JPH09218196A - Ready mixed concrete evaluation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge the fluidity, material separation resistance and aggregate distribution homogeneity of ready mixed concrete at the same time simply via the implementation of a single test, and lessen a trouble and a time required for evaluation. SOLUTION: A test bench 10 has four barriers 30 concentrically arranged on a steel rectangular flat plate 20. Also, a slump cone is laid at the center of the flat plate 20, and ready mixed concrete is placed in the slump cone. Then, when the slump cone is lifted, aggregate runs over the concrete due to viscosity, upon arrival of the concrete at barriers 30, thereby maintaining the continuity of the fluidity of the concrete. Also, a time for the concrete to reach each barrier 30 is measured, and the slump flow value of the concrete on the flat plate 20 is measured. At the same time, the quantity of coarse aggregate present in a ring-shape zone between the adjacent barriers 30 is used as a factor.

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 fluidity concrete when receiving and managing it.

[0002]

2. Description of the Related Art In the case of constructing ordinary concrete, it is indispensable to perform a compaction work at a place where it is placed, but this compaction work requires a lot of labor and a construction period. In addition, as the diversification and sophistication of concrete structures progresses, there are many examples in which structures with large effective cross sections and large amounts of reinforcing bars are designed. And ensuring homogeneity are important issues.

In recent years, self-compacting high-fluidity concrete (for example, "Neurocleat" of Obayashi Corporation) which has no need for compaction work, and has good fluidity and excellent material separation resistance has been developed. Has been put to practical use.

As described above, high fluidity concrete is required to have fluidity, material separation resistance and self-filling property. In order to manage these, a slump flow test and a funnel test, which have been generally adopted for ordinary concrete, are performed in combination, and the results are comprehensively evaluated to evaluate fresh concrete.

[0005]

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

1) Since high-fluidity concrete exhibits excellent fluidity (fillability), judgments such as a slump test, which is widely adopted as an index of workability of ordinary concrete, can be used as an index of high-fluidity concrete It is difficult to say that it is appropriate to use, and alternative test methods have been developed.However, unified official guidelines or standards have not been established yet, and evaluation methods are set independently by government offices and companies. And lacks in objectivity.

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

3) Not only is it time-consuming and time-consuming to carry out a plurality of types of tests, but it is also time-consuming and time-consuming to comprehensively judge and evaluate these results, and an appropriate evaluation is made. It also has the drawback of requiring skill.

The present invention has been made to solve the above problems, and it is possible to simultaneously judge the fluidity of fresh concrete, the resistance to material separation, and the homogeneity of aggregate distribution by conducting only one test. It is an object of the present invention to provide a method for evaluating fresh concrete, which can reduce the time and effort required for evaluation.

[0010]

In order to achieve the above object, the invention according to claim 1 of the present invention is one in which fresh concrete is placed in a slump cone installed on a flat plate by a predetermined method. A method of evaluating the fresh concrete from the condition of the fresh concrete flowing on the flat plate by pulling up the slump cone, wherein the fresh concrete flows on the flat plate under a resistance. It is characterized by including one or a plurality of barriers arranged concentrically with the slump cone at a pitch.

The invention according to claim 2 is characterized in that the fresh concrete is high-fluidity concrete.

The invention according to claim 3 is characterized in that the viscosity of the fresh concrete is evaluated by measuring the time taken for the fresh concrete to reach each barrier. Evaluation method.

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

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

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, basically, after pouring fresh concrete into a slump cone installed on a flat plate by a predetermined method, the slump cone is pulled up to flow on the flat plate. A method for evaluating the fresh concrete from the condition of the fresh concrete, wherein the flat concrete is arranged concentrically with the slump cone at a predetermined pitch so that the fresh concrete receives resistance and flows. It is provided with a plurality of barriers (Claim 1).

The fresh concrete in the present invention is mainly suitable 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 flat upper surface, but may have a rough surface. The arrangement pitch of the barrier is 5 cm to several 1
It is preferably about 0 mm. The barrier may be selected such that it is floated above the upper surface of the flat plate at a predetermined distance, it is arranged in contact with the upper surface of the flat plate, or the groove is recessed from the flat plate. The cross-sectional shape of the thing can be selected upright or bent in a mountain shape (including both pointed shape and curved surface shape), and the groove-shaped cross-sectional shape can be triangular, semicircular, rectangular, etc. You can choose.

The operation of placing fresh concrete on the slump cone is performed in the same manner as in the conventional slump flow test.

When the slump cone is pulled up, 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, but the viscosity of the concrete causes the aggregate to get over the barrier, so that the flow is continued. By measuring the time required for the fresh concrete to reach each barrier, the viscosity of the concrete can be evaluated (claim 3). When the test bench has a plurality of barriers, the same action is repeated for each barrier, and finally the flow of concrete is stopped.

By measuring the slump flow value (spread diameter) of concrete on a flat plate, the consistency (fluidity) can be evaluated (claim 4), and further, in the ring-shaped region between the barriers. Aggregate distribution can be evaluated by counting the amount of coarse aggregate present (claim 5).

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

From the above, the flowability of fresh concrete can be improved by performing only one test method according to the present invention.
Material separation resistance and homogeneity of aggregate distribution can be judged at the same time, and all of these can be managed as numerical values, which is objective.

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

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a test table 10 used in the present invention. The test table 10 comprises a rectangular steel plate 20 having four barriers 30 arranged concentrically. 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.
Through fourth barriers 32, 33, 34.

The first to fourth barriers are shown in FIG.
It has the cross-sectional shape shown in (b) and (c). FIG.
(A) shows that the first to fourth barriers 31A to 34A are
An example is shown in which a rectangular cross-section having a height of 10 mm, for example, is arranged upright while floating above the upper surface of the flat plate 20 by a predetermined distance (for example, 5 mm). In addition, FIG.
Means that the first to fourth barriers 31B to 34B are the flat plate 2
An example of a cross-sectional shape that is arranged in contact with the upper surface of No. 0 and is bent into a pointed mountain shape (the height to the ridge is 20 mm, for example). Further, FIG. 2C shows the flat plate 20.
An example is shown in which the groove is more concave.

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

1) A 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 work is performed in the same manner as in the conventional slump flow test. That is,
First, one layer of fresh concrete, which is divided into three layers of approximately equal amount, is placed, leveled with a stick, and then uniformly struck 25 times. After that, the second layer of fresh concrete is cast, and it is similarly struck with a stick so as to reach the top of the first layer of concrete, and then the third layer of fresh concrete is cast and the second layer of concrete is placed. Do the same with the cue stick to reach the end position.

2) The upper surface of the concrete cast on the slump cone is aligned with the upper end of the slump cone, and immediately thereafter the slump cone is gently pulled up in the vertical direction. The lifting of the slump cone causes the fresh concrete to flow outward on the flat plate. When the concrete reaches the first barrier 31, the resistance of the barrier 31 is exerted, but the viscosity of the concrete causes the aggregate to become a barrier.
By surpassing 1, the flow continues. Test bench 10
Has four barriers 31, 32, 33, 34, the same action is repeated in each barrier, and finally the flow of concrete is stopped. In addition, it is desirable to set, for example, 5 minutes as the stationary standard time.

3) Measure the time taken for the concrete to reach the first barrier 31 to the fourth barrier 34. With this value, the viscosity of concrete can be evaluated. That is, in order for the concrete to flow over the barrier 30, the viscosity is required as described above, and the fact that the material has flowed over the barrier without being separated can be used as an index of the viscosity. .

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

[0031]

As described above, the fluidity of fresh concrete, the resistance to material separation, and the homogeneity of the aggregate distribution can be determined at the same time by performing only one test method according to the present invention. Unlike the prior art, it is not necessary to carry out a plurality of types of tests, which saves labor and time, and does not require skill. Moreover, since fluidity and material separation resistance can all be managed as numerical values, they are objective.

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

[Brief description of drawings]

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

2 (a) is an embodiment showing a cross-sectional view taken along line II-II of FIG. 1. FIG. (B) Another embodiment. (C) Yet another embodiment.

[Explanation of symbols]

 10 Test Table 20 Flat Plate 30 Barrier 31 First Barrier 32 Second Barrier 33 Third Barrier 34 Fourth Barrier

Claims (5)

[Claims] 1. A fresh concrete is cast in a slump cone installed on a flat plate by a predetermined method, and then 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 is to provide on the flat plate one or a plurality of barriers arranged concentrically with the slump cone at a predetermined pitch so that fresh concrete receives resistance and flows. A method for evaluating fresh concrete characterized by. 2. The method for evaluating fresh concrete according to claim 1, wherein the fresh concrete is high-fluidity concrete. 3. The fresh concrete evaluation method according to claim 1, wherein the viscosity of the fresh concrete is evaluated by measuring the time taken for the fresh concrete to reach each barrier. 4. The fresh concrete evaluation method according to claim 1, wherein the consistency is evaluated by a slump flow value on the flat plate. 5. The fresh concrete evaluation method according to claim 1, wherein the aggregate distribution is evaluated based on the amount of coarse aggregate present in the ring-shaped region between the barriers. .