JPH0791103B2 - Concrete mix composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a concrete composition, and in particular, concrete capable of constructing a solid high-quality and highly durable concrete structure without vibration compaction. It relates to a compounded composition.

[Background of the Invention]

A conventional concrete compounding composition is produced by adding cement and water to an aggregate such as gravel or sand, and if necessary, an admixture such as an AE agent and a water reducing agent, and stirring and mixing. In order to construct a solid high-quality concrete structure using a concrete compounding composition having such a material composition, conventionally, a larger amount of water than that required for hydration of cement is contained in the composition. It is essential to add or add a fluidizing agent or the like, thereby increasing the softness of the composition to increase the fluidity, and carefully driving and compacting with a vibrator or a ram. .

However, if the softness is increased as described above,
Aggregate separation and bleeding are likely to occur, thus causing a loss of homogeneity of the concrete structure. And the above-mentioned breathing invites the retention of breathing water on the lower surface of aggregates, rebars, separators, etc., and the water that has entered from the outside makes the traces of breathing water rust and rusts the rebar, and the expansion that accompanies this rusting Destroys the concrete structure. This phenomenon is particularly noticeable when the concrete structure is underwater, underground, in a reservoir, etc., where it is in constant contact with water, and when seawater enters, the concrete structure deteriorates very early. It causes the inconvenience.

Also, in tall concrete structural members such as walls and columns, the reinforcing bars are often arranged at narrow intervals, and in such cases, it is difficult to carefully perform concrete compaction, It is practically impossible. Therefore, in these members, construction defects such as junkers, miniature boards, and cold joints are likely to occur, which is a cause of impairing the durability of the concrete structure.

On the other hand, even if an ordinary concrete mixture composition is used, a solid and highly durable concrete structure can be constructed if appropriate driving and sufficient compaction are performed. However, recently, due to the shortage of skilled workers and the promotion of labor saving, the environment of concrete structures is more likely to deteriorate, and nowadays high quality and It is desired to develop a concrete mixture composition capable of constructing a highly durable concrete structure.

Therefore, the present inventor has conducted various studies in view of the above situation, and includes 1. cement, aggregate, water, a cellulosic or acrylic thickener, a high-performance water reducing agent, an AE agent and an antifoaming agent. In the concrete composition, at a predetermined ratio, that is,
The high-performance water-reducing agent is blended at a particularly high blending ratio of 0.25 to 1.50 kg per 1 m ³ of the composition and 1500 to 5000 cc per 100 kg of cement in the composition. Not only is it difficult to cause aggregate separation and breathing when the agent is mixed, but the slump flow value can be adjusted to an extremely high value of 45 to 65 cm, resulting in the filling of concrete into densely reinforced members such as walls and columns. Even in the case, even without special vibration compaction, a very solid concrete having a filling property equal to or higher than that of a concrete structure obtained by vibration compaction using a conventional concrete mixture composition. That a concrete mixture composition capable of constructing a structure can be obtained, and 2. by the AE agent and the defoaming agent contained in the concrete mixture composition described above, A concrete mix which can construct a concrete structure having particularly improved strength and durability when the amount of fine air bubbles introduced into the mix composition is 4 to 6% by volume based on the volume of the composition. It was found that a composition was obtained.

[Object and Structure of Invention]

The present invention, which was invented based on the above findings, is a concrete mixture that is unlikely to cause aggregate separation or breathing, is extremely solid without vibration compaction, and can construct a highly durable concrete structure. A concrete composition for the purpose of providing a composition, which comprises cement, aggregate, water, a cellulosic or acrylic thickener, a superplasticizer, an AE agent and an antifoaming agent. It contains the thickening agent in a mixing ratio of 0.25 to 1.50 kg per 1 m ³ , and the high performance water reducing agent in a mixing ratio of 1500 to 5000 cc per 100 kg of cement in the composition, and has a slump flow value. : 45-65 cm and air content:
It relates to a concrete mix composition, characterized in that it has 4 to 6% by volume.

[Specific Description of the Invention]

What is important in the present invention is that, first of all, in order to obtain a concrete mixture composition that has sufficient fluidity and has appropriate softness and rheological characteristics that does not cause aggregate separation or breathing, thickening It is to use the agent and the superplasticizer together.

As the thickener, any of cellulose-based or acrylic-based thickeners can be used. For example, nonionic water-soluble cellulose-based thickeners such as hydroxyethyl cellulose, hydroxymethyl cellulose or hydroxypropylmethyl cellulose or polyacrylamide polymers. Acrylic thickeners such as

As the high-performance water reducing agent, a high-condensation product of naphthalenesulfonic acid formalin or a condensation product of sulfonated melamine formalin is used.

Any of these thickeners and high-performance water reducing agents can be used alone or in combination of two or more.

The amount of the thickener and the superplasticizer used is such that the slump flow value of the composition is 45 to 65 cm. Generally, the thickener 0.25 to 1.50 kg / m ³ , the superplasticizer 1,500 to 5,000. cc / C
= 100 kg, preferably 0.40 to 0.75 kg / m ³ , 2,000, respectively
It is important for the present invention to use ~ 4,000cc / C = 100kg.

As the AE agent, for example, a natural resin acid salt is used, and as the defoaming agent, for example, an organic polar compound is used.

In order to obtain a solid concrete structure without vibration compaction, in the concrete composition of the present invention 45 ~
A slump flow value of 65 cm is required, and this slump flow value is maintained at a predetermined value by adjusting the blending amount of the above-mentioned thickener and superplasticizer within the above range.
If the slump flow value is less than 45 cm, the fluidity is insufficient and voids are likely to occur, while if it is greater than 65 cm, the fluidity is high, but aggregate separation is likely to occur,
In the present invention, the slump flow value is set to 45 to 65 cm.

Furthermore, in the concrete mixture composition of the present invention,
Introducing 4 to 6% of air with respect to the total volume of the composition, in order to maintain sufficient durability of the concrete structure, specifically from the viewpoint of obtaining sufficient freeze-thaw resistance,
is necessary. In the concrete mix composition of the present invention, when the air content is less than 4%, the freeze-thaw resistance is lowered, while when it is more than 6%, the strength is significantly reduced, In the present invention, the air content is set to 4 to 6%.

The amount of air introduced depends on the amount of aggregate, thickener and high-performance water-reducing agent, especially thickener used, and also depends on the temperature, the type of kneading machine and the casting method. Therefore, it is necessary to adjust the amounts of AE agents and defoamers used by test kneading, depending on factors such as the amount of thickeners used and the temperature. It is important to the present invention that the amounts of AE agent and defoamer used are generally 0.005-0.3% and 0.001-0.2%, respectively, relative to the cement weight.

Moreover, it is preferable that the size of the introduced air bubbles is minute. Generally, in a high-fluidity concrete compounding composition to which a thickener and a water reducing agent are added, relatively large air bubbles are easily introduced at the time of stirring and mixing and pouring, but in the concrete compounding composition according to the present invention, the AE agent and the defoaming agent are Since they are contained in a predetermined amount, a large amount of air bubbles are eliminated by the action of both, and an appropriate amount of fine air bubbles that help improve strength and durability are introduced.

The typical composition of the concrete composition according to the present invention is as follows.

Cement 275~ 375kg / m ³ Aggregate 1700~1900kg / m ³ water 150 to 170 kg / m ³ cellulosic or acrylic thickeners 0.40~0.75kg / m ³ superplasticizer 2000~4000cc / C = 100kg AE agent 30 to 50 gr / C = 100 kg Defoamer 10 to 30 gr / C = 100 kg The composition of the present invention can be produced according to a conventional method,
For example, in a raw plant or on-site, a cellulose-based or acrylic-based thickener is added to cement, aggregate, and water, and a high-performance water reducing agent is added.
It is produced by adding an AE agent and an antifoaming agent and mixing with stirring.

The cellulose-based or acrylic-based thickener mixed in the present concrete composition has an effect of improving material separation resistance to prevent breathing and improving fluidity, and thus filling property, and has a high-performance water-reducing property. The agent imparts fluidity to the composition, and the AE agent and the defoaming agent allow introduction of an appropriate amount of fine air. Add these admixtures to conventional concrete mix compositions to increase the slump flow value from 45 to
The high-fluidity concrete composition according to the present invention, which is produced by introducing air of 65 cm and 4 to 6% by volume, makes it possible to suppress vibration even in a tall and very densely arranged structure such as a wall or a pillar. It is possible to construct an extremely solid concrete structure having a filling property equal to or higher than that of a concrete structure constructed by compaction using an ordinary concrete mixture composition without compaction. Also,
When such a high-fluidity concrete composition is used, breathing does not occur, so a bean board, a junker,
It is possible to construct a homogeneous concrete structure with less variation in quality and less likely to cause construction defects such as defective jointing. Furthermore, as a result of increasing the freeze-thaw resistance by introducing an air amount of 4 to 6%, the concrete structure constructed using the concrete mixture composition according to the present invention has high durability even in cold regions.

Further, since compaction can be omitted, it is possible to save labor, and there is an advantage that the quality of concrete is not influenced by the skill of the worker.

〔Example〕

Next, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Conventional concrete mix compositions (Comparative Samples 1 to 3) with various consistency shown in Table 3 based on the mix shown in Table 1 and the materials shown in Table 2 and high according to the invention. Fluid concrete mix composition (invention sample 1
Various tests were performed using 4).

In addition, the slump value and the slump flow value in Table 3 are values obtained by the following tests.

Slump test A concrete slump is divided into slump cones with a height of 30 cm, a bottom inner diameter of 20 cm, and a top inner diameter of 10 cm, divided into 1/3 volume and squeezed with a standard rod for a certain number of times. Then, when the cone is pulled up vertically to pull out the concrete, the concrete composition loses its shape depending on its softness. At this time, measure the height from the top surface to the slump value (cm).

Slump flow test A test similar to the above slump test is performed to measure the spread of concrete in the vertical and horizontal directions, and the average value in cm is taken as the slump flow value.

Flowability test in fresh concrete state, primary side 1A shown in Fig. 1: height 550 mm x diameter 100 mm,
Secondary side 1B: height 350 mm × diameter 100 mm and direct connection part connecting primary side 1A and secondary side 2B 1C: length L 550 mm × diameter 100 mm L-shaped fluidity measuring jig 1, Table 3 A fluidity test was performed by charging each sample S shown in 1) from the primary side 1A.

In this test, when the comparative sample was used, the concrete did not flow to the secondary side 1B unless a vibrator was used.
When the sample was put into 1A, it flowed to the secondary side 1B almost at the same time.
From this result, it became clear that the composition according to the present invention has higher fluidity than the conventional concrete composition.

Surface state observation test Each sample was charged from the primary side 2A and cured,
Primary side 2A shown in Fig. 2: 1400mm x 200mm x 350mm,
A secondary side 2B: 650 mm × 200 mm × 350 mm and a portion 2C connecting the primary side and the secondary side: An L-shaped sample having dimensions of 1050 mm × 200 mm × 350 mm was prepared, and the surface condition was observed.

The results are shown in Table 4.

As is clear from Table 4, a large difference was observed in the surface condition of the test piece after the mold was demolded. From Table 4, it can be seen that, in the case of the high-fluidity concrete composition, even if there is no vibration, a filling property equal to or higher than that when vibration compaction is performed using the conventional concrete composition is secured.

In addition, from Table 4, the relationship between the addition amount of the thickener and the slump flow value in the high fluidity concrete composition is
It can be seen that the test composition is greatly involved in the fluidity and the aggregate separation resistance. That is, the added amount of thickener is 0.375k
It can be seen that the proper slump flow value is about 45 to 55 for g / m ³ and about 55 to 65 for 0.75 kg / m ³ .

Compressive Strength Test Cores C _{1 to} C ₁₀ were sampled in the axial direction from the position shown in FIG. 3 of the L-shaped specimen subjected to the surface state observation test, and the compressive strength was investigated.

The compressive strength was measured by a uniaxial compressive strength test method in which a cylindrical test body having a length of 200 mm was prepared from a core having a diameter of 100 mm.

Further, for comparison, the compressive strength of a cylindrical test body obtained by curing each sample in Table 3 in a cylinder of Φ100 mm × 200 mm was also measured.

The results of the compressive strength test are shown in Table 5.

From the results shown in Table 5, the strength of the vibration-free test piece obtained using the sample of the present invention is almost the same as that of the test piece obtained using the comparative sample, and there is little variation in strength. In particular, it can be seen that the sample of the present invention has a higher compressive strength at the lowest compressive strength portion than the comparative sample. Further, the specimen of the present invention did not cause aggregate separation.

The samples of the present invention also showed results comparable to the comparative samples in terms of water permeability, neutralization rate, and reinforcing bar adhesion.

Example 2 In a shaded part 3A of the penthouse 3 of a three-story building shown in FIG. 4 (3a: elevation view, 3b: side view), a conventional concrete mix composition having a basic mix shown in Table 6 was added. , Thickener
0.375 to 0.75kg / m ³ , high performance water reducing agent 2250 to 4000cc / C = 100k
g, AE agent 35gr / C = 100kg and defoaming agent 25gr / C = 100kg were added and mixed by stirring, and at that time, 4.3% by volume of air was introduced to obtain the high fluidity concrete composition composition of the present invention. By doing so, the concrete structure was constructed.

As a result, even in a thin structure with a dense wall thickness of 15 cm of bar arrangement, if a properly adjusted high-fluidity concrete composition is used, it is equivalent to a normal concrete composition that was vibration-compressed even without vibration, Alternatively, it has been proved that a more solid flowability and filling property can be obtained, and a solid concrete structure without separation can be placed.

COMPARATIVE EXAMPLE Comparison samples 4 to 4 with the admixture loadings shown in Table 7 corresponding to the inventive sample 3 prepared in Example 1 under the basic formulation and materials used in Example 1. 7 were each prepared and tested for their performance, whereby four admixtures (thickener, superplasticizer,
The effect of the presence or absence of an AE agent and an antifoaming agent on the performance of the concrete composition was investigated. Table 8 shows the results of various tests on fresh concrete (uncured concrete) of these compounding compositions and the results of the compressive strength test on columnar specimens.

From the results of the above comparative tests, the following was found.

(A) Difference in Performance of Concrete Mixing Composition with and without Thickener In Comparative Sample 4, which does not include only the thickener among the four admixtures, the slump flow is 9.0 than that of Sample 3 of the present invention. The size of the fresh concrete after the slump flow test was 50.5 cm, which was smaller than the cm, and the mortar, cement paste, and water spread around the coarse aggregate remaining in the center.

In the fluidity test, coarse aggregate and mortar (water + cement +
Separation of sand and sand caused blockage due to coarse aggregate at the primary side bent part, and concrete did not flow to the secondary side.

From the above results, it is understood that the lack of the thickener among the constituent components of the concrete mixture composition of the present invention markedly impairs the material separation resistance of concrete. Therefore, without a thickener in a concrete composition such as the present invention, sufficient material separation resistance cannot be obtained, and as a result,
It is not possible to secure sufficient fluidity and fillability to fill concrete with a uniform composition throughout the formwork.

Further, in Comparative Sample 4, since a heterogeneous sample was created by material separation, a decrease in compressive strength of the cylindrical sample was also observed.

In addition, since the thickener having air entrainment was not included, the amount of air in Comparative Sample 4 was smaller than that of Sample 3 of the present invention.

(B) Difference in performance of concrete mixture composition with or without high-performance water-reducing agent For comparative sample 5 which does not include only high-performance water-reducing agent among four admixtures, slump flow showing high fluidity should be measured. Therefore, the slump becomes 9.5 cm, and the characteristic of the high-fluidity concrete that can easily flow for a considerable distance by its own weight like the sample 3 of the present invention cannot be obtained. It didn't flow at all.

As described above, when the high-performance water reducing agent is lacking among the components of the concrete mixture composition of the present invention, the high fluidity of concrete is significantly impaired, and the fluidity cannot be obtained at all by its own weight.

In this comparative sample 5, the amount of air is somewhat smaller than that of the sample 3 of the present invention because the viscosity of the concrete is poor and the thickener is not uniformly dispersed throughout the kneading.

(C) Difference in performance of concrete mixture composition with and without AE agent Comparative sample 6 containing no AE agent among the four admixtures
However, no significant difference was observed in the fluidity, the resistance to material separation, and the compressive strength of the cylindrical specimen, except that the amount of air was slightly reduced as compared with Sample 3 of the present invention. However, in the concrete composition which does not contain only the AE agent like this comparative sample 6, fine air bubbles which play an important role in securing the frost damage resistance (freeze-thaw resistance) are not introduced into the concrete. Concrete with poor frost resistance was generated.

(D) Difference in performance of concrete mixture composition with and without antifoaming agent Comparative sample 7 containing no antifoaming agent among the four admixtures, compared to invention sample 3, flowability of fresh concrete No significant difference was found in the value of slump flow and the result of the fluidity test, which is an index showing the degree of filling property. However, the amount of air is 5.
Since it increased by 0% to 9.5% (more than doubled), the compressive strength of the cylindrical specimen decreased from 266 kgf / cm ² to 187 kgf / cm ² (29.7% decrease).

As described above, it can be seen that excessively remaining bubbles cause a decrease in compressive strength due to the absence of the defoaming agent.

〔The invention's effect〕

As is clear from the above description, according to the present invention,
Provided is a concrete mixture composition which has excellent fluidity and is unlikely to cause separation and breathing of aggregates. Therefore, when the composition is placed in a place where the concrete is difficult to flow, for example, where the reinforcing bars are densely arranged. Also provided is a concrete mixture composition that is densely packed without vibration compaction and that can form a homogeneous and highly durable concrete structure.As a result, high-quality It is possible to achieve labor saving in construction and construction of a highly durable concrete structure.

[Brief description of drawings]

Fig. 1 is an L-shaped fluidity measuring jig, Fig. 2 is an L-shaped specimen with embedded reinforcing bars, and Fig. 3 is a core boring position in the L-shaped specimen shown in Fig. 2. , And 4a, 4b
The figures respectively show building outlines of penthouses of three-story buildings to which the high-fluidity concrete according to the present invention is applied. In the figure, 1 ... Fluidity measuring jig, 2 ... Specimen, 2D ... Reinforcing bar, 3 ... Penthouse.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Haruya Sahara 4-9-9 Akasaka, Minato-ku, Tokyo Within Japan Land Development Co., Ltd. (72) Inventor Yoshihiko Yokota 4-9-9 Akasaka, Minato-ku, Tokyo Within Japan Land Development Co., Ltd. (72) Inventor Osamu Onoue 4-9-9 Akasaka, Minato-ku, Tokyo Within Japan Land Development Co., Ltd. (56) Reference JP-A-63-284313 (JP, A) JP-A-57 -81530 (JP, A)

Claims (1)

[Claims] 1. A cement, aggregate, water, cellulose or acrylic thickeners, superplasticizers, a concrete mix composition comprising AE agents and antifoaming agents, the composition 1 m ³
It contains the thickener in a mixing ratio of 0.25 to 1.50 kg per 1500 kg per 100 kg of cement in the composition.
A concrete mixture composition containing the high performance water reducing agent in an amount of 000 cc and having a slump flow value of 45 to 65 cm and an air content of 4 to 6% by volume.