JPH0822549B2 - Method for early estimation of concrete unit water volume and strength - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for early estimation of concrete unit water content and strength, and more specifically, concrete unit water content used for quality control, shipment inspection and quality certification for delivered ready-mixed concrete in a ready-mixed concrete (fresh concrete) factory. A method for early estimation of strength.

[0002]

2. Description of the Related Art Regarding quality control, shipping inspection and quality assurance for delivered ready-mixed concrete at a ready-mixed concrete factory,
The quality of the ready-mixed concrete (generally 28 days strength))] was generally used.

[0003]

By the way, in the above-mentioned conventional method, the strength cannot be judged until four weeks have passed after the placement of the ready-mixed concrete. Therefore, if there is a quality defect, the ready-mixed concrete is solidified at that time, and the building must be demolished and the construction must be redone, resulting in great damage.

Therefore, the industry has made every effort to develop a method for determining the strength of ready-mixed concrete at an early stage. as a result,
The hot water curing 7-day method and the mortar rapid hardening method are being researched, but the judgment results are still obtained after the placement of the ready-mixed concrete and it is already late. Moreover, all of these methods are test specimen systems in which a part of the product is taken out when pouring fresh concrete, and it is impossible to estimate its strength prior to pouring fresh concrete. As described above, a method capable of promptly and simply estimating the strength is indispensable for both the manufacturer and the purchaser of ready-mixed concrete, but the current situation is that few methods have been put to practical use.

Therefore, the present invention has been proposed in view of the above problems, and an object of the present invention is to provide a method capable of estimating the strength of a ready-mixed concrete early by a simple means prior to placing the fresh mixed concrete. To do.

[0006]

As a technical means for achieving the above object, the method for early estimation of concrete unit water amount according to the present invention is to install the aggregate storage bottle or measuring tank on the surface of the aggregate. The water content including the moisture adhering to the
Wherein the output voltage and aggregate moisture meter for connection and accurately measure
Relational expression with water content V = Ae- ^PM [V: output voltage, M: bone
Moisture content of wood, A, P: constants that change depending on the type of aggregate
[A number] from the output
From the water content obtained from the voltage, absorbed inside the aggregate
The surface water rate excluding the water content is calculated, and the surface water rate and aggregate
The feature is that the surface water amount of the aggregate is calculated from the amount and summed with the measured water amount to obtain the total water amount, and the unit water amount of the concrete is obtained from the total water amount.

Further, the method for early estimation of concrete strength according to the present invention is based on the unit water content and cement obtained by the above method.
Based on the unit amount of cement obtained from the amount of cement, the relational expression a +
It is characterized in that the 28-day strength of concrete is estimated during the manufacturing process by b · C / W [C: amount of cement , W: total amount of water , a, b: constant].

Further, in the method for early estimation of concrete unit water amount and strength, the unit water amount and the unit water amount obtained by the above method together with the unit cement amount for each batch or ready-mixed concrete truck are 2
It is also possible to print and record the 8-day strength for quality certification and quality assurance.

[0009]

In general, the strength of ready-mixed concrete is determined by the relational expression a + b · C / W based on the ratio of cement and water.
If the exact amount of cement and total water in the ready-mixed concrete are known, the strength of the ready-mixed concrete can be estimated. Therefore, in the present invention, the aggregate is attached to a storage bottle or a measuring tank and attached to the surface of the aggregate.
Moisture content for continuous and accurate measurement of moisture content
Relational expression V = Ae between the output voltage of the meter and the water content of the aggregate
^-After calibrating A and P from ^PM , output
From the water content obtained from the voltage, absorbed inside the aggregate
Obtain the surface water ratio excluding water . And, with its surface water rate
Calculated on the total amount of water by totaling the aggregate amount and metering water by indexing the surface water of the aggregate, if dividing the concrete volume from the total water, unit water content of concrete is obtained. By fitting each unit cement amount based on the unit amount of water and cement amount to the equation a + b · C / W,
The strength of the ready-mixed concrete can be estimated in the first half of the mixing process during the preparation of the ready-mixed concrete.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of an apparatus for carrying out the method of the present invention will be described below with reference to FIG.

FIG. 1 shows the construction of an example of an apparatus used in a ready-mixed concrete factory. In FIG. 1, (1) to (3) are storage bins containing aggregate [gravel, sand], and (4) are storage bins ( Installed on the side of 1)-(3), storage bin (1)-
A moisture meter sensor for measuring the water content of aggregate (gravel, sand) in (3), and (5) a moisture meter amplifier for amplifying the output voltage detected by the moisture sensor (4) and converting it digitally. , (6) is a weighing hopper of an aggregate (gravel, sand) weighing machine,
(7) is a load cell which is a weighing sensor of an aggregate [gravel, sand] weighing machine, (8) is a discharge gate of a weighing hopper of the aggregate [gravel, sand] weighing machine, and (9) is a weighing hopper of a water weighing machine. ,
(10) is a load cell which is a weighing sensor of a water weighing machine,
(11) is the discharge gate of the weighing hopper of the water weighing machine, (1
2) is a weighing hopper of the cement weighing machine, (13) is a load cell which is a weighing sensor of the cement weighing machine, (14) is a discharge gate of the weighing hopper of the cement weighing machine, and (15).
Is a mixer for kneading aggregates, water and cement, which are raw materials compounded and weighed by each weighing machine, (16) is a measurement control panel, (17) is a CPU device, and (18) is a printer. A high-impedance amplifier that can obtain an accurate measured value is used for each measuring sensor.

In the method of the present invention, the water content of the aggregate [gravel, sand]
Amount (Amount of water absorbed inside the aggregate + adhesion to the surface of the aggregate
The amount of surface water) was accurately measured by the high-precision moisture meter sensor (4) and the moisture meter amplifier (5), and was measured by the load cell (7) in the weighing hopper (6) of the aggregate weighing machine.
Based on the amount of aggregate, it will adhere to the surface of the aggregate [gravel, sand]
The surface water was accurately indexing, which was weighed by load cell (10) in the metering hopper of water weighing machine (9) Weighing
The total amount of water is calculated by the CPU device (17) by summing it with the amount of water, and the unit amount of water is calculated by the CPU device (17) by dividing the total amount of water by the volume of concrete. ) To record. The unit cement amount is also calculated by the CPU device (17) based on the measured value of the cement measured by the load cell (13) in the weighing hopper (12) of the cement weighing machine and recorded by the printer (18).

The amount of water to be measured and the amount of cement are obtained by subtracting the weight before the start of weighing from the weight after the completion of weighing, and each weighing sensor detects the weight with high impedance and affects the existing weighing control panel (16). There is no consideration.

Further, based on the unit water amount and the unit cement amount obtained by the above-mentioned method, the estimated strength is calculated by the CPU device (17) by the relational expression [described later] by the ratio of cement and water, and the printer ( Record in 18). By recording the unit water amount, unit cement amount, and estimated strength by these printers (18), the quality certification and quality assurance of ready-mixed concrete is performed.

Next, the method of the present invention will be specifically described below based on an experiment conducted by the present inventor. The apparatus configuration in this experiment is as shown in FIG. 1 described above.

First of all, prior to carrying out the method of the present invention, raw concrete kneading is carried out in advance to collect the following data for each batch [for example, about 20 batches].

Storage bottle (1) for aggregate (gravel, sand)
From (3), the aggregate is sampled by an appropriate means at the time of charging into the weighing hopper (6), and its moisture [moisture content,
Surface water ratio] is measured by a predetermined method.

[0018] A raw concrete prepared by kneading the blended and measured aggregate, water and cement is put into a mixer truck and then stirred and sampled to measure the 28-day strength and slump (softness) which have been conventionally performed.

The weight of the aggregate [gravel, sand], water, cement, and admixture is collected by the measurement control board (16) in the same manner as in the conventional method.

After collecting the above-mentioned data, the amount of aggregate [gravel, sand] and measuring water in the example of the apparatus implemented by the method of the present invention
The amount of cement and the amount of cement are detected for each batch.

First, the water content of the aggregate [gravel, sand] sampled as described above is determined by using a moisture meter sensor (4) and a moisture meter amplifier (5) , for example, a microwave moisture meter.
It is measured by the method described below . This microwave moisture meter
By contacting the moisture sensor (4) with the aggregate
The microwave response transmitted from the moisture sensor (4)
It receives the waves, and the amount of water contained in the aggregate is high.
The microwaves are absorbed and the amount of reflected waves received decreases,
Has the characteristic that the reception amount increases as the water content decreases.
The output voltage is the value obtained by converting the received amount of reflected waves into a voltage value.
It This output voltage and the water content are generally V = Ae
^-PM [V: output voltage (V), M: moisture content (%) of aggregate,
A, P: constants that change depending on the type of aggregate]
Have a relationship. Here, the value that depends on the type of aggregate
If the numbers A and P are not determined, the water content can be calculated from the output voltage.
Area of the sampled aggregate has a high water content
And the lower part, select the moisture sensor in that part.
The output voltage detected by (4) and the JIS
According to the usual method for measuring water content [JIS A1125]
The constants A and P are obtained from the measured values of water content. The output power
You from the pressure in the above equation V = Ae ^-PM so that the moisture content is required
To obtain constants A and P, that is, output voltage and water content
As a result of performing calibration with
2 and 3 show the correlation between the output voltage and the water content.
You. In the calibrated waveforms of the output voltage and the water content shown in FIGS. 2 and 3, the solid line and the dotted line are based on the first and second measurements. In addition, Figure 2 shows the aggregate of coarse sand [ calibration
Line S1] and FIG. 3 are for fine sand aggregate [ calibration curve S2].

Next, in the calibration of the above-mentioned output voltage and water content,
The obtained water content is calibrated [converted] into the surface water content.
In addition, to calibrate [convert] the water content into the surface water rate,
Based on the reason. In other words, when placing ready-mixed concrete on site,
Factors such as fluidity and softness are related to workability and strength.
Will be important. This greatly affects workability and strength
Is the total amount of water kneaded into aggregate and cement.
In addition to the measured amount of water, the total amount of water
Surface water content. On the other hand,
The amount of absorbed water is not included in the total amount of water, so
Does not affect workability or strength. Therefore, the surface water ratio of the aggregate
Is very important for quality control.
On the other hand, the microwave moisture meter has the characteristics of the microwave.
Moisture content that has penetrated into the inside of the aggregate (absorption inside the aggregate
The amount of surface water adhering to the surface was added to the absorbed water amount.
Water content measured with a microwave moisture meter to determine
From water absorption rate (water absorption rate + surface water rate) to surface water rate [conversion]
Is required. Generally, this calibration method is
The amount of water absorbed inside the material is the type of aggregate (place of origin, etc.)
It has been found that the values are almost constant if
It From this, the type of aggregate used (such as the place of origin)
The corresponding water absorption rate was measured by using a microwave moisture meter.
Surface by subtracting from water rate (water absorption rate + surface water rate)
Calculate the water rate. In addition, the moisture meter amplifier of the microwave moisture meter
In (5), the output detected by the moisture sensor (4)
Based on the water content obtained from the relational expression between voltage and water content
The surface water ratio is calculated and converted into a BCD code,
Has a function to output the surface water ratio converted to BCD code.
I do. Where determined based on microwave moisture meter
Surface water rate (vertical axis) and aggregate measured by microwave moisture meter
Based on the same sampling as JIS method [JIS A
1125 or 1111] surface water determined by analysis
The relationship with the rate (horizontal axis) is shown in FIGS. 4 and 5. Incidentally, as in the case of FIGS. 2 and 3 described above, FIG. 4 is a coarse sand aggregate [test
The amount lines S1], Figure 5 shows those for aggregate fine sand [calibration curve S2]. 4 and 5, the dotted curve is
Shows the standard deviation obtained based on the measured data,
The solid line is the confidence limit line due to the variation of the data.
The straight line is an approximate straight line obtained from the confidence limit line.
It From this approximate straight line, the value is calculated based on the microwave moisture meter.
Determined by the measured surface water ratio and analysis by JIS method
The relationship with the surface water rate is required.

By the method of the present invention, the surface water content of the aggregate is calculated from the surface water content and the aggregate content calculated as described above.
The total amount of water is obtained by summing the amount of water and the total amount of water is divided by the volume of concrete to obtain the unit water amount of concrete by the CPU device (17). Based on this unit water amount and unit cement amount, the CPU device (17) calculates the ratio of cement and water. Showing the correlation between the 28 day strength was measured by the above-described this cement and water ratio in FIG. 7, following
The estimated strength is obtained as described below .

For comparison with this,
Total water volume and cement that is calculated by adding the measured water volume to the surface water volume calculated from the JIS method and the amount of aggregate [gravel, sand]
Fig. 6 shows the relationship between the ratio of cement and water obtained from the amount of cement and the actually measured 28-day strength.

Generally, the 28-day strength of ready-mixed concrete is
Ratio of water to water [C / W: C is the amount of cement, W is the total amount of water]
Is in a linear relationship with. That is, the relational expression is 28 days strength =
a + b ・ C / W [a, b: constant] and cement
The more water, the higher the strength, and the more water, the lower the strength.
is there. Here, the cement amount C in the above formula is the cement
Load cell (1) in the weighing hopper (12) of the weighing machine
3), and the total water content W is
In the load cell (10) of the weighing hopper (9) of the water weighing machine
It should be the amount of measured water plus the amount of aggregate surface water.
It In this way, the cement content C and the total water content W can be obtained.
For example, you can calculate the ratio C / W of cement and water,
28 days strength is measured by sampling fresh concrete from the same batch.
Once determined, the values of a and b in the above equation can be obtained and the cement
The relationship between the water / water ratio C / W and the 28-day strength is obtained. Figure 6
The scatter plot of is the surface measured by the JIS method according to the above.
Cement and water ratio C / W based on water rate and 28-day strength
The relationship is shown and the dotted curve is based on the measured data.
The standard deviation obtained by
It is the confidence limit line that comes out, and the straight line shown by the solid line is the above
Ru approximate line der obtained from the limit line. Where
Relationship, 28 days strength = a + b · C / W, sem
The ratio of water and water C / W is Xa, and the intensity on 28th is Ya.
For example, the approximate straight line obtained from this scatter diagram is Ya = 244.5Xa-76.9 (A) , and the correlation coefficient is 0.956.

On the other hand, the scatter diagram of FIG.
Surface water measured by a microwave moisture analyzer, for example
Between cement and water ratio C / W and 28-day strength based on rate
The curve shown by the dotted line is similar to the scatter diagram in FIG.
Indicates the standard deviation obtained based on the measured data, and
It is a confidence limit line due to the dispersion of data and is shown by the solid line.
The straight line is an approximate straight line obtained from the confidence limit line.
It Here, the above-mentioned relational expression, 28-day strength = a + b · C
/ W, the ratio of cement to water C / W is Xb, 28
If the daily intensity is Yb, the approximate straight line obtained from this scatter plot
The line is Yb = 216.7Xb-57.3 (B) , and the correlation coefficient is 0.962.

As a result, from the comparison between the equations (A) and (B), the correlation coefficient in the equation (B) is higher.
We show that the 28-day intensity can be estimated with fairly good accuracy.

FIG. 8 shows an example of printing by the printer.
In the items in the figure, TIME is the measuring time, W is the measuring water.
Amount [kg], S is the amount of aggregate [kg],% is the surface water rate of the aggregate [measured by a moisture meter], dW is the amount of surface water [kg], and dW = S ×
{0.01 × [%] / (1 + 0.01 × [%])}, TW is the total water amount [kg] and TW = dW + W, C is the cement amount [kg], and y is the estimated amount . Strength (a + b ・
C / TW) is shown.

[0029]

EFFECTS OF THE INVENTION Conventionally, the strength of the ready-mixed concrete could be judged only four weeks after the casting, but according to the present invention, the strength can be estimated in several tens of seconds, and in the factory, the mixing process during the preparation of the ready-mixed concrete can be performed. In the first half, the quality [strength] of the ready-mixed concrete can be estimated at an early stage, and it becomes possible to secure the built-in quality [strength] during the manufacture of the ready-mixed concrete. Issuance became possible.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of an implementation device in the present invention.

FIG. 2 is a correlation diagram showing calibration of the output voltage and moisture content obtained by a moisture meter for the aggregate [S1].

FIG. 3 is a correlation diagram showing calibration of the output voltage and moisture content obtained by a moisture meter for the aggregate [S2].

FIG. 4 shows an aggregate [S1] based on a microwave moisture meter.
Based on the surface water rate obtained by
Correlation diagram showing the relationship with the calculated surface water ratio

FIG. 5 shows an aggregate [S2] based on a microwave moisture meter.
Based on the surface water rate obtained by
Correlation diagram showing the relationship with the calculated surface water ratio

FIG. 6 is a scatter diagram showing the correlation between the ratio of cement and water based on the JIS method and the measured 28-day strength.

FIG. 7 is a scatter diagram showing the correlation between the ratio of cement and water based on the method of the present invention and the measured 28-day strength.

FIG. 8 is a diagram showing an example of printing by a printer.

[Explanation of symbols]

 1-3 Storage bottles 4 Moisture sensor 5 Moisture amplifier 17 CPU device

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Shin Takeyama 4-5-12 Benten, Urayasu City, Chiba Prefecture (72) Inventor Tadao Ono 6-13-17 Kofudai, Toyono-cho, Toyono-gun, Osaka Prefecture

Claims (3)

[Claims] 1. A mounting et al storage bin or metering tank of the aggregate
The moisture content including the moisture adhering to the surface of the aggregate is continuous.
Output Voltage of Moisture Meter and Accurate Water Content of Aggregate
Relational expression V = Ae ^−PM [V: output voltage, M: inclusion of aggregate
Water rate, A, P: constants that vary depending on the type of aggregate]
After calibrating A and P, from the output voltage
From the obtained moisture content, the moisture absorbed inside the aggregate was calculated.
It is characterized in that the surface water ratio to be excluded is calculated, the surface water amount of the aggregate is calculated from the surface water ratio and the amount of aggregate, and the total water amount is calculated by adding it to the measured water amount, and the unit water amount of concrete is calculated from the total water amount. Method for early estimation of concrete unit water volume. 2. A relational expression a + b.C / W based on the ratio of cement and water in which the compressive strength is calibrated in advance based on the unit water amount obtained by the method of claim 1 and the unit cement amount obtained from the cement amount. [C: amount of cement , W: total amount of water ,
a, b: constant], the 28-day strength of the concrete is estimated during the manufacturing process. 3. A unit of the amount of cement and the unit amount of water and the 28-day strength obtained by the above method are printed and recorded for each batch or each of the ready-mixed concrete cars for quality certification and quality assurance. Or the method for early estimation of concrete unit water content and strength according to 2.