JPS61202161A - Quality inspecting device for ready-mixed concrete - Google Patents

Abstract

PURPOSE:To enable the guaranteeing of compressive strength of ready-mixed concrete to be shipped, by using the results of calculation of the rate of surface water and the water/cement ratio for correction in the preparation of crude concrete. CONSTITUTION:Sand before being fed to a weighing/preparing section 1 and mortar following the preparation are sampled with a weighing section 2, where the weight S' and the underwater weight SW' of the sand sampled and the weight M and the underwater weight MW of the mortar are measured by a control signal from a sequencer 3 and the results of the measurement are sent to a computer 5. A device 5 calculates the surface water rate K of the sand from the weights S' and SW' and the water/cement ratio W/C of crude concrete. The results of the calculation are recorded on a printer 6 and fed to the weighing/ preparing section 1. Thus, a feed forward control is done to correct the amount of water to feed.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an apparatus capable of inspecting the quality of ready-mixed concrete during its manufacturing process and ensuring the quality of ready-mixed concrete to be shipped.

(b) Prior Art In general, compressive strength, which is the most important quality of concrete, is largely controlled by the ratio of the weight of water to the weight of mixed cement, that is, the water/cement ratio. Therefore, in a ready-mixed concrete production plant, particularly strict control is required regarding the mixing ratio of cement and water.

Conventionally, this water/cement ratio has been managed by measuring the weight of cement and water to be mixed.

By the way, the main components of ready-mixed concrete are cement,
These are sand, gravel, and water, but among these, sand and gravel contain surface water, and the absolute amount and fluctuation of the surface water of sand is particularly large. Therefore, even if the amount of cement to be added is accurately measured when producing ready-mixed concrete, the water/cement ratio of the product will change due to the above-mentioned fluctuations in surface water, and the concrete after solidification will At present, the compressive strength of the steel is not practically guaranteed.

(c) Purpose The present invention has been made in view of the above, and is intended to capture the amount of surface water in order to adjust the amount of water input at the time of mixing in the production process of ready-mixed concrete, and to control the amount of fresh concrete after mixing. The purpose is to provide a quality inspection device for ready-mixed concrete that can measure the water/cement ratio and guarantee quality.

(d) Principle and structure of the invention The present invention will be described in detail.

First, the ratio of surface water contained in sand can be determined as follows. If the weight of sand containing surface water is S', the weight of true sand is S1 and the weight of surface water is Wl, then S'=S+Wl - (11 Also, the underwater weight of sand with this weight S' is 3 w 'year,
If the true specific gravity of sand (specific gravity of dry sand) and specific gravity of water are ρS and ρW, respectively, then ρS
ρ W where ρS and ρW are known constants, in particular, ρw=1
Therefore, Sw′-3′ −−−Wl −(31ρ S +11. From (3), S−α・3 W′ −+41 and α− 1−□ ρ S. Therefore, the surface water of this sand The rate can be calculated by measuring the weight S' of sand and the weight 3w' in water.

In addition, the water/cement ratio of raw concrete after mixing is
It can be obtained as follows. 5f of fresh concrete
Pass through a mesh sieve to remove gravel and extract mortar. This mortar contains cement, sand, and water, but only the cement does not contain any moisture, and its blending ratio is known by measuring at the time of blending.

The weight of the extracted mortar is M, of which cement and sand (
The weights of real sand) and water (including input water and surface water) are C and S, respectively. and W, then M = C + S j + W - (61Mw is the weight of mortar in water, cement, sand.

and the specific gravity of water as ρS. Let ρS, and ρW, ρC ρS ρW ρC. Since ρS and ρW are known and ρw=1, ρ
From C ρ S (6), (8), ρ C ρ S ρ S ρ C ρ Sρ
If S ρ C ρ S, then Mw. -βM-rc-βW -Ol+101 Divide both sides of the equation by C and rearrange it. If the mixing ratio of cement (known) is P, then C=M-P -υ (I+), (from l, CP M It can be calculated by measuring the weight M of mortar and the weight Mw in water.

Based on the above principle, the quality inspection device of the present invention includes a means for sampling a predetermined amount of sand before mixing and measuring its weight and underwater weight, and a means for measuring the surface water contained in the sand based on the measurement results. a means for extracting a predetermined amount of mortar from mixed ready-mixed concrete and measuring its weight and weight in water; and a means for calculating the water-cement ratio of ready-mixed concrete based on the measurement results. and
The present invention is characterized in that the calculation results of the surface water ratio of sand and the water/cement ratio after mixing can be used for correction at the time of mixing.

(e) Examples Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention.

In the weighing and mixing section 1 of the Hasocha plant, the weights of each component of fresh concrete, cement, water, gravel, and sand are measured and added, and these are mixed to produce ready-mixed concrete. The sand before being supplied to the measuring/mixing section 1 and the mortar obtained by passing the mixed fresh concrete through a 5 mm mesh sieve or the like are each sampled into the sample measuring section 2 via a chute or the like.

As will be described later, the sample weighing section 2 includes an electronic balance, a water tank, a weighing container, a drive mechanism for each part, etc., and controls the weight S' of the sampled sand and the underwater weight S w by control signals from the sequencer 3. ', and the weight M of the mortar and the weight Mw in water can be measured. The measurement results are then input to the computer 5 via the interface circuit 4.

The computer 5 is equipped with a CPU, a ROM, a RAM, etc., and calculates the surface water of the sand using the above-mentioned equation (5) based on the program written in the ROM. The ratio K is calculated, and the water/cement ratio W/C of fresh concrete is calculated using the above-mentioned formula 0 using the amount M of mortar and the weight in water Mw. This calculation result is recorded on the printer 6 connected via the interface circuit 4 and is also supplied to the measuring/blending section 1.

FIG. 2 is a front view of the sample measuring section 2, and FIG. 3 is a right side view thereof. An electronic balance 12 equipped with a weighing hook 12a for suspending an object to be weighed is placed on the upper surface of the frame 11. A weighing container 13 is hung on the weighing hook 12a of the electronic balance 12. The weighing container 13 is supported by a moving cart 14, and the moving cart 14 is supported by a motor 15.
The vehicle can travel on the horizontal rail 16 by driving the vehicle. The movable cart 14 supports the weighing container 13 on rod-shaped protrusions provided on both sides thereof, and supports the weighing container 13 at the sample input position i,
It can be moved to the stirring position (■), the measuring position (■), and the washing position (■). In the weighing position (3), after the weighing container 13 is suspended from the weighing hook 12a of the electronic balance 12, only the moving cart 14 moves further to the left in FIG. It is configured to leave. In addition, in the washing position (■), the stopper 18 that moves up and down by the cylinder 17 is interlocked with the measuring container]3.
is configured to be inclined as shown in FIG.

A stirring blade 21 that is rotated and moved up and down by a motor 19 and a cylinder 20 is disposed above the stirring position (3).

At the measuring position (2), a water tank 25 is disposed, which is supported by a lid 24 that can be slid along a vertical rail 23 by driving a cylinder 22. This water tank 25 is provided with pipes 26 and 27 for water supply and drainage.

Nozzles 28 are installed at the stirring position ■ and the cleaning position ■, respectively.
and 29 are provided, each with an electromagnetic on-off valve 30
Water can be discharged by the operation of and 31.

The sample measuring section 2 configured as described above is driven by the following procedure in response to instructions from the sequencer 3 linked to the computer 5, and the sample weighing section 2 is driven by the following procedure to calculate the weight S' of the sand, the weight S w '+ of the water, and the mortar weight. Measure weight M and underwater weight Mw.

The measurement of sand is started by firstly stopping the weighing container 13 at the sample input position (3) and putting a predetermined amount of unmixed sand into the weighing container 13 through a chute or the like with the water tank 25 positioned downward. do. After adding sand, moving trolley 1
4 moves to the left in FIG. 2, suspends the weighing container 13 from the weighing hook 12a of the electronic balance 12, and measures its weight.

Note that the weight of the weighing container 13 itself is stored in advance in the electronic balance 12 or the computer 5 as a tare weight, and the measurement result is subjected to a tare weight subtraction process to determine the weight S' of the sampled sand. Next, the cylinder 22
is driven to move the water tank 25 upward, and the measuring container 13
submerge in water.

In that state, the weight is measured again and collected in the computer 5, but similarly, the weight when the empty weighing container 13 is submerged in water to the same extent is recorded as the underwater tare weight on the electronic balance 12.
Alternatively, it is stored in the computer 5, and the underwater weight SW' of the sampled sand is determined.

After measuring Sw', the water tank 25 is returned downward and the moving trolley 14
to the right in FIG.
Remove it from 2a and move it further to the cleaning position (■). The stopper 18 is interlocked to tilt the needle container 13, the sand inside is discharged, and the electromagnetic on-off valve 31 is released to discharge cleaning water from the nozzle 29 to clean the inside, and then the sample input position W is
Let I stand by.

The measurement of mortar is 5mm of manufactured fresh concrete.
The process begins by passing the sample through a mesh sieve or the like, extracting only the mortar content, and charging the sample through a chute or the like into the measuring container 13 located at the sample input position I. The process up to the measurement of the weight M of mortar is exactly the same as in the case of sand. After measuring M, the weighing container 1 is moved by driving the moving cart 14.
3 is moved to stirring position ■. And solenoid valve 3
0, water is discharged from the nozzle 28 and an appropriate amount of water is put into the measuring container 13. and stirring blade 2
1 is rotated and moved up and down to stir the inside of the measuring container 13. This removes the air mixed in the mortar,
This is to obtain accurate underwater weight. After stirring for a predetermined time, wait until the mortar settles to some extent in the measuring container 13, and then hang it on the measuring hook 12a. Then, the water tank 25 is moved upward and the underwater weight Mw of the mortar is determined.

After the measurement of Mw is completed, the measuring container 13 is similarly moved to the cleaning position (2), the mortar inside is thrown away, and the inside is cleaned with cleaning water from the nozzle 29. At the same time, the stirring blade 21 is also cleaned by discharging water from the nozzle 28. Then, the measuring container 13 is returned to the sample input position (2).

As mentioned above, the computer 5 calculates the surface water percentage K of sand from S' and Sw', and the water/cement ratio W/C of fresh concrete from M and Mw.
By linking the measuring and mixing section 1, the following control becomes possible.

That is, by determining the ratio K of surface water contained in the sand before mixing, it becomes possible to perform feedforward control to correct the amount of water to be added. Furthermore, by measuring the actual water-cement ratio W/C of fresh concrete after mixing, feedbank control can be performed to correct errors in the entire system.

Furthermore, by storing K and W/C in the computer 5 and creating a control chart or the like, the quality of ready-mixed concrete can be guaranteed.

The operation procedure of the above embodiment of the present invention can be summarized as shown in the flowchart shown in FIG. Note that this flowchart shows an example in which K and W/C are measured alternately and feedforward or feedback is applied each time, but it is possible to measure W/C once every time K is measured several times. Alternatively, the feed forward may be applied once based on the results of measuring K several times.

In the above embodiment, the sample measuring section 2 is used as one unit to measure the weight of sand and mortar14), but separate sample measuring sections may be provided for each of sand and mortar. Furthermore, feedforward or feedback can also be performed by artificially changing the opening rate of the weighing/compounding section 1 based on the measurement results of K or W/C.

(f) Effects As explained above, according to the present invention, in the production process of ready-mixed concrete, the ratio of surface water contained in the sand before mixing is adjusted to the water/cement ratio W of the ready-mixed concrete after mixing. /
Since C can be measured automatically, by adjusting the amount of water input during mixing based on K, the water/cement ratio W/C of fresh concrete after mixing can be maintained at the desired value. In addition, by performing a feedbank based on the actually determined W/C, errors in the entire system and the amount of surface water contained in the gravel can be comprehensively corrected, and the quality of ready-mixed concrete to be shipped can be improved. The most important quality, compressive strength, can be guaranteed.

[Brief explanation of drawings]

FIG. 1 is a brochure diagram showing the overall configuration of the embodiment of the present invention, FIGS. 2 and 3 are front and side views of the sample measuring section 2, respectively, and FIG. 4 is a diagram showing the operating procedure of the embodiment of the present invention. 3 is a flowchart showing an example. 1-Weighing/preparation section 2-Sample measurement section 3-Sequencer 5-Computer 12-Electronic balance
13-Measuring container 14-Moving trolley 16-Horizontal rail 21-Agitating blade 23-Vertical rail 24-Lifter 25-Water tank 28.29-Nozzle

Claims (1)

[Claims] It is a device installed in the production process of ready-mixed concrete to inspect its quality, and includes means for sampling a predetermined amount of sand before mixing and measuring its weight and underwater weight, and based on the measurement results. means for calculating the percentage of surface water existing in the sand; means for extracting a predetermined amount of mortar from the ready-mixed concrete and measuring its weight and the weight in water; Fresh concrete water/
1. A ready-mixed concrete quality inspection device, comprising means for calculating a cement ratio, and configured so that the calculated results of the surface water ratio and water/cement ratio can be used for correction at the time of mixing.