JPH043287B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Technical field The present invention relates to a method for correcting the mixture of ready-mixed concrete and a display device for displaying the contents of the correction of the mixture, and in particular, for use in temporarily correcting the mixture of ready-mixed concrete at the time of manufacturing or receiving the ready-mixed concrete, or The present invention relates to a method suitable for quickly providing feedback to a ready-mixed concrete factory as information for subsequent mixing, and a device for displaying the correction contents. (B) Background of the Invention At present, no inspection is conducted to confirm the mix during the production of ready-mixed concrete, and only inspection is relied upon at the time of acceptance. The acceptance inspection merely measures the slump and air content, and collects the specimen for compressive strength test. This cannot be determined until after the concrete has been placed, and therefore, currently, only after-the-fact judgments can be made after a predetermined number of days have passed after concrete pouring, and it cannot be said to be useful for true quality control. In other words, since the conditions of the materials used, equipment, etc. change from moment to moment, it is often not possible to thoroughly investigate the cause and take specific measures when the results are known. The action that can be taken for fresh concrete received at an actual work site is to correct the measured values of slump and air content from the slump test and air content test to the target values. For example, the slump can be easily adjusted by adjusting the unit amount of water. However, the cause of slump deviation is not only the change in unit water volume due to fluctuations in aggregate surface water, but also the aggregate particle size, mixing temperature, actual area ratio, air volume, etc. Therefore, if slump adjustment is easily carried out by adjusting the amount of water as is currently the case, the water/cement ratio of fresh concrete will be disturbed, and the compressive strength, which is the most important quality, will also be disturbed. Therefore, the present inventors conducted various experiments and investigations, and found that due to circumstances in the manufacturing process of ready-mixed concrete, the blending ratio of cement in the mix was within the allowable range of JIS A5308. Similarly, regarding the water in the preparation component, it can be easily adjusted using the adjustment dial to adjust the fluctuation and slump of the surface water of the aggregate mentioned above, and the unit water amount is JIS
Understand that there are many cases where the tolerance range of A5308 is exceeded, and measure the cement-water ratio (reciprocal of the water-cement ratio), which has a high correlation with the compressive strength of fresh concrete, in a short period of time before pouring. developed a method,
The quality of ready-mixed concrete can be judged when it is received. However, even if the water/cement ratio of ready-mixed concrete is known, there is no one in the actual workplace who understands concrete mixing theory, so it is not possible to specifically instruct the ready-mixed concrete factory to correct the mix. In addition, when making an emergency correction to the mix of fresh concrete before pouring, it is not possible to determine the correction of each component based solely on the water/cement ratio; It is necessary to match the cement ratio to the target value, and it is desired to standardize specific measures to simultaneously keep the three characteristics, including the amount of slump and the amount of air, within the allowable range. Alternatively, if this countermeasure is implemented at the time of production at a ready-mixed concrete plant, an even faster response will be possible. (c) Purpose of the Invention The present invention has been made in view of the above, and allows anyone to easily correct the mixture of ready-mixed concrete in a short time when receiving the ready-mixed concrete, or to make it possible for a ready-mixed concrete manufacturing plant to correct the mixing of the ready-mixed concrete. The purpose of the present invention is to provide a method for quickly instructing a correction during subsequent mixing of ready-mixed concrete, and a device capable of displaying the contents of the mixing correction. (d) Principle of the invention The present invention is based on the following principles and experimental facts. First, in the normal production process of ready-mixed concrete, the mixing of each component is controlled, for example, by a punch card system, and among the components, cement is free from measurement errors due to moisture content, and the precision of the measuring instrument is high. degree of error, i.e., JIS
The fact that it is well within the range specified in A5308. Next, as mentioned above, regarding water in the ingredients of ready-mixed concrete, the mixing ratio is greatly affected by fluctuations in the surface water of the aggregate, and slump adjustment of ready-mixed concrete mainly depends on the amount of water. Since the blending rate is JIS A5308
In many cases, the water/cement ratio W/C of normal ready-mixed concrete is determined by the amount of water contained in the ready-mixed concrete, based on the accuracy of the cement mixing ratio mentioned above. If you extract the mortar content of fresh concrete, sample an appropriate amount, and measure its weight (M) and weight in water (M'), you can immediately calculate the water-cement ratio of the fresh concrete using the following equation (1). Being able to determine W/C. W/C=M/C+k ₁ -k ₂・M'/C...(1) Here, C; unit cement amount k ₁ (constant) = (1/ρs-1/ρc)/(1-1/ ρs
) k ₂ (constant) = 1/(1-1/ρs) ρc: Specific gravity of cement ρs: Specific gravity of sand Also, if the unit cement amount C is close to the specified value, the concrete mixing theory Based on the RC specifications of Japan Society of Civil Engineers, and various experimental results, excluding special cases, using the case of ordinary concrete as described by Japan Society of Civil Engineers as an example, the mixture is corrected as shown in the table below. By correcting the accompanying change in the unit cement amount C, the slump, air amount, and water-cement ratio can be made to match the target values at the same time. In this table, the fine aggregate ratio and air content are volume %, and the water/cement ratio is dimensionless.

[Table] As shown above, in normally manufactured ready-mixed concrete, the unit water volume deviates from the allowable range due to slump adjustment and aggregate surface water, and the amount of other cement, etc. In view of the fact that ordinary ready-mixed concrete is almost within the specified range, and furthermore, the ratio of water to cement from mortar can be measured relatively easily at the pouring site, In addition to mixture correction, it is practically possible to include mixture correction including the water/cement ratio at the pouring site. This information can be useful as information for emergency formulation correction or feedback to the formulation process. In addition, the amount of coarse aggregate, admixtures, etc. must be within an appropriate amount or within an allowable range compared to variations in water amount, etc., taking into account the control method in the manufacturing process. (which can be said to be true), it is almost sufficient to use water volume, fine aggregate ratio, and cement volume as adjustment factors in order to set the water/cement ratio, slump volume, and air volume to the desired values. It is. (d) Structure of the method invention The method for correcting the mixture of ready-mixed concrete of the present invention involves sampling ready-mixed concrete whose unit cement amount (C) is known, and determining its slump amount (SL), air amount (A), and water/cement ratio. (W/C), and based on each measurement result, calculate the correction amount (ΔW) for the unit water volume of the fresh concrete using the following two formulas.
Calculate the correction amount (ΔS/a) for the fine aggregate ratio of the fresh concrete from the formula, and based on the measurement results of the obtained unit water volume correction amount (ΔW) and water/cement ratio (W/C). It is characterized by calculating the correction amount (ΔC) of the unit cement amount of the ready-mixed concrete from the following equation (4). ΔW=-{(SL-SL ₀ )×α-(A-A ₀ )×β}×C×W/C ……(2) ΔS/a=(A-A ₀ )×γ −(W/C −W ₀ /C)×δ ……(3) ΔC=C×W/C+ΔW/W ₀ /C−C ……(4) Here, SL ₀ ; Target slump amount (cm) A ₀ ; Target air amount (%) W ₀ /C; Target water/cement ratio (%) α, β, γ, δ; Coefficient (e) Structure of device invention The explanation will be based on the functional block diagram shown in the figure. The input means is for supplying measurement data of the slump amount (SL), air amount (A), and water/cement ratio (W/C) of fresh concrete to be corrected to the calculation means, and the function storage means stores the above-mentioned equations (2), (3), and (4) and each preset constant. The calculation means calculates each measurement data from the input means by substituting each function stored in the function storage means, and the display output means displays the results of each calculation, and the displayed values indicate the values of the ready-mixed concrete. It is configured to represent the correction amount of unit water amount, wood with fine aggregate ratio, and correction amount of single cement amount. (f) Examples Next, examples of the method and apparatus of the present invention will be described based on the drawings. FIG. 2 is a diagram showing an embodiment of the process of obtaining the corrected mixture of ready-mixed concrete according to the present invention, and FIG. 3 is a diagram illustrating the configuration of an embodiment of the display device for displaying the corrected mixture of ready-mixed concrete according to the present invention. FIG. First, when receiving ready-mixed concrete, the ready-mixed concrete with a known unit cement amount (C) is collected in a bucket at the unloading point from a ready-mixed concrete truck, for example, halfway through discharge, and is subjected to a well-known slump test and air volume test. Slump amount (SL) and air amount
While measuring PHA, water and
Measure the cement ratio (W/C). That is, an appropriate amount of the sampled fresh concrete is sieved through a 5 mm sieve, gravel is removed, mortar is extracted, and a specified amount, for example 400 g, of the mortar is weighed out using a scale. Next, water is added to the weighed mortar and stirred to remove air mixed in the mortar, and the mortar is left standing for several tens of seconds to allow the mortar to settle in the container.Then, the mortar is immersed in water. and measure the weight M′ in water. And as mentioned above
Assuming that the weight M in equation (1) is 400 g, calculate the water-cement ratio (W/C) of fresh concrete from the correlation graph or table of weight in water (M') - water-cement ratio (W/C) created in advance. Read. On the other hand, the display device 1 for displaying the mixture correction contents of fresh concrete shows the target slump amount (SL ₀ ),
Target air amount (A ₀ ) and target water/cement ratio (W/C), and unit cement amount (C) which is a known value,
and the coefficients α, β, γ and δ in equations (2) and (3)
In the case of ordinary concrete, input them as 0.012, 0.03, 0.7, and 20, respectively, based on the table mentioned above. In other words, α and β correspond to the required correction amount of the unit water volume for a slump amount of 1 cm and an air amount of 1%, respectively, and γ is the required correction factor of the fine aggregate ratio for an air amount of 1% (because the correction factor of volume % is calculated). %), and δ is the necessary correction factor for the fine aggregate ratio for the water/cement ratio of 0.05 (5%), and 1% in the table is 1% ÷ when used in the formula.
0.05 to 20%. Now, the meanings of equations (2) to (4) (same as equations (a) to (c) above) are explained in detail immediately from each data obtained in order to fulfill the contents of the table above. This is a formula for knowing the contents of each correction. That is, first, in the formula for calculating the correction amount of unit water volume in equation (2), based on the column of correction amount of unit water volume in the table, the coefficient α is added to the deviation amount of slump amount (SL−SL ₁ ).
(1.2% or 0.012), and from that value, the deviation amount of air amount (A - A ₀ ) is calculated by the coefficient β (3% or 0.03).
The correction rate is obtained by subtracting the value multiplied by The correction amount ΔW (Kg/m ³ ) for the unit water volume is obtained by multiplying by the water volume (representing the water volume). In addition, in equation (3), the amount of deviation in air amount (A-A ₀ )
is multiplied by the coefficient γ (0.7%), and from that value, the measured water
Cement ratio W/C and mixing water/cement ratio
The fine aggregate correction factor (%) is obtained by subtracting the difference from W ₀ /C multiplied by the coefficient δ (which is 20% as described above). Furthermore, in equation (4), the numerator of the first term on the right side is
The unit amount of water contained in the actual concrete is determined by multiplying the unit cement amount C in the mixture by the measured water/cement ratio W/C, and then the correction amount ΔW for the unit water amount obtained using equation (3) is added to that value. This is the value obtained by calculating the unit water volume after correction. Therefore, the first term on the right side, which is obtained by dividing the corrected unit water amount by the formulated water/cement ratio W ₀ /C, represents the corrected unit cement amount. Then, by subtracting the unit cement amount C in the formulation from the corrected unit cement amount, the correction amount ΔC (Kg/m ³ ) of the unit cement amount is obtained using equation (4). Note that if the correction amount ΔW of the unit water amount and the correction amount ΔC of the unit cement amount are positive values, water or cement can actually be added to the received ready-mixed concrete, but if these are negative values. , inform the ready-mixed concrete manufacturer of this fact and correct the mix of ready-mixed concrete to be delivered thereafter. Of course, if the value of ΔW or ΔC is considerably large, measures such as not pouring the ready-mixed concrete can be taken. Then, by inputting the measured slump amount (SL), air amount (A), and water/cement ratio (W/C), the unit water amount is calculated by calculating the above equations (2), (3), and (4). correction amount (ΔW),
Print out the correction amount for fine aggregate ratio (ΔS/a) and the correction amount for unit cement amount (ΔC). To explain in detail the display device 1 for displaying the contents of mixing correction for fresh concrete, as shown in FIG.
A microcomputer 2 consisting of a ROM 22, a RAM 23, etc., a keyboard 3 for inputting various numerical values and commands into the microcomputer 2, and a printer for printing out calculation results output from the microcomputer 2. 4 and its interface 5,
The above-mentioned function equations (2), (3), and (4) are stored in the ROM 22. Note that the CPU 21 executes calculations of its functions and controls each peripheral device, and the RAM 2
3 is configured to store various constants and measurement data from the keyboard 3. Therefore, by inputting the three characteristic values of the sampled fresh concrete: slump amount (SL), air amount (A), and water/cement ratio (W/C) from the keyboard 3, (2), (3), and From equation (4), we can immediately calculate the correction amount for the unit water amount (ΔW), the correction amount for the fine aggregate ratio (ΔS/a), and the correction amount for the unit cement amount (ΔC) for the fresh concrete.
is printed out, and based on the results, the received ready-mixed concrete can be corrected before pouring, and feedback can be provided to the ready-mixed concrete manufacturing process. Regarding the measurement of the water/cement ratio, the water/cement ratio may be calculated based on formula (1) from the weight of the sampling mortar and the weight in water, using an arbitrary amount instead of measuring a fixed amount of sampling mortar. It is also possible to automate everything from measuring the weight of sampling mortar to calculating the water/cement ratio.
By directly connecting the sensor and its automation device, the measurement data input from the keyboard can be limited to only the slump amount and air amount. Further, although the above-mentioned values are currently optimal for each coefficient in equations (2) and (3), the values can be changed as appropriate based on experimental results and others. Furthermore, if the display device 1 prints out the correction contents on the ready-mix concrete mixing correction contents display device 1, and at the same time sends a feedback signal to the ready-mixed concrete manufacturing plant based on the data, it is possible to automatically send a feedback signal to the ready-mixed concrete manufacturing plant. You can obtain the optimal formulation. (g) Effects As explained above, according to the present invention, temporary measures that could only be taken at the pouring site by correcting the slump amount and air amount can now be corrected by including the water/cement ratio, that is, compressive strength. It has also become possible to compensate for this and make accurate formulation corrections. In addition, when obtaining the correction content, it is possible to quickly derive the correction content even if you do not understand concrete mixing theory.
In addition to correcting the mix of received ready-mixed concrete before pouring, we also feed back the results to the ready-mixed concrete production department, ensuring workability and ensuring that ready-mixed concrete is always poured with the correct mix. It became. By applying the method and display device of the present invention not only to construction sites that receive ready-mixed concrete but also to ready-mixed concrete plants, ready-mixed concrete can be mixed quickly and accurately, resulting in great effects.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing the configuration of the display device of the present invention, FIG. 2 is a diagram showing an example of the process until the content of formulation correction is obtained according to the present invention, and FIG. 3 is a functional block diagram showing the configuration of the display device of the present invention. FIG. 2 is a block diagram showing the configuration of an embodiment. 1...Display device for mixing correction contents of fresh concrete, 2...Microcomputer, 3...Keyboard, 4...Printer, 5...Interface, 21...CPU, 22...ROM, 23...
RAM.

Claims (1)

[Claims] 1. Sample ready-mixed concrete with a known unit cement amount (C), and determine its slump amount (SL) and air amount.
(A) and the water/cement ratio (W/C), and based on the measurement results, calculate the correction amount (ΔW) for the unit water amount of the ready-mixed concrete using the formula (a) below, and calculate the correction amount (ΔW) for the unit water volume of the fresh concrete using the formula (b) below. ), calculate the correction amount (ΔS/a) for the fine aggregate ratio of the fresh concrete, and calculate the following ( c) A mixing correction method for ready-mixed concrete, characterized in that the correction amount (ΔC) of the unit cement amount of the ready-mixed concrete is determined from the formula. ΔW=-{(SL-SL ₀ )×α-(A-A ₀ )×β}×C×W/C ……(a) ΔS/a=(A-A ₀ )×γ −(W/C −W ₀ /C)×δ……(b) ΔC=C×W/C+ΔW/W ₀ /C−C……(c) Here, SL ₀ ; Target slump amount (cm) A ₀ ; Target air amount (Volume %) W ₀ /C; Target water/cement ratio (weight %) α, β, γ, δ; Coefficient 2 If the above α, β, γ, and δ are for ordinary concrete and are predetermined If the admixture is formulated within a predetermined tolerance for the unit amount of cement, each
0.012, 0.03, 0.7 and 20. The method for correcting the mix of ready-mixed concrete according to claim 1, wherein the ratio is 0.012, 0.03, 0.7 and 20. 3 The above method for measuring the water/cement ratio (W/C) involves removing gravel from the fresh concrete, extracting mortar, sampling an appropriate amount of the mortar, measuring its weight, and then submerging it in water. Claim 1 or 2 is a method of measuring the weight and deriving the water/cement ratio (W/C) of the fresh concrete as a function of the weight of the sampling mortar and the weight in water.
Method for correcting the mix of ready-mixed concrete as described in section. 4. Slump amount (SL), air amount (A), and water/cement ratio (W/C) of fresh concrete to be mixed and corrected
A means of inputting the measurement data of
means for storing the function formulas (a), (b), and (c), means for calculating each of the above function formulas based on the above input data, and means for displaying and outputting the calculation results of each of the function formulas. In preparation, the displayed values of the calculation results of the following functional formulas (a), (b), and (c) are the correction amount for the unit water amount (ΔW) and the correction amount for the fine aggregate amount (ΔS/ a) and correction amount of unit cement amount (ΔC)
A display device for displaying mixture correction contents of ready-mixed concrete. ΔW=-{(SL-SL ₀ )×α-(A-A ₀ )×β}×C×W/C ……(a) ΔS/a=(A-A ₀ )×γ −(W/C −W ₀ /C)×δ……(b) ΔC=C×W/C+ΔW/W ₀ /C−C……(c) Here, SL ₀ ; Target slump amount (cm) A ₀ ; Target air amount (Volume %) W ₀ /C; Target water/cement ratio (weight %) α, β, γ, δ; Coefficient