Quality control method for ready-mixed concrete and evaluation method for slump loss

Abstract

To provide a method for managing the quality of a ready mixed concrete which can easily manage the quality of a ready mixed concrete, and a method for evaluating a slump loss used by the method for managing the quality of a ready mixed concrete.SOLUTION: The method for managing the quality of a ready mixed concrete according to the present invention is a method for managing the quality of a ready mixed concrete in an agitator vehicle which includes a rotary drum designed to rotate around an axial line while storing a ready mixed concrete and a spiral blade arranged along an inner peripheral surface of the rotary drum. The agitator vehicle has an acceleration meter attached to an outer periphery of the rotary drum, and has a measurement step of measuring an acceleration by using the acceleration meter and a management step of grasping the freshness property of the ready mixed concrete on the basis of the measured acceleration.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a quality control method for ready-mixed concrete and a method for evaluating slump loss used in the quality control method for ready-mixed concrete. [Background technology]

[0002] Conventionally, ready-mixed concrete produced in a factory to meet the desired quality is transported to the pouring site by an agitator truck equipped with a rotating drum. At the pouring site, an acceptance inspection is conducted to measure the slump value, etc., to confirm whether the desired quality is met before pouring. However, if the desired quality is not met in the acceptance inspection, the ready-mixed concrete must be returned to the factory. Furthermore, after receiving the results of the acceptance inspection of the ready-mixed concrete transported by the first agitator truck, production of the ready-mixed concrete to be transported by the second agitator truck begins, resulting in long wait times at the pouring site until the ready-mixed concrete arrives.

[0003] To solve these problems, it is necessary to understand the fresh properties of ready-mixed concrete after production and before acceptance inspection, and to provide feedback to the plant. However, the fresh properties of ready-mixed concrete cannot be understood unless the slump value is measured during acceptance inspection. Therefore, various methods have been proposed to predict the slump value of ready-mixed concrete while it is being transported by an agitator truck.

[0004] For example, Patent Document 1 discloses a method of attaching blades to a rotating shaft that penetrates the center of the center shaft of a rotating drum, detecting the resistance that the blades receive from the fresh concrete, and estimating the slump value of the fresh concrete from the magnitude of that resistance. Patent Document 2 also discloses a method of measuring the oil pressure applied to an agitator wheel, whose rotating drum is driven by a hydraulic motor, when stirring the fresh concrete, and converting the measured oil pressure into the slump value of the fresh concrete. Non-Patent Document 1 also discloses a method of estimating the slump value by sensing pressure with a probe attached to the agitator wheel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 58-52546 [Patent Document 2] Japanese Patent Application Publication No. 11-194083 [Non-patent literature]

[0006] [Non-Patent Document 1] Yoshikazu Hiroto, Improving productivity through a continuous control system for concrete quality using probes, Concrete Engineering, Vol. 55, No. 9, pp. 783-787, September 2017 Summary of the Invention [Problem to be solved by the invention]

[0007] However, conventional methods for predicting the slump value of ready-mixed concrete all require modifications to the agitator vehicle or the installation of complex system devices, so there is a need for a simpler method for grasping the quality of ready-mixed concrete.

[0008] In view of the above circumstances, an object of the present invention is to provide a quality control method for ready-mixed concrete that enables easy control of the quality of ready-mixed concrete, and a method for evaluating slump loss used in the quality control method for ready-mixed concrete. [Means for solving the problem]

[0009] The quality control method for ready-mixed concrete of the present invention is a method for controlling the quality of ready-mixed concrete in an agitator vehicle that includes a rotating drum that is configured to be rotatable around an axis while containing ready-mixed concrete, and a spiral blade arranged along the inner surface of the rotating drum, wherein the agitator vehicle further includes an accelerometer attached to the outer surface of the rotating drum, and the method includes a measurement step of measuring acceleration using the accelerometer, and a control step of understanding the fresh properties of the ready-mixed concrete based on the measured acceleration.

[0010] In the quality control method for ready-mixed concrete, an accelerometer is attached to the outer peripheral surface of the rotating drum, and the accelerometer is used to measure acceleration, thereby detecting the movement of the ready-mixed concrete flowing down from the blade and, as a result, making it possible to grasp the fresh properties of the ready-mixed concrete. Therefore, the quality control method for ready-mixed concrete does not require improvements to the agitator car or the installation of a complex system device, and can simply control the quality of ready-mixed concrete.

[0011] The quality control method for ready-mixed concrete according to the present invention may be such that the rotating drum comprises a cylindrical front shell tapering from the front to the rear in the axial direction, a cylindrical rear shell tapering from the rear to the front in the axial direction, and a cylindrical center shell formed along the axis between the front shell and the rear shell, and the accelerometer is attached to the outer peripheral surface of at least one of the center shell and the rear shell.

[0012] In the quality control method for ready-mixed concrete, by attaching the accelerometer to the outer peripheral surface of at least one of the center shell or the rear shell, it becomes easier to detect changes in acceleration measured using the accelerometer, thereby making it possible to grasp the fresh properties of the ready-mixed concrete more accurately.

[0013] In the quality control method for ready-mixed concrete according to the present invention, the rotating drum may have a lowest point at the mounting position for the accelerometer at the lowest point of the orbit passed by the rotating drum as it rotates, and may contain ready-mixed concrete up to above the lowest point.

[0014] In the quality control method for ready-mixed concrete, by storing the ready-mixed concrete above the lowest point, the accelerometer can more easily detect changes in acceleration, thereby making it possible to grasp the fresh properties of the ready-mixed concrete more accurately.

[0015] In the quality control method for ready-mixed concrete according to the present invention, the accelerometer may be attached at a position where the blade is not disposed on the corresponding inner circumferential surface.

[0016] With this configuration, the quality control method for ready-mixed concrete makes it easier for the accelerometer to detect changes in acceleration, making it possible to grasp the fresh properties of ready-mixed concrete with greater accuracy.

[0017] In the quality control method for ready-mixed concrete according to the present invention, in the measurement step, acceleration may be measured when the mounting position of the accelerometer passes through a lower orbit among the orbits passed by as the rotating drum rotates.

[0018] With this configuration, the quality control method for ready-mixed concrete makes it easier for the accelerometer to detect changes in acceleration, making it possible to grasp the fresh properties of ready-mixed concrete with greater accuracy.

[0019] The slump loss evaluation method of the present invention is a method for evaluating slump loss of ready-mixed concrete in an agitator wheel that includes a rotating drum that is configured to be rotatable about its axis while containing ready-mixed concrete, and a spiral blade that is arranged along the inner surface of the rotating drum, wherein the agitator wheel further includes an accelerometer attached to the outer surface of the rotating drum, and the method includes a measurement step of measuring acceleration using the accelerometer, and an evaluation step of evaluating the slump loss of the ready-mixed concrete based on the measured acceleration.

[0020] In the slump loss evaluation method, an accelerometer is attached to the outer peripheral surface of the rotating drum and the slump loss of ready-mixed concrete can be evaluated by measuring acceleration using the accelerometer, so there is no need to modify the agitator car or install a complex system device. Thus, the slump loss evaluation method can simply evaluate the slump loss of ready-mixed concrete.

[0021] In the slump loss evaluation method according to the present invention, the evaluation step may calculate an acceleration difference between a maximum acceleration and a minimum acceleration in any one second, and determine that slump loss has occurred when a rate of change in the acceleration difference after a predetermined time has elapsed relative to the initial acceleration difference is 90% or less or 150% or more.

[0022] With this configuration, the slump loss evaluation method can more simply evaluate the slump loss of ready-mixed concrete based on the acceleration measured using the accelerometer. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a quality control method for ready-mixed concrete that can easily control the quality of ready-mixed concrete, and a method for evaluating slump loss used in the quality control method for ready-mixed concrete. [Brief explanation of the drawings]

[0024] [Figure 1]FIG. 1 is a schematic side view of an agitator wheel 1 used in the method for quality control of ready-mixed concrete and the method for evaluating slump loss according to this embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the rotary drum 2 provided in the agitator wheel 1 shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0025] The quality control method for ready-mixed concrete and the slump loss evaluation method according to this embodiment will be described below. Fig. 1 is a schematic side view of an agitator wheel 1 used in the quality control method for ready-mixed concrete and the slump loss evaluation method according to this embodiment. Fig. 2 is a cross-sectional view of a rotating drum 2 provided in the agitator wheel 1 shown in Fig. 1. Note that the same or corresponding parts in the following drawings are given the same reference numerals, and their description will not be repeated.

[0026] <Quality control method for ready-mixed concrete> First, we will explain the agitator wheel 1 used in the ready-mixed concrete quality control method according to this embodiment. The agitator wheel 1 includes a rotating drum 2 configured to be rotatable about axis X while containing ready-mixed concrete, and a spiral blade 3 disposed along the inner circumferential surface of the rotating drum 2. The agitator wheel 1 further includes an accelerometer 4 attached to the outer circumferential surface of the rotating drum 2.

[0027] Specifically, the agitator vehicle 1 is provided with a rotating drum 2 behind the driver's seat. Attached to the rear of the rotating drum 2 are a hopper 5 for supplying ready-mixed concrete to the rotating drum 2 and a discharge unit 6 for discharging the ready-mixed concrete from the rotating drum 2. Here, the ready-mixed concrete includes unhardened concrete and mortar.

[0028] The rotating drum 2 comprises a cylindrical front shell 21 tapering from the front to the rear in the direction of the axis X, a cylindrical rear shell 22 tapering from the rear to the front in the direction of the axis X, and a cylindrical center shell 23 formed along the axis X between the front shell 21 and the rear shell 22. The rotating drum 2 is disposed at an angle with respect to the horizontal plane so that the front shell 21 faces downward. The capacity of the rotating drum 2 is not particularly limited. The quality control method for ready-mixed concrete according to this embodiment is applicable to rotating drums with a capacity of, for example, 2.5 to 9.8 m 3 This can be applied to the agitator wheel 1.

[0029] A single spiral blade 3 is disposed on the inner peripheral surface of the rotating drum 2. As the blade 3 rotates in the forward direction, the rotating drum 2 stirs the ready-mixed concrete supplied from the hopper 5 while pushing it downward (towards the front shell 21), and as the blade 3 rotates in the reverse direction, the ready-mixed concrete is discharged from the discharge section 6.

[0030] The agitator wheel 1 has one accelerometer 4 attached to the outer peripheral surface of the rear shell 22. No blade 3 is disposed on the inner peripheral surface corresponding to the attachment position P where the accelerometer 4 is attached. The rotating drum 2 has a lowest point P' at the lowest point of the track that this attachment position P passes through as the rotating drum 2 rotates. Ready-mixed concrete is contained in the rotating drum 2 up to a point above the lowest point P' (towards the rear shell 22).

[0031] For example, a small, high-response, low-capacity uniaxial accelerometer ARGL-100A (manufactured by Tokyo Measuring Instruments Laboratory Co., Ltd.) can be used as the accelerometer 4. The accelerometer 4 can be easily attached to the outer circumferential surface of the rotating drum 2 using, for example, a magnet, adhesive, screws, etc.

[0032] The quality control method for ready-mixed concrete according to this embodiment is a method for controlling the quality of ready-mixed concrete in the above-mentioned agitator vehicle 1, and includes a measurement step of measuring acceleration using an accelerometer 4, and a control step of grasping the fresh properties of the ready-mixed concrete based on the measured acceleration.

[0033] Specifically, in the measurement step, acceleration is measured when the mounting position P where the accelerometer 4 is attached passes through the lower part of the tracks traversed by the rotation of the rotating drum 2. At this time, the rotation speed of the rotating drum 2 can be, for example, 0.5 rpm or more and 2 rpm or less. In addition, the volume ratio of the amount of ready-mixed concrete stored to the capacity of the rotating drum 2 can be, for example, 0.10 or more and 0.51 or less.

[0034] In addition, in the control step, based on the measured acceleration, the change in acceleration after a predetermined time has elapsed relative to the initial acceleration is monitored to grasp the change in the fresh properties of the ready-mixed concrete.

[0035] In the quality control method for ready-mixed concrete according to this embodiment, an accelerometer 4 is attached to the outer peripheral surface of the rotating drum 2, and the accelerometer 4 is used to measure acceleration, thereby detecting the movement of the ready-mixed concrete flowing down from the blade 3, and as a result, it is possible to grasp the fresh properties of the ready-mixed concrete. Therefore, the quality control method for ready-mixed concrete does not require any improvements to the agitator car 1 or the installation of a complex system device, and allows for simple quality control of ready-mixed concrete.

[0036] In the quality control method for ready-mixed concrete according to this embodiment, by attaching the accelerometer 4 to the outer peripheral surface of the rear shell 22, it becomes easier to detect changes in acceleration measured using the accelerometer 4, and therefore it is possible to grasp the fresh properties of the ready-mixed concrete more accurately.

[0037] In the quality control method for ready-mixed concrete according to this embodiment, the accelerometer 4 can more easily detect changes in acceleration by storing the ready-mixed concrete above the lowest point P', thereby making it possible to grasp the fresh properties of the ready-mixed concrete more accurately.

[0038] In the quality control method for ready-mixed concrete according to this embodiment, the mounting position P at which the accelerometer 4 is attached does not have a blade 3 disposed on the corresponding inner peripheral surface, making it easier for the accelerometer 4 to detect changes in acceleration, thereby enabling the fresh properties of the ready-mixed concrete to be grasped more accurately.

[0039] In the quality control method for ready-mixed concrete according to this embodiment, in the measurement process, the acceleration is measured when the mounting position P where the accelerometer 4 is attached passes through the lower orbit of the orbit passed by the rotating drum 2 as it rotates, which makes it easier for the accelerometer 4 to detect changes in acceleration, thereby enabling the fresh properties of the ready-mixed concrete to be grasped more accurately.

[0040] <Slump loss evaluation method> The agitator vehicle 1 used in the slump loss evaluation method according to this embodiment is the same as the agitator vehicle 1 used in the quality control method for ready-mixed concrete.

[0041] The slump loss evaluation method according to this embodiment is a method for evaluating the slump loss of ready-mixed concrete in the above-mentioned agitator vehicle 1, and includes a measurement step of measuring acceleration using an accelerometer 4, and an evaluation step of evaluating the slump loss of the ready-mixed concrete based on the measured acceleration.

[0042] Specifically, the measurement step is the same as the measurement method in the quality control method for ready-mixed concrete.

[0043] In the evaluation process, the difference between the maximum and minimum accelerations in any one second is calculated. If the rate of change in the difference in acceleration after a predetermined time has elapsed relative to the initial difference in acceleration is 90% or less or 150% or more, it is determined that slump loss has occurred. More specifically, the difference between the maximum and minimum accelerations in the initial one second is first calculated. Next, the difference between the maximum and minimum accelerations in any one second after the predetermined time has elapsed is calculated at the same measurement position as the initial one second. In other words, the measurement start position for the one second, i.e., the mounting position P of the accelerometer 4 when starting measurement, is the same position every time. Then, the rate of change in the difference in acceleration after a predetermined time has elapsed relative to the initial difference in acceleration measured at the same position is calculated. If the rate of change is 90% or less or 150% or more, it is determined that slump loss has occurred. Here, the "any one second" refers to any one second during which the mounting position P where the accelerometer 4 is mounted passes through a lower orbit among the orbits traversed by the rotation of the rotating drum 2.

[0044] The slump loss evaluation method according to this embodiment can evaluate the slump loss of ready-mixed concrete by attaching an accelerometer 4 to the outer peripheral surface of the rotating drum 2 and measuring acceleration using the accelerometer 4, so there is no need to improve the agitator vehicle 1 or install a complex system device. Therefore, the slump loss evaluation method can simply evaluate the slump loss of ready-mixed concrete.

[0045] The method for evaluating slump loss according to this embodiment calculates the difference in acceleration between the maximum acceleration and the minimum acceleration in any one second, and determines that slump loss has occurred if the rate of change in the acceleration difference after a predetermined time has elapsed relative to the initial acceleration difference is 90% or less or 150% or more. This makes it possible to more simply evaluate the slump loss of ready-mixed concrete based on the acceleration measured using the accelerometer 4.

[0046] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention. Furthermore, it goes without saying that the configurations, methods, etc. of the above and following embodiments may be arbitrarily adopted and combined (the configurations, methods, etc. of one embodiment may be applied to the configurations, methods, etc. of other embodiments).

[0047] For example, the agitator vehicle 1 used in the ready-mixed concrete quality control method and slump loss evaluation method according to the present embodiment has one accelerometer 4 attached to the outer peripheral surface of the rear shell 22. However, the present invention is not limited to this configuration, and one accelerometer 4 may be attached to the outer peripheral surface of the center shell 23. Furthermore, multiple accelerometers 4 may be attached to the outer peripheral surface of at least one of the center shell 23 and the rear shell 22. Furthermore, an accelerometer 4 may be attached to the outer peripheral surface of the front shell 21.

[0048] Furthermore, in the agitator wheel 1, the blades 3 are not disposed on the inner circumferential surface corresponding to the mounting position where the accelerometer 4 is attached. However, the present invention is not limited to this configuration, and the blades 3 may be disposed on the inner circumferential surface corresponding to the mounting position where the accelerometer 4 is attached.

[0049] In the ready-mixed concrete quality control method and slump loss evaluation method according to this embodiment, the ready-mixed concrete is contained up to a position above the lowest point P' of the rotating drum 2. However, the present invention is not limited to this configuration, and the ready-mixed concrete does not have to be contained up to the lowest point P'.

[0050] Furthermore, in the measurement process, acceleration is measured when mounting position P where accelerometer 4 is attached passes through a lower orbit among the orbits passed by as rotating drum 2 rotates. However, the present invention is not limited to this configuration, and acceleration may be measured when mounting position P where accelerometer 4 is attached passes through an upper orbit among the orbits passed by as rotating drum 2 rotates.

[0051] In the slump loss evaluation method according to this embodiment, the acceleration difference between the maximum acceleration and the minimum acceleration is calculated during any one second when the mounting position P where the accelerometer 4 is attached passes through a lower trajectory of trajectories passed by the rotation of the rotating drum 2. However, the present invention is not limited to this configuration, and the acceleration difference between the maximum acceleration and the minimum acceleration may be calculated during any one second when the mounting position P where the accelerometer 4 is attached passes through an upper trajectory of trajectories passed by the rotation of the rotating drum 2.

[0052] In addition, in the evaluation method, it is determined that slump loss has occurred when the rate of change is 90% or less or 150% or more. However, the present invention is not limited to this configuration, and the method for determining whether slump loss has occurred can be changed as appropriate depending on the quality required at the concrete placement site. [Example]

[0053] Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0054] <Test 1> The ready-mixed concrete used was a standard 33-18-20N mix. The rotating drum used had the structure shown in Figure 2. The accelerometer used was a small, high-response, low-capacity uniaxial accelerometer ARGL-100A (manufactured by Tokyo Measuring Instruments Laboratory Co., Ltd.), which was attached to the outer periphery of the rear shell using a magnet.

[0055] Next, the ready-mixed concrete was fed into the rotating drum and rotated at a rotation speed of 2 rpm. The volume ratio of the ready-mixed concrete to the capacity of the rotating drum was 0.50, which corresponds to the volume ratio of a large agitator truck that is almost fully loaded (5.0 m). 3 is equivalent to

[0056] The slump value of the fresh concrete was measured by sampling fresh concrete at the initial stage and after a certain time had passed, and was determined in accordance with JIS A 1101, the concrete slump test method. The measurement results of the slump value are shown in Table 1.

[0057] Then, the difference between the maximum acceleration and the minimum acceleration was calculated for each 5-second interval, initially and after a given time had elapsed when the slump value was measured, and the rate of change of the difference in acceleration after a given time had elapsed relative to the initial difference in acceleration was determined. The results are shown in Table 1. The given 5-second interval was a 5-second interval during which the mounting position of the accelerometer passed through the lower orbit of the rotating drum, and the measurement start position for each 5-second interval was the same for each measurement.

[0058] [Table 1]

[0059] <Test 2> Except for using a standard 27-12-20N mix of ready-mixed concrete, the slump value and the rate of change in acceleration difference were determined in the same manner as in Test 1. The results are shown in Table 2.

[0060] [Table 2]

[0061] As can be seen from the results in Tables 1 and 2, by attaching an accelerometer to the outer peripheral surface of the rotating drum and using the accelerometer to measure acceleration, it is possible to grasp the fresh properties of ready-mixed concrete or evaluate the slump loss of ready-mixed concrete. Therefore, there is no need to improve the agitator car or install a complex system device, and it is possible to simply manage the quality of ready-mixed concrete or simply evaluate the slump loss of ready-mixed concrete. [Explanation of symbols]

[0062] 1 agitator car 2 rotating drums 3 blades 4 Accelerometer 5 Hopper 6 Discharge section 21 Front shell 22 Rear shell 23 Center shell X axis P Mounting position P' lowest point

Claims

1. A method for controlling the quality of ready-mixed concrete in an agitator vehicle that includes a rotating drum configured to be rotatable about an axis while containing ready-mixed concrete, and a spiral blade disposed along the inner circumferential surface of the rotating drum, The agitator wheel further includes an accelerometer attached to the outer circumferential surface of the rotating drum, a measuring step of measuring acceleration using the accelerometer; A management process of calculating an acceleration difference between a maximum acceleration and a minimum acceleration based on the measured acceleration, and determining the fresh properties of the ready-mixed concrete from the rate of change of the acceleration difference after a predetermined time has elapsed relative to the initial acceleration difference; A quality control method for ready-mixed concrete comprising the steps of:

2. the rotating drum comprises a cylindrical front shell tapered from the front to the rear in the axial direction, a cylindrical rear shell tapered from the rear to the front in the axial direction, and a cylindrical center shell formed along the axis between the front shell and the rear shell, The method for quality control of ready-mixed concrete according to claim 1 , wherein the accelerometer is attached to an outer peripheral surface of at least one of the center shell and the rear shell.

3. 3. The method for quality control of ready-mixed concrete according to claim 1 or 2, wherein the rotating drum has a lowest point at the lowest position of a track traversed by the rotation of the rotating drum, and the ready-mixed concrete is contained up to a level above the lowest point.

4. The quality control method for ready-mixed concrete according to any one of claims 1 to 3, wherein the accelerometer is attached at a mounting position where the blade is not disposed on a corresponding inner peripheral surface.

5. The method for quality control of ready-mixed concrete according to any one of claims 1 to 4, wherein in the measurement step, acceleration is measured when the mounting position of the accelerometer passes through a lower track among the tracks passed by by the rotation of the rotating drum.

6. A method for evaluating slump loss of ready-mixed concrete in an agitator vehicle that includes a rotating drum configured to be rotatable about an axis while containing ready-mixed concrete, and a spiral blade disposed along the inner circumferential surface of the rotating drum, The agitator wheel further includes an accelerometer attached to the outer circumferential surface of the rotating drum, a measuring step of measuring acceleration using the accelerometer; an evaluation step of calculating an acceleration difference between a maximum acceleration and a minimum acceleration based on the measured acceleration, and evaluating the slump loss of the fresh concrete from a rate of change of the acceleration difference after a predetermined time has elapsed relative to the initial acceleration difference; A method for evaluating slump loss.

7. 7. The method for evaluating slump loss according to claim 6, wherein the evaluation step calculates an acceleration difference between a maximum acceleration and a minimum acceleration in any one second, and determines that slump loss has occurred when a rate of change in the acceleration difference after a predetermined time has elapsed relative to the initial acceleration difference is 90% or less or 150% or more.

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