JP3351608B2 - Test method and device for gap passing property 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 and an apparatus for testing the ability of fresh concrete to pass through a gap between fresh steel bars, which is suitable for examining the ability of the concrete to pass through the gap.

[0002]

2. Description of the Related Art Conventional concrete has a narrow range of properties at the time of fresh concrete, which is generally called ready-mixed concrete, and has been concerned only with softness as represented by a slump test. However, recently, concrete having a wide range of properties, such as high-fluidity concrete having high fluidity and separation resistance, has been put to practical use. This high-fluidity concrete is poured without vibrating compaction in principle and requires strict control of material properties, and therefore requires a higher material evaluation index than conventional concrete.

As one of them, high fluidity concrete is
Gap-passability, which indicates the ability to pass through gaps between reinforcing bars while maintaining the integrity of concrete, is mentioned.
This gap permeability is a characteristic that takes into account not only material properties but also construction conditions that are affected by external factors such as reinforcement arrangement, formwork or pressure, and predicts the placement and filling state of high fluidity concrete. In order to be a particularly important property.

By the way, various types of fluidity testing methods have been proposed for this high-fluidity concrete in which a reinforcing bar is obstructed. For example, as shown in FIG. 14, a box-shaped storage portion b for storing the sample supplied from the upper opening a portion, and a flat box-shaped flow extending horizontally from the lower side of the storage portion b. Part c, these storage part b and flow part c
Using a test device having a configuration including an opening / closing plate d provided at a boundary portion of a plurality of rebars f arranged at intervals in the storage portion b, a high-fluidity concrete as a sample is stored in the storage portion b. After opening the opening / closing plate d, the high fluidity concrete in the storage portion b is caused to flow to the fluidizing portion c, and the flowability is measured by measuring the flow distance.

[0005]

However, any of the conventional fluidity test methods including the test method shown in FIG. 14 is intended for use in a laboratory test when determining the mix of concrete. In many cases, there is a problem that the measurement is troublesome and is not suitable for a quality control test on site. In addition, various parameters such as the softness and adhesion properties of fresh concrete affect the measurement results in a complicated manner, and it is not only an evaluation of the gap permeability, but the gap permeability is quantified as a material property. There was a problem that it was not possible to perform measurement.

The present invention has been made in view of the above points, and it is possible to measure the permeability of fresh concrete through a gap by a very convenient method, and the ability of fresh concrete to pass through a gap. And a device for testing the permeability of fresh concrete, which can evaluate the ability of mortar to carry coarse aggregate when passing through the gap. It is intended to provide.

[0007]

The invention according to claim 1 is
Investigate the permeability of fresh concrete through the gap by penetrating the fresh concrete with a penetrating device having a ring part that assumes a concrete reinforcing material such as a reinforcing bar by its own weight, and measuring the sinking speed of the ring part of this penetrating device. It is characterized by:

According to a second aspect of the present invention, the sinking speed of the ring portion of the penetrating device is measured a plurality of times and the ratio of the sinking speed between the first measured value and the second and subsequent measured values is determined. It is characterized by evaluating the ability of mortar to carry coarse aggregate when passing through the gap of fresh concrete.

According to a third aspect of the present invention, there is provided a penetrating device having a ring portion for penetrating into fresh concrete by its own weight, and detecting means for detecting a speed at which the ring portion of the penetrating device sinks in the fresh concrete. ,
The penetrating device includes a support member connected to the ring portion to horizontally support the ring portion.

The invention according to claim 4 is characterized in that the penetrating device has a weight.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a method and an apparatus for testing the passability of fresh concrete according to the present invention. 1 and 2
1 shows an example of a test apparatus suitable for carrying out the test method of the present invention. This test apparatus 1 penetrates, for example, into fresh concrete 2 in a container 3 filled with fresh concrete 2 by its own weight. Ring part 4a for
And a ring portion 4a of the penetrating device 4.
Is provided with a detecting means 5 for detecting a speed of sinking in the fresh concrete 2, and a supporting member 6 connected to the ring portion 4a for horizontally supporting the ring portion 4a.

The supporting member 6 of the ring portion 4a has a curved portion 6a made of a round steel which is formed in an inverted U shape in the illustrated example.
And a bar-shaped portion 6b made of round steel, which extends upward from the upper center of the curved portion 6a, and both ends of the inverted U-shaped curved portion 6b correspond in the diametric direction of the ring portion 4a positioned horizontally. The ring portion 4a is set so as to be horizontally positioned in a state where the ring portion 4b is supported vertically with the bar-shaped portion 6b facing upward.

The rod-shaped portion 6b is provided with a small-diameter ring-shaped weight 7 for changing the weight of the ring portion 4a including the support member 6, that is, the weight of the penetrating device 4 itself. If necessary, a plurality of weights 7 or several weights having different weights are facilitated. The detection means 5 for detecting the sinking speed of the ring portion 4a is not specifically shown here, but is, for example, a non-contact type displacement meter capable of optically detecting the displacement of the upper end of the rod portion 6b. Is used.

A method of testing the gap permeability of fresh concrete using the test apparatus 1 having such a structure is described in, for example, FIG. Then, by penetrating the ring portion 4a of the penetrating device 4 by its own weight, and measuring the speed at which the ring portion 4a sinks, the consistency (consistency) of the fresh concrete 2 is evaluated. Hereinafter, the test method of the present invention will be described in detail together with the operation with reference to experimental examples.

(Experimental Example 1) In the following experimental example, the lowering of the upper end of the rod-shaped portion 6b was measured by a non-contact type displacement meter, and the time change curve of the amount of settlement was measured. 2 to 6, the shape, dimensions and weight of the test apparatus used are shown. The ring portion 4a has a diameter of Φ6 mm and a diameter of Φ10
mm round steel, the diameter of the ring portion 4a is 90 mm,
A thing of 70 mm was prepared. In addition, the ring section has four steps (3
A penetrating device arranged at 0 mm intervals) was also prototyped for comparison. Each of the penetrating devices 4, 4, 4, 4 Α has two types of own weight. In Experimental Example 1, the sample was filled in a cylindrical container 3 having an inner diameter of 230 mm to a depth of 180 mm as shown in FIG.

(1) Samples Table 1 shows the preparation of the samples. Assuming high fluidity concrete, blast furnace slag fine powder having a specific surface area of 600 m 2 / kg and a cellulose ether thickener were used. In order to investigate the effect of the change in the fluidity of cement paste on the flow behavior of the entire concrete system, the amount of the high-performance AE water reducing agent was set so that the slump follow value was maximized within a range where material separation was not visually observed. Then, based on this (F1
00), the addition amount was changed in the range of 60 to 120%.

[0017]

[Table 1]

(2) Ring Shape FIG. 7 shows the settlement distance (R) due to the difference in the shape of the ring portion 4a.
It compares the time change curve of d). Ring part 4
In the case of a, the sinking speed is gradually reduced, and both stop before the bottom. A-90 (Φ6mm) with different thickness of ring part 4a
And B-90 (φ10 mm), the settlement speed and the final settlement distance are different because the resistance of the ring part is different, but the settlement stops almost simultaneously in time. A similar tendency is observed for the difference between A-90 (1 step) and C-90 (4 steps). The difference in the number of ring portions in the penetration direction is as follows.
Does not significantly affect measurement results. However, in the case of B-70 (70 mm) having different diameters of the ring portion, it is observed that the sample does not pass through the inside of the ring portion but flows in from the outer peripheral portion of the sunk ring portion, and this influence is also exerted on the squat curve. Is appearing.

(3) Load Amount FIG. 8 shows an example of a result obtained by changing the weight of the penetrating device 1 and changing the load for penetrating the ring into the sample. As the applied load increases, the settlement curve becomes steeper and the settlement speed increases.

(4) Number of Repeated Penetration In order to examine the effect of repeated penetration, the same sample was continuously penetrated four times without stirring with the ring portion. FIG. 9 shows an example of the change of the time change curve. Also,
FIG. 10 shows the relationship between the time required to sink 5 cm from the surface (hereinafter simply referred to as the sink time) and the number of repetitions. By repeatedly penetrating the ring portion, the sinking speed gradually decreases, and converges to a substantially constant value four times. When the ring portion first penetrates, it is necessary to push out coarse aggregate existing in the passage, but after the second time, the amount of coarse aggregate on the passage gradually decreases, and finally, the mortar It can be considered that the sinking speed of the ring portion is determined by the resistance caused only by this.

FIG. 11 shows the relationship between the ratio Rv1 / Rv4 of the first settling speed to the fourth set (hereinafter referred to as the settling speed ratio) and the amount of the high-performance AE water reducing agent added. As the amount of the high-performance AE water reducing agent increases, the degree of material separation increases, and the settlement speed ratio increases. (5) Evaluation method of measurement results The blockage that occurs when fresh concrete passes through the gap is the case where the flow of the entire concrete stops, and the mortar precedes and only the coarse aggregate is left, resulting in blockage. It is conceivable that you do. The former occurs when the yield value of the whole concrete system is large, and the latter occurs when the adhesive strength of the mortar is small and coarse aggregate cannot be carried.

The first settling speed in the test method is as follows:
Considering that it indicates the ease of passage of the gap as a whole concrete system and that the settlement speed after converging to a constant value by repeated penetration indicates the resistance of mortar, the difference between the two is
This is the amount of work required to move the coarse aggregate. Therefore, a sample having a large settlement speed ratio and close to 100% means that the work amount is small and the coarse aggregate entrainment ability is small. It can be determined that it increases.

FIG. 12 shows the relationship between the settlement speed ratio and the first settlement speed. The measured value when the applied load amount is large is shifted to the upper right in the figure and easily passes through the gap, but the possibility of the mortar preceding type blockage increases. FIG.
Fig. 2 schematically shows the relationship between the gap permeability and the present test value. The zone A in FIG. 13 is an ideal range that is easy to pass through the gap and does not block, but the properties of ordinary fresh concrete change between the zone B and the zone C due to a change in mix. Further, it can be understood that the diameter of the ring portion is a parameter relating to the width of the gap, and the weight of the device is a parameter relating to the pressure applied to the concrete, and these need to be selected according to the construction conditions.

(Experimental Example 2) In order to examine the applicability of the ring penetration test to a wide range of mixable high fluidity concrete, the water binder ratio (35% and 50%) and the type of admixture (blast furnace slag fine powder and silica foam) were used. , A total of 1 due to the type of thickener (cellulose ether type and polysaccharide type)
This test method was carried out on four mixes of high fluidity concrete. Slump follow value of 5 for each formulation
It was changed to three levels of 00 mm, 600 mm, and 700 mm. The unit amount of coarse aggregate is 804 kg / m3 and 9
Two levels of 65 kg / m3.

In this experimental example 2, the penetrating device has a weight of 13
Only one A-90 type of 00 kg (weight) was used. In the measurement, the sample was filled in an air volume measurement container, and the sinking speed until the ring member sinks 10 cm from the surface was measured. Further, for comparison, an L-flow test (hereinafter, referred to as a filling L-flow) in which a cage-shaped reinforcing bar was installed in the flowing portion was also performed. As a result, it was found that in the range where the slump flow value was small, the settlement speed ratio was distributed in a narrow range, but the value was varied as the slump flow value was increased, and that the number of samples having a large settlement speed ratio was increased. This indicates that a part of the highly fluid concrete is likely to be clogged.

When the settlement speed ratio is compared with the ratio of the filling L flow value, in the filling L flow test, since the reinforcing steel bar hinders the flow of the coarse aggregate, the degree of material separation is reduced. The larger the value is, the more the distance between the coarse aggregate and the mortar is different. This phenomenon is relatively well predicted by the settlement speed ratio in the ring penetration test. Also, looking at the relationship between the settlement speed ratio and the first settlement speed, the linear correlation between the two is weak in high-fluidity concrete, it is easy to pass through the rebar, and
It seems that a mortar-advanced formulation that does not easily cause blockage is possible to some extent.

The findings obtained from the above experimental results and considerations are as follows. 1) The gap permeability test method of the present invention can easily quantify the gap permeability of high fluidity concrete, and can be applied to a quality control test on site. 2) The gap passage property can be evaluated by the ratio of the settlement speed of the first ring member to the settlement speed after repeated penetration.

[0028]

As described above, according to the present invention,
It has the following excellent effects.

In the method for testing the gap permeability of fresh concrete according to the first aspect, a penetrating device having a ring portion assuming a concrete reinforcing material such as a reinforcing bar is penetrated into the fresh concrete by its own weight. Since the method of examining the permeability of the fresh concrete through the gap is determined by measuring the speed at which the portion sinks, the ability of the fresh concrete to pass through the gap can be measured by a very simple test method. Therefore, the method can be carried out extremely easily as a quality control test method on site. Further, only the ability of the fresh concrete to pass through the gap can be measured and quantitatively grasped.

In the method for testing the permeability of a fresh concrete through a gap according to claim 2, the settlement speed of the ring portion of the penetrating device is measured a plurality of times, and the settlement speed between the first measurement value and the second and subsequent measurement values is measured. The method of evaluating the ability of mortar to entrain coarse aggregate when passing through the gap of fresh concrete by calculating the ratio of Basically, the evaluation can be made by a very simple operation of simply performing this operation a plurality of times and determining the ratio of the settlement speed.

According to a third aspect of the present invention, there is provided an apparatus for testing the ability of a fresh concrete to pass through a gap, wherein the penetrating device has a ring portion for penetrating the fresh concrete by its own weight, and the ring portion of the penetrating device sinks in the fresh concrete. A test device for detecting the speed, and the penetrating device includes a support member connected to the ring portion and horizontally supporting the ring portion, so that the concrete itself can flow as in the related art. Therefore, the apparatus can be configured as a very simple apparatus as compared with the above, and thus can be a sufficiently suitable apparatus as a quality control test apparatus on site.

In the apparatus for testing the ability of a fresh concrete to pass through a gap according to the present invention, the penetrating device is provided with a weight, and the weight of the penetrating device can be arbitrarily changed as required by the weight.

[Brief description of the drawings]

FIG. 1 is a perspective view of a penetrating device showing an embodiment of the present invention.

FIG. 2 is a perspective view of a test apparatus showing an embodiment of the present invention.

FIG. 3 is a perspective view of a penetrating device showing an embodiment of the present invention.

FIG. 4 is a perspective view of a penetrating device showing an embodiment of the present invention.

FIG. 5 is a perspective view of a penetrating device showing an embodiment of the present invention.

FIG. 6 is a perspective view of a penetrating device showing an embodiment of the present invention.

FIG. 7 shows an example of the present invention, and is a comparison diagram of a time change curve due to a difference in shape of a ring portion.

FIG. 8 shows an example of the present invention, and is a comparison diagram of a time change curve depending on a difference in a load amount.

FIG. 9 shows an example of the present invention, and is a diagram showing a change in a time change curve due to repetition.

FIG. 10 shows an example of the present invention, and is a diagram showing a change due to repetition of a settlement speed.

FIG. 11 shows an example of the present invention, and is a view showing the relationship between the settlement speed ratio and the amount of water reducing material added.

FIG. 12 illustrates an example of the present invention, and is a diagram illustrating a relationship between a settlement speed ratio and a first settlement speed.

FIG. 13 shows an example of the present invention, and is a diagram schematically showing a relationship between a gap passing property and a test value.

FIG. 14 is a perspective view showing a conventional test apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Test apparatus 2 Sample 3 Container 4 Penetration device 4a Ring part 5 Detection means 6 Support member 7 Weight

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiyuki Kurokawa Aichi Prefecture Nagoya City Chigusa-ku Furo-cho (Nagoya Nagoya) Inside Nagoya University (72) Inventor Kenji Watanabe Chichi-ku Nagoya-shi Aichi Prefecture Chiro-ku Furomachi (Banashi Nashi) Inside Nagoya University (72) Inventor Koji Teranishi 2-10-26 Fujimi, Chiyoda-ku, Tokyo Maeda Construction Industry Co., Ltd. (56) References JP-A-57-108637 (JP, A) JP, U) Koji Teranishi, Kenji Watanabe, Yoshiyuki Kurokawa, Hirotsugu Mori, Yasuo Tanigawa, Evaluation of pore permeability of high fluidity concrete by ring penetration test, 2nd Symposium on Superfluidity Concrete, Japan, Japan Concrete Institute of Technology, May 17, 1994, JC I-C35, pp. 1-8 (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01N 11/00-11/16 G01N 33/38 JICST file (JOIS)

Claims (4)

(57) [Claims] An intrusion device having a ring portion assuming a concrete reinforcing material such as a reinforcing bar penetrates into fresh concrete by its own weight, and the speed at which the ring portion of the intrusion device sinks is measured to measure the fresh concrete. A method for testing the gap permeability of fresh concrete, characterized by examining the gap permeability. 2. The test method according to claim 1, wherein the sinking speed of the ring portion of the penetrating device is measured a plurality of times.
The gap between fresh concrete, characterized by evaluating the ability of mortar to carry coarse aggregate when passing through the gap of fresh concrete, by determining the ratio of the sinking speed between the measured value of the first time and the measured value of the second and subsequent times. Passability test method. 3. A penetrating device having a ring portion for penetrating into fresh concrete by its own weight, and detecting means for detecting a speed at which the ring portion of the penetrating device sinks in the fresh concrete, wherein the penetrating device comprises: An apparatus for testing a gap passing property of fresh concrete, comprising: a support member connected to the ring part for horizontally supporting the ring part. 4. The test device according to claim 3, wherein the penetrating device is provided with a weight.