JP2589758B2 - Concrete quality test equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a concrete quality test apparatus, and more particularly to a quality test apparatus capable of accurately measuring workability in a state where concrete is not hardened.

[Conventional technology] Workability that indicates the filling property and pumping property of concrete is as follows. The concrete to be measured is filled into an iron cone with a height of 30 cm, an inner diameter of 10 cm on the upper surface, and an inner diameter of 20 cm on the lower surface, and the cone is quietly moved. It is customary to make a determination by measuring the amount of settlement of the concrete upper surface when vertically lifted (JIS A 1101). This test is called a slump test, and the numerical value representing the amount of settlement in cm is called a slump value. In addition, the slump test is relatively sensitive to a change in the unit water amount of concrete (for example, a change in the slump value of 1 cm corresponds to a change in the unit water amount of 2 to ³ kg / m3). This makes it possible to judge the approximate degree of variation in quality represented by the water-cement ratio of the concrete, and at the same time, it is possible to obtain an approximate guide for workability such as filling property in the formwork. The slump test is a very convenient workability test method, and the quality of concrete and the workability can be controlled by the slump value.

On the other hand, as a test method for concrete used for buildings different from the slump test, after filling concrete on one side of a box with a vertical partition plate in the center, raise the partition plate to a certain height, A test method for determining workability from the amount of concrete deformation has been proposed by Yokoyama and Saji et al., And is used in laboratory research (Concrete Journal VOl.5, No.10, Oc.
d, 1967).

[Problems to be Solved by the Invention] However, concrete, to which the workability test method is generally applicable, including the slump test and test methods other than the slump test, has a region in the property, It is difficult to measure the workability of concrete. The conventional slump test is
Although the test method can cover a wide range of concrete, it is difficult to measure the workability of extremely hard concrete or high concrete with a slump value of zero. The slump test measures the shape after the concrete filled in the cone is deformed by its own weight, that is, measures the yield value of the viscoplastic body, and does not measure any properties related to viscosity. It is not possible to measure the workability of concrete where the viscosity increases with concrete and the magnitude of the viscosity affects the workability. Therefore, with such high-strength concrete, it is impossible to control the variation of concrete quality and workability represented by the water-cement ratio by a slump test. This can lead to overlooking significant quality and workability fluctuations and making incorrect management decisions. In addition to the slump test described above, other proposed test methods basically measure the yield value of concrete, similar to the slump test, and therefore determine the workability of high-strength concrete where viscosity is a problem in construction. I can't. Conventional slump tests basically measure only the yield value to test the workability of unconsolidated concrete, which is a viscoplastic body having properties governed by two parameters, yield value and viscosity coefficient In order to judge the quality of high-strength concrete with high viscosity, it is necessary to measure the yield value and viscosity simultaneously. Accordingly, an object of the present invention is to provide a simple concrete quality test apparatus capable of simultaneously measuring the yield value and the viscosity.

Means for Solving the Problems In order to achieve the above object, the present invention provides a concrete quality test apparatus for performing a quality test on a concrete yield value and a viscosity, by separating the concrete yield value and the viscosity. A housing having a concrete storage portion having an opening with a dimension that can be measured and a concrete flow portion horizontally communicated in one direction from the opening,
Opening / closing means for opening / closing the opening, opening / closing detecting means for detecting whether or not the opening / closing means has opened the opening, and measurement for measuring an elapsed time from the time when the opening / closing detecting means detects opening of the opening. Means, movement amount detection means for detecting the movement amount of concrete in the concrete flowing portion which has flowed out of the opening under the control of the shape of the opening by its own weight, and calculates the flow speed of concrete from the elapsed time and the movement amount. Computing means for performing the calculation.

[Action] In the slump test, the yield value is measured by the amount of deformation of concrete filled in the cone caused by its own weight after lifting the cone. Therefore, in the present invention in which the yield value and the viscosity are simultaneously measured, it is preferable that the yield value is obtained by measuring the amount of deformation of the concrete due to its own weight. However, the viscosity of concrete cannot be measured only by measuring the amount of deformation.

By the way, the properties of the concrete that has not yet set as a viscoplastic body are similar to a Bingham fluid having the characteristics shown in FIG. The straight line portion in the figure is a region where the shear stress τ is proportional to the strain rate, and the viscosity of the fluid is determined by the gradient of this portion. Therefore, in order to measure the viscosity of the concrete that approximates the Bingham fluid, the relationship between the force when the concrete flows and the deformation speed may be measured. However, when the cone is filled with concrete and the cone is pulled up and deformed by its own weight, the applied force is considered to hardly change even if the properties of the concrete change if the density of the concrete is the same. By measuring the deformation speed at the time of deformation by its own weight from, the property corresponding to the viscosity can be measured.

Therefore, in the present invention, after the concrete is stored in the storage portion of the housing, the yield value and the viscosity of the concrete in the storage portion are separated from each other, and the opening formed in the lower side surface to the measured size is opened by the opening / closing means. The yield value is measured by detecting the amount of movement of the concrete in the flowing portion when the concrete is caused to flow by regulating the shape of the opening in one horizontal direction from the opening by its own weight. In addition, by measuring the elapsed time from the time when the opening detecting means detects the opening of the opening by the measuring means, and calculating the flow speed of the concrete from the moving amount detected by the moving amount detecting means and the elapsed time, Is measured, and the yield value and viscosity of concrete are measured simultaneously.

When the amount of movement and the deformation speed are to be measured according to the above principle, (1) the concrete deformation time should be as long as possible so that it can be measured.
(2) The condition of the start and end of the deformation of the concrete can be clearly determined, and (3) The force other than the own weight does not act on the concrete at the time of the test in order to cause only the deformation by its own weight, and the following three conditions are satisfied. Is preferred.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings. The test apparatus of this embodiment includes an L-shaped casing as shown in FIG. The housing includes a vertical section 10 acting as a storage section and a horizontal section 12 acting as a flow section. An upper end of the vertical portion 10 is open, and an opening 16 is formed in a portion corresponding to a lower side surface of the vertical cormorant 10.
A partition plate 14 is accommodated in the vertical portion 10 so as to be movable along a side surface of the vertical portion 10, and the opening 16 can be opened and closed by the partition plate 14. The top surface of the horizontal portion 12 is open, and the electrodes 20 and 22 are arranged in parallel on the bottom surface, as shown in FIG. 2 (1), and the amount of concrete movement can be measured visually. Is marked with zero as the zero point. These batteries 20 and 22 measure the amount of concrete movement based on the electrical resistance between the electrodes. Also, the second
As shown in FIG. 2B, a large number of light emitting elements 21 and a large number of light receiving elements are provided below the horizontal portion 12 along the flowing direction of the concrete.
22 may be arranged to face each other, and the movement amount may be detected from the number of light receiving elements shielded by concrete.
A limit switch 24 that is turned on when the partition plate 14 completely opens the opening 16 is attached to a side surface of the vertical portion 10, and a control device 30 including a liquid crystal display 26, a numeric keypad 28, and a micro computer is attached. ing. This microcomputer 32 is connected to electrodes 20, 22, a limit switch 24, a liquid crystal display 26, and a numeric keypad 28, as shown in FIG. The dimensions of the L-shaped casing are as shown in the third (unit: mm). In order to perform a concrete quality test using this test device, a predetermined amount of concrete is filled in the vertical portion 10 with the opening 16 closed by the partition plate 14, and then the partition plate 14 is pulled up in the vertical direction to lift the concrete. Flows from the opening 16 below the vertical portion 10 to the horizontal portion 12. At this time, the time point at which the deformation of the concrete starts is the time point at which the partition plate 14 is pulled up, and the time point at which the deformation of the concrete ends is the time point at which the movement of the concrete in the horizontal portion 12 stops, and both can be clearly detected. Further, the deformation of the concrete proceeds only from the opening 16 when the partition plate 14 is pulled up, and this L-shaped shape is a very effective form for extending the time until the deformation of the concrete is completed. . Further, the force other than the own weight acting on the concrete when starting the deformation is only the force when blowing up the partition plate 14, and the effect of the external force on the concrete can be extremely reduced.
And the horizontal part 12 when the deformation of the concrete is finished
The yield value can be obtained by measuring the amount of concrete movement at In addition, the time from the time when the concrete is lifted to the partition plate 14 to the time when the movement of the concrete is stopped is measured, and the flow rate of the concrete is determined by dividing the amount of the movement by the time to measure the flow rate of the concrete to obtain the viscosity. The viscosity can be determined by measuring. Hereinafter, this movement amount is referred to as an L-type slump value.

Next, a control routine of this embodiment will be described. This routine is executed every predetermined time (for example, 0.1 sec) from when the limit switch 24 is turned on, that is, when the opening is opened by pulling up the partition plate 14. Step 100
Then, by incrementing the count value T,
The elapsed time from when the opening is opened is counted. In the next step 102, it is determined whether or not the resistance between the electrodes has changed, thereby determining whether or not the concrete is flowing in the horizontal portion 12. When it is determined that the flow of concrete has stopped without any change in the resistance value, it is determined in step 104 whether or not a predetermined time (for example, 2 to 3 seconds) has elapsed. Judge. If it is determined that the predetermined time has elapsed and it is determined that the flow of concrete has definitely stopped, the process proceeds to step 106, and the amount of movement is divided by a value obtained by subtracting the predetermined time of step 104 from the count value T. Calculates the flow speed of the concrete. Here, when the movement amount due to the flow of the concrete increases, the area of the electrode portion conducted by the concrete increases, so that the resistance value between the electrodes decreases. Therefore, it is necessary to calculate the movement amount of the concrete from the resistance value between the electrodes. it can. Then, the movement amount and the flow velocity calculated as described above are displayed on the liquid crystal display.

FIG. 7 shows the measurement of the deformation speed (hereinafter referred to as L-shaped flow speed) in the horizontal portion 12 of concrete having a water cement ratio of 30, 35, and 40% shown in Table 1 below using the test apparatus of the above embodiment. FIG. 4 is a diagram showing a relationship between a water-cement ratio and an L-shaped flow rate at the time of performing the method. The measured values shown in FIG. 7 are plotted only for the L-type slump value of 17 to 23 cm.
Under conditions where the mold slump value does not change significantly, that is, the yield value does not change significantly, the L-flow rate decreases as the water-cement ratio decreases.
That is, the L-type flow rate tends to decrease as the viscosity increases. By measuring both the L-type slump value and the L-type flow rate by the test method of the present invention, it is possible to easily judge the fluctuation of the water-cement ratio of concrete even in the case of high-strength concrete with a water-cement ratio of more than 40%. Yes, quality control represented by the water-cement ratio of concrete can be controlled by this test.

FIG. 8 shows the measured values of the conventional slump test under the same conditions as described above. As can be understood from the figure, in the conventional slump test, since the change tendency of the slump value is not constant much more than the change of the water cement ratio, it is not possible to catch the change in the workability due to the difference of the water cement ratio by the slump value. Further, by measuring both the yield value and the viscosity by the test apparatus of the present embodiment, concrete having the same slump value but different viscosities can be distinguished, so that the contribution of the viscosity to the concrete filling property increases. it is possible to manage the strength concrete (compressive strength 350 kg / cm ² or higher) strength concrete construction of the fluctuation of (compressive strength 350 kg / cm ² or higher) or the like.

The two types of surfactants A and B were added to the three types of concrete having the water-cement ratios of 30, 35, and 40% shown in Table 1 above with varying concentrations, and the apparatus of this example was used. The test was performed. The relationship between the water cement ratio and the L-type flow rate at this time is as shown in FIG. 9, and the L-type flow rate decreases as the water-cement ratio decreases regardless of the type of the surfactant. Can understand. However, comparing the L-type flow rates of concrete with surfactant A and concrete with surfactant B,
The L-type flow rate of the concrete to which the surfactant B is added is higher, and as a result, it is possible to measure that the viscosity is small. Therefore, if the test apparatus of this embodiment is used,
The degree to which the viscosity of concrete is affected by the type of water cement, ratio, or surfactant can be quantitatively measured.

Next, the quality control of the high-strength concrete having a water-cement ratio of 37% shown in Table 2 was performed by the test apparatus of this example.
Ready-mixed concrete trucks transported by agitator car (total 20
Each time one vehicle arrived, a test using the apparatus of this example and a conventional slump test were performed, and at the same time, the water-cement ratio was directly measured by the hydrochloric acid dissolution heat method. Fig. 10 (1),
(2) and (3) show the measurement results of the L-type flow rate, slump value and water cement ratio, respectively, as x-Rs control x
This is shown in the control chart. L-type flow rate is average
CL was 6.2 cm / sec, and the 10th and 11th measured values exceeded or were close to the upper control limit line UCL, indicating that the water-cement ratio may have changed. However, no abnormalities were found in the tenth and eleventh measured values in the slump value obtained by the slump test. The measured values of the water-cement ratio directly measured at the same time are the 10th and 11th measured values 40
%, Which clearly deviates from the prescribed mix of concrete. As a result, it is shown that the fluctuation of the water-cement ratio of the concrete at the construction site due to the measurement of the viscosity by the test apparatus of the present embodiment is checked, and the quality can be controlled. In addition, according to the conventional slump test using a cone, it is difficult to control the quality of this type of concrete because no obvious change in the slump value is detected.

[Effects of the Invention] As described above, according to the present invention, since the yield value and the viscosity of concrete can be simultaneously and simply measured, it is difficult to determine the workability, and the determination can be performed in a test of high-strength concrete. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a test apparatus according to an embodiment of the present invention, FIG. 2 (1) is a partial plan view of the test apparatus of FIG. 1, and FIG. 2 (2).
FIG. 3 is a schematic view showing an example of optically measuring the amount of movement, FIG. 3 is an explanatory view showing the dimensions of the test apparatus, FIG. 4 is a block diagram showing the control apparatus shown in FIG. 1, and FIG. 6 is a flowchart showing a control routine of the example, FIG. 6 is a diagram showing the relationship between the shear stress of the Bingham fluid and the strain rate, FIG. 7 is a diagram showing the relationship between the water cement ratio and the L-type flow rate, and FIG. Is a diagram showing the relationship between the water cement ratio and the slump value, FIG. 9 is a diagram showing the relationship between the water cement ratio and the L-type flow rate when a surfactant is added, FIG. 10 (1), (2) and (3)
FIG. 3 is a diagram showing changes in an L-shaped flow rate, a slump value, and a water-cement ratio, respectively. 10 Vertical section, 12 Horizontal section, 24 Limit switch.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenro Mitsui 2-5-114 Minamisuna, Koto-ku, Tokyo Inside the Technical Research Institute, Takenaka Corporation (72) Inventor Shoji Sakuta 2-5-1-14 Minamisuna, Koto-ku, Tokyo No. Takenaka Corporation Technical Research Institute Co., Ltd. (72) Inventor Toru Okuno 8-21-1, Ginza, Chuo-ku, Tokyo Inside Tokyo Headquarters Takenaka Corporation (56) Reference Real Opening Sho51-30581 (JP, U.S.A.) ) Actual opening 58-138062 (JP, U)

Claims (1)

(57) [Claims] 1. A concrete quality test apparatus for performing a quality test on the yield value and viscosity of concrete, wherein an opening having a dimension that can be measured separately from the yield value and viscosity of the concrete is formed in a lower side surface. A housing provided with a concrete storage part and a concrete flowing part which is communicated in one direction horizontally from the opening, an opening / closing means for opening / closing the opening, and whether or not the opening / closing means has opened the opening. Opening / closing detecting means for detecting, measuring means for measuring an elapsed time from a point in time when the opening / closing detecting means detects opening of the opening, and Moving amount detecting means for detecting the moving amount of concrete, and calculating means for calculating the flow speed of the concrete from the elapsed time and the moving amount. Concrete quality testing device characterized by the following.