JPH0339802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing ready-mixed concrete, and in particular, the mixing ratio of raw materials necessary to determine the quality of concrete is determined by adjusting the mixing ratio of raw materials necessary for determining the quality of concrete, based on the ready-mixed concrete production conditions, the time of measuring the raw materials, and the time of mixing with a mixer. This invention relates to a method for manufacturing ready-mixed concrete that is modified and controlled through information processing with various sensor information.

By changing the mixing ratio of raw materials, concrete can be produced with different qualities depending on its purpose. In other words, based on the premise of obtaining uniform quality at an economical cost, by varying the proportions of raw materials such as cement, aggregate, water, and admixtures that make up concrete, we can create structures using concrete. It is necessary to select concrete of the desired quality by comprehensively considering differences in the type of concrete, construction conditions such as weather, and construction method. In this case, quality refers to the degree of ease of work, that is, workability, in the case of uncured concrete, and refers to properties such as compressive strength, durability, and watertightness in the case of hardened concrete. and,
The former, workability, is represented by the construction softness of concrete, that is, the slump value, which is closely related to the amount of water used in concrete.The latter, such as compressive strength, is represented by the amount of water in concrete and the ratio of water amount to cement amount (water It has been found that the most significant effect is on the cement ratio. Therefore, in order to obtain concrete of the desired quality, it is important to accurately grasp the amount of water involved in the concrete.

Conventionally, in the ready-mixed concrete production method, the specifications of the order from the customer, who is the consumer of the ready-mixed concrete, and the intended use of the product are often used at concrete product manufacturing plants, in many cases, the specified strength, specified slump, and specified air volume are specified. With the aim of receiving orders determined by the company, we select in advance through testing the mixing ratio of raw materials that will yield the desired compressive strength, durability, watertightness, etc. and quality according to the slump value when manufacturing ready-mixed concrete. (Select the specified mixing ratio), prepare many types of selected mixes, apply them to a batch plant, supply one mix of raw materials according to the mix ratio to a measuring bottle, and produce ready-mixed concrete for each mix. Ta. In this case, the blending ratio selected in the test mixing is determined by a single, almost pure type that is clearly differentiated, such as only aggregate for aggregate, only water for water, and only cement. We do not handle raw materials containing two or more types, such as aggregates containing water.

However, in this case, the problem that the amount of water mentioned above cannot be accurately grasped arises. Among the raw materials for concrete, the aggregates include coarse aggregate with a size of 5 mm or more and fine aggregate with a size of 5 mm or less, and the surface of these aggregates is in a so-called dry saturated state with no moisture adhering to the surface. (This refers to the so-called specified formulation). However, in reality, washing water or rainwater adheres to the surface of this aggregate during aggregate receiving or storage in the stockyard, and the aggregate that is then weighed in a weighing bin is free of the adhering water. The surface dryness and water saturation state of the specified formulation cannot be achieved with the included weight. Therefore, in order to manufacture concrete with a predetermined quality, it is necessary to calculate the amount of adhering water as part of the mixing water amount. In other words, it is necessary to correct the amount of water adhering to the aggregate as part of the mixing water amount, and after making this correction, unless measurement is performed, the specified mixing ratio will not be achieved (hereinafter referred to as the standard mix, or indicated mix). The target change is called correction, and here we calculate the amount of water adhering to the aggregate and the amount of dilution water in the aqueous admixture solution as part of the mixing water amount, and the operation to reflect it in the weighing ratio of raw materials is calculated based on the amount of water adhering to the aggregate and the amount of dilution water in the aqueous admixture solution. Mixture correction based on the amount of dilution water in the aqueous admixture solution (referred to simply as correction). In order to correct the amount of adhering water, conventionally some aggregates are collected several times a day during storage in stockyards or in storage bins or weighing bins, and the surface moisture content of the aggregates is measured by drying or other means, and the raw materials are weighed. The composition is being corrected. However, adhering water is not uniformly distributed in the aggregate and changes over time due to weather conditions such as temperature and humidity during transportation.
Measuring the surface water rate several times a day makes it impossible to accurately determine the amount of adhered water. Therefore, it is desirable to measure the surface water content of the aggregate used for each mixing, and considering the process of producing ready-mixed concrete in a batch plant, rapid and continuous measurement is required, requiring only a few seconds to several tens of seconds. Become. In the end, the method of measuring the surface water content by drying the aggregate to reduce its weight requires a great deal of labor and time if you want to accurately grasp the adhering water and perform continuous and quick measurements. As a practical matter, it is impossible to measure. In this way, since the amount of water involved in the concrete mix (in this case, correction by water adhering to the aggregate) cannot be accurately grasped, it is not possible to specify desired qualities such as slump value and compressive strength.

Assuming that the surface water content of the aggregate can be accurately determined, and after making appropriate corrections to obtain the desired quality of concrete, when considering whether or not the concrete has the desired quality, as mentioned above, There are two types of aggregate: coarse aggregate and fine aggregate, but due to recent aggregate conditions, their physical properties such as particle size and shape are changing in the short term. Quality such as slump value and compressive strength tend to be uncertain, and on-site mixing that takes into account the particle size and shape of the aggregate is further required.

Here we will discuss the particle size of aggregate, especially the particle size of fine aggregate, which affects the quality of concrete. As already mentioned, the particle size of fine aggregate is an extremely important factor in determining the mixing ratio of concrete with the required quality. The particle size of fine aggregate used for concrete is generally 0.15 mm, 0.3 mm, 0.6 mm, 1.2 mm, 2.5 mm, 5 mm, 10
It is expressed as the sum of the weight percentages remaining on each mm sieve (coarse particle ratio), and this coarse particle ratio is the mixing ratio of fine aggregate and coarse aggregate among the raw materials used for concrete (generally, the fine aggregate volume and It is an important factor in determining the fine aggregate ratio (expressed as the percentage of the fine aggregate volume to the total volume of coarse aggregate volume and is called the fine aggregate ratio), and the coarse grain ratio of the fine aggregate used in a ready-mixed concrete production plant is an important factor in determining the fine aggregate ratio. If the coarse grain ratio of the fine aggregate used to determine the mix differs, the fine aggregate ratio of the concrete must be appropriately reselected and the indicated mix initially determined by test mixing must be changed.

On the other hand, here we will discuss the slump value, which is the quality of concrete. As mentioned above, the slump value indicates the construction softness, but this measurement is performed by filling a truncated conical cylindrical formwork with mixed concrete and measuring the drop in height due to the concrete's own weight when the formwork is removed. It is done by measuring the amount. However, it is impossible to continuously carry out this measurement throughout the production period during the ready-mixed concrete manufacturing process due to labor and time constraints, so visual inspections are carried out by experienced personnel, but the judgments tend to be subjective and place a burden on the staff. Very large. In this way, it is quite difficult to accurately judge the slump value, but it is also difficult to accurately understand the factors that influence the slump value itself, and even if you do, it is difficult to create concrete that takes these factors into account. In other words, in addition to physical properties such as the surface water content of the aggregate and particle size of the aggregate mentioned above, the ripeness and temperature during storage are factors that have a great effect on the slump value, as they are brought into the batcher plant. The temperature of the mixed concrete, the temperature of the mixed concrete, and the concentration of sludge from the water collected after washing the mixer car, which is used as mixing water for pollution prevention measures, etc. These factors interact in a complex manner, so the slump value It is difficult to accurately grasp the quality of the product, which in turn makes it difficult to obtain the desired quality.
Based on the above-mentioned factors, even if the operation of changing the specified formulation determined through testing and practice was carried out frequently by hand, it would require a great deal of labor and time and would be practically impossible in the field.

The quality of concrete must not only be determined during the production process of fresh concrete, but also ensure the compressive strength of hardened concrete. However, during the production of ready-mixed concrete, the only option is to estimate the strength of the 28-day-old concrete empirically, or to prepare it with excessive additional strength in mind, which is extremely uneconomical. Moreover, as mentioned above, the amount of water in concrete,
Since there is uncertainty in the aggregate, slump value, etc., there are many uncertainties in determining the desired compressive strength of concrete that has passed a specified material age, and it is difficult to ensure that the concrete structure has the specified quality. Failure to do so may result in serious defects.

In this way, even if you want to specify the required quality such as slump value and compressive strength to obtain the appropriate concrete, it is realistic to accurately reflect factors such as the amount of attached water, particle size, temperature, etc. in the concrete mix ratio. It was impossible. That is, if the specified mix determined by conventional test mixing is used as is, concrete having the required quality cannot be obtained.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, the present invention aims to provide a method for producing ready-mixed concrete that allows concrete of desired quality to be obtained.

In order to obtain the required quality, the proportions of each raw material shown in the specified mix of concrete determined by test mixing are corrected (hereinafter, the specified mix (hereinafter referred to as the specified mix) is The operation of changing the blending ratio of each raw material shown in the table is called blending modification or simply modification.

Therefore, unlike the above-mentioned correction that aims at the indicated formulation, the correction aims at the actual formulation at the site (on-site formulation). ), it is based on the fact that information from sensors is added to preset ready-mixed concrete manufacturing conditions and information is processed and controlled by a computer.

To achieve the above purpose, when raw materials are discharged into a mixer for mixing after being weighed in a weighing bottle, information from raw materials, information from mixed ready-mixed concrete, and information from manufacturing conditions are processed. The basic idea is to modify the specified proportions of raw materials.

Examples of the present invention will now be described. Figure 1 shows two steps taken at the batchya plant of a ready-mixed concrete manufacturing factory that continuously produces ready-mixed concrete.
The relationship between the timings at which multiple weighing machines linked to the base mixer (No. 1, No. 2) operate based on sensor information is illustrated by focusing on one weighing machine. At a ready-mixed concrete manufacturing factory, an operator inputs a standard mixing ratio of raw materials prepared in advance based on the order specifications from a delivery destination. With this input, the raw material in the storage bin is supplied to the measuring bin according to the raw material measurement set value per kneading, and measurement is started. The start time of measuring the raw materials is shown at _T1 in Figure 1. 60% of raw material measurement set value
At time T ₂ , when approximately 80% rough measurement has been performed, a sensor installed in the weighing bin measures the surface water content of coarse aggregate and fine aggregate, cement temperature, and a portion of the mixing water. The sludge concentration of the recovered water is detected. In addition, the mixer No. is determined by weighing two batches before.
The slump value of the concrete mixed in step 1 and the temperature of the concrete are also detected and stored by the sensor. The measurement time of the surface water content, etc. is at the time _T3 when the mixing by mixer No. 1 is completed, which is before the time _T2 when the rough measurement is approximately completed.

Based on the aggregate surface water percentage, cement temperature, and sludge concentration detected at T ₂ and T ₃ , the standard mixing ratio set by the operator is corrected or modified in order to make the concrete conform to the ordered specifications. . Since this correction/correction is based on sensor information and computer processing, it can be carried out with plenty of time during weighing. After correcting and correcting the measured values, a micrometer of the raw materials is executed and the measurement of the mixing amount is completed at time T ₄ . After this, mixer No.1
After confirming that the mixed concrete inside has been discharged to the wet batch hopper (time T ₅ ), the weighed raw materials are discharged to mixer No. 1.
Mixing of the raw materials discharged to mixer No. 1 is immediately started (time T ₆ ), and during this mixing, the above-described detection of the slump value and concrete temperature is repeated. The measuring device that discharged the raw material to mixer No. 1 starts the next rough measurement again.

In this way, when the rough measurement is almost completed in the measuring device, the surface water percentage, cement temperature, and sludge concentration are detected, and the mixing ratio is corrected and corrected based on this detection immediately during this measurement, and the mixer based on the measurement two batches ago is The slump value and concrete temperature can be detected from the mixed concrete inside.
Corrections and corrections to the blending ratio based on this detection can also be made immediately during this measurement. In this case, the slump value and concrete temperature of the concrete mixed in the mixer are measured in order to reflect the mixing results in the mixer in the next mixing. In the above example, two mixers are used for one set of measuring devices, and mixing requires a relatively long time, such as a tilting mixer. In the case of a forced kneading mixer with a short purpose, one mixer may be provided for one set of measuring devices. In the case of this latter forced kneading mixer,
The slump value and concrete temperature from the just-mixed concrete will be detected.
In addition, in the case of a ready-mixed concrete factory equipped with the above-mentioned forced mixing mixer, if it is impossible to roughly measure and trace the raw materials due to lack of time in the ready-mixed concrete manufacturing process, It is also possible to measure the surface water content of the aggregate and use it as data for the measured proportions of raw materials for the concrete that will be mixed next.

The general method of this embodiment has been described above, and will be explained in detail below along with the calculations performed by the computer.
Ready-mixed concrete manufacturing equipment can be viewed as a continuous manufacturing system consisting of multiple processes. Conventionally, when inputting the raw material mix by an operator, first the raw materials cement, aggregate,
After confirming the quality of concrete when the mixing ratio of water, admixtures, etc. Create a standard recipe list in advance. next,
We compare the order items such as specified slump value, specified strength, maximum size of coarse aggregate, etc. from the delivery destination with the standard mixture table.
A compatible formulation is selected and entered.

In factories where a computer is connected to the batch plant, this standard formulation is stored in the computer, and when an operator inputs the order details in response to a shipping request, the computer can automatically extract the specified standard formulation. can.

As input information to the computer, information such as a mixture table, slump value, strength, maximum dimension of coarse aggregate, etc. can be associated with information on the delivery destination of ready-mixed concrete, and stored as a number. The amount of fresh concrete loaded onto the mixer truck and the mixer truck number can also be stored in association with each other. Additionally, it is possible to automatically record calculations of the total amount of ready-mixed concrete delivered to the delivery destination, clear indication of manufacturing time, and breakdown of the amount of ready-mixed concrete mixed in one mix. In this way, by storing all the predetermined information about the delivery destination in association with each other, it becomes possible to centrally manage the production and delivery of ready-mixed concrete.

Now, raw materials are supplied from the storage bin to the weighing bin according to the operator's mixing instructions, and rough weighing is also started. Then, when the rough weighing is almost completed, the second
Calculation is started based on the blocks shown in the figure.

FIG. 2 shows an arithmetic block by a computer. This calculation block is a case where two mixers are installed for one set of measuring devices. When the operator inputs the setting number on the operation panel 7, the mixing conditions of the concrete and the delivery destination of the ready-mixed concrete are checked, and the initial setting value 8 is determined by referring to the standard mixing table stored in advance according to the mixing conditions.
call. This initial setting value 8 indicates the standard blending amount of each material per 1 m ³ of ready-mixed concrete, and the amount of cement
C1 (Kg), coarse aggregate amount G1 (Kg), fine aggregate amount S1 (Kg), and water amount W1 (Kg) are determined, and the water-cement ratio F = W1 / C1, which is related to specified strength 1, is also determined. In the actual measuring step, the raw material is measured by multiplying this unit amount by the mixing amount of one kneading. Based on the raw material information in the rough weighing stored in the weighing bin and the information on the mixed concrete two batches ago, the computer performs correction calculations 8' and corrections for the unit quantity.
A correction calculation 9 is performed. The content of correction calculation 8' for the unit amount is correction 97 of the fine aggregate ratio based on the coarse particle ratio of fine aggregate, and the content of 9 is correction 91 of the aggregate amount based on the aggregate surface water percentage, and the amount of cement. Correction 92, water amount correction 93 based on aggregate surface water percentage, water amount correction 94 based on slump difference, water amount correction 95 based on sludge concentration difference of recovered water, and water amount correction 96 based on temperature difference of mixed concrete and cement temperature difference.
It is. This unit amount correction/correction calculation 9 is a calculation performed within the computer, and additions and subtractions can be made from the initial setting value 8. However, in actual weighing, the computer quickly provides the correction/correction calculation results as soon as the rough measurement is reached. Based on this, weighing of the remaining portion will proceed and be completed.

First, fine aggregate ratio correction by coarse particle ratio of fine aggregate97
I will explain about it.

The initial setting value of 8 is fine aggregate amount and coarse aggregate amount, respectively.
G1 (Kg) and S1 (Kg), coarse grain ratio FMM of fine aggregate described later, standard coarse grain ratio FMP of fine aggregate when determining the standard mix, fine aggregate ratio for increase of coarse grain ratio 1.00 The rate of change E (%), the specific gravity of fine aggregate SSG, the specific gravity of fine aggregate GSG, and the unit amounts of fine aggregate and coarse aggregate after correction are respectively S11 (Kg) and G11 (Kg).

The fine aggregate ratio SA1 (%) based on the initial setting value 8 is: SA1=S1/SSG/S1/SSG+G1/GSG×100=(100)(S1)
It is expressed as (GSG)/(S1)(GSG)+(G1)(SSG). In addition, fine aggregate ratio SA2 after mixing correction
(%) is expressed as SA2=SA1+(E)(FMM-FMP).

Therefore, the corrected fine aggregate unit amount S11 (Kg)
and coarse aggregate unit amount G11 (Kg) are determined by the following formulas.

S11=(SA2/100)(S1/SSG+G1/GSG)(SSG)=(1
/100) {(E) (FMM-FMP) + (100) (S1) (GSG) / (S1) (GSG) + (G1) (S
SG)} {S1+(SSG/GSG)(G1)} G11=(1-SA2/100)(S1/SSG+G1/GSG)(GSG)=
{1−(S1)(GSG)/(S1)(GSG)+(G1)(SSG) −(E)(FMM−FMP/100}{G1+(GSG/SSG)
(S1)} In this case, the means to obtain the coarse particle percentage of the fine aggregate used is to sample the fine aggregate in the stockyard, storage bin, or weighing bin an appropriate number of times a day, and conduct a test specified by JIS. In addition to the method of obtaining the measurement results using a method, there is also a method of continuously obtaining coarse particle ratio measurement results by applying an image analysis method or the like to fine aggregates falling from a conveyor belt or the like.

The value of the coarse grain ratio of the fine aggregate used thus obtained is input into the coarse grain ratio input device 21 each time the measurement result becomes clear. In this case, the standard coarse grain ratio FMP of the fine aggregate used when creating the standard recipe, the specific gravity SSG of the fine aggregate,
and the specific gravity GSG of the coarse aggregate are stored in advance in the computer along with other characteristic values.

The change rate E (%) in the fine aggregate ratio corresponding to the change in the fine aggregate coarse grain ratio in the above formula varies depending on the type of concrete, the grain shape of the aggregate used, etc., so these conditions Several types of values are stored in the computer and are selected and used according to the conditions.

Next, the aggregate unit amount correction 91 will be explained.
For coarse aggregate, the unit amount of coarse aggregate G11 (Kg) as a result of modifying the standard mix based on the correction of the fine aggregate ratio by the coarse grain ratio of fine aggregate, and the automatic measurement of aggregate surface water content as described below. Surface water percentage of coarse aggregate MG (%) determined by equipment,
From the correction amount G6 (Kg) of coarse aggregate due to surface water percentage and the weight G2 (Kg) of coarse aggregate after correction, G6=G1×(MG/100) G2=G1+G6=G1× {1+(MG/100) )}.

Similarly, for fine aggregate, the amount of fine aggregate S1 (Kg) with the initial setting value 8, the surface water percentage MS (%) of fine aggregate determined by the automatic aggregate surface water percentage measurement device described later, and the surface If the correction amount of fine aggregate due to water percentage is S6 (Kg) and the amount of fine aggregate after correction is S2 (Kg), then S6=S1×(MS/100) S2=S1+S6=S1× {1+(MS/100) )}.

Here, the automatic aggregate surface water rate measuring device will be described with reference to FIG. FIG. 3 exemplifies the case where the surface water content of aggregate is measured in a weighing bottle, and can also be measured in a storage bottle. FIG. 3 generally shows a weighing bin 22 in which the aggregate 21 discharged from the storage bin and to be coarsely weighed is retained. A suitable level meter detects the point at which the detection part insertion hole 27 formed in the lower part of the weighing bottle 22 is filled with aggregate 21 before the measurement is completed, and a signal from this level meter is sent to the detection part insertion air cylinder 26. Then, the air cylinder 26 is actuated to advance the needle-shaped detection part 25 of the surface water rate measuring device through the detection part insertion hole 27 into the protection tube 24 of the insertion detection part and insert it into the aggregate 21. The needle-like detection unit 25 measures the capacitance of the aggregate between the measurement electrodes, and stores the surface water percentage, which has a certain relationship with this capacitance, in the computer. The relationship between this capacitance and surface water content may change depending on the particle size of the aggregate, so several types are stored in the computer and selected according to the coarse particle size of the aggregate. . After measuring the capacitance, before the aggregate 21 is discharged from the weighing bottle 22, the air cylinder 26 is activated to return the needle-like detection section 25 to prepare for the next measurement. After the measurement is completed, the gate opening/closing air cylinder 29 is operated to open the discharge gate 28 and discharge the aggregate in the weighing bin 22 into the mixer. In addition,
Reference numeral 23 in FIG. 3 is a buffer plate for the aggregate that is supplied falling. The surface water percentage obtained by converting the electric signal obtained by the needle-shaped detection unit 25 as a capacitance is calculated as the above-mentioned MG (%) and MS (%) in block 16 of Fig. 2 as the aggregate correction amount. be involved in Block 16 is an automatic measuring device for aggregate surface water content, 161 and 162 are for supplying coarse and fine aggregates in a measuring bin, 163 and 164 are for measuring surface water content using a moisture meter, and 165 and 166 are for measurement. The surface water percentages obtained based on the results are shown below.

Figure 4 is an example of the results of measuring the surface water content of fine aggregate measured for ready-mixed concrete manufactured at a ready-mixed concrete manufacturing factory for each mixing using the measuring means shown in Figure 3. . At the same time, the surface water content obtained by measuring 20 times using the conventional absolute drying method is also listed. In FIG. 4, the horizontal axis indicates time, and the vertical axis indicates surface water percentage measured by a moisture meter. As a result, the third
The method using the diagram is more accurate with a difference of about ±0.4% compared to the absolute drying method, and furthermore, in this example, it is possible to measure each kneading process continuously and quickly. Fourth
As shown in the figure, the surface water content of fine aggregate changes significantly over time, and it has become clear that conventional measurements made several times a day are inaccurate. In this way, the surface moisture measurement of the aggregate for each milling can be used for highly accurate surface moisture correction.

As a result of the explanations in Figures 3 and 4, the surface water percentages MG (%) and MS (%) to calculate the corrected weights G2 (Kg) and S2 (Kg) of aggregate are accurate values. , the corrected weights G2 (Kg) and S2 (Kg) are extremely reliable.

Next, correction and modification of the unit amount of mixing water will be described. Regarding the correction and modification of the amount of mixing, in the calculation by the computer, water amount correction 93 based on aggregate surface water percentage, water amount correction 94 based on slump difference, water amount correction 95 based on sludge concentration difference of recovered water, temperature difference of mixed concrete, A water amount correction 96 is carried out based on the temperature difference in the cement.

The water amount correction amount W6 (Kg) based on the aggregate surface water percentage is the initial setting value of the aggregate in the surface water percentage MG and MS (%) mentioned above.
It is the product of G1 (Kg) and S11 (Kg), and corresponds to the addition of aggregate correction amounts G6 (Kg) and S6 (Kg) due to surface water content. In other words, W6=S1×(MS/100) +G1×(MG/100).

The unit water amount correction amount W7 (Kg) due to slump is calculated by feeding back the slump automatic measurement results, etc. from the previous batch to the current batch, and storing and processing the data in a computer, which will be explained below.

In the following description, only one of the two mixers will be described.

The unit water volume correction amount W7 of the current batch calculated by feeding back the slump related data of the previous batch
The breakdown of (Kg) is W7=W71+W72.

Here, W71 (Kg) is the unit water volume correction amount for the current batch calculated based on the difference between the target slump value and the automatically measured slump value for the previous batch, and W71 = A × (SLM ₂ - SLP) Using the formula ×W1, A (1/cm) is the rate of change in unit water volume per 1 cm increase in slump, SLP (cm) is the target slump value in the previous batch, SLM ₂ (cm) is the automatically measured slump value in the previous batch, and W1 ( Kg) is the unit water volume of the batch. Here, the target slump value is different from the specified slump value (see FIG. 2), and is a value obtained by adding the amount of water lost due to transportation etc. to the specified slump value.

W72 (Kg) is a correction made in proportion to the size of the unit water volume of the current batch in order to slide the slump-related unit water volume correction amount performed in the previous batch's measurement into the current batch's measurement. Using the formula W72 = W71'
(Kg) is the unit water volume of the current batch, and W1′ (Kg) is the unit water volume of the previous batch.

Here, for the automatic measuring device of the slump value, the fifth
This will be explained with reference to the figures. Since the stirring resistance during concrete mixing has a certain correlation with the slump value of concrete, the slump value can be determined by detecting the energizing current value or power consumption value of the mixer drive motor required for mixing. in this case,
A measurement method that can be put to practical use must be able to measure at a speed that does not cause any hindrance to the ready-mixed concrete manufacturing process, be able to obtain the measured information as an electrical signal, and have a measurement accuracy that can be put to practical use. Any material may be used as long as it is capable of continuous operation during the production of ready-mixed concrete and is durable in the measurement environment. In the example shown in FIG. 5, a current corresponding to the motor load is extracted from the mixer driving motor 30 using a current transformer, and then converted to voltage by a voltage converter 31, and a detected voltage signal is created in advance via a voltage filter 32. Based on the correlation between the voltage and the slump value, the slump value is converted into a slump value by a slump value conversion device 33, and the slump value is displayed. When measuring the current of the drive motor of the mixer, the current consumption rises rapidly after the raw material starts to be discharged into the mixer, and reaches its maximum when discharge is completed. Next, as the mixing of the concrete progresses, the current value decreases, and when it reaches a substantially constant value and stabilizes, the mixing of the concrete is completed. There is no difference in the pattern of such current changes even if there is a change in mixer type, such as a gravity type or a forced type. In this way, the output of the slump value conversion device 33 when the current consumption value is stabilized is the desired slump value. FIG. 6 is an example of the relationship between the slump value measured by the slump value measuring device shown in FIG. 5 and the slump value measured by the above-mentioned conventional test method specified in JIS. As can be seen from this figure, the slump value of the measurement method according to Figure 5 has a variation of only ±8.4% compared to the slump value of the JIS test method, that is, for concrete with slump values of 8 cm and 18 cm. 0.7cm and ±1.5
Since the fluctuation is on the order of cm, a sufficiently accurate slump value can be obtained by measuring the current of the mixer drive motor.

The automatic slump value measuring device 17 shown in FIG. 2 includes kneading 171 of raw materials using a mixer, measurement 172 using a slump value converting device 33 (see FIG. 5) when a stable current value of this kneading is obtained, and measurement. Each block has a slump value of 173 (SLM ₂ ) obtained based on . In this case, the stirring resistance changes depending on the concrete type KC, which has a different unit volume weight, such as the specified concrete type 4, ie, ordinary concrete or lightweight concrete, so this difference must be taken into account when measuring the slump value. Mixing amount of concrete V
Regarding (m ³ ), it is necessary to adjust the slump value depending on the specified mixing amount 5 and the difference in stirring resistance depending on whether one mixer or multiple mixers are used, and the adjustment between mixers. Furthermore, due to the specified maximum dimension 6 of the coarse aggregate, the difference in this dimension GS (mm) is reflected in the difference in the slump value, so it is necessary to take this difference into account. These items to be considered and adjusted may be tested or information obtained through testing may be stored in the computer in advance and used as necessary.

In this way, the slump value automatic measuring device 17 determines the slump value SLM ₂ (cm). In the explanation so far, the slump value SLM ₂ (cm) is calculated for mixing the raw materials two batches ago, but in a batch plant equipped with one mixer for one weighing device, the slump value SLM 2 (cm) is calculated for the mixing of the raw materials two batches ago. The slump value of mixed concrete according to SLM ₁ (cm) can be adopted. The above formula W71=A×(SLM ₂ −SLP ₂ )×W1
In this case, the rate of water change A (1/cm) may differ depending on the softness of the concrete, so several types are stored in the computer according to the slump value of the concrete, and the specified slump value 2 (SLP )
The selection may be made by comparing the information. In this case, the water amount correction W7 (Kg) can be made more accurately.

Regarding the correction of water amount due to the difference in sludge concentration in recovered water95, the amount of water corrected due to the difference in sludge concentration in recovered water.
W8 (Kg) is the rate of change in water volume B (1/%) for an increase of 1% in sludge concentration, the sludge concentration BM (%) determined by a sludge concentration measuring device, and the standard for recovered water used when determining the recommended mix. Sludge concentration BP
(%), water content W1 (Kg) at initial setting value 8
It is expressed by the following formula.

W8=B×(BM-BP)×W1 In this case, the sludge concentration measuring device 19 exists as a means to obtain the sludge concentration, but this device 1
9 measures the sludge concentration BM (%) using, for example, ultrasonic waves, scattered light-transmitted light characteristics, etc. for recovered water supplied from a measuring bottle as mixing water for producing each batch of concrete. It is something. In addition, the standard sludge concentration BP (%) takes a value of zero when clean water such as tap water is used as mixing water when determining the recommended mixture.

In the water amount correction 96 due to the temperature difference of mixed concrete or cement, the correction amount W9 (Kg) is determined by the concrete temperature CM ₂ (℃) of two batches ago obtained by a mixed concrete temperature measuring device, and the automatic cement temperature measurement. Cement temperature DM (°C) of the batch determined by the device, standard concrete temperature CP (°C) when the design mix was determined, standard cement temperature DP (°C) when the design mix was determined, and mixed concrete temperature Based on the water amount change rate C (1/℃) for an increase of 1℃, the water amount change rate D (1/℃) for a 1℃ increase in cement temperature, and the water amount mixture W1 (Kg/m ³ ) of the initial setting value 8. The following equation is obtained.

W9 = {C x (CM ₂ - CP) + D x (DM - DP)} x W1 In the above formula, C x (CM ₂ - CP) x W1 is for the purpose of adjusting the water amount according to the concrete mixing temperature. , D×(DM-DP)×W1 is a water amount adjustment to cope with the fact that when the cement temperature used is higher than the concrete mixing temperature, some sland drop occurs in the mixed concrete.

In this case, the concrete temperature CM ₂ (°C) is measured for the concrete mixed two batches ago, similar to the slump value described above. In a batch plant that is equipped with one mixer for one measuring device, the temperature of the concrete in the previous batch, CM ₁ (°C), can be used as the temperature of the mixed concrete. The temperature measuring device 20 measures temperature for cement and mixed concrete supplied to a measuring bottle for producing concrete for each mixing.
Measurements are made using thermocouples, electrical resistance, thermistors, etc. In addition, the rate of change in water amount D (1/℃) per 1℃ of cement temperature may differ depending on the cement temperature, so several types are stored in the computer depending on the cement temperature range, and the cement temperature It may be selected according to the measurement results.

In this way, for correction and correction of the unit amount of mixing water, unit amount correction 93 based on aggregate surface water percentage, water amount correction 94 based on slump difference, water amount correction 95 based on sludge concentration of recovered water, and water amount based on mixed concrete temperature and cement temperature. After performing the correction 96, the weight W2 (Kg) of water after the correction-correction is given by the following equation.

W2=W1−(W6+W7+W8+W9) =W1×{A×(SLM ₂ −SLP ₂ ) +B×(BM−BP)+C× (CM ₂ B−CP)+D×(DM−DP)} −S1×MS−G1 ×MG The correction/revision calculation of the unit quantity is also performed for the correction of the cement quantity. In the initial setting value 8, the unit amount of cement C1 (Kg) and the water-cement ratio F=W1/C1, which is related to the compressive strength of concrete, are determined. Therefore, in order to obtain concrete having a predetermined compressive strength, it is necessary to keep the water-cement ratio constant, and it is necessary to correct the cement weight in relation to the amount of water at the point. That is, regarding the unit amount correction 92 of the cement amount, it is necessary to add the water amount correction amount to the unit amount C1 (Kg) of the initial setting value 8 of cement, assuming the specified water-cement ratio F. That is, the corrected water amount W7 (Kg) is based on the slump difference, the corrected water amount W8 (Kg) is based on the sludge concentration difference in the recovered water, and the corrected water amount W9 (Kg) is based on the temperature of the mixed concrete and cement.
In this way, the cement correction amount of cement correction 92
C6 becomes the following formula.

C6 = (W7 + W8 + W9) × C1 / W1 Therefore, the corrected cement weight C2 (Kg) is the following formula.

C2=C1+C6 =C1×{1+(W7+W8+W9)/W1} Until now, in the unit amount correction/correction calculations, unit amount correction of aggregate91, unit amount correction and correction of mixing water93,94,95,96 , In the calculation in cement unit amount correction 92, the rate of change in water amount per 1 cm increase in slump value, which is A (1/cm), B
(1/%) is the rate of change in water amount per 1% increase in sludge concentration, C (1/℃) is the rate of change in water amount per 1℃ increase in mixed concrete temperature, D
(1/℃) is the rate of change in water volume per 1℃ increase in cement temperature, and E is the rate of change in fine aggregate with respect to an increase in coarse grain ratio of 1.00. These are experimentally determined values that include positive or negative signs. becomes. Furthermore, the surface water percentage MG (%) of coarse aggregate and the surface water percentage MS (%) of fine aggregate also include positive or negative signs.
In this case, a negative case is a state in which the aggregate has passed the surface dry saturated state and can absorb water, that is, an air dry state, and in this case, it is necessary to add an excessive amount of water until the surface dry saturated state is reached.

As a result of the above, after unit amount correction/correction calculation 9 in the computer, the weight of cement after correction C2 (Kg), the weight of coarse aggregate after correction G2 (Kg), with unit correction setting value 10, Weight of fine aggregate after correction S2 (Kg),
The corrected/corrected water volume W2 (Kg) can be obtained. In this case, at the initial setting value of 8, 1 m ³ of ready-mixed concrete
Although it shows the mixing ratio of raw materials per unit, the unit quantity correction set value 10 is after correction and correction, and the total volume of raw materials is not necessarily 1 m ³ . Since the mixing amount is determined, it is necessary to re-correct the unit amount correction setting value 10 and calculate the volume correction setting value 11 for the total volume of 1 m ³ .

The quantities required to calculate the volume correction setting value 11 are: specific gravity of cement SG, volume correction coefficient K, weight of cement after volume correction C3 (Kg), weight of coarse aggregate after volume correction G3 (Kg) , the weight of fine aggregate after volume correction S3 (Kg), the weight of water after volume correction W3 (Kg), and the specified air amount AI (%). In this case, the specified air amount
AI (%) is a pre-specified amount that is the air content in concrete that is involved in quality such as durability. The volume correction set value 11 is expressed by the following equation.

C3=K×C2 G3=K×G2 S3=K×S2 W3=K×W2 K=1000{1-(AI/100)}/ [1000{1-(AI/100)} +{(C6/SG )+W7+W8+W9}] Next, the measurement setting value 12, which is the actual kneading setting value, is calculated by multiplying by the kneading amount 5 for one kneading instructed on the operation panel 7 of the operator. The amounts required to calculate the measurement setting value 12 are the mixing volume of concrete for one mix V (m ³ ), the weight of cement after changing the mixing amount C4 (Kg), and the coarse aggregate after changing the mixing amount. Let the weight of fine aggregate be G4 (Kg), the weight of fine aggregate after changing the mixing amount S4 (Kg), and the weight of water after changing the mixing amount W4 (Kg). The measurement setting value 12 is expressed by the following equation.

C4=V×C3 G4=V×G3 S4=V×S3 W4=V×W3 This measurement setting value 12 determines the appropriate mixing amount of raw materials after carrying out unit amount correction/correction calculation 9. This signal is output to each weighing device, and this signal continues to perform coarse and fine weighing, resulting in the actual weight values C5 (Kg), G5 (Kg), S5 (Kg), W5.
(Kg) is carried out and completed. This point in time is time _T4 shown in FIG. Then, information on actual weighing values 13 from each weighing bin is stored in the computer.

Although the quality of concrete is ensured by appropriately setting the mixing ratio of the raw materials mentioned above, in this example, the strength of a predetermined material age is further estimated. The strength of concrete and the cement-water ratio are in a proportional relationship as long as the concrete has the required workability.
Utilizing this proportional relationship, concrete strength estimation 18 is performed. In other words, the relationship between the cement water ratio of concrete and the strength of concrete at a predetermined material age such as 28 days, prepared in advance in a laboratory, is compared with the amount of cement and water obtained from the actual measurement value 13, etc. The strength of concrete is estimated at the time of manufacturing ready-mixed concrete. now,
The amounts necessary for estimating the age of wood are H, J (Kg/cm ² )
is a constant determined by the relationship between the cement water ratio of concrete and the strength at a given material age,
cm) is the estimated strength, C5 (Kg) is the actual weight of cement, W5 (Kg) is the actual weight of water, S5 (Kg) is the actual weight of fine aggregate, G5 (Kg) is the actual weight of coarse aggregate. Actual weight value, MS
(%) is the surface water percentage of fine aggregate, MG (%) is the surface water percentage of coarse aggregate, and WCR is the water-cement ratio determined from the actual measured value. The water-cement ratio WCR and estimated strength are as follows:

WCR = [{MS×S5/(100+MS)} +{MG×G5/(100+MG)} +W5]/C5 ST=(H/WCR)+J In this case, the water-cement ratio of concrete and the concrete The constants H and J determined in relation to strength depend on the type of aggregate used,
For example, information can be stored in advance in the computer according to the type of lightweight concrete, river gravel concrete, crushed stone concrete, etc., the admixture used, the type of cement used, etc. In this way, for the concrete manufactured at the ready-mixed concrete factory,
Being able to estimate the strength of concrete at a specified material level before delivery to a delivery location is extremely effective for quality control for ready-mixed concrete manufacturers, early strength determination, and quality assurance for ready-mixed concrete purchasers. In addition, the water-cement ratio obtained from the measured values
As a result of comparing the WCR and the water-cement ratio calculated from the initial setting value 8 stored in the computer in advance, if the difference between the two is outside the predetermined range, check the measuring bottle and raw materials according to this abnormality. It enables early detection, investigation of causes, and early response to abnormalities, making it extremely effective in preventing malfunctions at Batchia plants and strengthening quality control of ready-mixed concrete. The surface water content MG (%) and MS (%) of coarse aggregate and fine aggregate are also used for this strength estimation, but automatic measurement 16 of this surface water content is based on the predetermined mixing ratio for concrete to be manufactured. Each time the appropriate coarse aggregate and fine aggregate are fed into the weighing bin, it can be measured at a speed that does not interfere with the production process of ready-mixed concrete.Moreover, the measurement results can be obtained as electrical signals, and the measurement accuracy is high. The device can be applied to various measuring means as long as it satisfies the following conditions: the surface water content can be corrected, the device can be operated continuously for producing fresh concrete, and it is durable in the measurement environment.

The example in Figure 2 is shown for concrete that does not contain any admixtures, but the same treatment is possible for concrete that contains admixtures, and for example, the amount of admixtures can be determined relative to the amount of cement, etc. If it is mixed, it can be calculated using the cement measurement setting value C4 (Kg) after changing the mixing amount, the concrete mixing amount V (m ³ ) for one mixing, etc.

Furthermore, in the above embodiment, information from the weighing bin was used to perform calculations to ensure accuracy, but instead of using the weighing bin, information was taken from the storage bin that supplies raw materials to this weighing bin. Correct calculations are also possible.

In this example, the modified blending of raw materials for one kneading was described, but this blending result by calculation processing was
Of course, it can also be used to adjust the mixing ratio of raw materials for kneading.

As explained above, according to the present invention, the mixing ratio of raw materials for each mixing is based on information obtained from raw materials, information obtained from mixed ready-mixed concrete, and information obtained from the manufacturing conditions of ready-mixed concrete. Because it is automatically controlled using information processing, it is possible to obtain ready-mixed concrete with the required quality such as water volume, slump value, and water-cement ratio. It is extremely effective for labor saving, automatic correction of mixing ratio, quality control of ready-mixed concrete, and quality assurance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the operating status of a metering device and a mixer in a batch plant for producing ready-mixed concrete, FIG. 2 is a block diagram showing an example of the method for producing ready-mixed concrete according to the present invention, and FIG.
The figure shows a configuration diagram of an example of a device for measuring aggregate surface water percentage using a weighing bottle, Fig. 4 is a graph showing a comparative example of daily surface water percentage, and Fig. 5 shows a device for measuring slump value. The configuration diagram and FIG. 6 are graphs showing the measurement results of slump values of the device according to FIG. 5 and the conventional device. In the drawing, 1 is the specified strength, 2 is the specified slump value,
3 is the designated air amount, 4 is the type of concrete, 5 is the mixing amount, 6 is the maximum size of coarse aggregate, 7 is the operation panel, 8 is the initial setting value, 9 is the correction/correction calculation of the unit amount, 91 is Correction of aggregate amount by aggregate surface water percentage, 92
is the cement amount correction, 93, 94, 95, 96 is the water amount correction, 10 is the unit amount correction setting value, 11 is the volume correction setting value, 12 is the measurement setting value, 13 is the actual measurement value,
16 is automatic measurement of aggregate surface water percentage, 17 is automatic setting of slump value, 18 is strength setting, 19 is automatic setting of sludge concentration, and 20 is automatic concrete and cement temperature measurement.

Claims (1)

[Claims] 1. In a method for producing ready-mixed concrete in which raw materials containing cement, aggregate, and water in a storage bottle are supplied to a measuring bottle and weighed, the raw materials in the measuring bottle are discharged into a mixer and mixed for each mixing,
Based on the surface moisture content of the aggregate obtained from the raw materials during or before the above measurement, the aggregate and water amount to be measured is corrected to the indicated mixing ratio, while the amount of fresh concrete manufactured based on the indicated mixing ratio is Based on the calculation of the difference between the latest measured slump value and the target slump value among the measured slump values, the amount of water to be measured is calculated to obtain ready-mixed concrete with the target slump value, and based on the water amount after this correction calculation. A method for producing ready-mixed concrete, characterized in that the amount of cement to be measured is corrected to obtain a predetermined water-cement ratio, and the indicated mixing ratio is corrected for the amount of water and cement to be measured by these correction calculations.