JP3282100B2 - Method for measuring water absorption, surface specific gravity, and surface water content of aggregate, quantitative container used therefor, and water dispenser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring water absorption, surface specific gravity, and surface water content of aggregates, and a measuring container and a water dispenser used therefor.

[0002]

2. Description of the Related Art Aggregates of ready-mixed concrete are usually treated as wet aggregates having moisture adhered to the surface thereof. On the other hand, the quality of the aggregate is such that the aggregate contains water in a saturated state and has no water on its surface (hereinafter referred to as a surface dry state).
, That is, controlled by the specific gravity of surface dryness and water absorption,
As for the moisture adhering to the aggregate surface, the ratio to the surface dry weight is managed as the surface water content. Wet aggregate is a natural material and is used in large quantities, so it is necessary to constantly measure these values and estimate and monitor the true values.

[0003] The methods for testing the surface specific gravity and water absorption of aggregates are described in JIS A 1109 and JIS A 1100.
Stipulated. According to the regulations, when measuring the surface dry specific gravity of the fine aggregate, the aggregate sample is placed in water at 20 ± 5 ° C.
After leaving it for a while to absorb water to make it saturated, spread it thinly on a flat surface, blow it, and dry it.When there is some water on the surface, pack the aggregate sample into a flow cone, squeeze it, and then pull up the flow cone . By repeating this operation, when the aggregate cone slumps for the first time, it is determined that the surface is dry, and the specific gravity is calculated by measuring the surface dry weight using a pycnometer or a graduated flask.

[0004] However, it takes time to prepare the surface dry sample, and the flow condition differs depending on the grain shape of the aggregate, and the judgment of the surface dry condition varies from individual to individual. It is difficult to ask. Further, when a graduated flask is used, there are also problems such as reading errors. When determining the water absorption, the sample after measuring the surface dry weight is 105 ± 5.
It is dried to a constant weight at ℃ to make it absolutely dry (hereinafter referred to as absolutely dry), and the reduced weight is taken as the water absorption. Will be done.

[0005] The measurement of surface water content is based on JIS A1.
111, stipulated in JIS A 1125. However, since the above surface dry specific gravity value is also used for measuring the surface water content,
The error and the individual difference are reflected, and there are also individual differences in a method of removing air attached to the aggregate. Regardless of the graduated flask or pycnometer used for measurement, the sample inlet is small, it is difficult to perform the work, and it takes a long time, and it is extremely troublesome as a whole.

[0006] As described above, if the measured value varies among individuals, it cannot be handled technically, and if the measurement takes time, the number of measurements cannot be increased. When the measurement is performed by the method specified in JIS, it is difficult in operation to increase the number of times of measurement for obtaining the variance and estimating the true value from the measured value.

[0007]

The above problem in the conventional measuring method is caused by the fact that human factors and errors are inevitable in the surface dry sample itself, which is the basis of all measured values.
Even if the surface dry state is significant in evaluating the quality of the aggregate, if the surface dry state that can be actually produced is poor in reproducibility, the significance of spending a lot of time and labor on the work is It is sparse.

[0008] The present invention, in view of the above points of the prior art,
By eliminating individual differences in measured values, simplifying the measurement method and shortening the measurement time, the number of measurements can be increased,
Aggregate water absorption, which can provide reliable measurements,
The purpose of the present invention is to provide a method for measuring surface dry specific gravity and surface water content.

[0009]

In order to achieve the above object, according to the present invention, an aggregate sample is put into an absolutely dry state,
The sample was placed in a quantitative container to determine the absolute dry weight, and then
Water was added to the fixed amount container, the total weight was measured in a full state, the absolute specific gravity was determined from these, the sample was further heated in water to absorb water, and after being saturated, the mixture was allowed to cool naturally and then Return to the quantitative container, add water to the quantitative container, measure the total weight in a full state, and determine the difference between the total weight and the total weight as the water absorption,
The water absorption and the specific gravity of the surface dryness were determined.

[0010] Further, the aggregate sample in a wet state is accommodated in a quantitative container, the wet weight is determined, and then the total weight is measured in a full state by adding water to the quantitative container. The surface water content was determined from the surface dry specific gravity determined in the above.

In carrying out each of the above-mentioned methods, a container body having a cylindrical shape, an upper surface serving as an entire opening, and an inner surface and an upper end surface of the opening being smoothed, and an opening in the container body. A lid body for closing the upper end face of the container body, and a joining surface between the lid body and the upper end face of the opening of the container body is subjected to a grinding process, and the lid body is a lower surface portion facing the inner space of the container in a closed state. It is preferable to use a quantitative container having a step formed therein, a swelling portion to be fitted into the space in the container, and a small through-hole penetrating from the swelling portion to the upper surface side of the lid.

[0012] Further, in carrying out each of the above-mentioned methods, a substantially horizontal or vertically downward radial direction is provided at the tip of a nozzle having a sufficient length that can be inserted to the inner bottom of the quantitative container containing the aggregate sample. It is preferable to use a water dispenser connected to a water supply pipe via a water flow controller capable of opening and closing or controlling the flow of water at the base end, while opening a plurality of water spouts in an oriented manner.

[0013]

1 and 2 show an embodiment of a metering container 1 and a water dispenser 2 used in the method of the present invention.

As shown in FIGS. 1 (a) and 1 (b), the metering container 1 has a cylindrical body, a container body 11 having an opening 10 on the entire upper surface, and a substantially closed opening 10. And a disc-shaped lid 12. The upper end surface 10a and the inner surface 11a of the opening 10 of the container body 11 are processed smoothly, and the contact surface between the upper end surface 10a and the peripheral lower surface 12a of the lid body 12 is processed to be hermetically sealable.

A step 12b is provided in a portion of the lid 12 which faces the inside of the container body 1 in the closed state.
A bulging portion 13 that fits inside 1 is formed, and a small through hole 14 is formed in the center of the bulging portion 13 so as to penetrate toward the upper surface of the lid. The step 12b has a tapered shape to facilitate the fitting into the inside of the container main body 11 and to facilitate the discharge of air at the time of full water injection described later. Further, the volume of the bulging portion 13 (the volume of fitting into the container body 11) needs to be larger than the internal volume of the small through hole 14. In the metering container 1 of the embodiment, the inner volume is 1000 cc and the depth is about 10 cm.
The thickness of the lid 12 was about 10 mm, and the height of the step 12b was 5 mm. The material of the quantitative container 1 is
Although not particularly limited, it is preferable to use a metal having a small coefficient of thermal expansion and excellent corrosion resistance, for example, a stainless steel.

As shown in FIGS. 2 (a) and 2 (b), the water dispenser 2 is horizontally and vertically attached to the tip of a nozzle 21 having a sufficient length and strength and rigidity that can be inserted to the inner bottom of the container body 11. A plurality of sprinkling ports 22 (for example, horizontal 22a × 8, vertical 22b × 1) are opened by radially orienting downward,
A water supply pipe 24 is connected to the base end via a water flow controller 23. The water flow controller 23 is provided with a valve 26 capable of opening and closing the water passage 25 inside the casing 23 as shown in FIG.
And the valve sliding shaft 2 reaching the outside of the casing 23.
7 is connected to the tip of a lever 28. The valve slide shaft 27 is urged by a spring 29 in a direction to close the valve 26. By operating the lever 28 to move the valve slide shaft 27 up and down, it is possible to open and close the water flow and adjust the flow rate. It has become.

(1) Measurement of Total Weight / Content Volume of Quantitative Vessel At the time of measurement, the weight P of an empty quantitative container 1 and the total weight W in a state in which the quantitative container 1 is filled with water (hereinafter referred to as the total Weight). When the metering container 1 is filled with water, the water is injected using the water dispenser 2 so that air bubbles do not adhere to the inner wall of the container body 11, and then the lid 12 is closed.
When the opening 10 is closed by fitting into the opening, surplus water in the container is eliminated by the bulging portion 13 and flows out to the outside through the small through hole 14, so that water adhering to the upper surface of the lid 12 and the outer periphery of the container main body 11 is removed. If you wipe it off, it will be full. Since the opening area of the small through hole 14 is sufficiently smaller than the opening area of the upper surface opening 13 of the container body 11, errors due to surface tension are small, and excess water is forcibly discharged by the lid 12. Therefore, errors due to the operation of the measurer are unlikely to occur.

The water temperature t is measured together with the full water weight W, and the internal volume V of the quantitative container 1 is obtained as V = (WP) / Ct. Here, Ct is the density (specific weight) of water at the water temperature t ° C. In the subsequent measurement, the total water weight W can be calculated from W = V · Ct + P simply by measuring the water temperature. As the density Ct of water in the normal temperature range, for example, a value published every 1 ° C. in a scientific chronological table is used.

According to the method of the present invention, when measuring the surface dry specific gravity and the water absorption of the aggregate, the absolutely dry sample is used instead of using the conventional dry sample which requires time and effort to prepare because the standard is not clear. Prepare and use. Absolutely dried samples are samples collected from aggregates.
It is dried to a constant weight at 105 ± 5 ° C. using a dryer, and used in an absolutely dry state.

(2) Measurement of Absolutely Dry Specific Gravity An absolutely dry sample is contained in the quantitative container 1 at least two-thirds or more, preferably almost completely, leaving a space of 5 to 10 mm on the upper side, and the absolute dry weight m0 is measured. I do. Then, after allowing to cool naturally to a normal temperature range, the water dispenser 2 is inserted until the tip of the water dispenser comes into contact with the fixed part of the fixed quantity container 1, and the sample 31 is slowly stirred by the water dispenser 2 itself as shown in FIG. While intermittently adding water 32, gently pull it up and fill it with water. By adding water from the deepest part of the sample 31 in this way, the air can be discharged well upward, and it becomes possible to perform water injection in a very short time.

After confirming that the water is full and measuring the water temperature t, the opening 10 of the container body 11 is closed with the lid 12. At this time, the lid 12 is slid laterally along the opening 10 of the container body 11 as shown in FIG.
The bubbles 33 generated near the water surface are cut off to disappear, and the opening 10 is closed with the lower surface of the lid 12 and the water surface in close contact with each other. The water 32 is eliminated, the metering container 1 is filled with no air bubbles left inside, and the excess water is discharged to the outside through the small through holes 14 (FIG. 3C).

When the total weight W0 is measured by wiping off moisture adhering to the outer periphery of the fixed quantity container 1, the weight ms of water having the same volume as the absolute volume of the sample 31 is given by the following equation, where the specific gravity of water at the water temperature t is Ct. Is required. ms = (W + m0−W0) / Ct From this, the absolute dry specific gravity ρ0 is as follows: ρ0 = m0 / ms = m0 · Ct / (W + m0−W0) = m0 · Ct / (V · Ct + m0−T0) Here, W is the total weight of the full water obtained in (1), and T0 is the sum of the weight of the sample and water (W0-P). The above-described water injection into the absolutely dry sample and the measurement of the total weight W0 need to be performed promptly before the absolutely dry sample absorbs water. However, in the present invention, the quantitative container 1 and the water dispenser 2 are used. It can be measured in a very short time.

(3) Measurement of Surface Dry Specific Gravity and Water Absorption Rate The water and the sample in the quantitative container 1 were transferred to a separate heating container (pan, not shown) for heating, heated, and further heated for 10 minutes. Heat for at least a minute to allow the sample to fully absorb water, and then stop heating after reaching a saturated state.

After allowing to cool naturally to a normal temperature range, it was confirmed that the inside of the container was separated into the sample and the supernatant, and the supernatant water was once collected in another container, and the remaining water in the heating container was removed. The saturated sample is returned to the original quantitative container 1, and the recovered supernatant water is further returned. When the water is not full, the water is further filled with water, and the water temperature t is measured. Then, the fixed amount container 1 is closed with the lid 12 to remove the excess water, and the water adhering to the outer periphery of the container is wiped to remove the total weight. If W1 is measured, the amount of water absorption q can be obtained from the amount of water actually absorbed by: q = W1-W0 = T1-T0. Here, T1 is the sum of the weight of the sample and water (W
1-P).

The water absorption Q is the ratio of the water absorption q to the absolute dry weight, and the absolute dry weight m0 is obtained by multiplying the absolute volume of water, ms, by the absolute volume of water, by the absolute dry specific gravity ρ0. The water absorption rate Q is determined as follows: Q = (q / m0) × 100 (%) = (q / ρ0 · ms) × 100 (%)

Since the surface dry weight m1 is obtained by adding the water absorption q to the absolute dry weight m0, the specific gravity ρ of the surface dry is given by: ρ = m1 / ms = (m0 + q) / ms = (ρ0 · ms + q) / Ms. Therefore, the relationship between the surface dry specific gravity ρ, the absolute dry specific gravity ρ0, and the water absorption Q is as follows. ρ = ρ0 · (1 + Q / 100)

(4) Measurement of Surface Moisture Rate The wet sample is placed in the fixed quantity container 1 at least 2/3 or more, preferably almost fully left so as to leave a space of 5 to 10 mm on the upper side, and the wet weight m2 is measured. Next, water is intermittently added using the water dispenser 2 while removing air from the bottom of the container in the same manner as described above, and the water dispenser 2 is gently pulled up to be filled with water.
After measuring the water temperature t, the fixed amount container 1 is closed with the lid 12 to remove excess water, and the moisture attached to the outer periphery of the container is wiped off, and then the total weight W2 is measured. The surface water rate H is the surface water quantity h
Is the ratio of the surface dry weight to the surface dry weight, and the surface dry sample is obtained by removing the surface water from the wet sample.
Then, the surface water amount h is represented by h = m2-m1.

On the other hand, assuming that the specific gravity measurement similar to the case of the absolute dry specific gravity ρ0 was performed using the surface-dried sample, the total weight of the surface-dried sample filled with water was completely different from that of the water-added amount. It becomes equal to the total weight W2 when water is added to the wet sample to make it full.
From this, the surface dry specific gravity ρ is represented by the following equation. ρ = m1 · Ct / (W + m1−W2) = m1 · Ct / (V · Ct + m1−T2) where W is the total water weight obtained in (1), and T2 is the sum of the weight of the wet sample and water (W2 -P). Rearranging the above equation, the surface dry weight m1 is expressed by the following equation. m1 = (W2-W) / (1-Ct / ρ) = (T2-V · Ct) / (1-Ct / ρ)

Accordingly, the surface water content H is H = (h / m1) × 100 (%) = [{(W + m2-W2) -m2 / ρ} / (W2-W)] × 100 (%) = [ {(V · Ct + m2−T2) −m2 / ρ} / (T2−V · Ct)] × 100 (%).

[0030]

EXAMPLE 10 samples were collected from fine aggregates loaded on one dump truck, and the absolute dry weight m0 (g) was determined using a fixed volume container having an internal volume V of 1000 cc, and the sample and water after water addition were added. Of the sample, water is added to the saturated sample, and the total sum T1 of the sample and water is determined.
(G) was measured to determine a water absorption q (g), a water absorption Q (%), and a specific gravity ρ of surface dryness. Table 1 shows the results.

[0031]

[Table 1]

Next, one sample was collected from the fine aggregate described in one dump truck for 10 days, and the same measurement as above was performed every day. Table 2 shows the results.

[0033]

[Table 2]

In this case, the average value of the absolute dry specific gravity ρ0 for 10 days is 2.53, and the standard deviation σn-1 is 0.013.
The average value ρ of the surface dry specific gravity ρ is 2.58, and the standard deviation σn−1 =
It was 0.012.

Next, in order to estimate the surface water content H of the fine aggregate (wet sand) loaded on one dump truck, aggregate samples were placed at three places from the upper layer, five places from the middle layer, and two places from the lower layer. The sample was sampled and the wet weight m2 and the weight sum T2 of the sample and water after water addition were measured, and the water absorption Q (%) and the surface water H
(%) Was determined. Table 3 shows the results.

[0036]

[Table 3]

[0037]

According to the present invention, as described above, when calculating the water absorption, surface specific gravity and surface water content of the aggregate, it takes time and effort for the measurement as in the prior art, and the individual difference of the measurer is inevitable. It is not necessary to prepare a surface dry sample with poor reproducibility, and the water absorption and the specific gravity of the aggregate can be obtained under the same conditions by a relatively simple procedure in a short time. By obtaining the value, it is possible to obtain a highly reliable measurement value, which is advantageous in quality control of the aggregate and in designing the mixture.

In carrying out each of the above methods, a container body having a cylindrical shape and an upper surface serving as an entire opening and having an inner surface and an upper end surface of the opening smoothed is provided. A lid body for closing the upper end face of the container body, and a joining surface between the lid body and the upper end face of the opening of the container body is subjected to a grinding process, and the lid body is a lower surface portion facing the inner space of the container in a closed state. The container is filled with water by using a quantitative container having a step formed therein, a swelling portion that fits into the space inside the container, and a small through hole that penetrates from the swelling portion to the upper surface of the lid. Water injection can be performed easily, quickly and accurately, and the wide opening allows easy and reliable access to the aggregate.

Further, in carrying out each of the above-mentioned methods, the tip of a nozzle having a sufficient length that can be inserted to the inner bottom of the fixed quantity container containing the aggregate sample is radiated substantially horizontally or vertically downward. A plurality of water spouting ports are opened with orientation, and a water heater connected to a water supply pipe via a water flow controller that can open and close the water flow or adjust the flow rate is used at the base end, so that the water heater itself agitates. By adding water from the lowermost layer of the aggregate sample, the air adhering to the aggregate is discharged well, and accurate water addition and water filling can be performed in a short time.

[Brief description of the drawings]

FIG. 1A is a longitudinal sectional view showing an embodiment of a fixed amount container in a state where a lid is opened, and FIG. 1B is a closed state.

FIG. 2 (a) is a side view showing an embodiment of a water dispenser,
(B) is a sectional view of a main part.

FIG. 3 (a) shows a state in which water is added to a fixed quantity container containing an aggregate sample using a water dispenser, FIG. 3 (b) shows a state in which a lid is closed after adding water, and FIG. 3 (c) shows excess water discharged by the lid. It is a figure which shows the filled full state.

FIG. 4 is a flowchart showing an outline of a measurement procedure in the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quantitative container 2 Watering device 10 Opening 11 Container main body 12 Lid 13 Swelling part 14 Small through-hole 21 Nozzle 22, 22a, 22b Sprinkling port

Claims (4)

(57) [Claims] 1. An aggregate sample is put into an absolutely dry state, the sample is stored in a quantitative container, and the absolute dry weight is determined. Then, the total weight is measured in a full state by adding water to the quantitative container, and the absolute weight is measured. After determining the dry specific gravity, further heating the sample in water to absorb water to make it saturated, then allowing it to cool naturally, returning it to the quantitative container, adding water to the quantitative container, and measuring the total weight in a full state And
The difference between the gross weight and the gross weight is taken as the amount of water absorption, and the water absorption,
A method for measuring water absorption and surface dry specific gravity of an aggregate, which comprises determining the surface dry specific gravity. 2. A wet aggregate material is placed in a quantitative container, and a wet weight is determined. Then, the wet weight is added to the quantitative container and the total weight is measured in a full state, and the total weight is measured. A method for measuring the surface moisture content of an aggregate, comprising determining the surface moisture content from the surface dry specific gravity determined by the method described in 1 above. 3. A container body having a cylindrical shape, an upper surface of which is an entire opening, and an inner surface and an upper end surface of the opening processed to be smooth, and a lid for closing an upper end surface of the opening of the container body. The joining surface between the lid and the upper end surface of the opening of the container body is made by a grinding process, and the lid is provided with a step on a lower surface portion facing the inner space of the container in a closed state. 3. The quantitative container according to claim 1, wherein a bulging portion which fits into the space is formed, and a small through-hole is formed to penetrate from the bulging portion to the upper surface of the lid. 4. A plurality of water outlets which are radially oriented substantially horizontally or vertically downward at the tip of a nozzle having a sufficient length which can be inserted to the inner bottom of a fixed volume container containing an aggregate sample. 3. The water dispenser used in the measuring method according to claim 1 or 2, wherein a water supply pipe is connected to the base end via a water flow controller capable of opening and closing the water flow or adjusting the flow rate.