JP2003103513A - Method for controlling quality of ready-mixed concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling quality of ready-mixed concrete capable of carrying out quality control of all ready-mixed concrete to be shipped based on a water content of the ready-mixed concrete by accurately grasping the water content of all ready-mixed concrete to be manufactured in real time. SOLUTION: A discharging velocity of the ready-mixed concrete is calculated based on discharge amount data of the ready-mixed concrete from a distance sensor 29 installed on a concrete hopper 6 of a ready-mixed concrete manufacturing plant. An opening of a rubber gate 21 is changed by controlling a cylinder 26 based on the discharging velocity. The discharging velocity of the ready mixed concrete is always controlled at a specific constant velocity. Then, the water content in the ready mixed concrete is accurately measured with a water content sensor 31 under this condition, W/C and a compression strength are accurately presumed based on the water content to carry out quality control of the ready-mixed concrete.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling quality during production of green concrete, and more particularly to a method for measuring a water content of green concrete and a method for estimating a compressive strength based on the water content.

[0002]

2. Description of the Related Art Conventionally, as a quality control method for ready-mixed concrete produced at a ready-mixed concrete manufacturing plant, a part of the ready-mixed concrete is sampled to produce a test piece, and after 28 days, the test piece is prepared. Various tests such as compressive strength tests are conducted to collect data, and these data are statistically aggregated to control the quality of ready-mixed concrete manufactured and shipped, and to feed it back to the later mix design. . By the way, recently, ready-mixed concrete for special applications such as high-fluidity concrete and high-strength concrete is often used. In these ready-mixed concrete, it is possible to control the water content and the compressive strength as compared with normal ones. The method, which is required even higher and requires many days until the quality of green concrete is grasped like the above method, cannot be said to be sufficient.

Therefore, sampling is carried out at the time of production of fresh concrete, the water content is directly measured by a water content meter, etc., and the unit water content is obtained from the water content thus obtained.
The unit amount of cement is obtained from this and the measured value of the actually mixed cement, and W /
While C (water cement ratio) is derived, W / C has a certain relationship with the compressive strength of green concrete, so there is a method of estimating the compressive strength based on the derived W / C. With this method, it is possible to determine in real time when the fresh concrete is produced in the plant whether the water content or W / C of the fresh concrete and the compressive strength estimated from these are as designed. It can be fed back to the subsequent formulation design.

[0004]

[0007] However, the water content of fresh concrete is likely to occur is inevitably variation due largely due to the surface water of the sand as well kneading water, and at one time or sampling as above methods It was difficult to know the exact water content of all the ready-mixed concrete to be manufactured. A method of sampling all the ready-mixed concrete to be manufactured can be considered, but actually, it is not realistic to carry out the sampling every time from the viewpoint of work efficiency.

In view of the above points, the present invention can accurately grasp the water content of all ready-mixed concrete to be manufactured in real time, and can control the quality of all ready-mixed concrete to be shipped based on the water content. It is an object to provide a quality control method for ready-mixed concrete.

[0006]

In order to achieve the above object, the present invention provides a quality control method for ready-mixed concrete according to claim 1, wherein a ready-mixed concrete in a hopper of a ready-mixed concrete manufacturing plant is used. In addition to the increase / decrease amount detecting means for detecting the increase / decrease amount of the concrete hopper, the discharge gate at the bottom of the concrete hopper is provided with the opening degree adjusting means for adjusting the gate opening degree, and the side wall of the concrete hopper has a moisture sensor for measuring the moisture amount of the fresh concrete. Provided, when discharging the fresh concrete from the concrete hopper, the discharge amount of the fresh concrete is detected by the increase / decrease amount detecting means, the discharging speed is calculated from the discharging amount per unit time, and this discharging speed is always a predetermined speed. The gate opening is adjusted by the opening adjusting means as described above, and the water content is removed from the fresh concrete discharged in that state. It is characterized in that so as to measure the moisture content in service.

Further, in the quality control method of green concrete according to claim 2, while the unit water amount is obtained from the water amount of the green concrete measured by the method, the unit water amount is actually measured in the cement measuring tank of the plant. The unit amount of cement is calculated from the measured value of cement, and W / C (water cement ratio) is derived from these unit water amount and unit cement amount.
The feature is that the compressive strength of green concrete is estimated based on C.

Further, in the quality control method for ready-mixed concrete according to claim 3, the composition value of ready-mixed concrete to be manufactured next time is corrected based on the compressive strength of the ready-mixed concrete estimated by the method. Is characterized by.

[0009]

According to the quality control method for ready-mixed concrete according to claim 1 of the present invention, when the ready-mixed concrete in the concrete hopper is dispensed, the distance sensor provided above the concrete hopper is used to prepare the ready-mixed concrete in the hopper. Continuously detect the level of concrete surface. Here, since the capacity of the concrete hopper is known in advance, the discharge amount of ready-mixed concrete can be naturally detected. Then, the discharge rate is calculated from the discharge amount of green concrete in an arbitrary unit time. This discharge speed varies depending on the properties and kind of the ready-mixed concrete, and the opening of the discharge gate is adjusted accordingly to control so that the discharge speed is always the same regardless of the kind. In this way, the amount of water is measured from the ready-mixed concrete discharged with the discharge rate adjusted by the moisture sensor provided in the concrete hopper.

In this way, the discharge rate of all the ready-mixed concrete to be shipped from the concrete hopper is always adjusted to the same rate, and the moisture amount is measured by the moisture sensor provided in the concrete hopper. Regardless of the type and property of green concrete, you can always measure the stable water content without the need for sampling.
It is possible to grasp the accurate water content of all ready-mixed concrete while continuing to ship normally.

According to the quality control method for ready-mixed concrete according to claim 2, the unit water content is obtained from the water content measured by the method, and the unit cement content is obtained from the measured value of the cement mixed at that time, The W / C (water cement ratio) is derived from the unit water amount and the unit cement amount.
Since W / C has a certain relationship with the compressive strength of green concrete, the compressive strength of green concrete is estimated using a calibration curve based on the derived W / C.

Further, according to the quality control method of green concrete as claimed in claim 3, the compressive strength of the green concrete estimated by the method is compared with the planned compressive strength planned at the stage of mixing design, If there is a difference of more than a predetermined value, the mix value of the ready-mixed concrete to be manufactured next time is corrected appropriately based on this difference value amount, so the manufacturing data is immediately fed back to the subsequent manufacturing. Therefore, it is possible to stably produce high-quality fresh concrete with little variation in compressive strength.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a part of a ready-mixed concrete manufacturing plant adopting the quality control method for ready-mixed concrete of the present invention. A water measuring tank 1 for measuring water as a concrete material, and a cement measuring for measuring cement. Tank 2, sand measuring tank 3 for measuring sand, and gravel measuring tank 4 for measuring gravel
A concrete mixer 5 for kneading these concrete materials and a concrete hopper 6 used in the shipping process for temporarily storing and shipping the fresh concrete after kneading
Are installed.

Each of the measuring tanks is provided with load cells 7, 8, 9, 10 which are material measuring means, and
A drain valve 11 is provided below the water measuring tank 1, and discharge gates 12, 13 and 14 are provided below the remaining measuring tanks.

In this embodiment, a biaxial mixer is used as the concrete mixer 5. The biaxial mixer penetrates the kneading tank 15 through the two parallel kneading shafts 16 and 16 ', and they are opposite to each other. It is rotatably supported in any direction. A large number of arms 17 are radially arranged on the kneading shafts 16 and 16 ', and a blade 18 having an appropriate angle is attached to the tip of the arms 17, and a driving motor (not shown).
To rotate at a predetermined speed. Reference numeral 19 denotes a discharge gate for discharging the raw concrete in the concrete mixer 5 from the lower portion of the kneading tank 15, which is opened and closed by expanding and contracting the piston rod of the cylinder 20.

Below the concrete mixer 5, a concrete hopper 6 for temporarily storing the fresh concrete kneaded in the concrete mixer 5 is arranged. Below the concrete hopper 6, a concrete hopper 6 is provided as a discharge gate for discharging the fresh concrete. A flexible rubber gate 21 having a tubular shape is provided. The rubber gate 21 has a pair of rollers 2 which are nipped and pressed from both sides to open and close the opening.
2 are arranged. The roller 22 is pivotally attached to the lower end of an arm 25 rotatably attached to a support member 23 fixed to the hopper body by a shaft body 24, and the roller 22 is rotatable around the shaft body 24 as a fulcrum. There is. On the other hand, the rollers 22 are attached to the tips of the piston rods 27 of the pair of cylinders 26 attached to both ends of the support member 23. The rollers 22 are moved forward and backward according to the expansion and contraction of the piston rods 27, and the rubber gate 21 is moved. The pressure is applied from both sides and the pressure is released.

Further, a potentiometer 28 is provided on the shaft 24 to detect the rotation angle of the arm 25. The opening angle of the rubber gate 21 is accurately determined from the rotation angle of the arm 25, and Based on the above, the piston rod 27 of the cylinder 26 is controlled to expand and contract to adjust the opening degree.

Further, an ultrasonic or laser type distance sensor 29 is provided on the ceiling of the concrete hopper 6, and the distance sensor 29 specifies the level position of the surface of the fresh concrete in the concrete hopper 6 in real time.
The information is transmitted to the operation panel 30.

Here, since the capacity of the concrete hopper 6 is known in advance, as shown in the figure, for example, reference points A and B are set at different depth positions of the concrete hopper 6, and the surface of the fresh concrete being discharged is set. The discharge speed of the fresh concrete discharged from the concrete hopper 6 can be calculated based on the time required for the level position to pass the reference points A and B. At this time, if the type of ready-mixed concrete is high-fluidity concrete or the like, the surface of the ready-mixed concrete is substantially horizontal, so that a more accurate value can be expected for the indexed discharge rate. As a means for detecting the increase / decrease amount of the fresh concrete in the hopper, other than using the distance sensor 29, the concrete hopper 6 is provided with a plurality of level meters for direct detection, or the concrete hopper 6 is provided with a load cell. For this purpose, it is possible to employ an apparatus in which the increase / decrease amount of green concrete is detected from the variation amount of the weight of the hopper.

Further, the side wall of the concrete hopper 6 is provided with a moisture sensor 31 utilizing microwaves or neutrons for measuring the moisture content of green concrete,
The sensor portion at the tip is passed through the side wall of the concrete hopper 6 to face the inside of the hopper.

Here, the moisture sensor 31 has 0.1 to 1
Since the total amount of water contained in all the measurement objects in the measurement range around the sensor part is integrated within a unit time of about a second, if the measurement object flows, and it flows. If the speed is different each time, the amount of the measurement object passing through the measurement range within the unit time naturally changes, and as a result, the amount of water varies unexpectedly and accurate measurement cannot be performed. Since the flowability of green concrete varies greatly depending on its properties and types, even if the gate opening is set to be the same, there will be a large difference in the discharge rate, and it will not always be possible to obtain a stable and accurate water content. Can not. Meanwhile, while measuring the water content, the concrete hopper 6
There is also a method of temporarily storing fresh concrete in the inside, but in the case of high-fluidity concrete, etc., aggregate parts such as gravel will sink during storage, and the amount of water will be biased Not only that, but it also leads to a decrease in the shipping efficiency of ready-mixed concrete.

Therefore, a standard discharge speed, which is a reference, is set in advance as the discharge speed of the green concrete, and compared with the actual discharge speed derived from the data of the distance sensor 31, so that both are substantially constant speed. By appropriately adjusting the opening of the rubber gate 21 and controlling the discharge rate to be constant at all times, it is possible to measure the water content in a stable and accurate manner.

Further, on the operation panel 30, the rotation angle data of the arm 25 sent from the potentiometer 28, and
Input / output unit 3 for inputting / outputting the increase / decrease amount data of fresh concrete from the distance sensor 29, the water amount data from the moisture sensor 31, and the mixture value data of concrete materials.
2 and the standard mix value for each type of ready-mixed concrete, the correction value of the mix value according to the water content of the ready-mixed concrete, or the rotation angle data, the increase / decrease data, and the water content data are stored. Storage unit 33 for storing
And calculating the gate opening degree from the rotation angle data of the arm 25, calculating the discharge speed of the fresh concrete from the increase / decrease amount data, and deriving the W / C based on the water content data and the cement measurement value, An arithmetic unit 34 for estimating the compressive strength of green concrete based on this W / C, or for adding / subtracting the correction amount of the mixture value to the standard mixture value.
An input unit 35 for inputting and setting various data, a display unit 36 for displaying various data and compound values, a control unit 37 for controlling these units, and the like.

Next, a procedure for producing ready-mixed concrete by the above apparatus will be described with reference to a flow chart. Note that S1 to S28 in the figure represent each step.

First, based on each standard mix value of each fresh concrete such as high-fluidity concrete and high-strength concrete in advance, based on the planned compressive strength planned at the time of mix design and the water content of the freshly mixed concrete. The correction amount of the blending value to be adjusted according to the estimated difference in estimated compression strength is calculated.

Then, as an initial setting on the operation panel 30,
The standard mixture value for each of the ready-mixed concrete obtained earlier is input and stored (S1), and then the amount of correction of the composition value is calculated according to the difference between the estimated compressive strength and the expected compressive strength estimated from the mixed ready-mixed concrete. An input is stored (S2), and a reference discharge speed serving as a reference is set as the discharge speed of the ready-mixed concrete discharged from the concrete hopper 6 to be input and stored (S3). Then, it is determined whether or not the initialization is to be ended (S4), and if it is to be continued, the process returns to step S1 to continue the input, while if it is to be completed, the process proceeds to END to end.

Next, if there is a request for shipment of ready-mixed concrete, the type of ready-mixed concrete is input to the operation panel 30 (S
5) The standard mixture value corresponding to the type of green concrete input from the storage unit 33 is read (S6). Then, the standard mixture value is set on the operation panel 30 (S7), and each of the measuring tanks 1 for water, cement, sand and gravel is set based on the set mixture value.
Each material is weighed in 2, 3, and 4 (S8), and each weighed material is discharged to the concrete mixer 5 and kneaded (S8).
9) Then, the ready-mixed concrete thus kneaded is discharged to the concrete hopper 6 (10), and then discharged from the concrete hopper 6 to a mixer truck on standby (S11). Then, it is judged whether or not the production of ready-mixed concrete is to be finished (S12), and if it is to be continued, step S13.
While proceeding to step to correct the blended value, EN when finishing
Proceed to D to finish manufacturing.

When producing ready-mixed concrete subsequently,
The distance sensor 29 continuously measures the level of the fresh concrete surface discharged from the concrete hopper 6 to detect the discharge amount of the fresh concrete (S13), and calculates the discharge rate of the fresh concrete from the discharge amount per unit time. Yes (S14). Next, this actual discharge speed and step S
3 is compared with the reference discharge speed set in step 3 (S15), and it is determined whether there is a speed difference between the two (S16). If there is a speed difference, the cylinder 26 is controlled to control the rubber gate 21. The opening is changed, and the discharge rate of the fresh concrete is adjusted so that the two become approximately constant speed (S17). Then, the water content in the fresh concrete is measured by the water sensor 31 (S18). On the other hand, if there is no difference in speed, the water content is measured while maintaining the gate opening.

Next, while the unit water content is calculated from the water content thus obtained (S19), the unit cement content is calculated from the measured value of the cement actually measured to produce this fresh concrete (S20). And W / C is derived from the unit cement amount (S21). And this W /
Based on C, the compressive strength after pouring fresh concrete is estimated by the calibration curve stored in advance in the storage unit 33 (S2).
2).

Next, the estimated compressive strength thus obtained is compared with the planned compressive strength planned at the stage of compounding design (S2
3) It is determined whether or not the strength difference between the two is greater than or equal to a predetermined size (S24). S25), input this correction amount to the operation panel 30 (S2
6) Addition / subtraction is performed on the standard mixture value to obtain a corrected mixture value (S27), and this corrected mixture value is reset on the operation panel 30 (S28). Then, based on this new corrected mixture value, the process returns to step S8 and the steps of weighing, kneading, and discharging are performed again. On the other hand, if the difference in strength is within the predetermined range, the process returns to step S8 without correction, and the steps of weighing, kneading, and discharging are similarly performed to produce ready-mixed concrete.

It should be noted that the compressive strength of green concrete produced with this corrected mixture value is similarly estimated, and if there is a variation compared with the previously estimated compressive strength, the compressive strength is the same as the previous time. The correction amount of the blended value corresponding to the strength is read out, the calculation is performed to correct the blended value again, and the corrected blended value is set again in the operation panel 30.

As described above, the water content at the time of kneading is measured every time the fresh concrete is manufactured, and W is calculated from the water content.
/ C is derived, and the compressive strength is estimated based on the W / C, and the estimated compressive strength is fed back to the mix value of the fresh concrete to be manufactured next time, so that the optimum amount of water that is consistent with the current water content of the fresh concrete is always obtained. It is possible to manufacture ready-mixed concrete with the mixture value.

It should be noted that the allowable range of the fluctuation amount of the compressive strength estimated from the ready-mixed fresh concrete is stored in the operation panel 30 in advance, and when the estimated compressive strength of the ready-mixed concrete is out of the allowable range. It may be configured to issue an alarm or the like, and the compound value may be corrected only when the alarm is issued.

Of the above steps, step S13
If the operation panel 30 is configured to automatically perform steps from Step S28 to Step S28, it is possible to always produce the ready-mixed concrete with the optimum mix value without the need for the operator to bother.

[0036]

As described above, according to the quality control method for ready-mixed concrete according to the first aspect of the present invention, the discharge speed for detecting the discharge speed of the ready-mixed concrete in the hopper of the concrete hopper of the ready-mixed concrete manufacturing plant. Equipped with a detection means, the discharge gate at the bottom of the concrete hopper is equipped with an opening adjustment means for adjusting the gate opening, and the sidewall of the concrete hopper is equipped with a moisture sensor for measuring the water content of the fresh concrete. At the time of discharging, the gate opening is adjusted by the opening adjusting means so that the discharging speed of the fresh concrete detected by the discharging speed detecting means is always a predetermined speed, and from the fresh concrete discharged in that state, Since the moisture content is measured by the moisture sensor, it does not affect the type and properties of fresh concrete. Not, the moisture content of all raw concrete rose kneaded in real time and can be accurately grasped, it is possible to make the quality control of the raw concrete based on this.

According to the quality control method of green concrete according to the second aspect of the present invention, while the unit water amount is obtained from the water amount of the green concrete measured by the method,
The unit cement amount is calculated from the measured value of the cement actually measured in the cement measuring tank of the plant, and W / C (water cement ratio) is derived from these unit water amount and unit cement amount, and based on this W / C, ready-mixed concrete Since the estimation of the compressive strength is performed, the estimation of the compressive strength of the ready-mixed concrete after placing can be made with little error.

According to the quality control method for green concrete according to the third aspect of the present invention, the composition value of the green concrete to be manufactured next time is corrected based on the compressive strength of the green concrete estimated by the method. Therefore, the production data of this time can be immediately fed back to the subsequent production, and high-quality ready-mixed concrete with little variation in compressive strength can be stably produced.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a part of a ready-mixed concrete manufacturing plant adopting a quality control method for ready-mixed concrete according to the present invention.

FIG. 2 is a flowchart showing a quality control procedure of green concrete.

[Explanation of symbols]

1 ... Water measuring tank 2 ... Cement measuring tank 3 ... Sand measuring tank 4 ... Gravel measuring tank 5 ... Concrete mixer 6 ... Concrete hopper 21 ... Rubber gate 22 ... Roller (opening degree adjusting means) 26 ... Cylinder (opening degree adjusting means) 28 ... Potentiometer (opening degree adjusting means) 29 ... Distance sensor (increase / decrease amount detecting means) 30 ... Operation panel 31 ... Moisture sensor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasunori Suzuki             Sumitomo Osaka Center, 585 Tomimachi, Funabashi, Chiba Prefecture             Cement Concrete Research Co., Ltd.             In-house (72) Inventor Motoaki Yoshida             1 of 1013 Eijima, Okubo-cho, Akashi-shi, Hyogo               Nikko Co., Ltd. F term (reference) 4G056 AA07 CB17 CB20 DA05 DA08

Claims (3)

[Claims] 1. A concrete hopper of a fresh concrete manufacturing plant is provided with an increase / decrease amount detecting means for detecting an increase / decrease amount of raw concrete in the hopper, and an opening adjusting means for adjusting a gate opening degree is provided at a discharge gate below the concrete hopper. Along with the concrete hopper side wall equipped with a moisture sensor to measure the water content of the fresh concrete, when the fresh concrete is discharged from the concrete hopper, the increase / decrease amount detecting means detects the discharge amount of the fresh concrete and discharges it per unit time. The discharge rate is calculated from the amount, the gate opening is adjusted by the opening adjusting means so that this discharge rate is always a predetermined speed, and the water content is measured by the moisture sensor from the fresh concrete discharged in that state. A quality control method for ready-mixed concrete, characterized by being measured. 2. The unit water content is calculated from the water content of the fresh concrete measured by the above method, while the unit cement content is calculated from the measured value of the cement actually measured in the cement measuring tank of the plant. W from the amount of cement
The method for controlling quality of ready-mixed concrete according to claim 1, characterized in that / C (water cement ratio) is derived and the compressive strength of the ready-mixed concrete is estimated based on this W / C. 3. The quality control method for ready-mixed concrete according to claim 2, wherein the compounding value of ready-mixed concrete to be produced next time is corrected based on the compressive strength of the ready-mixed concrete estimated by the method.