JPH09194247A - Flowing controlled concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain concrete exhibiting high fluidity in a vibrated state and reducing fluidity in a vibration suspended state. SOLUTION: A prescribed fluidizing agent is added to cement so as to set the yield value of the resultant concrete at 100-250Pa and the cement is further mixed with admixtures such as fine powder of blast furnace slag, fly ash, silica fume and limestone powder so as to set the plastic viscosity of the concrete at 10-100Pa.s. For example, 20vol.% cement is mixed with 50vol.% fine powder of blast furnace slag, 25vol.% fly ash and 5vol.% silica fume.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a flow control type concrete suitable for constructing an inclined portion such as a slope.

[0002]

2. Description of the Related Art Since ordinary concrete specified in JIS has a fluidity of about 5 to 18 cm in terms of slump, compaction with a vibrator is indispensable and a great deal of labor is required for compaction work. .

In order to solve such a problem, recently, self-filling type high fluidity concrete has been attracting attention. For high-fluidity concrete, by adding a high-performance AE water reducing agent in an amount of 10 kg / m ³ , the yield value τ _f , which is an index of resistance to flow deformation, is made extremely small. It is a concrete that has been set to improve fluidity.

[0004]

If such a high-fluidity concrete is used, it is possible to omit the troublesome compaction work, but on the other hand, the fluidity is too high and the concrete flows, so that However, there is a problem that it is not suitable for construction of sloped parts such as tracks, slopes, etc.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a flow control type concrete which exhibits high fluidity in a vibrating state and can suppress fluidity in a vibration stopped state. To do.

[0006]

To achieve the above object, the flow control type concrete of the present invention has a concrete yielding value of 100 by adding a predetermined fluidizing agent to cement as described in claim 1. In addition, the plastic viscosity of the concrete is set to 5 to 100 Pa · s by adding admixtures such as blast furnace slag fine powder, fly ash, silica fume, and limestone powder to the cement.

In the flow control type concrete of the present invention, the mixing ratio (volume) of the admixture and the cement is
Blast furnace slag fine powder 40 to 60%, fly ash 2
0-30%, silica fume 3-8%, cement 1
It is set to 5 to 35%.

In the flow control concrete of the present invention, the yield value of the concrete is set to 100 to 250 Pa and the plastic viscosity of the concrete is set to 5 to 100 Pa.
Since it is set to Pa · s, in a static state where concrete is not vibrated, it has higher fluidity than normal concrete, but does not flow too much like high-fluidity concrete, and maintains a constant shape. Further, in a dynamic state in which concrete is vibrated, it has higher fluidity than high-fluidity concrete.

Therefore, when the flow control type concrete of the present invention is poured, it flows to some extent without operating the vibrator, but since it does not flow too much like conventional high flow concrete, it is suitable for construction on inclined surfaces. No problem.

On the other hand, if the vibrator is slightly actuated as necessary, the cast concrete will have higher fluidity than conventional high-fluidity concrete, will flow quickly, and will be filled in every corner. Then, when the vibrator is stopped, it immediately returns to the static state, and a certain shape is maintained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a flow control type concrete according to the present invention will be described below with reference to the accompanying drawings.

The flow control type concrete of this embodiment is
In general, ordinary cement such as ordinary Portland cement is added with a fluidizing agent similar to that of conventional high-fluidity concrete and further mixed with a predetermined admixture, and the mixing ratio thereof is set as follows. The amount of cement, the amount of unit water, the amount of aggregate, and the like are appropriately mixed according to the required strength, etc., as in ordinary fresh concrete.

First, the fluidizing agent is mainly used for the purpose of reducing the flow deformation resistance of concrete, that is, the yield value of concrete, and the yield value is 1
The amount of the fluidizing agent used is adjusted so as to be 00 to 250 Pa (1 Pa = 1 N / m ² ). Specifically, for example, when using a high-performance AE water reducing agent, it is about one-third of conventional high-fluidity concrete, that is, 2 to 4 kg / m ^3.
And

Table 1 shows what happens to the slump and the slump flow when the yield value of concrete is set to the above-mentioned value, and also shows normal concrete and conventional high-fluidity concrete. There is.

[0015]

[Table 1] As can be seen from the table, the yield value of the flow control type concrete of the present embodiment is smaller than that of normal concrete and larger than that of conventional high flow concrete. As can be seen by comparing slump and slump flow, this is because the flow control concrete of the present embodiment is more likely to flow than ordinary concrete in a static state in which the vibration of the vibrator is not acted, so to speak, in a conventional state. It shows that it does not flow as much as liquid concrete.

Next, regarding the admixture, the plastic viscosity of concrete is 5 to 100 Pa · s (1 Pa · s = 10 P).
The type and blending ratio are selected so that

FIG. 1 (a) is a graph showing the average flow rate (index for measuring the plastic viscosity of concrete) when the compounding ratio of ordinary cement and blast furnace slag fine powder or fly ash is changed. In addition, the so-called binder volume, which is a mixture of the admixture such as blast furnace slag fine powder and cement, is 140 l / m ³ , and the water amount is 160 l / m.
^{3. The} fine aggregate ratio is 51.5%.

As can be seen from the figure, the average flow rate of cement alone is about 17 cm / sec, whereas if the blast furnace slag fine powder is mixed in an amount of 30% or more by volume,
More than 0 cm / sec, 50% blast furnace slag fine powder,
The average flow velocity when the fly ash is 30% increases to about 40 cm / sec.

FIG. 1 (b) shows 50% blast furnace slag fine powder,
It is a graph showing the average flow rate when ordinary Portland cement is 20% and admixtures such as fly ash and silica fume are 30%. When silica fume is not mixed, the blast furnace slag fine powder 50 of Fig. 1 (a) is shown. %, The same as the case when the fly ash is 30%. Then, when the silica fume is set to 5%, the average flow rate becomes about 48 cm / sec, which is nearly three times as high as that of the ordinary cement alone, and it is understood that the viscosity of the concrete is remarkably improved.

From the above experimental results, the blending ratio (volume) of the admixture and cement was determined to be 50% blast furnace slag fine powder, 25% fly ash, 5% silica fume, and cement 2.
It is good to set it to 0%.

Table 2 shows what happens to the O funnel time when the plastic viscosity of concrete is set to the above-mentioned value, and the ordinary concrete and the conventional high fluidity concrete are also shown. is there.

[0022]

[Table 2] As can be seen from the table, the plastic viscosity of the flow control type concrete of the present embodiment is smaller than that of the conventional high flow concrete. This is because the flow control type concrete of the present embodiment, in a dynamic state, in which the vibration of the vibrator acts, is, as can be seen by comparing the O funnel times,
It shows that it has higher fluidity than conventional high-fluidity concrete.

As described above, according to the flow control type concrete of the present embodiment, the concrete when the vibration of the vibrator is applied is adjusted by optimally selecting and adjusting the kinds of admixtures and their mixing ratio. The viscosity value of concrete is set to be slightly larger than that of high-fluidity concrete when the vibration of the vibrator is not applied by reducing the amount of superplasticizer used, so a vibrator is used. It can be made to flow to some extent without doing so, and it does not flow too much like conventional high-fluidity concrete, so there is no problem in construction on inclined surfaces.

On the other hand, if the vibrator is slightly actuated as required, the poured concrete will have a higher fluidity than the conventional high-fluidity concrete, will flow quickly, and will be filled in every corner. Then, when the vibrator is stopped, it immediately returns to the static state, and a certain shape is maintained.

That is, the flow control type concrete of the present embodiment exerts a fluidity superior to that of the conventional high flow concrete by operating the vibrator, and stops the vibrator to make the flow control concrete more than the conventional high flow concrete. Liquidity can be suppressed. In other words, while conventional high-fluidity concrete cannot control its high fluidity, in the flow control type concrete of the present embodiment, it is possible to control the fluidity by switching the operation and stop of the vibrator, Concrete with excellent workability and labor saving.

Therefore, the flow control type concrete of this embodiment is the most suitable concrete on sloped ground such as roads and slopes.

Further, in the dynamic state, the high-performance AE water reducing agent is used in an amount of about one-third of that of the conventional high-fluidity concrete, although it exhibits higher fluidity than the conventional high-fluidity concrete. Since the unit water amount can be reduced and the cement amount can be reduced, the material cost can be significantly saved.

In this embodiment, although not particularly mentioned,
Fine powder materials such as coal ash and rock fine powder may be used instead of the admixtures such as fly ash. In the first place, the gist of the present invention is that the plastic viscosity of concrete is 5 to 100 Pa.
Therefore, it is within the scope of daily design work to appropriately combine known fine powder materials.

Further, in the present embodiment, the mixing ratio (volume) of the admixture and cement was limited to 50% blast furnace slag fine powder, 25% fly ash, 5% silica fume, and 20% cement from the experimental results. Based on experience while considering experimental error, 40 to 60 blast furnace slag fine powder
%, Fly ash 20 to 30%, silica fume 3 to 8%, and cement 15 to 35%.

It is to be noted that such a configuration does not mean that all the numerical values included in the range can be arbitrarily combined, but that the combination can be arbitrarily selected within a possible limit. To do.

[0031]

As described above, in the flow control type concrete of the present invention, the predetermined fluidizing agent is added to the cement to set the yield value of the concrete to 100 to 250 Pa, and the blast furnace slag fine powder and fly Admixtures such as ash, silica fume, and limestone powder are mixed into the cement to set the plastic viscosity of concrete to 5 to 100 Pa · s, so high fluidity is exhibited in the vibration state and fluidity is suppressed in the vibration stopped state. It becomes possible to do.

[0032]

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an admixture ratio of an admixture and an average flow rate in a flow control type concrete according to the present embodiment. (A) is a mixture of ordinary cement and blast furnace slag fine powder or fly ash. The graph when the ratio was changed, (b) shows the blending ratio of silica fume when blast furnace slag fine powder was 50%, ordinary Portland cement was 20%, and admixtures such as fly ash and silica fume were 30%. The graph of the case.

[Explanation of symbols]

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Claims (2)

[Claims] 1. A predetermined fluidizing agent is added to cement to set the yield value of concrete to 100 to 250 Pa, and admixtures such as blast furnace slag fine powder, fly ash, silica fume and limestone powder are mixed into the cement. The flow control type concrete is characterized in that the plastic viscosity of the concrete is set to 5 to 100 Pa · s. 2. The blending ratio (volume) of the admixture and the cement is 40 to 60% blast furnace slag fine powder, 20 to 30% fly ash, and 3 to 8% silica fume.
The flow control concrete according to claim 1, wherein the cement content is 15 to 35%.