JP7241647B2 - Concrete test method - Google Patents

Description

The present invention relates to a method for testing concrete.

A slump test is known as a method for evaluating the workability of concrete. For example, Patent Literature 1 describes an example of a method for evaluating the workability of concrete. In the test method of Patent Literature 1, a barrier device having a cage-like wall made up of a plurality of bars is used. Concrete samples have been made to flow by applying vibrations or repeated impacts to the bedplate.

JP-A-2003-106973

By the way, there is a need to predict the workability of concrete with higher accuracy.

The present disclosure has been made in view of the above problems, and an object thereof is to provide a concrete testing method capable of predicting the workability of concrete with high accuracy.

In order to achieve the above object, a method for testing concrete according to one aspect of the present disclosure includes an installation step of installing a barrier device having a plurality of pillars arranged in an annular shape and a slump cone on a flat plate; a filling step of filling a concrete sample; after the filling step, a removing step of pulling up the slump cone; a vibrating step of vibrating a sample; and a calculating step of calculating an index relating to ease of flow when the concrete sample passes through the gaps of the plurality of columns by the vibrating step.

As a desirable aspect of the concrete test method, the index is the gap passage speed.

As a preferred aspect of the concrete testing method, in the calculating step, the gap passing velocity is calculated based on the excitation ring flow, which is the diameter of the concrete sample after being deformed by the vibrating step.

As a desirable aspect of the concrete testing method, in the vibrating step, the concrete sample is vibrated for 7 seconds or longer.

As a desirable aspect of the concrete testing method, in the vibrating step, the distance from the tip of the internal vibrator to the flat plate is equal to or greater than the maximum length of the coarse aggregate of the concrete.

According to the concrete test method of the present disclosure, the workability of concrete can be predicted with higher accuracy.

FIG. 1 is a flow chart showing the method for testing concrete according to the present embodiment. FIG. 2 is a plan view of the barrier device of this embodiment. FIG. 3 is a front view of the barrier device of this embodiment. FIG. 4 is a schematic diagram showing the installation steps. FIG. 5 is a schematic diagram showing the filling step. FIG. 6 is a schematic diagram showing the removal step. FIG. 7 is a schematic diagram showing a vibration step. FIG. 8 is a schematic diagram showing a vibration step. FIG. 9 is a diagram showing test conditions for the first experiment. FIG. 10 is a graph showing the results of the first experiment. FIG. 11 is a diagram showing the composition and the like of concrete samples used in the second experiment. FIG. 12 is a schematic diagram of a box-shaped container for measuring the gap passage speed of a concrete sample. FIG. 13 is a graph showing the relationship between the excitation ring flow and the coarse aggregate ratio outside the barrier device in the second experiment. FIG. 14 is a graph showing the relationship between the excitation flow and the excitation ring flow in the second experiment. FIG. 15 is a graph showing the relationship between the excitation ring flow and the excitation blocking value in the second experiment. FIG. 16 is a graph showing the relationship between the excitation PJ value (column) and the excitation PJ value (between columns) in the second experiment. FIG. 17 is a graph showing the relationship between the vibration ring flow and the vibration PJ value in the second experiment. FIG. 18 is a graph showing the relationship between the excitation ring flow in the second experiment and the maximum difference in the excitation PJ value (column) depending on the measurement position. FIG. 19 is a graph showing the relationship between slump and gap passage speed in the second experiment. FIG. 20 is a graph showing the relationship between the excitation PJ value and the gap passage speed in the second experiment. FIG. 21 is a graph showing the relationship between the vibration blocking value and the gap passage speed in the second experiment. FIG. 22 is a graph showing the relationship between the vibration ring flow value and the gap passage speed in the second experiment. FIG. 23 is a diagram showing an output table of regression analysis. FIG. 24 is a graph showing the relationship between the measured values and predicted values of the gap passage speed. FIG. 25 is a diagram showing the mix of verification concrete. FIG. 26 is a diagram showing the details of the verification concrete material.

Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the form (henceforth embodiment) for implementing this invention. In addition, components in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those that fall within a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be combined as appropriate.

(embodiment)
FIG. 1 is a flow chart showing the method for testing concrete according to the present embodiment. FIG. 2 is a plan view of the barrier device of this embodiment. FIG. 3 is a front view of the barrier device of this embodiment. FIG. 4 is a schematic diagram showing the installation steps. FIG. 5 is a schematic diagram showing the filling step. FIG. 6 is a schematic diagram showing the removal step. 7 and 8 are schematic diagrams showing vibration steps.

The concrete testing method of this embodiment is a method for evaluating the workability of concrete that requires vibration compaction. As shown in FIG. 1, the concrete testing method of the present embodiment includes a placement step S11, a filling step S13, a removal step S15, a vibration step S17, and a calculation step S19.

The barrier device 20 shown in FIGS. 2 and 3 is used in the concrete testing method of the present embodiment. The barrier device 20 is a device also called a J-ring. The barrier device 20 comprises a top plate 21 and a plurality of pillars 23 . The upper plate 21 is an annular plate. The outer diameter of the upper plate 21 is 330 mm. The pillar 23 is a cylindrical member. The diameter of the pillar 23 is 16 mm. A plurality of pillars 23 are fixed to one end surface of the upper plate 21 . Sixteen pillars 23 are fixed to the upper plate 21 . The 16 pillars 23 are arranged at regular intervals along the circumferential direction of the upper plate 21 . The 16 pillars 23 are arranged in a ring. The distance between adjacent posts 23 is 42.5 mm. The length by which the column 23 protrudes from the upper plate 21 is 100 mm. The distance between the center of one pillar 23 and the center of the farthest pillar 23 from that pillar 23 is 300 mm. That is, the centers of the 16 pillars 23 in plan view overlap a circle with a diameter of 300 mm.

As shown in FIG. 4, the barrier device 20 and the slump cone 30 are installed on the flat plate 10 in the installation step S11. The slump cone 30 is arranged inside the barrier device 20 . The slump cone 30 is a truncated cone-shaped hollow member. The lower end and upper end of the slump cone 30 are open. The height of the slump cone 30 is 300 mm. The outer diameter of the lower end of the slump cone 30 is 200 mm. The outer diameter of the upper end of the slump cone 30 is 100 mm. The maximum outer diameter of the slump cone 30 is smaller than the inner diameter of the upper plate 21 of the barrier device 20 . A gap exists between the barrier device 20 and the slump cone 30 when placed on the flat plate 10 .

As shown in FIG. 5, the slump cone 30 is filled with the concrete sample 41 in the filling step S13. A concrete sample 41 is placed inside the slump cone 30 through an opening at the upper end of the slump cone 30 . The concrete sample 41 is filled until the slump cone 30 is filled with the concrete sample 41 .

As shown in FIG. 6, the slump cone 30 is pulled up in the removal step S15. When the slump cone 30 is pulled up, a concrete sample 41 remains on the flat plate 10. - 特許庁The concrete sample 41 left on the flat plate 10 is deformed. The value of the difference between the height of the slump cone 30 and the height of the concrete sample 41 after deformation is the slump.

As shown in FIG. 7, in the vibrating step S17, a rod-shaped internal vibrator 51 is inserted into the concrete sample 41 left on the flat plate 10, and the concrete sample 41 is vibrated. The internal vibrator 51 is inserted in the center of the concrete sample 41 in plan view. The internal vibrator 51 is supported by a jig 53 . The supports of the jig 53 are arranged outside the flat plate 10 and come into contact with the ground.

As shown in FIG. 8, when the concrete sample 41 is vibrated by the internal vibrator 51, the concrete sample 41 deforms more. A portion of the concrete sample 41 passes through the gaps between adjacent columns 23 of the barrier device 20 and out of the barrier device 20 .

In the calculation step S19, the gap passage speed is calculated. The gap passage speed is an index for evaluating the workability of concrete. The gap passage speed is an index (value) relating to the ease of flow when the concrete sample 41 passes through the gaps of the multiple columns 23 . In the calculation step S19, the gap passage speed is calculated based on, for example, the vibration ring flow. The vibration ring flow is the diameter of the concrete sample 41 after being deformed by the vibration step S17. The excitation ring flow is measured outside the pillars 23 of the barrier device 20 . For example, the vibration ring flow is measured at four locations. The four measurement positions are arranged at regular intervals in the circumferential direction of the barrier device 20 . The excitation ring flow is calculated as the average value of the measured values at the four measurement positions.

A first experiment and a second experiment were conducted with respect to the concrete testing method of the present embodiment. FIG. 9 is a diagram showing test conditions for the first experiment. FIG. 10 is a graph showing the results of the first experiment.

In the first experiment, the slump flow after vibration deformation was measured under the conditions shown in FIG. The slump flow after vibration deformation is the diameter of the concrete sample left on the flat plate 10 after the slump cone 30 is removed and the internal vibrator 51 vibrates the concrete sample. In the concrete samples used in the first experiment, the maximum length of coarse aggregate is 2 cm. Circles in FIG. 10 indicate the results under conditions No. 1 to No. 3 in FIG. The cross marks in FIG. 10 indicate the results under conditions Nos. 4 to 6 in FIG. The square marks in FIG. 10 indicate the results under conditions Nos. 7 to 9 in FIG. Triangular marks in FIG. 10 indicate the results under conditions Nos. 10 to 12 in FIG.

As shown in FIG. 10, under conditions Nos. 1 to 6 in FIG. 9, the slump flow after vibration deformation is less than 400 mm. As shown in FIG. 2, the diameter of the top plate 21 of the barrier device 20 is 330 mm. Therefore, in order to measure the PJ value of JIS A 1159, it is desirable that the slump flow after vibration deformation is 400 mm or more. Under conditions Nos. 7 to 12 in FIG. 9, the slump flow after vibration deformation is 400 mm or more. Therefore, it is desirable that the distance from the tip of the internal vibrator 51 to the flat plate 10 is 2 cm rather than 3 cm. Further, interference between the internal vibrator 51 and the coarse aggregate is suppressed because the distance from the tip of the internal vibrator 51 to the flat plate 10 is 2 cm. As a result, the posture of the internal vibrator 51 is stabilized. It is desirable that the distance from the tip of the internal vibrator 51 to the flat plate 10 be equal to or greater than the maximum length of coarse aggregate in the concrete sample.

As shown in FIG. 10, the slump flow after vibration deformation when the vibration time (the time to vibrate the concrete sample 41) is 7 seconds is greater than when the vibration time is 5 seconds. The slump flow after vibration deformation when the vibration time is 9 seconds is not much different from that when the vibration time is 7 seconds. Therefore, in order to sufficiently deform the concrete sample, it is desirable that the vibration time is 7 seconds or longer.

FIG. 11 is a diagram showing the composition and the like of concrete samples used in the second experiment. FIG. 12 is a schematic diagram of a box-shaped container for measuring the gap passage speed of a concrete sample.

In the second experiment, slump, vibration ring flow, vibration PJ value, and vibration blocking value were measured for the concrete sample shown in FIG. Also, in the second experiment, the relationship between the above-described values (slump, excitation ring flow, excitation PJ value, and excitation blocking value) and the gap passing speed was obtained.

In the second experiment, the vibration ring flow was measured at four locations. The four measurement positions are arranged at regular intervals in the circumferential direction of the barrier device 20 . The excitation ring flow was calculated as the average value of the measurements at four measurement locations.

The excitation PJ value is the PJ value after excitation deformation. The excitation PJ value was calculated according to the PJ value of JIS A 1159. The excitation PJ value is calculated based on the height of the central portion of the concrete sample after the excitation deformation and the height of the concrete sample outside the column 23 or between the adjacent columns 23 after the excitation deformation. . In the following description, the excitation PJ value (column) means the excitation PJ value calculated based on the height of the concrete sample outside the column 23 after excitation deformation. In the following description, the excitation PJ value (between columns) means the excitation PJ value calculated based on the height of the concrete sample between the adjacent columns 23 after excitation deformation.

The vibration blocking value is a blocking value after vibration deformation. The vibration blocking value was calculated in the same manner as the JIS A 1160 blocking value. The excitation blocking value is the difference between the excitation ring flow and the excitation flow. The vibration flow is the diameter of the concrete sample after applying vibration to the concrete sample by the internal vibrator 51 without using the barrier device 20 .

In the second experiment, the gap passing speed of the concrete sample shown in FIG. 11 was measured using the box-shaped container 90 shown in FIG. As shown in FIG. 12, the box-shaped container 90 includes an A chamber 91 , a B chamber 92 , a flow obstruction 95 , and a gate 97 separating the A chamber 91 and the B chamber 92 . A flow obstruction 95 is positioned between the A chamber 91 and the B chamber 92 . Flow obstruction 95 is a device that obstructs the flow of the concrete sample. Flow obstruction 95 comprises three posts 951 . The diameter of the pillar is 13 mm. The three posts 951 are spaced apart by 35 mm.

First, the A chamber 91 is filled with a concrete sample. After that, an internal vibrator 93 is inserted into the center of the concrete sample in the A chamber 91 . After that, the concrete starts flowing by opening the gate 97 . After the concrete has stopped flowing, the concrete sample is vibrated by starting the internal vibrator 93 . The concrete sample in chamber A 91 passes through flow obstruction 95 and flows into chamber B 92 . Therefore, the height of the concrete sample in the B chamber 92 gradually increases.

The gap passage speed is calculated based on the following formula (1). In equation (1), V _pass is the gap passing speed (mm/s). t ₁₉₀ is the time (seconds) from when the concrete sample in chamber A is vibrated by internal vibrator 93 until the height of the concrete sample in chamber B 92 reaches 190 mm. t ₃₀₀ is the time (seconds) from when the concrete sample in the A chamber is vibrated by the internal vibrator 93 until the height of the concrete sample in the B chamber 92 reaches 300 mm. That is, (t ₃₀₀ −t ₁₉₀ ) is the time (seconds) from when the height of the concrete sample in chamber B 92 reaches 190 mm to when it reaches 300 mm.

V _pass =110/(t ₃₀₀ −t ₁₉₀ ) (1)

FIG. 13 is a graph showing the relationship between the excitation ring flow and the coarse aggregate ratio outside the barrier device in the second experiment. FIG. 14 is a graph showing the relationship between the excitation flow and the excitation ring flow in the second experiment. FIG. 15 is a graph showing the relationship between the excitation ring flow and the excitation blocking value in the second experiment. FIG. 16 is a graph showing the relationship between the excitation PJ value (column) and the excitation PJ value (between columns) in the second experiment. FIG. 17 is a graph showing the relationship between the vibration ring flow and the vibration PJ value in the second experiment. FIG. 18 is a graph showing the relationship between the excitation ring flow in the second experiment and the maximum difference in the excitation PJ value (column) depending on the measurement position.

As shown in FIG. 13, there is a positive correlation between the excited ring flow and the coarse aggregate fraction outside the barrier device 20 . The coarse aggregate rate outside the barrier device 20 is calculated based on the following formula (2). In equation (2), δ _o is the coarse aggregate fraction outside the barrier device 20 . G _o is the mass of the coarse aggregate outside the barrier device 20 . G _i is the mass of coarse aggregate inside the barrier device 20 .

_δo = _Go /( _Go + _Gi ) (2)

As shown in FIG. 14, the vibration ring flow tends to be larger than the vibration flow. As shown in FIG. 15, the larger the vibration ring flow, the more likely the vibration blocking value becomes a negative value. That is, as the vibration ring flow increases, the vibration ring flow tends to be larger than the vibration flow. As shown in FIG. 16, the excitation PJ value (column) is larger than the excitation PJ value (column interval). As shown in FIG. 17, the excitation PJ value tends to decrease as the excitation ring flow increases. The maximum difference between the excitation PJ values (columns) depending on the measurement positions in FIG. 18 is the difference between the maximum and minimum values of the excitation PJ values (columns) at the four measurement locations. As shown in FIG. 18, the difference between the maximum and minimum values of the excitation PJ values (columns) at the four measurement points tends to increase as the excitation ring flow decreases.

FIG. 19 is a graph showing the relationship between slump and gap passage speed in the second experiment. FIG. 20 is a graph showing the relationship between the excitation PJ value and the gap passage speed in the second experiment. FIG. 21 is a graph showing the relationship between the vibration blocking value and the gap passage speed in the second experiment. FIG. 22 is a graph showing the relationship between the vibration ring flow value and the gap passage speed in the second experiment. 19 to 22, the gap passing speed on the vertical axis is the measured value measured using the box-shaped container 90 of FIG.

As shown in FIGS. 19-22, the excitation ring flow has a stronger correlation with the gap passage velocity than the other values (slump, excitation PJ value, and excitation blocking value). In order to calculate the gap passing speed with high accuracy, it is desirable to calculate the gap passing speed based on the vibration ring flow value. A prediction formula obtained by regression analysis of the relationship between the excitation ring flow and the gap passage velocity is the following formula (3). In Equation (3), V _pass is the gap passing speed (mm/s). RF is the excitation ring flow (mm). C/W is the cement water ratio of the concrete sample 41; FIG. 23 is a diagram showing an output table of regression analysis. The gap passing speed is desirably calculated based on Equation (3).

V _pass =0.827×(RF/100) ³ ×C/W−7.39 (3)

FIG. 24 is a graph showing the relationship between the measured values and predicted values of the gap passage speed. FIG. 25 is a diagram showing the mix of verification concrete. FIG. 26 is a diagram showing the details of the verification concrete material.

Using concrete for verification, the accuracy of the predicted value of the gap passage velocity calculated by the equation (3) was verified. As shown in FIGS. 25 and 26, the verification concrete has properties different from those of the concrete sample shown in FIG. The black circles shown in FIG. 24 indicate the predicted value and the measured value of the gap passage speed of the verification concrete. As shown in FIG. 24, Equation (3) can predict the gap passing velocity with high accuracy. Equation (3) is widely applicable to the evaluation of various concretes with different properties.

In addition, in the calculation step S19 of the concrete testing method of the present embodiment, the gap passage speed does not necessarily have to be calculated based on the formula (3). In the concrete testing method of the present embodiment, the gap passing speed may be calculated by some method after the vibration step S17 using the internal vibrator 51 . In the calculation step S19, the gap passage speed does not necessarily have to be calculated based on the vibration ring flow. In the calculation step S19, the gap passing speed may be calculated based on other values. Further, the index calculated in the calculation step S19 may not be the gap passage speed, and may be another index related to the ease of flow when the concrete sample 41 passes through the gaps between the plurality of columns 23. good.

As described above, the concrete testing method of this embodiment includes the installation step S11, the filling step S13, the removal step S15, the vibration step S17, and the calculation step S19. The installation step S<b>11 is a step of installing the barrier device 20 having the plurality of pillars 23 arranged in a ring shape and the slump cone 30 on the flat plate 10 . The filling step S13 is a process of filling the slump cone 30 with the concrete sample 41 . The removing step S15 is a step of pulling up the slump cone 30 after the filling step S13. The vibrating step S17 is a step of inserting a rod-shaped internal vibrator 51 into the concrete sample 41 left on the flat plate 10 after the removing step S15 to vibrate the concrete sample 41 . The calculation step S19 is a step of calculating an index relating to the ease of flow when the concrete sample 41 passes through the gaps between the plurality of columns 23 by the vibration step S17.

As a result, the deformation of the concrete sample that occurs in the vibration step S17 is close to the deformation of concrete that requires vibration compaction at the actual construction site. The concrete testing method of the present embodiment can better reflect the behavior of concrete under dynamic conditions associated with vibration compaction. Therefore, the concrete test method of the present embodiment can predict the workability of concrete with high accuracy. Moreover, the concrete test method of the present embodiment can predict the workability of concrete with high accuracy without using a device such as the box-shaped container 90 shown in FIG. 12 . The method for testing concrete according to this embodiment can reduce the number of concrete samples to be used as compared with the case of using an apparatus such as the box-shaped container 90 . The concrete test method of the present embodiment can easily predict the workability of concrete at the construction site.

The index provided in the calculation step S19 is the gap passage speed. As a result, the concrete test method of the present embodiment can predict the workability of concrete with higher accuracy.

In the calculation step S19, the gap passage speed is calculated based on the vibration ring flow, which is the diameter of the concrete sample 41 after being deformed by the vibration step S17.

The excitation ring flow has a high correlation with the gap passage velocity. Therefore, the concrete testing method of the present embodiment can calculate the gap passage speed with higher accuracy. As a result, the concrete test method of the present embodiment can predict the workability of concrete with higher accuracy.

In the calculation step S19, the gap passage speed is calculated based on the following formula (3). However, in equation (3), V _pass is the gap passage velocity (mm/s), RF is the excitation ring flow (mm), and C/W is the cement water ratio of the concrete sample.

V _pass =0.827×(RF/100) ³ ×C/W−7.39 (3)

As a result, the concrete testing method of the present embodiment can calculate the gap passage speed with higher accuracy. As a result, the concrete test method of the present embodiment can predict the workability of concrete with higher accuracy.

In the vibrating step S17, the time for vibrating the concrete sample 41 is 7 seconds or longer.

Thereby, the concrete sample 41 is sufficiently deformed in the vibrating step S17. Therefore, it is easy to measure the size of the concrete sample 41 after deformation. Therefore, the concrete testing method of the present embodiment can calculate the gap passage speed with higher accuracy. As a result, the concrete test method of the present embodiment can predict the workability of concrete with higher accuracy.

In the vibrating step S17, the distance from the tip of the internal vibrator 51 to the flat plate 10 is greater than or equal to the maximum length of the coarse aggregate of concrete.

This suppresses interference between the internal vibrator 51 and the coarse aggregate in the vibrating step S17, so that the posture of the internal vibrator 51 is stabilized. Further, in the vibrating step S17, the concrete sample 41 is sufficiently deformed. Therefore, it is easy to measure the size of the concrete sample 41 after deformation. Moreover, therefore, the concrete testing method of the present embodiment can calculate the gap passage speed with higher accuracy. As a result, the concrete test method of the present embodiment can predict the workability of concrete with higher accuracy.

10 flat plate 20 barrier device 21 upper plate 23 pillar 30 slump cone 41 concrete sample 51 internal vibrator 53 jig 90 box-shaped container 91 chamber A 92 chamber B 93 internal vibrator 95 flow obstruction 951 pillar 97 gate S11 installation step S13 filling step S15 removal step S17 vibration step S19 calculation step

Claims (5)

an installation step of installing a barrier device having a plurality of circularly arranged pillars and a slump cone on a flat plate;
a filling step of filling the slump cone with a concrete sample;
a removal step of pulling up the slump cone after the filling step;
a vibrating step of inserting a bar-shaped internal vibrator into the concrete sample left on the flat plate after the removing step to vibrate the concrete sample;
a calculating step of calculating an index relating to ease of flow when the concrete sample passes through the gaps of the plurality of columns by the vibrating step;
Test method for concrete with The concrete testing method according to claim 1, wherein the index is a gap passage speed. 3. The method of testing concrete according to claim 2, wherein in said calculating step, said gap passage speed is calculated based on an excitation ring flow, which is a diameter of said concrete sample after being deformed by said vibrating step. The concrete testing method according to any one of claims 1 to 3, wherein in the vibrating step, the concrete sample is vibrated for 7 seconds or longer. The concrete testing method according to any one of claims 1 to 4, wherein in the vibrating step, the distance from the tip of the internal vibrator to the flat plate is equal to or greater than the maximum length of coarse aggregate of the concrete.

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