determined as appropriate. Further, the method for determining the tendency of material separation is not limited. For example, the tendency of material separation may be determined by the following method. First, the relationship between the unit amount of coarse aggregate calculated from the mass of coarse aggregate and compaction time is plotted (see FIG. 6). Next, an approximate curve is created from the plot, for example, by the least squares method. Read the unit coarse aggregate amount when the compaction time is zero from the approximate curve. If the ratio of the unit coarse aggregate amount when the compaction time to the unit coarse aggregate amount at the time of mixing design is zero is equal to or higher than a threshold value (for example, 95%), it is determined that the separation is not performed.

Next, the results of an experiment conducted regarding the concrete evaluation method of this embodiment will be explained.
First, two types of concrete samples (sample A, sample E) with different compositions were respectively put into separation resistance evaluation container 1 and compacted for 0 seconds, 5 seconds, 10 seconds, and 20 seconds. Coarse aggregate was collected at each depth. Next, the mass of the coarse aggregate collected for each cylinder 3 was measured, and the unit coarse aggregate amount for each cylinder 3 was calculated. Then, the ratio of the calculated unit coarse aggregate amount to the unit coarse aggregate amount at the time of blending was calculated. Table 1 and Figure 6(a) show the proportions of the amount of coarse aggregate for each cylinder 3 of sample A, and Table 2 and Figure 6(b) show the proportions of the amount of coarse aggregate for each cylinder 3 of sample E. show.

As shown in Table 1 and Figure 6(a), in sample A, when the compaction time is 0 seconds, 5 seconds, and 10 seconds, the unit coarse aggregate amount at a height of 350 mm (the top cylinder 37) is It was around 80%, and in other height ranges it was around 90% to 110%. In addition, when the compaction time is 20 seconds, the amount of coarse aggregate in a unit with a height of 350 mm is significantly reduced by 41%, and the amount of coarse aggregate in a unit with a height of 100 mm (cylindrical body 32 in the second stage from the bottom) is significantly reduced by 41%. Although the material amount increased to about 130%, the other heights were within the range of about 90% to 120%.
As shown in Table 2 and Figure 6(b), in sample E, the unit coarse aggregate amount decreased significantly at a height of 350 mm (the top cylinder 37), and at a height of 300 mm (the second cylinder from the top). Although the cylindrical body 36) in the third step also showed 100% or less, at other heights, the linear shape was close to horizontal and the result was that it was almost evenly distributed.
Therefore, in both samples A and E, the decrease in the amount of coarse aggregate in the uppermost cylindrical body 37 is remarkable, and if the amount of coarse aggregate in the uppermost cylindrical body 37 is measured, material separation can be confirmed. It was confirmed that it can be evaluated.
In addition, in sample E, even at a position with a height of 300 mm, a difference in the progress of material separation appears depending on the compaction time. Therefore, if the separation resistance evaluation container 1 made of a plurality of stacked cylinders 3 is used, the position of material separation can be evaluated by measuring the amount of coarse aggregate for each cylinder 3.

As described above, according to the concrete evaluation method of the present embodiment, a certain amount of fresh concrete can be collected from the upper part of the container by simply removing the cylinder 3 (cylinder 36) at the upper part of the container. In addition, by measuring the mass of coarse aggregate in the fresh concrete sampled, it is possible to check the degree of settling of the aggregate, and as a result, it is possible to easily evaluate the material separation resistance of fresh concrete. Become.
Moreover, since the cylinders 3 are engaged with each other via the engagement member 5, the cylinders 3 do not shift when fresh concrete is poured in, and fresh concrete does not flow out.
Further, since fresh concrete that overflowed when the uppermost cylinder 3 was removed is received by the receiving material 4, it is easy to collect fresh concrete.

Moreover, the separation resistance evaluation container 1 of this embodiment can also be used for setting a standard compaction time for concrete. For example, after concrete having a predetermined mix is put into the separation resistance evaluation container 1 and compacted, coarse aggregate is collected from the uppermost cylindrical body 37, and the unit coarse aggregate amount is calculated. Next, the relationship between the ratio of the measured coarse aggregate amount to the mixed coarse aggregate amount and the compaction time is plotted, and an approximate curve is created from this plot. Then, depending on the concrete structure, it is possible to set a tolerance for the remaining amount of coarse aggregate, and set a rough estimate of the compaction time from the intersection of this tolerance for the remaining coarse aggregate and the approximate curve. . Table 3 and FIG. 7 show the results of experiments conducted on six types of concrete samples (samples A to F) with different formulations. In this experiment, samples A to F were put into the separation resistance evaluation container 1 and compacted for 0 seconds, 5 seconds, 10 seconds, and 20 seconds, and then coarse aggregate was collected from the cylinder 37 at the top. , the unit coarse aggregate amount (measurement unit coarse aggregate amount) was calculated. Next, calculate the ratio of the measurement unit coarse aggregate amount to the mixing unit coarse aggregate amount, plot the relationship between the measurement unit coarse aggregate amount to the mixing unit coarse aggregate amount and compaction time, and An approximate curve was created from the plot. By using this graph, you can set a guideline for concrete compaction time depending on the structure. For example, when the threshold for the remaining amount of coarse aggregate is set to 80%, the approximate compaction time for each sample is about 4 to 5 seconds for samples A, C, and D, and about 2 to 3 seconds for sample B. Sample E may be heated for about 1 second, and sample F may be heated for about 7 seconds.

Although the embodiments according to the present invention have been described above, the present invention is not limited to the above-described embodiments, and each of the above-mentioned components can be modified as appropriate without departing from the spirit of the present invention.
For example, in the embodiment described above, the case where the separation resistance evaluation container 1 is formed by stacking six cylinders 3 is explained, but the number of cylinders 3 constituting the separation resistance evaluation container 1 is limited. It is not something that will be done. For example, it may be configured with two cylinders 3, an upper cylinder and a lower cylinder. At this time, it is desirable that the lower cylinder has a greater height than the upper cylinder.
Furthermore, in the embodiment described above, the case where the sedimentation status of coarse aggregate is estimated by measuring the amount of coarse aggregate in the upper part of fresh concrete has been described, but the amount of coarse aggregate at each depth may also be measured. . In this case, the cylindrical bodies 3 of the separation resistance evaluation container 1 are removed in order from the top, and the amount of coarse aggregate in the concrete sampled each time the cylindrical bodies 3 are removed is measured.
Further, the receiving material 4 may be installed as necessary.
In the embodiment described above, a case has been described in which the engagement member 5 is attached to the lower end of the cylinder 3. However, the engagement member 5 is inserted into another cylinder 3 directly above the cylinder 3 by protruding from the upper end of the cylinder 3. It may be something that Note that the engaging member 5 may be a part integrally formed with the cylindrical body 3. Further, the engaging member 5 may be provided as necessary, or may be omitted.
In the embodiment described above, a case has been described in which a part of the concrete is sampled after compaction, but the compaction step S3 may be omitted.
In the embodiment described above, the relationship between the unit coarse aggregate amount and compaction time is plotted and an approximate curve is created from this plot. However, it is not necessary to plot the relationship between the unit coarse aggregate amount and compaction time. The formula of the approximate curve may be calculated from the relationship with time. Using this formula, it is possible to calculate the unit coarse aggregate amount when the compaction time is zero.

1 Separation resistance evaluation container 2 Bottom plate 3 Cylindrical body 4 Receiving material 5 Engaging member S1 Container preparation process S2 Filling process S3 Compaction process S4 Concrete sampling process S5 Aggregate amount measurement process S6 Evaluation process

Claims (3)

The bottom plate and
a plurality of cylinders stacked vertically on the top surface of the bottom plate;
A receiving material provided around the outer surface of the cylindrical body ,
The container for evaluating separation resistance, wherein the cylindrical body includes an engagement member that protrudes from the upper end or the lower end of the cylindrical body and is inserted into another adjacent cylindrical body. 2. The separation resistance evaluation container according to claim 1, wherein the engaging member is a cylindrical member having an outer diameter equivalent to an inner diameter of the cylindrical body. The receiving material includes a bottom portion that is annular in plan view, and an inner wall portion and an outer wall portion that are erected on the upper surface of the bottom portion,
According to claim 1 or 2 , the volume of the space surrounded by the bottom, the inner wall, and the outer wall is larger than the volume of the inner space of one of the cylindrical bodies. Container for evaluating separation resistance.

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