JPH0345544A - Concrete blend composition - Google Patents

Abstract

PURPOSE:To obtain the title composition capable of constructing dense, high- quality and highly durable concrete especially without carrying out vibration hardening, containing cement, aggregate, water, thickening agent such as cellulose-base, high-performance water reducing agent, AE agent and antifoamer and having specific slump flow value and specific air content. CONSTITUTION:A concrete blond composition containing cement, an aggregate, water, a cellulose-based or acrylic thickening agent, a high-performance water reducing agent, an AE agent and an antifoamer and having 45-65cm slump flow value and 4-6vol.% air content. The composition uses the thickening agent and the high-performance water reducing agent to provide a concrete blend composition maintaining sufficient fluidity and rheological properties of proper softness not to cause aggregate separation and bleeding.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a concrete mix composition, and in particular to a concrete composition that can be used to construct solid, high-quality, highly durable concrete structures without vibration compaction. Concerning blended compositions.

[Background of the invention]

Conventional concrete mix compositions are manufactured by adding cement and water to aggregates such as gravel or sand, and if necessary, admixtures such as AE agents and water reducers, and then stirring the mixture.

In order to construct a solid, high-quality concrete structure using such a material composition, it is necessary to
Conventionally, the composition contains a larger amount of water than necessary for hydration of the cement, or a fluidizing agent is added to the composition, thereby increasing the softness of the composition and increasing its fluidity. It was essential to carefully drive and compact the concrete using a pie break or a ram.

However, when trying to increase the softness as described above,
Aggregate separation and breathing become more likely to occur, thus causing loss of homogeneity of the concrete structure. The above-mentioned breathing causes the accumulation of breathing water on the bottom surfaces of aggregates, reinforcing bars, separators, etc., and the breathing traces become water channels, and the water that enters from the outside rusts the reinforcing bars, causing expansion due to this rusting. causes the concrete structure to fail. This phenomenon is particularly noticeable when concrete structures are in environments where they are constantly in contact with water, such as underwater, underground, or in reservoirs, and if seawater or the like invades, concrete structures deteriorate extremely quickly. This causes an inconvenience.

In addition, in tall concrete structural members such as walls and columns, reinforcing bars are often placed at narrow intervals, and in such cases, it is difficult to carefully compact the concrete. In reality, it's close to impossible. For this reason, construction defects such as jumpers, dowels, and cold joints are likely to occur in these members, which impairs the durability of the concrete structure.

On the other hand, even if a normal concrete mix composition is used, a dense and highly durable concrete structure can be constructed if proper pouring and sufficient compaction are performed. However, in recent years, the quality of concrete structures has deteriorated more easily due to the lack of skilled workers and the promotion of labor-saving. It is desired to develop a concrete mix composition that can construct highly durable concrete structures.

Therefore, as a result of various studies in view of the above-mentioned situation, the inventor of the present invention found the following results: 1. In the conventional concrete mix composition as described above, a predetermined proportion of a cellulose-based or acrylic thickener and a high-performance water-reducing agent are combined. 2. To adjust the air content in the concrete mix composition containing the above-mentioned thickener and high-performance water reducer. If the AE agent and antifoaming agent are mixed in a predetermined ratio and the air content is 4 to 6% by volume, the durability of the concrete structure will be improved. 3. As mentioned above, the thickener and high performance In concrete mix compositions containing water reducing agents, the slump flow value is 45.
~65cm, even in members with dense reinforcement such as walls and columns, it is equivalent to a concrete structure obtained by vibration compaction using a conventional concrete mix composition without vibration compaction. or an extremely dense concrete structure having a filling property of
I found out.

[Object and structure of the invention]

The present invention was invented based on the above findings, and is a concrete formulation that is resistant to aggregate separation and breathing, and is capable of constructing extremely dense and durable concrete structures without vibration compaction. For the purpose of providing a composition, comprising cement, aggregate, water, cellulosic or acrylic thickener, superplasticizer, AE agent and antifoaming agent, and having a slump flow value of 45 to 65c
m and air content: 4 to 6% by volume.

[Detailed description of the invention]

What is important in the present invention is, first of all, to obtain a concrete mix composition that maintains sufficient fluidity and has appropriate softness and rheological properties that do not cause aggregate separation or breathing. and a high performance water reducing agent.

As the thickener, either cellulose or acrylic thickeners can be used, such as nonionic water-soluble cellulose thickeners such as hydroxyethyl cellulose, hydroxymethyl cellulose, or hydroxypropyl methyl cellulose, or polyacrylamide polymers. Acrylic thickeners such as

As the high performance water reducing agent, a naphthalene sulfonic acid formalin high condensate or a sulfonated melamine formalin condensate is used.

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

The amount of thickener and superplasticizer used is such that the slump flow value of the composition is 45 to 65 cm, and generally 0.25 to 1.50 kg/bo of thickener and 1 g/g of superplasticizer are used. , 500-5,000 cc/C=100kg, better than 0.40-0.75kg/rrr,
It is important for the present invention to use 2,000-4,000 cc/C=100 kg.

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

In order to obtain a dense 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 loadings of the above-mentioned thickener and superplasticizer. If the slump flow value is less than 45 marks, the fluidity is insufficient and voids are likely to occur; on the other hand, 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 determined to be 45 to 65c111t.

Furthermore, in the concrete mix composition of the present invention,
It is necessary to introduce 4 to 6% air based on the total volume of the composition in order to maintain sufficient durability of the concrete structure, specifically to obtain sufficient freeze-thaw resistance. It is. Concrete mixing amount I′Ii,′!
! lJ, when this air content is less than 4%,
Freeze-thaw resistance is now reduced, while it is 6
%, the strength decreases significantly, so
In the present invention, the air content is set at 4 to 6%.

The amount of air introduced depends on the amount of aggregate, thickener and superplasticizer, in particular the thickener used, and also on the temperature, the type of mixing machine and the method of pouring. For this reason, it is necessary to adjust the amounts of the AE agent and antifoaming agent according to test lines in accordance with factors such as the amount of thickener used and temperature. The amount of AE agent and antifoaming agent used is generally 0.005 to 0.05 to the weight of cement.
0.3% and 0.001-0.2% are important to the invention.

Further, the size of the introduced air bubbles is preferably fine. In general, high fluidity concrete mix compositions containing thickeners and water reducers tend to introduce relatively large air bubbles during stirring and mixing, but in the concrete mix composition according to the present invention, AE agents and antifoaming agents are added. Since they are contained in a predetermined amount, large air bubbles are defoamed by the action of both, and an appropriate amount of fine air bubbles are introduced which are useful for improving strength and durability.

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

Cement 275 ~ 375 kg / Aggregate 1700 ~ 1900 kg /
Bosui 150-170k
g/rrr Cellulose-based or acrylic thickener 0.40-0.75 kg/bo High performance M liquid agent 2000-4000 cc/C=10
0kgAE agent 30 to 50 gr/C
=100kg antifoaming agent 10 to 30
gr / C = 100 kg The composition of the present invention can be manufactured according to conventional methods, for example, by adding a cellulose or acrylic thickener to cement, aggregate and water in a ready-mixed concrete plant or on-site; It is manufactured by adding a high performance water reducing agent, an AE agent and an antifoaming agent, and stirring and mixing.

The cellulose-based or acrylic-based thickener mixed in this concrete mix composition has the effect of improving material separation resistance, preventing breathing, and improving fluidity and therefore filling properties. In addition to imparting fluidity to the Kigumi acid compound, the AE agent and antifoaming agent make it possible to introduce an appropriate and fine amount of air. By adding these admixtures to conventional concrete mix compositions, the slump flow value can be increased from 45 to 45.
The high fluidity concrete mix composition according to the present invention prepared by introducing 4-6% air by volume at 65cn+ is suitable for vibration clamping even in tall and very densely reinforced structures such as walls and columns. A very dense concrete structure can be constructed without compaction, with a filling property equal to or better than that of a concrete structure constructed by compaction using a normal concrete mix composition. . In addition, when such a high fluidity concrete mix composition is used, no breathing occurs, so construction defects such as dowels, jumpers, and poor pour joints are less likely to occur, and a homogeneous concrete structure with less variation in quality can be constructed. Is possible. Furthermore, as a result of increasing the freeze-thaw resistance by introducing an air content of 4 to 6%, concrete structures constructed using the concrete mix composition according to the present invention have high durability even in cold regions.

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

〔Example〕

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

Example 1 Conventional concrete mix compositions (comparative samples 1 to 3) having various consistencies shown in Table 3, based on the formulation shown in Table 1 and the materials shown in Table 2, and according to the present invention High fluidity concrete mix composition (invention samples 1 to 4)
) were used to conduct various tests.

Note that the slump value and slump flow value in Table 3 are values obtained from the following test.

Divide the concrete mixture into 1/3 volumes into a slump cone of zz length z Gk class height 30 cm, lower end inner diameter 20 cm, upper end inner diameter 10 cm, and fill it by poking it a certain number of times with a standard rod. The cone is then pulled up vertically to remove the concrete, and the concrete composition loses its shape depending on its softness.

At this time, measure the height from the top surface to the slump value (ctl)
shall be.

Soump flow: A test similar to the above slump test was conducted to measure the spread of concrete in the vertical and horizontal directions, and the average value was calculated as Cl11
The value expressed by is the slump flow value.

”≦” basis Book Distribution bowed messenger for material fee In the table, FM represents the coarse grain ratio.

As shown in Figure 1 of the Shukon-cho, - Outgoing side IA: height 550mm x diameter 100mm, secondary side IB: height 350mm + x diameter 10
0 order and direct connection part IC connecting primary side IA and secondary side 2B
1 of each sample S shown in Table 3 was placed in an L-shaped fluidity measuring jig with dimensions of = length 550mm x diameter 100mm+.
A fluidity test was conducted by charging from the next IA.

In this test, when using the comparative sample, the concrete did not flow to the secondary side IB unless a vibrator was used, whereas in the case of the inventive sample, the concrete did not flow to the primary side IA even without vibration. Almost at the same time, it flowed into the secondary side IB. These results revealed that the blended composition according to the present invention has higher fluidity than conventional concrete blended compositions.

White i Each of the above samples was introduced from the primary side 2A and cured, and the -next side 2A shown in FIG. 2: 1400 PengX
200 aaX350 mm, secondary side 2 B: 65
0 mm x 200 mm x 35011 I11 and the part 2 that connects the primary side and the secondary side C: 1050 an x 2
An L-shaped specimen having dimensions of 00+nm x 350mm was prepared, and its surface condition was observed.

The results are shown in Table 4.

As is clear from Table 4, there was a large difference in the surface condition of the specimens after demolding the mold. From Table 4, it can be seen that in the case of the high fluidity concrete mix composition, even without vibration, filling properties equivalent to or better than when vibration compaction is performed using a conventional concrete mix composition are ensured.

In addition, from Table 4, the relationship between the amount of thickener added and the slump flow value in the high fluidity concrete mix composition is as follows:
It can be seen that this significantly affects the fluidity and aggregate separation resistance of the test composition. That is, the amount of thickener added is 0.3
It can be seen that for 75 kg/rrf, a suitable slump flow value is about 45-55, and for 0.75 kg/rrf, about 55-65.

Compressive Strength Test Cores C2 to CIO were sampled in the axial direction from the position shown in FIG. 3 of the L-shaped specimen on which the surface state observation test was conducted, and the compressive strength was examined.

Compressive strength is 200 in. long from a 100 in. diameter core.
A cylindrical test specimen was prepared and measured using the -axial compressive strength test method.

For comparison, the compressive strength of cylindrical test specimens obtained by curing each sample in Table 3 in a cylinder of Φ100 mm x 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 non-vibration specimen obtained using the sample of the present invention is almost the same as that of the specimen 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 region than the comparative sample. In addition, no aggregate separation occurred in the specimens of the present invention.

In addition, in terms of hydraulic conductivity, carbonation rate, and reinforcing steel adhesion, the samples of the present invention were comparable to the comparative samples of conventional concrete compositions.

Example 2 A conventional concrete mix composition having the basic mix shown in Table 6 was applied to the shaded area 3A of the vent house 3 of the three-story building shown in Figure 4 (3a: elevation view, 3b: side view). , thickener 0.375~0.75kg/rrr, high performance water reducer 2250~4000CC/C・100kg, AE
Agent 35gr/C = 100kg and antifoaming agent 25gr/C
= 100 kg and stirred and mixed, and at that time air was added to 4.
A concrete structure was constructed by applying the high fluidity concrete mix composition of the present invention obtained by introducing 3% by volume.

As a result, even in a thin structure with a wall thickness of 15 cm with dense reinforcement, if a properly adjusted high-flow concrete mix composition is used, vibration compaction can be performed without vibration. Fluidity equal to or better than that of concrete mix compositions,
It was demonstrated that filling properties were obtained and a solid concrete structure without segregation was cast.

〔Effect of the invention〕

As is clear from the above description, according to the present invention,
Provided is a concrete mix composition that has excellent fluidity and does not easily cause aggregate separation and pleating, and is therefore used when pouring in places where concrete is difficult to flow, such as where reinforcing bars are densely arranged. The present invention provides a concrete mix composition that can be densely filled without vibration compaction and form a homogeneous and highly durable concrete structure. Construction of highly durable concrete structures and labor saving can be achieved.

[Brief explanation of drawings]

Figure 1 shows an L-shaped fluidity measurement jig, Figure 2 shows an L-shaped specimen with embedded reinforcing bars, and Figure 3 shows a building outline of a three-story bent house using cleats. Each is shown below. In the figure, l...fluidity measuring jig, 2...
Specimen, 2D...reinforcing bar, 3...bent house.

Claims (1)

[Claims] Contains cement, aggregate, water, cellulosic or acrylic thickener, superplasticizer, AE agent and antifoaming agent, and slump flow value: 45-65 cm and air content:
Concrete mix composition with 4-6% by volume.