JP2997893B2 - Highly-fillable concrete material, reinforced concrete structure and steel-concrete composite structure using the concrete material - Google Patents

Description

The present invention relates to a highly-fillable concrete material used for cast-in-place concrete and secondary concrete products, and a reinforced concrete structure using the highly-fillable concrete material. And a steel-concrete composite member.

[Conventional technology]

When placing concrete in places where reinforcing bars are densely arranged, or when filling concrete in steel-concrete composite structures with closed sections, such as concrete-filled steel pipe structures, double steel shell box structures, hybrid wall structures, etc. Is
One point is how concrete can be filled to every corner.

However, in the construction using the conventional general cement material, increasing the water-cement ratio will decrease the strength and other properties of the concrete, material separation,
Problems such as breathing also occur.

Also, for example, for grout concrete used for installation of equipment, the unit water volume is increased, or high-performance water reducing agents, flowability is improved by using a fluidizer, but material separation easily occurs, Blockage of the coarse aggregate occurs in the mold due to blocking of the coarse aggregate, and the filling property cannot be ensured. On the other hand, by increasing the amount of cement, the material separation resistance is improved, and the filling property is secured.However, the temperature increase due to heat of hydration tends to occur due to the increase in the amount of cement. There's a problem.

On the other hand, studies have been conducted on concrete excellent in fluidity and material separation resistance for general structures and reinforced concrete structures having very dense reinforcing bars. For example, there are the following documents.

Kazumasa Ozawa, Koichi Maekawa, and Fu Okamura: Development of Hyper-Performance Concrete, Annual Report on Concrete Engineering, Japan Concrete Institute, Vol.11, No.1, 1989 Takefumi Shinto, Yasukunori Matsuoka, Jun Sakamoto, Somnouk Tangtherm Siricle: Properties of compaction-free concrete in fresh condition, Japan Society of Civil Engineers 45th Annual Scientific Lecture, September 1990 Deformation to the extent that compaction is unnecessary in fresh concrete condition High-performance concrete is defined as a high-quality concrete that is excellent in heat resistance and material separation resistance and solves various problems immediately after casting and after hardening. A model of the blast furnace slag fine powder (brane Value 5,680cm ² /
g), using fly ash and intumescent materials, and using a high-performance AE water reducing agent in combination with a small amount of a thickener.

In addition, the above-mentioned literature describes a study on compaction-free concrete using a biopolymer produced by fermentation technology as a thickener. The concrete examined in this document is ordinary Portland cement and blast furnace slag (Brain value 4,270cm ² / g) as binder
And fly ash in the proportions of 30%, 30% and 40%, respectively, using the above-mentioned biopolymer and high-performance water reducing agent as an admixture, by adjusting the unit water amount and the amount of the biopolymer. It has been reported that concrete having excellent fluidity and resistance to material separation to the extent that compaction is unnecessary is obtained.

[Problems to be solved by the invention]

As described above, the increase in the amount of cement (binder) used to improve the resistance to material separation and filling, which is carried out in grout concrete, involves the problem of temperature cracking due to the generation of heat of hydration. It cannot be applied to reinforced concrete structures and steel-concrete composite structures.

The present invention relates to the concrete described in the above-mentioned documents, the type of binder, admixture such as fly ash (in which fly ash is used as a binder), a water reducing agent, a thickener and the like. By specifying the type and amount of the agent, concrete that does not require compaction is realized, but from the same idea, cement and brane specific surface area of 5,000 to 10,000 cm ² / g as binder Combining very fine blast furnace slag fine powder with a surfactant to give water-reducing action, without using admixtures such as fly ash, special thickeners, etc. It is intended to provide concrete that does not require compaction. In the following description, terms of high filling property and fluidity are used, which are described in detail in Examples of the present invention.
It is used as a concept defined by numerical limits necessary for achieving the compaction unnecessary as the object of the present invention.

[Means for solving the problem]

The highly-fillable concrete material of the present invention comprises cement,
A blast furnace slag fine powder with a brane specific surface area of 5,000 to 10,000 cm ² / g and a replacement ratio (weight ratio in the binder) of 45 to 90% By adding water and an amount of a surfactant necessary to obtain a slump flow value of 59 cm or more, the filling rate of the boundary between the concrete upper surface form and the non-compacted form filled into the form is increased. By providing material separation resistance that achieves the indicated filling rate of 98% or more, compaction at the time of filling can be made unnecessary. The high-filling concrete material used herein includes mortar without coarse aggregate, fine aggregate, cement paste without coarse aggregate, and the like.

When the highly-fillable concrete material of the present invention is used for mixing concrete, required amounts of fine aggregate and coarse aggregate are mixed, and the water binder ratio (weight ratio of water to cement and granulated slag) is 25 to 40%.

The blast furnace slag fine powder used in the present invention has a specific surface area of the blast furnace slag mixed with ordinary blast furnace cement.
3,000~4,000cm while a ² / g, the Blaine specific surface area obtained by the 5,000~10,000cm ² / g, was ground blast furnace slag with a pulverizer, obtained by, for example classified with a classifier.

As the cement to be mixed with the blast furnace slag fine powder, commercially available ordinary Portland cement, early-strength Portland cement, fly ash cement, blast furnace cement, and other cements are used.

Increase the specific surface area of blast furnace slag fine powder to 5,000 to 10,000
The range of 0 cm ² / g is a range that does not become disadvantageous in cost compared to a commercially available cement material, and defines a range in which both material separation resistance and required fluidity can be secured by improving viscosity, and 5,000 cm If it is lower than ² / g, the effect on fluidity and material separation resistance is insufficient, and if it is higher than 10,000 cm ² / g, the material cost is mainly high.

The reason for setting the replacement ratio of blast furnace slag fine powder to 45 to 90% is that
%, The effect on the material separation resistance due to the use of the blast furnace slag having a finer fineness is insufficient.
If it is higher than%, the difference in effect is small.

The surfactant referred to in the present invention is used for reducing the amount of water and the water binder ratio required for the hydration reaction of the binder, such as a high performance water reducer, a high performance AE water reducer, an AE water reducer, a water reducer, and the like. It is an admixture, and the amount mixed in the formulation varies depending on the type.

In addition, the reason why the water binder ratio is set to 25 to 40% is to define a range in which required fluidity can be secured and an adverse effect on the quality of concrete due to an increase in the amount of water is small.

The highly-fillable concrete material of the present invention, as described above,
Material separation resistance and fluidity have been greatly improved, and by filling the reinforcing bar with the reinforcing bar arranged in the form, it can be spread to every corner of the form without compaction, Due to the hardening, a high-quality reinforced concrete structure can be constructed. In particular, the effect is large in a structure in which reinforcing bars are arranged very densely.

Also suitable for concrete filling in closed-section steel-concrete composite structures such as concrete-filled steel pipe structures, double steel shell box structures, hybrid wall structures, etc.
In particular, with regard to the concrete-filled steel pipe structure, high-quality concrete can be press-fitted from the column base of the steel pipe column at a high pressure, and the concrete-filled steel pipe column covering multiple floors can be constructed at once.

(Operation)

In the present invention, the Blaine specific surface area is 5,000 to 10,000.
By using blast furnace slag fine powder of 0 cm ² / g, it is required for compaction-free concrete without increasing the amount of binder per unit amount and without using admixtures such as thickeners and fly ash. Material separation resistance and fluidity are secured.

Fig. 2 shows the effect of binder type on fluidity and viscosity. The horizontal axis shows the slump flow value of the mortar showing the fluidity (cm), and the vertical axis shows the flow down time (seconds) of the P funnel showing the viscosity. I am taking.

The correspondence between the curve in the graph and the type of binder is as follows.

□: Normal Portland cement ○: Blast furnace slag fine powder with a specific surface area of 3,800 cm ² / g (replacement rate 70%) ●: Blast furnace slag fine powder with a specific surface area of 6,000 cm ² / g (replacement rate 70%) △ ： Blast furnace slag fine powder with a specific surface area of 8,000cm ² / g (replacement rate 70%) ▲ ： Fly ash with a specific surface area of 2,800cm ² / g (replacement rate 15%) Weight ratio.

As can be seen from the figure, with respect to each binder, it is considered that as the fluidity increases, the viscosity decreases and the material separation is more likely to occur. In addition, in the case of mixing blast furnace slag fine powder with a brane specific surface area of 3,800 cm ² / g corresponding to ordinary blast furnace cement C, the curve is lower than that of ordinary Portland cement, and the same fluidity is obtained. In the case of slag mixed with blast-furnace slag, the viscosity is lower and material separation is more likely to occur. That is, it is disadvantageous with respect to the filling property as compared with the case of ordinary Portland cement. On the other hand, the brane specific surface area is 6,000cm ²
When blast-furnace slag fine powder having a high fineness of / g is used, the curve is on the upper side as compared with the case of ordinary Portland cement, and the material having the same fluidity has a higher resistance to material separation. Further, when the brane specific surface area is 8,000 cm ² / g while maintaining the substitution rate as it is, it is more advantageous in terms of fluidity and material separation resistance.

Fig. 3 shows the effect of the blast furnace slag replacement rate on the fluidity and viscosity. The slump flow value (cm) of the mortar showing the fluidity is also plotted on the horizontal axis, and the P funnel falling time showing the viscosity on the vertical axis. (Seconds).

Blaine specific surface area is 6,000c as blast furnace slag fine powder
m ² / g was used. The relationship between the curve in the graph and the type of binder is as follows: □: 0% replacement rate, ○: 50%, ●: 70
% And △ are 85%.

From this figure, it can be seen that the larger the Blaine specific surface area, that is, the greater the fineness of the blast furnace slag fine powder, the more advantageous in terms of fluidity and material separation resistance.

In addition, when considering thermal cracking due to heat of hydration, the binder is of a low heat generation type, and the amount of the binder required to obtain a predetermined filling property (or material separation resistance) can be reduced. Danger can be reduced.

FIG. 4 shows the test results of an adiabatic temperature rise test based on the composition shown in Table 1 below. In the case of the ordinary concrete, the composition 1 has a Blaine specific surface area of 6,000.
In the case where the blast furnace slag fine powder of 0 cm ² / g was used and the replacement ratio was 68%, the composition 3 was also the case where the replacement ratio was 79%.

As shown in FIG. 4, heat generation is particularly small in Formulations 1 and 3 using the blast furnace slag fine powder, especially in the early stage of the material age, and in Formulation 3, heat generation is small for a long time. Therefore, it is advantageous in preventing temperature cracks.

Regarding blast furnace slag fine powder, the Japan Society of Civil Engineers has created “Blast Furnace Slag Fine Powder Standard for Concrete (Draft)” and “Design and Construction Guidelines for Concrete Using Blast Furnace Slag Fine Powder (Draft)”. Further, it is known that the use of fine blast furnace slag fine powder increases the resistance to separation in water and the viscosity, and the use of this property is disclosed in Japanese Unexamined Patent Publication No. 63-11553. Japanese Patent Application Laid-Open No. 63-74943 discloses an invention of a cement composition for shotcrete.

On the other hand, the inventor of the present application has confirmed that, by the predetermined blending using the blast furnace slag fine powder, it is possible to simultaneously secure the material separation resistance and the fluidity as described above. As a result, concrete with excellent filling properties could be obtained.

〔Example〕

 Hereinafter, examples will be described.

Fig. 1 shows an example of application to reinforced concrete structures.
It is a figure which showed the dimension of the model formwork used for the filling test which simulated the tight arrangement.

(Unit is mm).

L ₁ (opening width): 200 L ₂ : 400 L ₃ : 980 L ₄ : 100 L ₅ : 180 L ₆ : 180 L ₇ : 900 L ₈ : 100 L ₉ (Reinforcing): 40 L ₁₀ : 58 L _{11: 60 L 12: 46 L} 13 ( distance rebar 6): 60 rebar 6 diameter: 19 inch frame width: 200 using the model mold, the opening of the upper end, Table 2
Concrete having the composition shown in (1) was poured without compaction by vibration or the like.

Table 3 shows the results of the concrete tests using the above-mentioned formulations 1 to 5. Here, the filling rate indicates the filling rate at the boundary between the concrete and the upper mold.

The highly-fillable concrete material of the present invention corresponds to the case of the composition 1, and good results were obtained in both the filling property and the filling rate.

Formulation 2 was a case in which a blast furnace slag fine powder having a brane specific surface area of 3,800 cm ² / g was used. Since the material separation resistance was poor, clogging occurred on the way due to separation of coarse aggregate.

Formulation 3 was a case in which only cement was used as a binder and fine blast furnace slag was not used, and clogging occurred in the middle of filling properties.

Formulation 4 is a case in which the material separation resistance is improved by increasing the amount of cement, and the filling property and the filling rate are relatively good. However, the cracking is likely to occur due to the increase in the amount of cement. The quality of concrete is a problem.

Formulation 5 was made to have fluidity by reducing the amount of surfactant and increasing the ratio of water binder, but the material separation resistance was poor, the filling property was poor, and the filling rate was low. .

FIG. 5 shows a concrete-filled steel pipe column 1 as an example of application to a structure of the present invention. By using the highly-fillable concrete material 7 of the present invention having improved fluidity and material separation resistance, a high-strength, high-quality concrete material can be spread at once from the pressure inlet 2 of the column base of the steel pipe column 8 over multiple floors. Can be press-filled. In the figure, 3 is a pump pipe, 4 is a joint diaphragm, and 5 is a girder.

In addition, although not shown, concrete is filled in a steel shell having a closed cross section, such as a double steel shell structure applied to a common groove, a steel-concrete composite segment applied to a tunnel, a hybrid wall, and the like. In the case of a composite structure, it can be used as a suitable material.

〔The invention's effect〕

According to the present invention, by using a blast furnace slag fine powder having a high degree of fineness, fluidity and a predetermined material separation resistance can be realized with a small amount of a binder, and the invention is applied to a concrete structure or a steel-concrete composite structure. In this case, good filling properties can be obtained without compaction.

Further, since no thickener is used, high quality of concrete after curing can be ensured without impairing drying shrinkage, freeze-thaw properties, durability and the like.

Furthermore, since only a small amount of binder is required, the amount of temperature rise is small, and the risk of temperature cracking due to heat of hydration can be reduced.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a model formwork used for a filling test of a highly-fillable concrete material of the present invention, FIG. 2 is a graph showing a test result on the effect of the type of binder, and FIG. 3 is a blast furnace slag. FIG. 4 is a graph showing the results of a test on the effect of the replacement ratio, FIG. 4 is a graph showing the results of an adiabatic temperature rise test, and FIG. 5 is a perspective view showing the case where the present invention is applied to a concrete-filled steel pipe column. 1 ... Concrete-filled steel column, 2 ... Press-in, 3 ...
Pump piping, 4 …… Joint diaphragm, 5 …… Girder,
6 Reinforcing bar 7 Highly filling concrete material 8
Steel pipe columns.

Continued on the front page (72) Inventor Masato Miyake 1 Kimitsu, Kimitsu City, Chiba Prefecture Inside the Nippon Steel Corporation Kimitsu Works (72) Inventor Toshiya Kawahara 1-1-1 Edamitsu, Yawatahigashi-ku, Kitakyushu-shi, Fukuoka Nippon Steel Corporation (56) References JP-A-61-242942 (JP, A) JP-A-64-72949 (JP, A)

Claims (4)

(57) [Claims] (1) a cement having a brane specific surface area of 5,000 to 1;
In 0,000cm ² / g, substitution rate (weight ratio occupied in the binder) is 45
Water with a water binder ratio (weight ratio of water to binder) of 25 to 40% is added to the binder consisting of ~ 90% blast furnace slag fine powder,
By adding a surfactant in an amount necessary to obtain a slump flow value of 59 cm or more, the filling rate expressed by the filling factor at the boundary between the concrete and the upper formwork filled non-compacted into the formwork. A highly-fillable concrete material characterized by having a material separation resistance of achieving a filling rate of 98% or more. 2. A cement having a brane specific surface area of 5,000 to 1
In 0,000cm ² / g, substitution rate (weight ratio occupied in the binder) is 45
A binder consisting of 90% of blast furnace slag, and the unit coarse aggregate volume 0.29 m ³ / m ³ or more coarse aggregate, and fine aggregate fine aggregate volume ratio is less than 48% in the mortar , With a unit water volume of 185 kg / m ³ or less and a water binder ratio (weight ratio of water to binder) of 25
By adding ~ 40% of water and the required amount of surfactant to obtain a slump flow value of 59 cm or more, the boundary between the concrete top form and the non-compacted form in the form A highly-fillable concrete material characterized by having a material separation resistance that achieves a fill rate of 98% or more expressed by a fill rate of: 3. A reinforced concrete structure in which a highly-fillable concrete material according to claim 1 or 2 is filled in a form having reinforcing bars arranged therein, and then hardened. 4. A steel-concrete composite structure in which a highly-fillable concrete material according to claim 1 or 2 is filled in a steel pipe or a steel shell and hardened.