JPH1158356A - Method and device for mesh through transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a constitutional law which becomes a measurement criterion for the material separation resistance and the filling property of concrete by a method wherein coarse aggregates are separated from mortar by applying a specified vibration to a strainer, and a relationship between the period of time for which the vibration is applied to the strainer and the weight of the mortar which has passed the strainer, is measured. SOLUTION: Concrete is statically placed on a strainer 30, and a vibration is applied by a shaking table 20. Then, a material separation between various kinds of aggregates and mortar contained in the concrete starts, and only the mortar passes the strainer 30. The separated mortar is collected by a specimen receiving tray 40 below, and the weight measurement is performed with time by a metering apparatus 50 which hangs the specimen receiving tray 40. The measured values are transmitted to a generally known apparatus 60 such as an analyzing device or the like, which is separately provided, and a relationship between the period of time for which the vibration is applied to the strainer 30, and the weight of the mortar which has passed the strainer 30, is analyzed, and a through transmission weight curve is prepared. By this method, a constitutional law which becomes a measurement criterion for the material separation resistance and the filling property of concrete can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete mesh permeation method and a mesh permeation apparatus.

[0002]

2. Description of the Related Art When concrete is used in a site such as civil engineering or construction, it is necessary to quantitatively determine whether concrete can be easily separated from various materials such as coarse aggregate, that is, the material separation resistance of concrete. At present, the method of examining the material separation resistance of concrete is limited to a measurer ascertaining whether or not the separation is easy by visual observation. Therefore, the measurement of the material separation resistance of concrete by visual observation has become a subjective measure for the measurer, the range of error including the measured value has been widened, and the measurement itself has been ambiguous. Therefore, at present, there is no method and apparatus for accurately measuring the material separation resistance of concrete up to the degree of separation of gravel, and a new proposal is desired. In addition, when filling concrete with rebar inserted into the formwork, it is necessary to understand the degree of concrete filling in advance so that voids due to uneven filling in concrete do not occur. is there. However, in order to measure the filling property of concrete, a large-scale test apparatus was required, and it could not be said that the actual work was expressed. Therefore, a new proposal of a method and an apparatus capable of easily measuring the filling property of concrete is desired.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is an object of the present invention to propose a constitutive rule which is a standard for measuring the material separation resistance of concrete and the filling property of concrete. Another object of the present invention is to provide a mesh permeation method and a mesh permeation apparatus that can accurately and quantitatively evaluate the quality of concrete by each measurement.

[0004]

According to the present invention, concrete is poured into a container provided with a sieve, and a predetermined vibration is applied to the sieve to separate coarse aggregate and mortar. By measuring the weight of the concrete on the screen over time, and measuring the relationship between the time of applying vibration to the screen and the weight of the mortar that has passed through the screen, the material separation resistance between the aggregate and the mortar of various mixed concretes is measured. This is a mesh transmission method characterized in that the property is measured. Also, in the mesh transmission method described above, the weight of concrete passing through the screen or concrete remaining on the screen is measured with time by appropriately changing the size of the screen of the screen and applying a predetermined vibration or only its own weight. By measuring the relationship between the time when the screen is vibrated and the weight of the concrete that has passed through the screen or the weight of the concrete remaining on the screen, it is possible to measure the resistance when the concrete passes through a narrow space. The mesh transmission method is characterized by the following. Further, the apparatus used in each mesh transmission method described above, a vibration table, a sample receiver placed on the vibration table, and a sieve positioned on the sample receiver, which is provided with vibration, and the sample A mesh transmission device, comprising a load cell that can measure a receiver and a sieve, respectively, and being capable of measuring a sample placed on a sieve and a sample collected in a sample receiver, respectively. is there.

[0005]

First Embodiment <A> Configuration of Mesh Transmission Device Overall Configuration As shown in FIG. 1, a mesh transmission device 10 includes a vibration table 20, a screen 30 that receives vibrations, and concrete that is transmitted through the screen 30. And a measuring device 50 for measuring the weight of the sample pan 40.
In addition, a publicly known device 60 such as an analyzer and a recording device for measuring and analyzing the amount (weight) of permeation of mortar and time measured by the mesh transmission device 10 is also required. The mesh permeation device 10 can be used for both the measurement of the material separation resistance of concrete and the measurement of the filling property of concrete.

Vibration Table The vibration table 20 is a device that gives a predetermined vibration to the screen 30 in order to leave various aggregates in the concrete placed on the screen 30 to be described later and transmit the mortar. As the vibration table 20, if it can place components such as a screen 30 and a sample pan 40 described later,
Known ones can be employed.

[0007] The screen 30 is used for measuring concrete for 1-2 k.
It is a member that can be left standing by about g, and is a member for separating various aggregates and mortar contained in concrete and for permeating concrete itself. The sieve 30 is distinguished from the one used for measuring the material separation resistance of concrete and the one used for measuring the filling property of concrete by the size of eyes. Therefore, the screen 30 is appropriately replaced depending on the purpose of measurement. For the former, for example, if the eye size is 5
A screen 30 having a size of about 30 mm is used as the latter. The screen 30 is placed on the vibration table 20 and is configured to be able to vibrate if necessary at each measurement.

The sample pan 40 is a container for collecting the mortar in the concrete that has passed through the screen 30 described above. The sample pan 40 is located below the screen 30 and the screen 3
It is ensured that mortar that permeates from zero can be recovered. The sample pan 40 is connected to a weighing device 50 to be described later, and can measure the weight of the mortar transmitted from the screen 30 with time.

The weighing device 50 is a device for measuring the weight of the mortar collected in the sample pan 40 described above. As the weighing device 50, a known load cell or the like can be used.

In the first embodiment, as shown in FIG. 1, a sample tray is arranged below a screen placed on a vibration table, and the sample tray is hung by a connecting tool extended from a measuring instrument. An example is described. However, the present invention is not limited to this example, and other configurations can be employed as long as vibration can be applied to the screen and the weight of the mortar transmitted from the screen can be measured over time.

<B> Measuring Method 1 Before describing the measurement of the material separation resistance of concrete by the mesh transmission method, the definition of the material separation of aggregate will be described.

Definition of Aggregate Material Separation a. Aggregate material separation There are many types of material separation phenomena, including separation of solids and water, separation of paste and fine aggregate, and separation of mortar and coarse aggregate. In the present invention, the separation of the mortar 71 and the coarse aggregate 72 constituting the concrete 70 is referred to as material separation of the aggregate. The sample is a two-phase material composed of an aggregate phase 72 and a matrix phase (mortar) 71, and it is assumed that the matrix phase (mortar) 71 maintains homogeneity. When the concrete 70 deforms and flows, the relative position between the rigid aggregate 72 and the matrix phase 71 is changed, and the deformation of the matrix phase 71 and the adhesion failure between the matrix phase 71 and the aggregate phase 72 simultaneously proceed. doing. Further, even in the material separation in which the coarse aggregate 72 is settled in the sample, the matrix phase 71 is deformed, and the adhesion failure occurs between the matrix phase 71 and the aggregate phase 72.
As described above, two of the deformation characteristics and the flow characteristics affect both the flowability and the material separation resistance.

B. Modeling of Material Separation The material separation phenomenon of aggregate is modeled as shown in FIG. 2, and it is assumed that the matrix phase 71 is unilaterally reduced only by the adhesive force (material separation of aggregate proceeds). In this model, the aggregate 72 is assumed to be a flat plate having a surface area (S), and the matrix phase 71 is assumed to be attached to the aggregate 72 with a uniform thickness (L). External force acting here (F)
Is only the vertical load applied to separate matrix phase 71 and aggregate 72. In this model,
The volume of the matrix phase 71 attached by the separated matrix 73 decreases, and the matrix phase 71 is rearranged on the surface of the aggregate 72, and the film thickness of the matrix 71 decreases by ΔL. This phenomenon occurs during the minute time Δt. At the adhesion interface, when the tensile force (σsg: adhesion resistance stress) per unit area of the external force (F) exceeds the adhesion yield value (σad), the matrix phase 71 is peeled off, and the material separation of the aggregate has progressed. Here, the change in the thickness of the film of the matrix phase 71 is regarded as an apparent strain.
d). From this, the adhesion resistance stress (σsg) when the matrix phase 71 film is deformed in the thickness direction at the strain rate (γ) is calculated by using the adhesion yield value (σad) and the adhesion viscosity (ηad) as follows: Can be expressed as

[0014]

(Equation 1)

Measurement Method a. Vibration application to sieve Using a mesh transmission device, adhesive properties (adhesion yield value and adhesive viscosity), which are material separation resistance of concrete, are measured. First, the concrete is placed on the screen. The amount of the concrete to be left to stand is, for example, about 1 to 2 kg. Vibration is applied to the screen where the concrete is left standing from a vibration table. By giving vibration to the screen, concrete starts to separate materials into various aggregates and mortar contained therein, and only mortar permeates through the screen.

B. Measurement of mortar weight The mortar separated from various aggregates in the concrete by vibration is transmitted through the sieve and collected in the sample pan located below. The weight of the mortar collected in the sample pan is measured over time. The measurement of the mortar weight is performed by a measuring instrument that suspends the sample pan. Also,
The measured value is transmitted to a known device such as an analyzer installed separately.

C. Analysis of measured values The measured values sent to the analyzer are used to analyze the relationship between the time during which the sieve was vibrated and the weight of the mortar that passed through the sieve. Analysis yields a permeation weight curve as schematically illustrated in FIG. This figure shows the permeation weight curve obtained when three different types of concrete were measured. Type A indicates that by applying vibration to the screen, the mortar in the concrete gradually permeates through the mesh and eventually converges to a constant value. Type B indicates that the weight permeating through the mesh is greater than Type A because more mortar is separated from the various aggregates than Type A. Type C indicates that, although mortar equivalent to that of type A is separated, more mortar is separated in a shorter time than type A. From this, looking at type A as a reference,
Type B and type C are both considered to be concrete that is easier to separate than type A. However,
Since it is not possible to compare concretes having different mortar amounts (different unit coarse aggregate amounts) with each other only in a curved shape, it is necessary to calculate the adhesion properties in order to generalize. In this case, the amount of coarse aggregate that cannot pass through the mesh is constant, so the weight that has passed is the weight of the mortar that has fallen off,
From this, it is possible to approximate the thickness of the remaining mortar and the rate of change of the thickness using the following equation.

[0018]

(Equation 2)

Here, Wt: amount of change in film thickness at time t, t: time, Wu: Wt value when t = ∞ (permanent film thickness ratio), Wo: Wt when t = 0 (Initial film thickness loss ratio), p: film pressure attenuation coefficient.

D. Calculation method Adhered mortar (film thickness) decreases as the material separation progresses. The stress applied to the adhesion interface is the product of the mass (M) of the mortar and the vibration acceleration (a). Since the vibration acceleration is constant, the stress applied to the adhesion interface also decreases. Therefore, the adhesion yield value (σad) and the adhesion viscosity (ηad) can be defined as follows using the initial film thickness (W).

[0021]

(Equation 3)

[0022]

(Equation 4)

<C> Measuring method 2 A description will be given below of the measurement of the resistance to the passage of the concrete through the gap by the mesh transmission method. The measurement of the resistance to the passage of concrete through the gap is performed in substantially the same manner as the resistance to material separation of the concrete described in Measurement 1. That is, concrete is first placed on a sieve. As the sieve used at this time, a sieve having a mesh size of about 30 mm, or a sieve having a mesh size not less than the maximum size of the aggregate in the concrete or a size considering the construction conditions is used. For the concrete placed on the screen, the weight of the sample passing through the screen in a state where predetermined vibration is applied or without vibration is measured with time.

[0024]

As described above, the present invention has the following effects. <B> Conventionally, a constitutive rule that is a standard for measuring the material separation resistance and concrete filling property of concrete, which has no means other than visual observation, is proposed. <B> It is possible to accurately and quantitatively evaluate the quality of concrete by measuring the material separation resistance and concrete filling property of concrete. <C> It is possible to accurately measure the material separation resistance of concrete up to the adhesion characteristics of gravel and mortar. Therefore, concrete having appropriate material separation resistance can be adopted for on-site construction. <D> It is possible to easily and accurately measure the filling property of concrete. Therefore, it is possible to employ concrete having a filling property suitable for each site construction that does not cause uneven filling.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a mesh transmission device according to the present invention.

FIG. 2 is an explanatory view of a modeled concrete according to measurement 1.

FIG. 3 is a permeation weight curve of the mortar according to the measurement 1.

Claims (3)

[Claims] 1. A concrete is poured into a container provided with a sieve, a predetermined vibration is applied to the sieve to separate coarse aggregate and mortar, and the weight of the mortar that has passed through the sieve or the weight of concrete on the sieve is measured with time. By measuring the relationship between the time of applying vibration to the screen and the weight of the mortar that has passed through the screen, the material separation resistance of the aggregate and the mortar of various prepared concrete is measured. To the mesh transmission method. 2. The mesh permeating method according to claim 1, wherein the size of the mesh of the screen is changed appropriately and a predetermined vibration is applied or only the weight of the screen causes the concrete to pass through the screen or the concrete remaining on the screen. By measuring the weight of the concrete over time, the concrete passes through the narrow space by measuring the relationship between the time of applying vibration to the sieve and the weight of the concrete passing through the sieve or the weight of the concrete remaining on the sieve. A mesh transmission method characterized in that resistance at the time can be measured. 3. The apparatus used for the mesh transmission method according to claim 1 or 2, wherein: a vibration table; a sample receiver mounted on the vibration table; and a sample receiver positioned on the sample receiver. A vibrating sieve, a load cell configured to be able to measure the sample receiver and the sieve, respectively, and capable of measuring a sample placed on the sieve and a sample collected in the sample receiver. A mesh transmission device, characterized in that: