JP3139363B2 - Evaluation method of fresh concrete - 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 evaluating fresh concrete, and more particularly to a method for evaluating high-concrete concrete when receiving and managing it.

[0002]

2. Description of the Related Art When an ordinary concrete is constructed, compaction work at a casting site is indispensable, but this compaction work requires a lot of labor and a lot of construction time. In addition, as the diversification and sophistication of concrete structures progress, there are many cases where structures with large effective sections and large amounts of rebar are designed. And ensuring homogeneity are important issues.

In recent years, self-compacting high fluidity concrete (for example, "Nurocrete" of Obayashi Corp.), which does not require compaction work, has good fluidity, and has excellent material separation resistance, has been developed. Has been put to practical use.

As described above, high fluidity concrete is required to have fluidity, resistance to material separation, and self-compacting property. In order to manage these, fresh concrete is evaluated by comprehensively judging these results by combining slump flow tests, funnel tests, and the like generally used for ordinary concrete.

[0005]

However, in such a conventional method for evaluating a high fluidity concrete,
There are the following issues.

[0006] 1) Since high-fluidity concrete exhibits excellent fluidity (fillability), judgments such as slump tests widely used as an index of workability of ordinary concrete are directly used as indices of high-fluidity concrete. Although it is not appropriate to use it and alternative test methods have been developed, unified official guidelines or standards have not yet been established, and evaluation methods have been independently set by government offices and companies. Poor objectivity.

2) For example, a slump flow value (mainly a value relating to a yield value (flow resistance)) is 60 ± 7.5 cm,
The funnel value (mainly the value related to plastic viscosity (viscosity)) is 1
When the flowability and material separation resistance of fresh concrete are determined with 5 ± 3 seconds as the control value,
It was difficult to determine the homogeneity of the aggregate distribution because the cement paste and the aggregate were separated. This is presumed to be due to the width of the management value being too large.

[0008] 3) Not only does it take time and effort to perform a plurality of types of tests itself, but also it takes time and effort to comprehensively judge and evaluate these results, and an appropriate evaluation is performed. There is also a disadvantage that it requires skill.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to simultaneously determine the fluidity, resistance to material separation, and homogeneity of aggregate distribution of fresh concrete by performing only one test. It is an object of the present invention to provide a method for evaluating fresh concrete, which can reduce the labor and time required for the evaluation.

[0010]

Means for Solving the Problems In order to achieve the above object, the invention according to claim 1 of the present invention relates to a method in which fresh concrete is poured into a slump cone installed on a flat plate by a predetermined method. A method of evaluating the fresh concrete from the situation of the fresh concrete flowing on the flat plate by pulling up the slump cone, wherein a predetermined amount of the fresh concrete flows on the flat plate under resistance. It is characterized by comprising one or a plurality of barriers arranged concentrically with the slump cone at a pitch.

[0011] The invention described in claim 2 is characterized in that the fresh concrete is high-fluidity concrete.

According to a third aspect of the present invention, the viscosity of the fresh concrete is evaluated by measuring a time required for the fresh concrete to reach each barrier. Evaluation method.

According to a fourth aspect of the present invention, the consistency is evaluated by a slump flow value on the flat plate.

The invention according to claim 5 is characterized in that aggregate distribution is evaluated based on the amount of coarse aggregate present in a ring-shaped region between the barriers.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is basically based on a method in which fresh concrete is poured into a slump cone placed on a flat plate by a predetermined method, and then the slump cone is pulled up to flow on the flat plate. A method of evaluating the fresh concrete from the condition of the fresh concrete, wherein, on the flat plate, one or more concentrically arranged with the slump cone at a predetermined pitch so that the fresh concrete flows under resistance. It is provided with a plurality of barriers (claim 1).

The fresh concrete in the present invention is suitable mainly for use in high-fluidity concrete (claim 2).

As the flat plate, various materials such as steel or plastic can be used. The flat plate preferably has a smooth upper surface, but may have a rough surface. Arrangement pitch of barrier is from 5cm to several 1
It is preferably about 0 mm. As the barrier, there can be selected one that is floated and disposed at a predetermined interval from the upper surface of the flat plate, one that is disposed in contact with the upper surface of the flat plate, a groove-shaped one that is recessed from the flat plate, and the like. The cross-sectional shape of the object can be selected to be upright or bent into a mountain shape (including both a pointed shape and a curved surface). The cross-sectional shape of the grooved shape can be triangular, semicircular, rectangular You can choose.

The operation of pouring fresh concrete into a slump cone is performed in the same manner as in a conventional slump flow test.

When the slump cone is raised, the fresh concrete flows outward on the flat plate. When the concrete reaches the barrier located outside the slump cone, it receives the resistance of the barrier. However, the viscosity of the concrete causes the aggregate to climb over the barrier, so that the flow continues. By measuring the time until fresh concrete reaches each barrier, the viscosity of the concrete can be evaluated (claim 3). When the test bench includes a plurality of barriers, the same operation is repeated in each of the barriers, and finally the flow of the concrete is stopped.

By measuring the slump flow value (expansion diameter) of the concrete on the flat plate, the consistency (fluidity) can be evaluated (claim 4). Aggregate distribution can be evaluated by counting the amount of coarse aggregate present (claim 5).

In order for concrete to flow over the barrier, as described above, viscosity is required, and the fact that the material has flowed over the barrier without separation can be used as an index of viscosity. .

From the above, it can be seen that the fluidity of fresh concrete,
The material separation resistance and the homogeneity of the aggregate distribution can be determined at the same time, and these can all be managed as numerical values, so that there is objectivity.

Further, when the fresh concrete flows, the barrier becomes a resistance, so that the flow value is smaller than that of a conventional test table for performing a slump flow test. As a result, the shape of the test table is smaller than that of the conventional test table. It can be.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a test table 10 used in the present invention. The test table 10 has four barriers 30 arranged concentrically on a rectangular steel plate 20. The barrier 30 includes a first barrier 31 provided at a position 15 cm from the center of the flat plate, and a second barrier 31 at a pitch of 5 cm from the first barrier 31.
Or fourth barriers 32, 33, 34.

The first to fourth barriers are shown in FIG.
The cross-sectional shape is shown in (b) and (c). FIG.
(A) shows that the first to fourth barriers 31A to 34A are:
An example in which a rectangular cross-section having a height of, for example, 10 mm and having a rectangular cross section having a height of, for example, 5 mm from the upper surface of the flat plate 20 is arranged upright is shown. FIG. 2 (b)
The first to fourth barriers 31B to 34B are
0 shows an example of a cross-sectional shape that is arranged in contact with the upper surface of the zero and bent into a pointed mountain shape (the height to the ridge is, for example, 20 mm). Further, FIG.
An example is shown in which the groove is more concavely curved.

Next, a method for evaluating fresh concrete, especially high-fluidity concrete, using the test stand 10 will be described.

1) A well-known slump cone (not shown) is installed at the center of the flat plate 20, and fresh concrete is poured into the slump cone. This operation is performed similarly to the case of the conventional slump flow test. That is,
First, an approximately equal amount of one layer of fresh concrete, divided into three layers, is poured, leveled with a piercing rod, and then uniformly pierced 25 times. After that, the second layer of fresh concrete is poured in, and similarly pushed with a stick so as to reach the top position of the first layer of concrete, and further, the third layer of fresh concrete is poured into the second layer of the concrete. Poke in the same way with a stick to reach the end position.

2) After aligning the upper surface of the concrete poured into the slump cone with the upper end of the slump cone, immediately raise the slump cone gently in the vertical direction. By pulling up the slump cone, the fresh concrete flows outward on the flat plate. When the concrete reaches the first barrier 31, the resistance of the barrier 31 causes the aggregate to be formed due to the viscosity of the concrete.
By overcoming 1, the flow is continued. Test stand 10
Has four barriers 31, 32, 33, and 34, so that the same operation is repeated in each of the barriers, and finally the flow of concrete is stopped. Note that it is desirable to set, for example, 5 minutes as the stationary standard time.

3) The time required for the concrete to reach the first to fourth barriers 31 to 34 is measured. From this numerical value, the viscosity of the concrete can be evaluated. That is, in order for concrete to flow over the barrier 30, as described above, viscosity is required, and the fact that the material has flowed over the barrier without separation can be used as an index of viscosity. .

4) The slump flow value of the concrete on the flat plate 20 is measured, and the amount of the coarse aggregate present in the ring-shaped region between the adjacent barriers is calculated. The ability to evaluate the consistency by the slump flow value is the same as the conventional one, and the aggregate distribution can be evaluated by the amount of the coarse aggregate in each region.

[0031]

As described above, it is possible to simultaneously determine the fluidity, resistance to material separation, and homogeneity of aggregate distribution of fresh concrete by only performing one test method according to the present invention. Unlike the related art, it is not necessary to perform a plurality of types of tests, so that labor and time are reduced, and skill is not required. In addition, fluidity, resistance to material separation, and the like can all be managed as numerical values, so there is objectivity.

Further, since the barrier becomes a resistance when the fresh concrete flows, the flow value is smaller than that of a conventional test table for performing a slump flow test. As a result, the shape of the test table is smaller than that of the conventional test table. It can be.

[Brief description of the drawings]

FIG. 1 is a plan view showing a test table used to carry out the present invention.

FIG. 2A is an embodiment showing a cross-sectional view taken along the line II-II of FIG. (B) Another embodiment. (C) Still another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Test stand 20 Flat plate 30 Barrier 31 First barrier 32 Second barrier 33 Third barrier 34 Fourth barrier

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 33/38 G01N 11/00

Claims (5)

(57) [Claims] 1. After fresh concrete is poured into a slump cone placed on a flat plate by a predetermined method, the slump cone is pulled up to evaluate the fresh concrete from the condition of the fresh concrete flowing on the flat plate. The method according to claim 1, wherein the flat plate includes one or a plurality of barriers disposed concentrically with the slump cone at a predetermined pitch so that the fresh concrete flows under resistance. Evaluation method of fresh concrete characterized by the following. 2. The method according to claim 1, wherein the fresh concrete is a high-fluidity concrete. 3. The method according to claim 1, wherein the viscosity of the fresh concrete is evaluated by measuring a time required for the fresh concrete to reach each barrier. 4. The method for evaluating fresh concrete according to claim 1, wherein the consistency is evaluated by a slump flow value on the flat plate. 5. The method for evaluating fresh concrete according to claim 1, wherein an aggregate distribution is evaluated based on an amount of coarse aggregate present in a ring-shaped region between the barriers. .