JPH01113661A - Estimating method for slump in concrete mixing - Google Patents

Abstract

PURPOSE:To enable the quick and accurate estimation of slump of concrete, by fitting a torque meter to the rotating shaft of a mixer and by measuring thereby a rotational torque on the occasion when the concrete is mixed. CONSTITUTION:A torque meter 2 is fitted to a rotating shaft 1 of a mixer blade of a batcher plant, while a kinematic strain gage 3, which converts a torsion amount (surface shearing stress) corresponding to the torque of the rotating shaft 1 of the mixer blade into an electric output (minute voltage) and takes it outside, is connected to the torque meter 2. The electric output obtained through the conversion by the kinematic strain gage 3 is printed out on an oscillograph 4 as a change on a time basis. The torque of the rotating shaft 1 of the mixer blade can be measured exactly in the scope from a stationary state to a high-speed rotation in this way, and the slump of concrete can be estimated rapidly and accurately from the qualitative relationship between this rotational torque and the slump.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an estimation method for estimating the slump value of concrete during mixing of concrete.

[Prior Art] Conventionally, as a method for determining the consistency of concrete during mixing, a method using a slump meter has been widely put into practical use. This method using a slump meter is a method of estimating the slump value of concrete from the power consumption of a mixer during mixing of concrete.

[Problems to be solved by the invention] However, in the conventional slump meter that estimates the slump value of concrete from the power consumption of the mixer, the power consumption is not limited to the slump, but also the amount of mixing and the maximum coarse aggregate. The problem is that various corrections are necessary because the slump value changes depending on the size and type, the degree of wear of the mixer blades, etc., and the reality is that no slump meter with reliable accuracy has been developed at present. be.

The present invention was invented with the aim of solving the above problems.

[Means for solving the problem] The present invention measures the rotational torque during mixing of concrete by attaching a torque meter to the rotating shaft of the mixer blade, and estimates a qualitative slump value from this measured value. By doing so, the above problem was solved.

[Operation] According to the method of the present invention described above, the slump value of concrete can be estimated much more quickly and accurately than the rotational torque of the mixer blades from the qualitative relationship between rotational torque and slump.

[Example] Embodiments of the present invention will be described in detail below.

The power consumption of the mixer when mixing concrete is ■
the net power required to move the substances in the mixer,
It consists of ■The power required to rotate the mixer blades, and ■The power consumed by friction loss in the reducer and power transmission device. This power consumption can be determined by measuring the power consumption of the motor and the torque fluctuations of the rotating blades. In the case of a forced mixing mixer, the net power involved in mixing can be determined by the sum of the pressure resistance of the concrete caused by the rotating blades, the shear force, and the inertial resistance associated with rotation. Therefore, the power consumption of a particular mixer is greatly influenced by the fluidity, density, mixing volume, and rotational speed of the concrete being mixed.

From the above perspective, the present inventor clarified the correlation between the slump value, which is a dominant factor in the fluidity of concrete, and the rotational torque of mixer blades, and found that the slump value can be estimated by accurately capturing the rotational torque fluctuation. After thinking about it, we completed the present invention.

That is, since the device used in the estimation method of the present invention estimates the slump value while mixing concrete in a batcher plant, a torque meter 2 is attached to the rotating shaft 1 of the mixer blade in the batcher plant. At the same time, a force strain meter 3 is connected to the torque meter 2, which converts the amount of twist (surface shear stress) corresponding to the torque of the rotating shaft 1 of the mixer blade into an electrical output (micro voltage) and takes it out to the outside. An oscillograph 4 is connected to the dynamic strain meter 3, which inputs the electrical output converted by the strain meter 3, measures temporal changes, and prints out the results as a record. This makes it possible to accurately measure the torque of the rotating shaft of the mixer blade from a stationary state to high-speed rotation.

In addition, in the figure, 5 is a motor, and 6 is a mixer main body.

In order to find out the qualitative relationship between the rotational torque of the mixer blades and the slump value, the inventor conducted an experiment described below using the above device, and found that the qualitative relationship between the rotational torque of the mixer blades and the slump value was I was able to learn about the relationship between

Experimental Example The experiment was conducted using concrete with the standard mix shown in Attached Table 1. The purpose of the experiment was to find out the change in slump during the mixing process and the relationship between slump and power consumption for mixes with different unit water volumes. 10～
It can be changed over a wide range of 2000 seconds, and the unit water is 150 seconds.
The formulation was carried out at ~180ffg/m3.

During mixing, torque fluctuations of the rotating blades and power consumption of the motor were measured. After mixing, concrete was sampled from three locations in the batch and subjected to a slump test, and the average value was taken as the slump value.

The change curves of slump, torque, and power consumption during mixing in the mixer were as shown in FIG. These values are for each batch, and the torque and power consumption are obtained by subtracting the value when the mixer is idle from the value immediately before the end of mixing.

As is clear from the figure, the torque change curve shows good correspondence with the slump change accompanying the progress of mixing, and the torque is at its minimum when the slump is at its maximum. On the other hand, the power consumption was in a nearly steady state during the mixing time after the slump reached its maximum value, and no correlation with the slump change was observed.

Figure 3 shows the relationship between slump value and torque, and in addition to the experimental data in Figure 2, formulations with different unit water amounts (mixing time 120 seconds) are also plotted. In this way, it is clear that torque has an excellent correlation with slump value despite the difference in unit water volume and mixing time, and the curve in Figure 3 shows the qualitative relationship between average slump and torque. It can be determined that the relationship curve is

Therefore, as a result of this experiment, changes in slump during the mixing process and changes in slump due to differences in unit water volume can be determined by measuring the torque fluctuation of the mixer rotating blades and applying the torque fluctuation value to the curve in Figure 3. It has become clear that this can be accurately captured.

[Effects of the Invention] Since the present invention is as described above, by knowing the rotational torque of the rotary blades of the mixer when mixing concrete, the slump value of concrete can be estimated very quickly and accurately, thereby improving quality control. can be carried out smoothly and efficiently.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of the apparatus used in the method of the present invention;
The figure shows slump during the concrete mixing process.
FIG. 3, which is a diagram of changes in torque and power consumption, is a qualitative relationship diagram between slump and torque. In the figure, 1 is a rotating shaft, and 2 is a torque meter. October 27, 1985 Applicant: Maeda Construction Co., Ltd. Figure 1 Figure 2 mmL"MP'l (+ small)

Claims (1)

[Claims] A torque meter is attached to the rotating shaft of the mixer blade to measure the rotational torque during mixing of concrete.
A method for estimating a slump value during mixing of concrete, characterized by estimating a slump value from this measured value.