JP5283555B2 - Estimation method of concrete properties - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for continuously estimating fresh properties of ordinary concrete with sufficient accuracy. <P>SOLUTION: The method for estimating the properties of the ordinary concrete includes the steps of pouring fresh ordinary concrete C into a hopper 13 of a concrete pump 1, and estimating the fresh properties of the ordinary concrete based on a hydraulic pressure p3 of a stirring hydraulic motor 35 associated with rotation of stirring blades 15 stirring the fresh concrete C in the hopper 13, and a rotation frequency r3 of the stirring blades 15. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for estimating the properties of concrete for estimating the properties of ordinary concrete.

  In quality control of concrete structures, it is necessary to manage the fresh properties of concrete when placing concrete. In general, it is known that the fresh properties of concrete vary depending on changes in the surface water ratio of aggregates, changes in the quality of materials used, environmental conditions, and the like. In particular, the influence of the surface water ratio of the aggregate is large, and if the setting of the surface water ratio at the time of concrete production is different from the actual setting, the unit water volume may be larger than the prescribed composition, and in this case the durability of the concrete will be reduced To do.

  Because of this, in order to drive concrete of a certain quality during the construction of concrete structures, acceptance inspection and management are performed by the slump test (JIS A 1101) and the air volume test (JIS A 1128) of fresh concrete before placing. Has been done. However, since these tests are based on sampling inspection, it is not possible to confirm the fresh properties of concrete in lots that are not inspected. For this reason, when concrete that is out of the allowable range is driven, there is a possibility that durability will be lowered and troubles such as pump blockage and jumper may be caused. Moreover, even if it is within the allowable range, if the variation is large, the driving may be affected. For example, in the JIS, a concrete with a slump of 8 cm has an allowable range of a slump of 8 ± 2.5 cm in consideration of the variation in fresh properties as described above, and a concrete with a slump of 5.5 to 10.5 cm is recognized. However, although concrete with a slump of 10.5 cm can be pumped and compacted relatively well, concrete with a slump of 5.5 cm may have initial defects due to poor pumping and compaction. In view of the above, in order to ensure the quality of the concrete structure, it is desirable to manage the quality of the fresh concrete by simply monitoring the whole quantity at the site and taking corrective action if variations are observed.

  Therefore, in addition to sampling inspection, estimation methods described in Patent Documents 1 and 2 below are known as techniques for estimating the properties of concrete continuously to some extent. In the estimation method of Patent Document 1, when fresh concrete is loaded on a truck agitator, the rotational speed and driving pressure of the truck agitator are detected, and the water-cement ratio of the fresh concrete is estimated based on the rotational speed and the driving pressure. Is. Moreover, the estimation method of patent document 2 provides the obstacle frame which can rotate along the flow direction of the said high-fluidity concrete in the flow path of high-fluidity concrete, and the resistance force which an obstacle frame receives when high-fluidity concrete flows down is provided. By measuring, the quality of the high fluidity concrete is quantitatively determined.

JP 2001-174389 A Japanese Patent Laid-Open No. 10-176982

  However, in the track agitator drum in the estimation method of Patent Document 1, the entire volume is not filled with fresh concrete, but usually fresh concrete and air are mixed in the drum. Therefore, a sufficiently clear correlation does not hold between the fresh property and the rotational speed and driving pressure of the track agitator, and the fresh property cannot be estimated with sufficient accuracy by the estimation method of Patent Document 1. . Moreover, the estimation method of patent document 2 measures the resistance force of an obstruction frame, flowing down fresh concrete. Therefore, it can be applied to high-fluidity concrete with high fluidity, but when applied to ordinary concrete, fresh concrete does not flow down sufficiently in the flow path, so there is a gap between the fresh properties and the resistance of the obstacle frame. No clear correlation is established, and the method of Patent Document 2 cannot be applied to ordinary concrete.

  An object of this invention is to provide the estimation method which can estimate a fresh property continuously in sufficient accuracy with sufficient precision.

The concrete property estimation method according to the present invention is a concrete property estimation method for estimating the property of ordinary concrete, in which fresh concrete concrete is put into a concrete pump hopper and the fresh concrete in the hopper is agitated. A property estimation step for estimating the fresh property of ordinary concrete based on a load value related to the rotation of the blade for stirring and a stirring load expressed as a function of the number of rotations of the blade is provided. In the property estimation step, the fresh concrete in the hopper Detecting the level of the water, setting an appropriate range of the stirring load corresponding to the detected level, obtaining the actual stirring load value, comparing the actual stirring load and the appropriate range, and estimating the fresh properties It is characterized by that.

  In this estimation method, since fresh concrete is continuously put into the hopper of the concrete pump and the load value and the rotational speed can be continuously obtained while stirring, the fresh property can be estimated continuously. . Moreover, since fresh concrete is stirred in a hopper, it is thought that the correlation between a blade load value and rotation speed and fresh properties becomes clear. Therefore, according to this estimation method, it is possible to obtain the load value and the rotation speed under a condition where a clear correlation appears between the blade load value and the rotation speed and the fresh property of ordinary concrete. Based on the value and the number of rotations, the fresh property of ordinary concrete can be estimated with sufficient accuracy.

The property estimation step may be further performed based on the volume of fresh concrete accumulated in the hopper. For example, when the agitation blade is not completely buried in fresh concrete, it is considered that the degree of burial of the blade affects the correlation between the rotation state of the blade and the fresh property. Since this estimation method uses a method of storing fresh concrete in the hopper, the degree of impregnation of the blades is almost uniquely determined from the volume of fresh concrete stored in the hopper. Therefore, according to this estimation method, it is possible to estimate the fresh property in consideration of the degree of burial of the stirring blade.

  According to the concrete property estimating method of the present invention, it is possible to continuously estimate fresh properties with sufficient accuracy in ordinary concrete.

It is sectional drawing which shows the concrete pump used for the estimation method of the concrete property which concerns on 1st Embodiment of this invention. It is a block diagram which shows the information acquisition part which acquires information, such as a load value of the concrete pump of FIG. It is a graph which shows an example of transition of the agitation load in pumping of fresh concrete. It is sectional drawing which shows the concrete pump used for the estimation method of the concrete property which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the other type concrete pump used for the estimation method of the concrete property which concerns on this invention.

  Hereinafter, a preferred embodiment of a concrete property estimation method according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
The concrete pump 1 shown in FIG.1 and FIG.2 is used for the concrete property estimation method according to the present invention. The concrete pump 1 is a piston-type concrete pump that is mounted on a concrete pump car and continuously pumps normal concrete fresh concrete C supplied from a truck agitator. Here, “ordinary concrete” refers to those having a slump value of 5 to 21 cm and requiring compaction by a vibrator. In particular, ordinary concrete which is generally used has a slump value of 8 to 15 cm. On the other hand, the one having a slump value of 23 cm or more and requiring no compaction by a vibrator is referred to as “highly fluidized concrete”.

  The concrete pump 1 includes a hopper 13 into which fresh concrete C, which is ordinary concrete, is charged and temporarily stored, and a stirring blade 15 provided in the hopper 13. The agitation blade 15 agitates the fresh concrete C stored in the hopper 13 by rotating around the horizontal axis. The concrete pump 1 further includes a transport pipe 17 that extends in the horizontal direction below the hopper 13 and transports the fresh concrete C, and a connecting portion 19 that connects the transport pipe 17 and the hopper 13.

  Furthermore, the concrete pump 1 includes a slip valve 21 that opens and closes the connecting portion 19 and a piston 23 that pushes the fresh concrete C in the transport pipe 17 in the horizontal direction. When the slip valve 21 and the piston 23 operate in cooperation, the fresh concrete C in the hopper 13 is sent out to the transport pipe 17. That is, the fresh concrete C is put into the hopper 13, stirred by the stirring blade 15, passes through the connecting portion 19 that is opened / closed by the slide valve 21, and then pushed through the transport pipe 17 by the piston 23. The concrete pump 1 includes a slip valve hydraulic cylinder 31 that reciprocates the slide valve 21, a main hydraulic cylinder 33 that reciprocates the piston 23, and a stirring hydraulic motor 35 that rotates the stirring blade 15. The hydraulic cylinders 31 and 33 are supplied with hydraulic pressure from the main hydraulic pump 41, and the agitation hydraulic motor 35 is supplied with hydraulic pressure from the agitation hydraulic pump 45. The main hydraulic pump 41 and the agitation hydraulic pump 45 are driven by an engine 51 of a concrete pump vehicle connected via a PTO 53.

  Further, as means for measuring the load value of the concrete pump 1, a pressure gauge P1 for measuring the hydraulic pressure of the slide valve hydraulic cylinder 31, a pressure gauge P2 for measuring the hydraulic pressure of the main hydraulic cylinder 33, and a stirring hydraulic pump 35 A pressure gauge P3 for measuring the hydraulic pressure is attached. Further, a tachometer R3 for measuring the rotation speed of the stirring blade 15 is attached to the shaft of the stirring blade 15 of the concrete pump 1. The measured values obtained by the pressure gauges P1 to P3 are input to the computer 61 as hydraulic pressures p1, p2, and p3, respectively, via a pressure transducer, a dynamic strain amplifier, and an AD converter. The measurement value obtained by the tachometer R3 is input to the computer 61 as the rotation speed r3 via the FV converter and the AD converter. As the pressure gauges P1 to P3 and the tachometer R3, those having a known configuration may be used.

  Furthermore, a level sensor 63 that detects the level of fresh concrete C accumulated in the hopper 13 is provided inside the hopper 13. The level sensor 63 is a sensor that is attached to a position of a predetermined height on the inner wall surface of the hopper 13 and detects fresh concrete C. As the level sensor 63, for example, an electrode sensor, an ultrasonic sensor, an optical sensor, or the like is used. The level sensor 63 can detect whether the fresh concrete C is filled up to the predetermined height in the hopper 13. Information from the level sensor 63 is input to the computer 61 via the AD converter. The predetermined height of the inner wall surface of the hopper 13 is a position higher than the upper end of the stirring blade 15, and the computer 61 determines whether or not the stirring blade 15 is completely buried below the liquid surface of the fresh concrete C. Can be detected.

  Then, the estimation method which estimates the fresh property of the said fresh concrete C during the pumping of the fresh concrete C using the above-mentioned concrete pump 1 is demonstrated.

  During the pumping of the fresh concrete C, the slip valve 21, the piston 23, and the stirring blade 15 are driven, and information on the hydraulic pressures p1 to p3 and the rotation speed r3 is constantly input to the computer 61.

  Since the load generated in the concrete pump 1 is related to the fluidity and viscosity of the fresh concrete C, the load value of the concrete pump 1 and the rotational speed r3 of the stirring blade 15 are monitored as the total amount of fresh properties. The load values used here are the hydraulic pressures p1 to p3 as described above. The measurement data of the hydraulic pressures p1 to p3 and the rotation speed r3 are singly or combined to grasp the relationship with the fresh property in advance, and when the measurement data fluctuates, it is determined that the fresh property varies. be able to. The correlation between the above measured data and the slump value is not uniquely determined by the type of pump car, individual variations, concrete composition, materials used, etc. It is necessary to keep it.

  Below, the estimation of the slump value (fresh property) of the fresh concrete C using the stirring oil pressure p3 and the rotation speed r3 will be described as an example.

  Here, an index such as “stirring load L” expressed as a function of the stirring hydraulic pressure p3 and the rotation speed r3 is considered. Considering the state where the fresh concrete C is accumulated up to the position of the level sensor 63 in the hopper 13, in such a state that the stirring blade 15 is completely buried under the liquid surface of the fresh concrete C, stirring is performed. It can be considered that a clear correlation is established between the load L and the slump value of the fresh concrete C. While the fresh concrete C is being pumped, the computer 61 constantly acquires the stirring load L based on the stirring hydraulic pressure p3 and the rotational speed r3. In this case, the stirring load L may be derived based on measurement data of the stirring hydraulic pressure p3 and the rotation speed r3 for several minutes, for example. In this way, the influence of sudden fluctuations in the stirring hydraulic pressure p3 and the rotational speed r3 due to factors unrelated to the slump value can be eliminated from the stirring load L.

  First, in concrete placing work, fresh concrete from a track agitator is put into the hopper 13, and the fresh concrete is pumped by the concrete pump 1. At this time, during the operation of the concrete pump 1, the computer 61 calculates the agitation load L based on the agitation hydraulic pressure p3 obtained from the pressure gauge P3 and the rotation speed r3 obtained from the tachometer R3.

And when the fluctuation | variation of the stirring load L is large, the computer 61 considers that the slump value (fresh property) of the fresh concrete C is fluctuate | varied largely, and performs the process which issues a warning. Specifically, the upper limit value and the lower limit value of the slump value allowed for the fresh concrete C are determined, and as shown in FIG. 3, the lower limit value L ₁ of the stirring load L corresponding to the upper limit slump value, and the lower limit value We calculated in advance by the preliminary test and an upper limit value L ₂ of the stirring load L corresponding to slump value. Then, variation such as stirring load L falls below the lower limit L ₁ as 46 batched 3, or variations such as stirring load L exceeds the upper limit value L ₂ as 23 batched 3 occurs In such a case, the computer 61 performs processing for issuing a warning.

  Moreover, since the stirring load L is influenced by the volume of the fresh concrete C in the hopper 13, it is necessary to exclude these influences in order to estimate the slump value of concrete correctly. Therefore, the agitation load L needs to be managed using measurement data when the fresh concrete C accumulated in the hopper 13 is accumulated up to the position of the level sensor 63. As such a management method, for example, when adding fresh concrete C to the hopper 13, when the fresh concrete C is charged so that the level of the level sensor 63 is filled, the charging is temporarily stopped. In this state, a method of obtaining the stirring hydraulic pressure p3 and the rotation speed r3 is conceivable.

  Further, as another management method, for example, the fresh concrete C is intermittently charged into the hopper 13, the stirring load L is constantly obtained, and the level of the fresh concrete C accumulated in the hopper 13 is measured by the level sensor 63. A method of estimating the slump value by using only the data of the stirring load L acquired when the level is equal to or higher than this level is conceivable. In view of construction efficiency, the latter management method is desirable. In this case, the computer 61 can determine whether or not the fresh concrete C has reached the level based on the signal from the level sensor 63. Here, the volume of the fresh concrete C accumulated in the hopper 13 is determined almost uniquely from the level of the fresh concrete C in the hopper 13.

  It is also possible to grasp the variation in the slump value of the fresh concrete C by grasping how much the stirring load L of the batch has changed with respect to the stirring load L of the previous batch. Regarding the correlation between the slump value and the stirring load L, it is desirable that the slump value can be estimated directly from the variation of the stirring load L. Even when the estimation cannot be performed directly, it is sufficient if the accuracy is such that it can be determined that the slump value of the fresh concrete C varies when the stirring load L fluctuates beyond a certain level.

  If the above warning is issued, the fresh concrete C will be tested by performing a slump test and air volume test to confirm the actual fresh properties. If it is out of specification, contact the plant and correct it. Manage properties. At this time, if the slump test and the air amount test result in non-standard values, the fresh concrete C accumulated in the hopper 13 is discharged through a branch valve (not shown) provided in the hopper 13. It is not used for driving work.

  According to the method for estimating the fresh property, the fresh concrete C can be continuously supplied to the hopper 13 of the concrete pump 1 and the oil pressure p3 and the rotation speed r3 can be continuously obtained while stirring. Therefore, the fresh property is estimated. Can be performed continuously. Further, since the fresh concrete C is put into the hopper 13 of the concrete pump 1 and stirred, the stirring blade 15 can be rotated in a state where the stirring blade 15 is buried in the fresh concrete C in the hopper 13. Thus, in the state where the stirring blade 15 is buried in the fresh concrete C, it is considered that the correlation between the hydraulic pressure p3 and the rotational speed r3 and the fresh properties of the fresh concrete C is clear. Therefore, according to this estimation method, the stirring load L can be acquired under a condition where a clear correlation appears between the stirring load L and the fresh property, and sufficient accuracy can be obtained based on the stirring load L. Can be used to estimate the fresh properties of ordinary concrete.

  In addition, the fresh concrete C gradually hardens during the concrete placing operation, and the slump value tends to gradually decrease. According to the fresh property estimation method, the tendency of the slump value to decrease as described above can be continuously recognized during pumping, and appropriate measures can be taken.

  According to the concrete management as described above, it is possible to ensure a predetermined durability of the concrete structure and prevent initial defects by placing concrete of a stable quality, thereby ensuring the quality of the concrete structure. be able to. In addition, it can be used as data for proving that the quality of the concrete structure is secured.

(Second Embodiment)
In this embodiment, the fresh property is estimated based on the volume of the fresh concrete C accumulated in the hopper 13.

  Specifically, as shown in FIG. 4, a plurality of level sensors 65 are attached to the positions of the respective levels in the hopper 13. The level sensor 65 has the same configuration as the level sensor 63 described above. Information from each level sensor 65 is input to the computer 61. The computer 61 can detect to what level the fresh concrete C in the hopper 13 is accumulated based on the signals from the level sensors 65. That is, the plurality of level sensors 65 function as level detection means for detecting the level of fresh concrete C accumulated in the hopper 13 (volume of fresh concrete C).

In this embodiment, it defines the upper limit value and the lower limit value of the slump value allowed for fresh concrete C, and stirred load lower limit L ₁ of L corresponding to the upper limit slump value, agitation load corresponding to the lower limit slump value of L and upper limit value L ₂ of the preliminary test, determined in advance for each level of the fresh concrete C. During concrete pumping, the computer 61 detects the level of the fresh concrete C together with the stirring load L, sets the lower limit L ₁ and the upper limit L ₂ corresponding to the level, and the stirring load L is the lower limit. If the variation as below the value L _1, or stirring load L that exceeds the upper limit value L ₂ changes occur, performs processing computer 61 issues a warning.

  For example, when the stirring blade 15 is not completely buried in the fresh concrete C, it is considered that the degree of embedding of the stirring blade 15 affects the correlation between the stirring load L and the fresh property. Since this estimation method uses a method of storing fresh concrete C in the hopper 13, the degree of embedding of the stirring blade 15 is determined almost uniquely from the level of the fresh concrete C stored in the hopper 13. Therefore, according to this estimation method, it is possible to estimate the fresh property in consideration of the degree of embedding of the stirring blade 15.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the fresh property is estimated based on the stirring hydraulic pressure p3 and the rotation speed r3, but the fresh property may be estimated based on information obtained by further combining the hydraulic pressures p1 and p2. Similarly to the hydraulic pressure p3, the hydraulic pressures p1 and p2 have a correlation with the fresh properties, and are considered to vary according to the fresh properties.

  Moreover, in the said embodiment, although the piston-type concrete pump is used, the estimation method of this invention can be used also at the time of concrete pumping by the squeeze-type concrete pump 201 as shown, for example in FIG. The concrete pump 201 includes a hopper 213 into which fresh concrete C is charged, and a stirring blade 215 that stirs the fresh concrete C in the hopper 213. The hopper 213 is connected to the transport pipe 217 via a pumping tube 263 provided in the drum 261. The drum 261 includes a rotor 265 that rotates inside the pumping tube 263, and a roller 267 that can rotate with respect to the rotor 265 and is pressed against the pumping tube 263. In this concrete pump 201, the rotor 265 rotates and the roller 267 rolls in the conveying direction while being pressed against the pumping tube 263, whereby the fresh concrete C in the hopper 213 is pushed to the conveying pipe 217 through the pumping tube 263. .

  In this case, the fresh properties are estimated based on the hydraulic pressure (load value) of the stirring hydraulic motor that rotates the stirring blade 215 and the rotational speed of the stirring blade 215. At this time, the fresh property may be estimated based on information obtained by further combining the hydraulic pressures of the rotor hydraulic motor that rotates the rotor 265.

  DESCRIPTION OF SYMBOLS 1,201 ... Concrete pump, 13,213 ... Hopper, 15,215 ... Stirring blade, 31 ... Sliding valve hydraulic cylinder, 33 ... Main hydraulic cylinder, 35 ... Stirring hydraulic motor, C ... Fresh concrete, P1, P2, P3 ... Pressure gauge, R3 ... tachometer.

Claims (2)

A method for estimating the properties of concrete to estimate the properties of ordinary concrete,
The normal concrete fresh concrete is put into a hopper of a concrete pump, and based on the load value related to the rotation of a stirring blade that stirs the fresh concrete in the hopper and the stirring load expressed as a function of the rotational speed of the blade. And a property estimation step for estimating the fresh property of the ordinary concrete ,
In the property estimation step,
Detecting the level of the fresh concrete in the hopper, setting an appropriate range of the stirring load corresponding to the detected level, obtaining the value of the actual stirring load, the actual stirring load and the A method for estimating the properties of concrete, characterized in that the fresh properties are estimated by comparing with an appropriate range . The property estimation step includes:
The method for estimating a property of concrete according to claim 1, wherein the method is further performed based on a volume of the fresh concrete accumulated in the hopper.

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