JPS6336454B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for measuring aggregate surface water, which is necessary for adjusting the measured values of aggregate and water used during concrete mixing and the like. For example, in concrete, cement,
Maintaining a certain mixing ratio of sand, gravel, and water is a major factor in achieving the required workability and quality of concrete, and it is known that the strength of concrete is determined by the ratio of water to cement. ing. Cement can be mixed quantitatively by weight measurement using a screwdriver, but sand and gravel with moisture attached to their surfaces are sometimes used, so the water attached to their surfaces (hereinafter referred to as ``aggregate surface'') is used. It is not possible to obtain the accurate weight of aggregate without subtracting the amount of water (referred to as "water"), and the amount of water on the surface of the aggregate must be subtracted from the amount of water added to obtain the correct mixing ratio of concrete. It cannot be kneaded as such. Conventionally, the amount of water on the surface of aggregates has been measured by detecting the amount of water on the aggregate surface by detecting capacitance through the conduction of an electric current, or by measuring the diffuse reflection energy ratio of two types of infrared light: wavelengths that are absorbed by water and wavelengths that are not. Detection methods include methods that detect neutrons by the rate at which the hydrogen nuclei of the hydrogen element that makes up water convert fast neutrons emitted from a fast neutron source into thermal neutrons. These measured values are sent from each detector to an arithmetic circuit and converted to moisture content, and are converted into display signals by performing various signal processing with a converter.
Based on the display signal, the amount of water added and the amount of aggregate are adjusted by manual correction or automatic control on the operation panel of the batcher plant, for example. However, with either of these methods, particles of the aggregate, which is the object to be measured, adhere to the sensitive part of each detector,
Alternatively, if the particle size of the aggregate changes, if the bulk volume changes due to the consolidated state of the aggregate, or if the water contains salt, the detection accuracy of the detector will decrease.
Moreover, since there is a limit to the sensitive space of the detector, the measured value becomes a local value. In addition to the method described above, a method is known in which the surface water content of aggregate is measured by placing moist aggregate in a container filled with water (Utility Model Publication No. 39-2599). However, this method involves placing a container filled with water on an indicator scale, weighing it, placing sampled aggregate into the container to replace the water, and calculating the difference in weight between the replaced water and the aggregate. Not only does it take a lot of time and effort to calculate, but it also requires intermittent measurements, such as placing a container in which aggregate has been replaced with water on an indicator scale and indicating the difference in weight of aggregate replaced. It is completely impractical as it is obvious that this is the case. An object of the present invention is to provide a method for measuring aggregate surface water that does not cause such problems. That is, in the method for measuring aggregate surface water according to the present invention, a suitable amount of water,
The aggregate to be measured is filled with additional water, and the weight is measured at each stage. By calculating the specific gravity of aggregate when it is completely dry (hereinafter referred to as "surface dry specific gravity of aggregate"), the unit is calculated based on the weight when the aggregate, which is the object to be measured, is in a dry state. The amount of water adhering to the surface of the aggregate is calculated as a weight ratio from the specific gravity of the aggregate and water (hereinafter referred to as the "surface water ratio"), and the aggregate is kneaded as a concrete material at that surface water ratio. The mixing ratio of cement, aggregate, and added water is set accurately by determining the total weight of the aggregate in a surface dry state and the total weight of water contained in the aggregate. This will be explained below based on the first to third illustrated embodiments. In the illustrated embodiment, cement, aggregate, water, and admixtures are stored in tanks 1, 2, 3, and 4 in a batcher plant.
When supplying the aggregate to the mixer 5 for kneading, the aggregate to be used is dripped into the measuring tank 6, and the surface water percentage of the aggregate is measured, and the amount of water supplied from the storage tank 3 is calculated from the aggregate from the storage tank 2. The amount of supply is controlled. The aggregate is placed in a cylinder 11 at the bottom of the storage tank 2.
1 is arranged diagonally, and a screw 12 is rotatably mounted in the cylinder diameter by a motor 13, and the aggregate that enters the diameter through the opening of the cylinder 11 is measured via the shooter 14 by driving the screw 12. It is dripped out by falling into the tank 6. In addition, water can be supplied to the measurement tank 6 from a water injection pipe 21, and the water is injected in an appropriate amount at the beginning, and additional water is added to fill the measurement tank 6 after the aggregate is added as described above. Supplied throughout. Among these, when pouring an appropriate amount of water before adding the aggregate, which is the object to be measured, the air contained between the particles of the aggregate is dispersed as air bubbles as the aggregate is added, and it remains contained in the aggregate and is not sealed with water. It is possible to prevent measurement errors caused by air bubbles. Even if the appropriate amount of water is poured, the volume of the measuring tank 6 is constant, so the surface water percentage of the aggregate can be calculated by simply increasing or decreasing the amount of water poured after adding the aggregate, which is the object to be measured. It has no effect on anything.
When supplying the additional water, the water overflowing from the measurement tank 6 is provided through holes 22a, 22b, 22c.
An overflow pipe 23 is provided in the opening 22a to discharge the wastewater from the measurement tank 6.
is provided. In addition, the water supply to the measuring tank 6 can be controlled by measuring needles 24a and 24b inserted into the tank, with the measuring needle 24a controlling the initial appropriate amount of water to be injected, and the measuring needle 24b controlling the additional water. It is configured to stop the water supply by doing so. When supplying these water and aggregates, the measuring tank 6 is filled up by adding the weight of the appropriate amount of water, the weight of that water + the weight of the aggregate to be measured, and additionally adding water. It is designed to measure the weight when The measurement can be performed using load cells 25a and 25b as in the illustrated embodiment, or a rod-type measuring instrument may be used. Among these, the load cells 25a and 25b have 1/1000 to 1/
4,000, whereas with the rod type, a weighing accuracy of about 1/400 can be obtained, and in the former case, 3 digits and in the latter case, 2 digits are each practically effective net weight, and the calculation circuit of the microcomputer 7 described later can be sent to. After measuring these weights, the weighing tank 6
The aggregate to be measured and water therein are discharged to the mixer 5 via a discharge hopper 8. The discharge is performed by operating an on-off valve 26 attached to the measurement tank 6. In addition, after the water and aggregate to be measured are released, a certain amount of water is poured from the washing tank 9 into the measuring tank 6 to wash away the aggregate to be measured that adheres or remains on the tank walls and bottom. can be released to The information obtained from this bathhouse plant, namely,
Weight of water when properly poured into measuring tank 6: wo
(g) Weight of aggregate and water to be measured: Ws (g) Weight of aggregate and water to be measured when calculation tank 6 is full: W (g), and is incorporated into the arithmetic circuit of microcomputer 7. The information that is set in advance as a constant on the variable dial, that is, the aggregates to be measured have the same surface dry specific gravity if they are from the same production area, and the capacity of the measuring tank is also constant, so these are set as constants. It can be entered as . Therefore, as the surface dry specific gravity of the aggregate to be measured: S and the capacity of the measuring tank: Wc (cm ³ ), the microcomputer 7 calculates the surface water percentage of the aggregate to be measured P (%) by performing the following calculation. can be calculated. P={(Ws-Wo)(1-1/s)/W-Wc-1}×100
(%) This calculation formula is

[Table] Then, W _G = W _P + Wd, V _G = W _P + Wd/S (= Vd), W _p = V _G − W _G /S/1-1/S, Wd = W _G − V _G /1-1/
Since S, P=W _P /Wd×100=V _G −W _G /S/W _G −V _G ×100(%), and furthermore, W _G = Ws−Wo, V _G = W _G +Wc−W =Ws+Wc-Wo-W, so P={(Ws-Wo)(1-1/S)/W-Wc-1}×100
(%) is theoretically required. In addition, the surface dry weight W's (g) of the aggregate to be measured discharged into the mixer 5 can be determined by W's = (Ws - Wo) x 100/100 + P (g). The amount of water released W' (g), including the washing water Wu, can be calculated as W' = (Wc - W's/S) + Wu. The calculated values P, W's, W' thus obtained by the microcomputer 7 are sent as calculated signals to the converter 10, where they are converted into control signals or display signals, and are incorporated into the batcher plant operation panel 10a. The aggregate moisture correction device can automatically or manually correct the amount of water corresponding to the aggregate. As described above, according to the method for measuring aggregate surface water according to the present invention, the surface dry specific gravity of the aggregate to be measured, which can be set in advance as a constant based on the measured weight, can be directly expressed from the mathematical relationship with the volume of the measuring tank. To find the surface water percentage of the aggregate using the ratio of dry aggregate weight to surface water weight, subtract the amount of water actually contained in the aggregate to be mixed as concrete material and calculate the required amount of added water. In addition, since the measuring tank is filled with an appropriate amount of water before adding the aggregate to be measured, the air occupying between the sand particles becomes fine bubbles and seals the water. Measurement can be carried out immediately without any leakage, and measurement errors caused by air bubbles can also be avoided.

[Brief explanation of the drawing]

FIG. 1 is an overall view of a batcher plant that implements the method for measuring aggregate surface water according to the present invention, and FIGS. 2 and 3 are partially enlarged side sectional views of the same apparatus. 1: Cement storage tank, 2: Aggregate storage tank, 3: Water storage tank, 4: Admixture storage tank, 5: Mixer, 6: Measuring tank, 7: Microcomputer, 8: Discharge hopper, 9: Washing water tank, 10: Converter , 10a: Operation panel, 11: Aggregate extraction cylinder, 12: Screw, 13: Motor, 14: Shooter, 21: Water injection pipe, 22a, 22b, 22c: Opening hole, 23: Overflow pipe, 24a, 24b: Measuring needle , 25
a, 25b: Load cell, 26: Open/close valve.

Claims (1)

[Claims] 1. A desired amount of water is poured into a measuring tank having a certain volume, and after filling the measuring tank with aggregate, which is an object to be measured, additional water is added to fill the measuring tank. The weight of water is measured at each stage and the appropriate amount of water is poured into the measuring tank: Wo
The weight of the aggregate, which is the object to be measured, and the water initially injected: Ws The weight of the aggregate, which is the object to be measured, and the water, when the measuring tank is full: W is the measured value, and the aggregate, which is the object to be measured. Surface dry specific gravity: S Capacity of measuring tank: Wc is a constant, (Formula: {(Ws-Wo) (1-1/S)/W-Wc-1} x 10
0 (%)), the calculation circuit of the microcomputer calculates the surface water percentage of the aggregate to be measured, and uses this surface water percentage to determine the amount of water adhering to the surface of the aggregate that is actually used as a concrete material. A method for measuring aggregate surface water, characterized in that: