JP2001289766A - Percentage of aggregate water absorption measuring method, aggregate surface moisture ratio measuring method, surface moisture removing device, and mortar constituent extracting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily and quickly measuring a percentage of water absorption and the surface moisture ratio of aggregate contained in concrete. SOLUTION: From the aggregate 1a in a wet condition, surface moisture 2 is removed and the surface is turned into a dried condition. Subsequently, the weight of a dried aggregate 1b is measured, then the aggregate 1b is heated with a high frequency into an absolutely dried condition, and the weight of an absolutely dried aggregate 1c is measured. The difference in weight between the aggregate 1b before heating and the aggregate 1c after heating is the total of water content 3 which is contained inside the aggregate 1b. Accordingly, the percentage of water absorption can be calculated, when the weight difference between the aggregate before heating and that after heating is divided by the weight of the aggregate 1c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for easily and quickly measuring the water absorption and the surface water content of aggregate contained in concrete, and a method for removing surface water adhering to the surface of aggregate from a wet state. The present invention relates to a surface water removing device for removing and a mortar component extracting device for extracting mortar component from raw concrete.

[0002]

2. Description of the Related Art Concrete is a mixture of water and cement mixed with an aggregate of sand and gravel at an appropriate ratio and then hardened. However, concrete has a great effect on the strength of concrete. It is the mixing ratio of water and cement. For example, concrete containing more water than specified may have reduced strength, reduced water tightness, and reduced durability, such as poor durability. As a method of inspecting the flowability of raw concrete before casting, a slump test is prescribed, and a compressive strength test using a test piece may be performed to measure the strength of concrete after hardening. is there. However, the slump test is not suitable for estimating the strength because it does not specify the water content. This is because when the admixture is added to the raw concrete, the fluidity of the raw concrete and the water
This is because there is no correlation between the cement ratio (the weight ratio of water and cement per unit amount). In addition, this test has a problem that errors tend to occur due to the procedure of the work such as a method of collecting a sample and a method of extracting a cone, and the objectivity is poor. Further, in the compressive strength test, it takes about 4 weeks to harden the concrete of the test piece, and it is impossible to know the concrete strength before casting. Therefore, various methods for objectively and quickly measuring the ratio of water to cement prior to placing concrete have been proposed. For example, JP-A-2-40531 discloses a method of estimating the strength of hardened concrete by measuring the ratio of water to cement in raw concrete without waiting for a chemical reaction between water and cement. It is shown.

[0003]

As described above, the concrete strength varies depending on the water / cement ratio. However, in order to make the mixing ratio accurate, it is necessary to make the water absorption rate and the surface water rate especially of the sand which is the aggregate. It is necessary to take into account. For example, when the water absorption of sand is high, it is necessary to increase the water content in the raw concrete, and when the water absorption is low, the water content is low. In addition, when the surface water content is high at the time of manufacturing, it is necessary to reduce the water content.
The water absorption and surface water content of sand have a great effect on concrete strength. As an example, 1m ³ per 800Kg
If the sand absorption rate fluctuates by 1%, 8kg
Water volume fluctuates, resulting in concrete strength of about 1.
It fluctuates by about 5 N / mm ² . However, in the method of measuring the water / cement ratio disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2-40531, the water absorption of sand is set as a predetermined value. For this reason,
Even if the water-cement ratio is measured by the method disclosed in the above-mentioned publication, in recent years, there are many variations due to deterioration of the aggregate condition, and accordingly, if the water absorption rate fluctuates, the estimated concrete strength after hardening is estimated. In some cases. In addition, when producing raw concrete at the factory,
The surface water content of the sand is measured by the capacitance or the like to correct the amount of water, but the measured value actually varies considerably.

[0004] In addition, JIS requires that the water absorption of sand is measured by a method called "test method for density and water absorption of lightweight lightweight aggregate for structure" (JIS A110).
9). In this test method, after drying the sand surface,
Sand is packed in a container called a flow cone, and the water absorption of the sand is measured by observing the degree of collapse when the cone is pulled upward. However, in this measurement method, it is necessary to repeat the drying and pulling out of the cone, and if the drying is excessive, it is necessary to re-wet the sample again, and it takes a lot of time. It is difficult. In particular, due to the depletion of domestic sand in recent years, some plants are actually using a mixture of sand from various places including foreign origin, but for such a wide variety of quality sand,
It is extremely difficult to repeat the above test every time.
Furthermore, in recent years, the pressure of recycling has been increasing from various aspects such as the government, and the use of recycled aggregate has been increasing.
The fluctuation of the water absorption of the recycled aggregate is not a conventional ratio, and it is a great burden for those skilled in the art to perform the above-mentioned test on such recycled aggregate. This test also has a problem in that there is room for the subjectivity of the tester and in that skill is required, and it is difficult for an unskilled person to perform measurement easily and accurately.

[0005] On the other hand, as for the surface water content of sand, a method called "test method for surface water content of fine aggregate" is generally performed (JIS A 1111). However, this test
As in the case of the water absorption test method above, it is easy to be affected by the surrounding environment such as temperature and humidity, and it is necessary to repeat the test several times in order to improve the measurement accuracy. To do this every time changes, again puts a heavy burden on those skilled in the art.

[0006] An object of the present invention is to provide a method capable of easily and quickly measuring the water absorption and the surface water content of an aggregate with high accuracy. It is another object of the present invention to provide a surface water removing device capable of quickly removing surface water attached to the surface of an aggregate in a wet state.

[0007]

The water content of concrete aggregate can be shown in FIG. The wet state is
This refers to a state in which surface water 2 is attached to the surface of the aggregate and the voids inside the aggregate are filled with the contained water 3 (1a). The surface-dry state refers to a state in which the surface of the aggregate has no surface water 2 and the voids inside the aggregate are filled with the contained moisture 3 (1).
b). The completely dry state means a state in which the water content 3 contained in the aggregate is also removed (1c). Further, the water absorption of the aggregate means the percentage of the total water content contained in the aggregate 1b in the surface-dry state with respect to the weight of the aggregate 1c in the absolutely dry state. Absolutely dry aggregate 1c with water volume
Means the percentage by weight. An object of the present invention is to measure the water absorption and surface water of these aggregates easily and quickly, and with high accuracy.

As a method of measuring the water absorption, as shown in FIG. 2, the surface water 2 adhered to the surface of the aggregate 1a in a wet state is removed to obtain a surface dry state. Is heated with high frequency, and the aggregate 1 before and after heating is heated.
From the weight difference between b and 1c, the water absorption of the aggregate 1 is calculated. Thus, the surface water content can be measured using the water absorption of the obtained aggregate 1. Specifically, the aggregate 1a in a wet state is heated with high frequency, and the surface water rate of the aggregate 1 is calculated from the weight difference between the aggregates 1a and 1c before and after heating and the water absorption of the aggregate 1. . Desirably, the aggregate 1 is a fine aggregate having a relatively small particle size, and the water absorption and the surface water content of the fine aggregate are measured.

Further, the method for measuring the water absorption and the surface water content of the aggregate according to the present invention uses a raw concrete obtained by kneading water, cement and an aggregate, and uses the raw concrete contained in the raw concrete. It measures the water absorption and surface water of the material. Specifically, as shown in FIG. 6, water 22 is applied to raw concrete 20 placed on a sieve 21,
The cement 23 is washed away from the raw concrete 20 to extract the aggregate 1a, and the surface water attached to the surface of the aggregate 1a is removed from the aggregate 1a to make the aggregate 1a a surface-dry state. Is heated at high frequency, and aggregates 1b and 1 before and after heating
From the weight difference of c, the water absorption of the aggregate 1 is calculated. Using the water absorption of the aggregate 1 thus obtained, the raw concrete 2
The surface water content of the aggregate 1 contained in 0 can also be measured. Specifically, the aggregate 1a extracted from the raw concrete 20 is heated at high frequency, and the surface water rate of the aggregate is determined from the weight difference between the aggregates 1a and 1c before and after heating and the water absorption of the aggregate 1. calculate.

The aggregate contained in the raw concrete 20 generally includes a fine aggregate 1 having a relatively small particle size and a coarse aggregate 25 having a relatively large particle size. Here, it is desirable to separate and remove the coarse aggregate 25 from the aggregate extracted from the raw concrete 20 and measure the water absorption rate and the surface water rate of the fine aggregate 1 before the high frequency heating.

In removing the surface water, a centrifugal separator 7 may be used as shown in FIG. 2B, or wind power may be used as shown in FIGS.

The present invention also relates to a method for manufacturing an aggregate 1a in a wet state.
Therefore, the present invention is directed to a surface water removing device for removing surface water 2 attached to the surface. This surface water removal device is shown in FIG.
As shown in FIG. 1, a cylindrical container 12 having a fine bottom 11 and containing the aggregate 1a in a wet state, and a cylindrical container 12
A rotating wing 13 that rotates intermittently or continuously within and stirs the aggregate 1a, and a motor 14 that rotates the rotating wing 13;
It comprises an ammeter 15 for measuring the drive power value of the motor 14 and a blower for blowing air from above the cylindrical container 12 toward the aggregate 1a. The rotating wings 13 are rotated while blowing air on the aggregates 1 a in the cylindrical container 12 by a blower.
While the change of the drive current value of the motor 14 when the is rotated is detected by the ammeter 15 and the removal state of the surface water 2 is detected,
The surface water 2 is removed.

As shown in FIG. 5, a flat plate member 17 having an insertion hole 18 is put in the cylindrical container 12 and
Removes the surface water 2 while detecting the removal state of the surface water 2 by capturing the change in the drive current value of the motor 14 when the rotating wings 13 rotate while pressing the aggregate 1a by It may be.

The present invention is also directed to a mortar extractor for removing coarse aggregate 25 from raw concrete 20 and extracting mortar 40. The mortar extractor includes a cylindrical container 31 having a bottomed cylindrical shape, and a motor 32 for rotating the cylindrical container 31. The side surface of the cylindrical container 31 has a mesh structure of 5 mm,
0 is rotated by a motor 32 and the centrifugal action generated by the rotation causes the cylindrical container 3 to rotate.
The mortar component 40 contained in the raw concrete 20 is sieved from the side surface of the raw concrete 20 to leave the coarse aggregate 25 in the cylindrical container 31 so that the mortar component 40 can be extracted.

[0015]

The effect of the present invention is as follows.
As shown in FIG. 1, from the aggregate 1a in the wet state to the surface water 2
Is removed and the surface is dried. Next, after measuring the weight of the aggregate 1b in the surface dry state, the aggregate 1b is heated at a high frequency to make it completely dry, and the weight of the aggregate 1c in this absolute dry state is measured. The weight difference between the aggregates 1b and 1c before and after heating is
b is the sum total of the contained water 3 contained inside. Therefore, the water absorption can be calculated by dividing the difference in weight before and after heating by the weight of the bone aggregate 1c in a completely dried state. In a similar manner, it is also possible to measure the water absorption of the aggregate 1 using the aggregate 1a extracted from the raw concrete 20 before casting.

As a method for measuring the surface water content, first, after measuring the weight of the aggregate 1a in a wet state, the aggregate 1a is heated at a high frequency to a completely dried state, and the aggregate in the completely dried state is measured. Measure the weight of 1c. The difference in weight before and after heating is (total of surface water 2 + total of contained water 3). Therefore, by dividing this by the weight of the aggregate in the dry state, (surface water rate +
Water absorption) can be calculated. Further, the surface water content can be obtained by subtracting the water absorption obtained in claim 1 from this value. Moreover, it is also possible to measure the surface water content of the aggregate 1 extracted from the raw concrete 20 by the same method.

According to the method for measuring the water absorption and the surface water content of the aggregate according to the present invention, the aggregate 1 is heated by high frequency and the water absorption and the surface water content can be calculated based on the weight difference before and after that. Therefore, compared with the conventional JIS test method, those values can be obtained with less and easy operation steps,
Test time is greatly reduced. That is, the water absorption rate and the surface water rate of the aggregate 1 can be measured easily and quickly. In addition, even when using aggregates having uneven quality, such as aggregates or recycled aggregates produced in foreign countries, the water absorption and the surface water can be obtained in a short time. Can quickly respond to fluctuations. The work process is also very simple work such as weight measurement and high-frequency heating,
Does not require any skill. Therefore, even inexperienced workers can easily and accurately measure them. Furthermore, if the method of measuring the water absorption and the surface water content according to the present invention is used, quality control can be performed with higher precision than JIS, because it has an advantage particularly in terms of precision.

In general, the aggregate refers to fine aggregate having a relatively small particle size and coarse aggregate having a relatively large particle size. In the measuring method according to the present invention, a high frequency heating step is performed. However, the coarse aggregate may be ruptured when heated with the high frequency. Therefore, in the present invention, the water absorption and the surface water content of the fine aggregate are measured. In addition, raw concrete 20
When the water absorption rate and the surface water rate of the aggregate 1 are measured by using
By separating and removing the coarse aggregate 25 from the aggregate extracted from the sieve using a sieve or the like, a rupture accident can be prevented.

The surface water 2 is quickly removed from the wet aggregate 1a by using a centrifuge 7 as shown in FIG. 2 (b) or by wind as shown in FIGS. 4 and 5. It becomes possible. as a result,
The speed of measuring the water absorption can be improved.

If the surface water removing apparatus shown in FIG. 4 is used, the surface water 2 can be quickly removed from the wet aggregate 1a, and it can be accurately confirmed that the aggregate 1 has come to the surface dry state (1b). Can be detected. In this surface water removal device, first, when the aggregate 1a in a wet state is stirred with a rotary wing, the aggregate 1a is in a nodule shape.
And the drive current value indicated by the ammeter 15 is large. Next, when the surface water 2 is removed by receiving a blow from the blower, the aggregate 1a gradually breaks down into a nodule state and decomposes into respective particles. Therefore, the drive current value of the motor 14 decreases. Finally, when the surface water 2 is completely removed and the aggregate 1 is put into a surface-dry state (1b), the ammeter shows a constant value. It can be detected accurately. In addition, since there is no need to blow the aggregate 1b in a state of being usedlessly,
The surface water 2 can be quickly removed. As shown in FIG. 5, a flat plate member 17 having an insertion hole 18 is placed in the cylindrical container 12, and the driving current value of the motor 14 when the rotary wing 13 rotates while pressing the aggregate 1a by the flat plate member 17 is shown. 4 can be obtained by the ammeter 15 to detect the removal state of the surface water 2 and obtain the same operation and effect as those of the surface water removal device of FIG.

The mortar extractor 3 of the present invention shown in FIG.
If 0 is used, the cylindrical container 31 containing the raw concrete 20 is rotated by the motor 32, and the centrifugal action caused by the rotation causes the raw concrete 20 from the side of the cylindrical container 31 having a mesh structure of 5 mm. The coarse aggregate 2 is removed by sieving mortar 40 contained in
The mortar component 40 can be extracted by leaving 5 in the cylindrical container 31. When a person shakes a sieve to separate coarse aggregate from raw concrete and extracts a mortar component, it is difficult to accurately extract the mortar component due to an artificial element. However, if the mortar fraction extracting device 30 of the present invention is used, the mortar fraction can be obtained with high accuracy excluding such an artificial element. In addition, the mortar content here means what removed coarse aggregate (gravel) from raw concrete.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS. 1 to 3 show a first embodiment of a method for measuring the water absorption and surface water content of an aggregate according to the present invention. In FIG. 1, reference numeral 1 (1a, 1b, 1c)
Is sand (fine aggregate) kneaded and mixed as aggregate in raw concrete. The sand 1 is in a wet state in the raw concrete. That is, the surface water 2 is attached to the surface, and the water 3 is contained inside the essence. The water content 3 is irrelevant to concrete strength. That is, the moisture taken in by the sand 1 has no relation to the water / cement ratio in the raw concrete. The purpose of the present invention is to easily and quickly measure the rate at which the sand 1 can take in moisture therein, ie, the water absorption rate, and the adhesion rate of the surface water 2, ie, the surface water rate. The purpose is to estimate the concrete strength after hardening by finding a proper water / cement ratio. To be precise, the water absorption is the weight (absolute dry weight) of the absolutely dry sand 1c of the total water content contained in the surface dry sand 1b.
And the surface water percentage means the percentage of the total amount of surface water 2 to the weight of absolutely dry sand 1c (absolute dry weight).

First, a method of measuring the water absorption of the sand 1 will be described.
This will be described with reference to FIG. As shown in FIG. 2A, the wet sand 1a is put into a metal cup 5 together with a sample bag 4 made of filter cloth. This metal cup 5 has an inner diameter of 5 to 7c.
m, cylindrical shape with a depth of 12 to 15 cm, drain hole 5 at the bottom
a. The upper opening of the metal cup 5 is closed by a dropping lid 5b, and a filter 6 made of non-woven fabric is laid at the bottom.

In the surface water removing step, as shown in FIG. 2B, the sand 1a is put together with the metal cup 5 into a centrifuge (centrifuge).
Multiply by 7. The centrifugation time is about 2 minutes. As a result, the surface water 2 adhering to the surface of the sand 1a falls through the drain hole 5a through the filter 6, and the sand from which the surface water 2 has been removed, ie, as shown in FIG. Dry sand 1
b remains. The metal cup 5 and the centrifuge 7
Is a JIS test method for concrete production process control A
1802 (Test method for surface water content of fine aggregate by centrifugal force).

In the surface dry weight measuring step, as shown in FIG. 2C, the sand 1b in the sample bag 4 is transferred to a beaker 8, and the weight (surface dry weight) is measured by an electronic balance 9. At this time,
It goes without saying that the weight of the beaker 8 is subtracted.

In the moisture removal step, as shown in FIG. 2 (d), sand 1b in a surface-dry state is placed in a microwave oven equipped with a magnetron, and the sand 1b is heated by high frequency wave for about 4 minutes to remove the moisture 3. Is evaporated off. Thereby, as shown in FIG. 1, the sand 1b releases the contained water 3, and becomes in a completely dry state (1c).

Finally, as shown in FIG. 2E, the weight (absolute dry weight) of the completely dry sand 1c is measured by the electronic balance 9.

The value obtained by subtracting the absolute dry weight from the surface dry weight is
It is the total water content contained in the sand 1b in the surface dry state. Therefore, the water absorption of the sand 1 can be expressed by the following equation 1.
The water absorption can be calculated. (Equation 1) Water absorption = (Table dry weight-Absolute dry weight) / Absolute dry weight

The steps (c), (d), and (e) in FIG. 2 are performed in a microwave oven having a built-in electronic balance 9. That is, high-frequency heating and weight measurement before and after heating are performed in one microwave oven. This microwave oven with the electronic balance 9 is
A display unit for displaying the result of weight measurement is provided, and the result of measurement such as surface dry weight is displayed. Equipped with a memory to store the surface dry weight,
The water absorption may be automatically calculated and displayed. When such a microwave oven with the electronic balance 9 is used,
The water absorption can be determined in about 10 minutes. Furthermore, if a microwave oven provided with the centrifugal separator 7 and the electronic balance 9 is used, the water absorption rate measurement step of FIG. 2 can be performed by one apparatus, and the water absorption rate can be measured more quickly. In addition,
With the sand 1 placed in the sample bag 4, surface dry weight measurement, moisture removal, and absolute dry weight measurement (FIGS. 2 (c), (d), and (e))
Needless to say, it may be performed.

Next, a method of measuring the surface water content of sand will be described.
This will be described with reference to FIG. First, after measuring the weight (wet weight) of the wet sand 1a, as shown in FIG. 3 (a), put the sand 1a into a microwave oven and heat it for about 4 minutes by high frequency to obtain a wet state. The water is removed from the sand 1a in the above to make it completely dry.

Finally, as shown in FIG. 3 (b), the weight (absolute dry weight) of the completely dry sand 1c is measured by the electronic balance 9 (absolute dry weight measuring step).

The value obtained by subtracting the absolute dry weight from the wet weight is
The total amount of water contained in the wet sand 1a (surface water 2+
Water content 3). Therefore, a value obtained by adding the surface water content and the water absorption of the sand 1 can be expressed by the following equation (2). The surface water percentage can be calculated by subtracting the water absorption rate, which is the calculated value of Equation 1, from the calculated value of Equation 2. (Equation 2) Surface water rate + water absorption rate = (wet weight-absolute dry weight) / absolute dry weight

The steps of FIGS. 3A and 3B are also performed in a microwave oven with an electronic balance 9 as described above. The above-mentioned water absorption rate may be stored using the microwave oven used for the water absorption rate measurement, and the surface water rate may be automatically calculated and displayed. The time required for measuring the surface water content is about 10 minutes.

As described above, according to the method for measuring the water absorption and the surface water content of the aggregate according to the present embodiment, the sand 1 is heated by high frequency and the water absorption and the surface water content are determined based on the weight difference before and after that. Rate can be calculated. The work process is easier than the conventional JIS test method. Therefore, the test time of the water absorption and the surface water can be significantly reduced, and the water absorption and the surface water of the aggregate can be measured easily and quickly. Also, the work process is very simple work such as weight measurement and high-frequency heating, and does not require any skill. Therefore,
Even inexperienced workers can easily and accurately measure them. In addition, foreign aggregates have been used due to the deterioration of aggregates in recent years, and concrete pieces from building demolition sites have to be used as recycled aggregates from the viewpoint of effective use of resources. It is possible to accurately obtain the water absorption rate and the like in a short time with respect to the aggregate having such quality variation and the aggregate obtained by mixing the aggregates, thereby enabling prompt response. Furthermore, since this measuring method has an advantage particularly in terms of accuracy, quality control with higher accuracy than JIS can be performed.

In the above embodiment, the surface water 2 was removed from the wet sand 1a using the centrifuge 7.
A surface water removing device for removing surface water 2 using wind power as shown in FIG. 4 may be used. This surface water removal device,
Tubular container 12 having bottom 11 made of non-woven filter
Rotating intermittently or continuously in the cylindrical container 12,
a, a motor 14 for rotating the rotating wings 13, an ammeter 15 for measuring a driving power value of the motor 14, and a blower for blowing air from above the cylindrical container 12 toward the sand 1 a ( Blower) (not shown).
Reference numeral 16 indicates a wind from the blower.

In this surface water removing device, sand 1a is put into a cylindrical container 12, and the rotating blades 13 are intermittently or continuously rotated by a motor 14, while the wind 1
6 removes surface water 2 adhering to the surface of the sand 1a in a wet state. The motor 14 has an ammeter 1
5 is connected and the wind 16 is applied to perform surface water removal work until the current value of the ammeter 15 becomes constant.
This is because while the surface of the sand 1a is wet,
a is a nodular shape, the resistance applied to the rotating wings 13 is large, and the driving current value indicated by the ammeter 15 is large.
Is blown off by the wind 16 from the blower, and as the surface of the sand 1a dries, the sand 1a gradually dissolves into a nodule state and decomposes into particles, so that the drive current value of the motor 14 decreases, When it finally reaches the surface dry state (1b),
This is because the drive current value of the motor 14 is constant.

As described above, the surface water 2 is removed by blowing air from the blower while measuring the resistance applied to the rotary wings 13 as a current value. Can be detected. In addition, since there is no needlessly blowing air to the sand 1b in the surface dry state, the surface water removing step can be speeded up.

As another embodiment of the surface water removing apparatus, an apparatus as shown in FIG. 5 may be used. There is sand 1a
While pressing with a flat plate member 17 having an insertion hole 18.
While rotating the rotating wings 13 (see FIG. 4), the wind 16
It is guessing. Pressing with the flat plate member 17 in this manner is based on piercing the sand with a ram in accordance with JIS A 1109 (test method for density and water absorption of lightweight structural fine aggregate). Water absorption can be measured. The method of detecting the removal state of the surface water 2 is the same as that shown in FIG. In FIGS. 4 and 5,
The air 16 from the blower may be warm air.

(Second Embodiment) In the first embodiment, the water absorption rate and the surface water rate were measured using the sand 1.
Even if the raw concrete before casting is used, the water absorption and the surface water content of the sand 1 contained in the raw concrete actually used can be measured. Hereinafter, a method of measuring the water absorption rate and surface water rate of aggregate using fresh concrete will be described in a second embodiment.

First, as shown in FIG. 6 (a), a sample (raw concrete) 20 is extracted from raw concrete before casting by about 1 kg. The sample 20 may be extracted at the time of shipment from the factory or when the mixer truck arrives at the site. Here, the raw concrete refers to a material obtained by kneading water, cement, and aggregate. In addition, the aggregate generally means fine aggregate and coarse aggregate, that is, sand and gravel. The difference between sand and gravel depends on whether the particle size is 5 mm or less. To be precise, 85 sieves of 5mm
The material that passes by% is called sand. In the case of containing gravel, there is a risk of explosion when subsequently heated by high frequency. Therefore, as shown in FIG. 6 (b), the sample 20 is placed on a 0.15 mm sieve 21 and a large amount of water 22 is applied from above to wash away the cement component 23 contained in the sample 20 and aggregate. The sand and the gravel which are 1 are extracted, and
As shown in (c), sand and gravel are passed through a 5 mm sieve 24 to remove the gravel 25.

100 g of sand 1 passed through sieve 21 and 40 g
Divide into two of 0g. 100 g of sand 1 is used in the process of FIG.
400 g of sand 1 is sent to the process of FIG. In this state, the sand 1 is in a wet state as shown in FIG. 1, the surface water 2 is attached to the surface, and the water content 3
Contains.

A process equivalent to that of FIG. 2 is performed on 100 g of the sand 1. That is, as shown in FIG. 7, the water absorption of the sand 1 is calculated from the difference between the surface dry weight and the absolute dry weight through the surface water removing step, the surface dry weight measuring step, the contained moisture removing step, and the absolute dry weight measuring step. Is done. The equation for calculating the water absorption is the same as Equation 1.

A process equivalent to that shown in FIG. 3 is performed on 400 g of sand 1. That is, as shown in FIG. 8, (surface water ratio + water absorption ratio) of the sand 1 is calculated from the difference between the wet weight and the absolute dry weight through the surface water / content moisture removing step and the absolute dry weight measuring step. Equation 3 shows the calculation formula of the surface water ratio + water absorption ratio. (Equation 3) Surface water content + water absorption = (400 g-absolute dry weight) /
Absolute dry weight The surface water content of sand can be obtained by subtracting the water absorption already obtained from the value calculated by Equation 3. In addition,
Needless to say, these high-frequency heating and weight measuring steps are performed in a microwave oven with an electronic balance. In addition, the measurement time of the water absorption rate and the surface water rate can be about 10 minutes each.

As described above, according to the method for measuring the water absorption and the surface water content of the aggregate according to the present embodiment, the same effects as in the first embodiment can be obtained. That is, the water absorption and surface water content of the sand 1 contained in the raw concrete can be easily and quickly measured. Even an unskilled worker can easily and accurately measure them. In particular, it is possible to obtain water absorption rate etc. in a short time and with high accuracy, and to quickly respond to aggregates with variable quality such as foreign and recycled aggregates, and aggregates obtained by mixing them. Becomes possible. JI
Quality control with higher accuracy than S is also possible. In addition, since raw concrete is used as an original sample, it is possible to measure the water absorption and the like at the time of shipment from a factory or on site. In this embodiment, a 0.15 mm sieve 21 is used.
Although the cement portion 23 is removed from the raw concrete sample 20, the sand 1 having a size of 0.15 mm or less falls off the sieve 21 together with the cement portion 23 in this method. Therefore, if it is desired to more accurately measure the water absorption and the surface water, it is necessary to make some correction to the above calculation result.

In this embodiment, when sand is extracted from raw concrete (see FIG. 6B), a mortar extractor 30 as shown in FIG. 9 can be used.
The mortar extractor 30 includes a cylindrical container 31 having a mesh structure with a side surface of 5 mm and having a bottom.
, An inner case 33 surrounding the entire cylindrical container 31, and an outer case 34 surrounding the inner case 33 as main components. The inner case 33 is configured to be detachable from the outer case 34. At the bottom of the outer case 34, a rotating shaft 36 that rotates via a belt 35 when the motor 32 is started is provided. The bottom of the inner case 33 is provided with a hole 33a that allows the rotation shaft 36 to be fed in. When the inner case 33 is set in the outer case 34, the rotation shaft 36 supports the cylindrical container 31 through the hole 33a. . When the motor 32 is started, the cylindrical container 31 rotates together with the rotating shaft 36.

When the raw concrete 20 is put in the cylindrical container 31 and the motor 32 is started to rotate the cylindrical container 31, the mortar 40 is shaken from the mesh portion on the side surface of the cylindrical container 31 by the centrifugal separation action. It is dropped, and the gravel 25 remains in the cylindrical container 31. Here, the rotation speed of the rotation shaft 36 is set to 100 to 500 ppm, and the rotation time is set to 30 seconds to 3 minutes. As described above, the mortar 40 can be extracted by removing the gravel 25 from the raw concrete 20. Since the mortar 40 is accumulated in the inner case 33, the mortar 40 is collected and placed on a 0.15 mm sieve (see FIG. 6 (c)).
Is applied, the cement content contained in the mortar component 40 can be washed out and sand can be extracted.

As described above, the mortar is extracted from the raw concrete by the centrifugal action, and then a large amount of water is applied to the mortar to extract the sand. The mortar and even the sand can always be extracted with a certain degree of accuracy compared to the case where the gravel is separated from the raw concrete using. In other words, when using a sieve to separate sand and gravel, there is a slight difference in the size of aggregate passing through the sieve between the case where the sieve is shaken patiently and the case where the sieve is shaken only for a short time. As a result, it is inevitable that an error occurs in the water absorption rate, surface water rate, and the like. However, if the mortar extractor of the present invention is used, such an artificial element can be eliminated and gravel can always be separated under the same conditions.

When the water-cement ratio is measured, mortar is extracted by removing gravel (coarse aggregate) from raw concrete. At that time, the mortar extractor of the present invention is used. be able to. When trying to extract mortar from raw concrete using a sieve, the quality and amount of mortar passing through the sieve depends on whether raw concrete is soft with a large amount of water or hard with a small amount of water. Therefore, the water-cement ratio cannot be accurately obtained as a result. However, if the mortar extractor of the present invention is used, the mortar can always be extracted with a constant accuracy irrespective of the amount of water contained in the raw concrete, so that the water-cement ratio can be accurately calculated.
As described in JP-A-2-40531, when the water mortar ratio is calculated by removing water contained in the mortar sample using a high-frequency heating means such as a microwave oven, the inner case is used as described above. If the inner case 33 is configured to be detachable from the outer case 34, the inner case 33 can be placed in a microwave oven and subjected to high-frequency heating treatment, and the water-cement ratio can be obtained more quickly and accurately.

In the first and second embodiments, the water absorption and the surface water content of the fine aggregate (sand) were measured. However, the water absorption and the like of the coarse aggregate (gravel) were measured in the same manner. It may be measured. In this case, to prevent the coarse aggregate from bursting and damaging the inside of the microwave oven when heated by high frequency,
You need to take some measures. For example, it is conceivable to put coarse aggregate in a ceramic container.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a water-containing state of an aggregate.

FIG. 2 is a work process diagram showing a method for measuring the water absorption of the aggregate.

FIG. 3 is a work process diagram showing a method of measuring the surface water content of the aggregate.

FIG. 4 is an external perspective view showing a surface water removing device.

FIG. 5 is an external perspective view showing another surface water removing device.

FIG. 6 is a work process diagram showing a method of measuring a water absorption rate and a surface water rate of aggregate using fresh concrete.

FIG. 7 is a flowchart showing a process of measuring the water absorption of the aggregate.

FIG. 8 is a flowchart showing a process of measuring the surface water content of the aggregate.

FIG. 9 is an internal configuration diagram showing a mortar extractor of the present invention.

[Explanation of symbols]

 1a, 1b, 1c Sand (fine aggregate) 2 Surface water 3 Water content 11 Bottom part 12 Cylindrical container 13 Rotating wings 14 Motor 15 Ammeter 17 Plate member 18 Insertion hole 20 Sample (raw concrete) 21 Sieve 22 Water 23 Cement Minute 24 sieve 25 gravel (coarse aggregate) 30 mortar extractor 31 cylindrical container 32 motor 40 mortar

Claims (13)

[Claims] 1. After removing surface water 2 adhering to the surface of the aggregate 1a in a wet state, the aggregate 1b is heated at a high frequency, and the weight difference between the aggregates 1b and 1c before and after heating is calculated as follows. A method for measuring the water absorption of an aggregate, comprising calculating the water absorption of the aggregate 1. 2. A method for measuring the surface water content of the aggregate 1 using the measurement result of the water absorption rate of the aggregate according to claim 1, wherein the aggregate 1a in a wet state is heated at a high frequency, A method for measuring a surface water rate of an aggregate, comprising calculating a surface water rate of the aggregate 1 from a weight difference between the aggregates 1a and 1c before and after heating and a water absorption rate of the aggregate 1. 3. The method according to claim 1, wherein said aggregate 1 is a fine aggregate having a relatively small particle size. 4. The method according to claim 2, wherein the aggregate 1 is a fine aggregate having a relatively small particle size. 5. A method for measuring the water absorption of aggregate contained in raw concrete, comprising: applying water 22 to raw concrete 20 placed on a sieve 21; After extracting the aggregate 1a and removing the surface water 2 adhering to the surface of the aggregate 1a, the aggregate 1b is heated at a high frequency, and the weight difference between the aggregates 1b and 1c before and after heating indicates that the aggregate 1a A method for measuring the water absorption of an aggregate, comprising calculating the water absorption of the aggregate. 6. A method for measuring the surface water content of the aggregate 1 using the measurement result of the water absorption rate of the aggregate according to claim 5, wherein the aggregate 1a extracted from the raw concrete 20 is subjected to high frequency. A method for measuring the surface water content of an aggregate, comprising heating and calculating the surface water content of the aggregate 1 from a weight difference between the aggregates 1a and 1c before and after the heating and the water absorption of the aggregate 1. 7. The aggregate extracted from the raw concrete 20 is composed of a fine aggregate 1 having a relatively small particle size and a coarse aggregate 25 having a relatively large particle size. The method for measuring the water absorption of an aggregate according to claim 5, wherein the coarse aggregate 25 is separated and removed. 8. Aggregate extracted from raw concrete 20 is composed of fine aggregate 1 having a relatively small particle size and coarse aggregate 25 having a relatively large particle size, and prior to high-frequency heating. The method for measuring the surface water content of an aggregate according to claim 6, wherein the coarse aggregate 25 is separated and removed. 9. The method for measuring water absorption of an aggregate according to claim 1, wherein surface water or moisture is removed using a centrifuge. 10. The method for measuring the water absorption of an aggregate according to claim 1, wherein the surface water or moisture is removed by wind power. 11. A surface water removing device for removing surface water 2 attached to a surface of a wet aggregate 1a, the fine aggregate having a fine bottom 11 and the wet aggregate 1a being provided. A cylindrical container 12 to be put therein, a rotating wing 13 that rotates intermittently or continuously in the cylindrical container 12 and stirs the aggregate 1a,
It comprises a motor 14 for rotating the rotary wings 13, an ammeter 15 for measuring a drive power value of the motor 14, and a blower for blowing air from above the cylindrical container 12 toward the aggregate 1 a. While applying wind to the aggregate 1a
Removing the surface water 2 while rotating the rotating blades 13 and detecting a change in the drive current value of the motor 14 when the rotating blades 13 are rotated by the ammeter 15 and detecting the removal state of the surface water 2. Surface water removing device characterized by the above-mentioned. 12. A driving current value of the motor 14 when the rotary wing 13 is rotated while pressing the aggregate 1a by the flat plate member 17 having the insertion hole 18 in the cylindrical container 12. The surface water removing device according to claim 11, wherein the surface water 2 is removed while detecting the state of removal of the surface water 2 by detecting a change in the surface water 2 with an ammeter 15. 13. A method of producing raw aggregate 20 from raw concrete 20.
5 is a mortar extractor for extracting a mortar component 40 by removing 5, comprising a cylindrical container 31 having a bottomed cylindrical shape and a motor 32 for rotating the cylindrical container 31. It has a mesh structure. The cylindrical container 31 containing the raw concrete 20 is
2 and the centrifugal action produced by the rotation causes the raw concrete 2
A mortar fraction extraction apparatus characterized in that the mortar fraction 40 contained in the mortar fraction 40 is sieved to leave the coarse aggregate 25 in the cylindrical container 31 so that the mortar fraction 40 can be extracted.