JP2726465B2 - Super hardened concrete - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to a super-hardened concrete,
The present invention relates to a super-hardened concrete used for concrete members and skeletons constructed by means such as rolling compaction, vibration pressurization and vibration compaction.

<Conventional technology and its problems> Conventionally, slumping of concrete is several cm to 20 cm.
It has been practiced using a degree of hardened or softened concrete. However, there was a problem that the driving speed was as small as about 30 m ³ / h at the maximum, and the construction cost was large. for that reason,
For example, in the installation of dams, etc., super-hard concrete with a slump of 0 cm or less and a VC value of about 40 seconds is kneaded in a ready-mixed plant, transported, scattered by a loader, compacted by rollers or vibratory rollers, etc. Mass casting is being carried out at a casting speed of 200m ³ / hr or more by making full use of the force (Cement Concrete, No. 42
0, Feb. '82, p26-35).

Here, the VC value is a factor indicating the workability of the ultra-hardened concrete, and is measured by a VC tester. Concretely, concrete was packed in a fixed amount in a φ24 × 20h (cm) iron container, a transparent plastic plate was placed on top of it, and a load of 20 kg was applied at 3,000 vpm and an amplitude of 1.0
The number of seconds until the mortar in the concrete vibrated in mm and overflowed at one location from the small holes provided in the plastic plate is shown.

However, in the above-mentioned conventional technology, (1). To increase the casting speed and reduce the construction cost, the compacted concrete layer to be cast in a single operation is about twice as large as the conventional one, about 75cm. Heating from hydration accumulates and heat cracks occur due to successive overstrikes. (2). By using ultra-hardened concrete on the concrete parts and skeleton surface of the applied concrete, the concrete will be non-breathing, and before hardening, a large amount of moisture on the concrete surface evaporates and plastic cracks occur . Even if plastic cracks do not occur, the concrete strength at a depth of about 0.5 to 1.0 cm from the surface decreases, and phenomena such as ragging and peeling occur. (3). Slow onset of bending strength. There were issues such as.

The present inventors have characteristics suitable for construction by means such as pressurization and compaction, for example, that the working time is 1 hour or more,
At the time of compaction, by the application of force and vibration, the concrete is easily stretched and the filling property is good. By adjusting the time until the cement starts to harden arbitrarily and obtaining high strength, the inventors have found that the above-mentioned problems can be solved, and have completed the present invention.

<Means for Solving the Problems> That is, the present invention comprises, as a main component, 100 parts by weight of cement, 0.1 to 4 parts by weight of calcium aluminate, 1 to 8 parts by weight of anhydrous gypsum, a water reducing agent and an aggregate, and a unit cement amount. Is 50-400k
g / m ³ , a unit water content of 60 to 110 kg / m ³ , and a VC value of 5 to 100 seconds.

 Hereinafter, the present invention will be described in detail.

The cement used in the present invention is ordinary / early strong / very early strong /
Various portland cements such as moderate heat and sulfate resistance, and various mixed cements obtained by mixing portland cement with pozzolans such as fly ash, silica and blast furnace slag. The pozzolans to be mixed can be arbitrarily mixed depending on the purpose. As the hydraulic property of the cement increases, the strength absolutely increases, and the initial strength development at low temperatures is also advantageous.

In addition, the calcium aluminate used in the present invention (hereinafter, referred to as calcium aluminate)
Ca Aluminate) means that CaO is C, Al ₂ O ₃ is A, F
If e ₂ O ₃ is F and SO ₃ , C ₃ A, C ₄ AF and C ₁₂ A
₇ , CA, C ₄ A ₃ , C ₁₁ A ₇ CaF _2, C ₃ A ₃ CaF _2, etc., one or more of which can be used.
Preferably one composed mainly of ₁₂ A ₇ and CA.

Ca aluminate can be either crystalline or amorphous.

The amount of Ca aluminate used is 0.1 to 4 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of cement. 0.
If the amount is less than 1 part by weight, the effect of accelerating the setting hardening is small, and
Exceeding the parts by weight is not preferred because some of them show pseudo-setting and quick-setting properties.

The fineness of Ca aluminate is the Blaine value (porosity is
0.50) and preferably 2,500 cm ² / g or more, and more preferably 3,000 to 5,000 cm ² / g in terms of performance such as acceleration of setting and hardening and economics.

In addition, anhydrous gypsum (hereinafter referred to as anhydrous) used in the present invention generally has an X-ray diffraction pattern of Form II C, and there is no limitation on impurities industrially contained. Anhydrous can be used in combination with Ca aluminate to prevent the setting and hardening of cement due to the use of anhydrous alone, and to increase initial flexural strength and reduce the amount of cement to obtain the same strength, reducing heat of hydration. Is what you do.

The amount of anhydrous used is 1 to 8 with respect to 100 parts by weight of cement.
Parts by weight, preferably 2 to 6 parts by weight. If the amount is less than 1 part by weight, the effect of use is small in strength. If the amount exceeds 8 parts by weight, the setting hardening is delayed, the initial bending strength is small, the drying before hardening is long, and the concrete surface peels off. There is a tendency and it is not preferable.

Anhydrous fineness is a Blaine value (porosity 0.50) of 2,50
0 cm ² / g or more is preferable, and from performance and economy 3,000 to 6,000
cm ² / g is more preferred.

Further, the water reducing agent used in the present invention is a general water reducing agent containing lignin sulfonates, polyols and oxycarboxylates as main components, and a high water content reducing agent containing alkyl allyl sulfonates and sulfonated melamine condensates as main components. All performance reducing agents can be used.

The water reducing agent reduces the unit water amount and increases the strength. At the same strength, the unit cement amount is reduced to reduce the heat of hydration. The performance water reducing agent has the highest strength effect and has a synergistic effect, and is the most preferable water reducing agent. The reasons for this, although not clear, are anhydrous dissolution rate, formation of ettrine guides, hydrolysis of calcium silicate, the main hydraulic mineral in cement, and Ca (OH)
It seems to be related to the supersaturation state of ₂ .

High-performance water reducing agents containing alkylallyl sulfonates as main components are referred to as naphthalene sulfonates, alkylallyl sulfonates, diethylnaphthalenes and aromatic sulfonates, and lignin sulfonates and others. Some of them have been commercialized by adding a small amount of a water reducing agent, and exhibiting their respective characteristics. Specifically, Kao Co., Ltd., product names "Mity 150", "Mity 100",
"Mighty 2000", "Mighty 150R" and "Mighty H"
S, etc., Denki Kagaku Kogyo Co., Ltd., trade names “FT-80”, “FT-5”
00V "and" FT-500G ", etc., Daiichi Kogyo Seiyaku Co., Ltd., brand name" Cell Flow 110P ", etc., Sanyo Kokusaku Pulp Co., Ltd., brand name" Sunflow PS ", etc., Takemoto Yushi Co., Ltd., brand name "Pole Fine 510N" and Pozoris Bussan Co., Ltd., trade name "NL14
50 "and the like.

Examples of other water reducing agents include lignin sulfonates of Nisso Master Builders Co., Ltd., trade name "Pozzolith No.8IMP", and polyols of Nisso Master Builders Co., Ltd., trade name of Pozoris No. .100N ", oxycarboxylates are Fujisawa Pharmaceutical Co., Ltd., trade name" Palic T ", sulfonated melamine condensate is Showa Denko KK, trade name" Melment F-10 ", and the like.

The amount of water reducing agent used is about the amount specified by the manufacturer for general water reducing agents, and 0.3 to 100 parts by weight of cement for high performance water reducing agents.
It is preferably 3 parts by weight, and more preferably 0.5 to 2 parts by weight from the viewpoint of economy. If the amount is less than 0.3 parts by weight, the water reduction rate and the elongation of the concrete at the time of compaction are small, and it is likely to be a junker, and the strength cannot be expected.

 The aggregate used in the present invention is not particularly limited.

Further, in the present invention, it is preferable to further use a setting and hardening accelerator of the cement (hereinafter referred to as an accelerator), because the rate of developing strength at a low temperature such as 15 ° C. or lower can be arbitrarily controlled.

Sulfates, chlorides, nitrates, nitrites, sulfites, inorganic salts such as thiosulfate and rhodanic acid except for gypsum, K salts of formic acid and acetic acid, Na salts and Ca salts are used as the accelerator. Although possible, the use of nitrates is most preferred.

Examples of nitrates include K salt, Na salt, Li salt, Ca salt, Mg salt, etc., while ensuring workability, it is possible to arbitrarily control the setting hardening of cement at low temperature, and the highest initial hardening, Under the conditions of the ultra-compacted concrete of the present invention, it is the most balanced accelerator.

The use of the accelerator is preferably at most 1% by weight, based on 100 parts by weight of cement, as long as rapid setting does not occur. Can not expect.

The mixing method of each of the above-mentioned materials is not particularly limited.For example, Ca aluminate, anhydrous, a water reducing agent and a promoter may be previously mixed with the cement, or separately added at the time of kneading the ready-mixed concrete. Alternatively, Ca aluminate, anhydrous, a water reducing agent and a promoter may be mixed as an admixture and added during kneading of ready-mixed concrete.

In the present invention, the unit cement amount (hereinafter referred to as “unit semester”) is 50 to 400 kg / m ³ . If it is less than 50 kg / m ³ , sufficient strength cannot be obtained, and if it exceeds 400 kg / m ³ , the concrete becomes dango-like during kneading, and it becomes difficult to knead.

Also, in the present invention, the unit water amount is 60 to 110 kg / m ³ , which is characterized by being significantly smaller than the unit water amount of ordinary concrete. If it is less than 60 kg / m ³ , even if a large amount of water reducing agent is added, the concrete is too hard to compact and cannot easily be compacted.If it is more than 110 kg / m ³ , it is too soft, and the When construction is performed by means, it is not preferable because construction becomes difficult because the concrete surface is wavy or the like, and even if the construction can be performed by increasing the fine aggregate ratio or the like, the strength decreases greatly.

In the present invention, the VC value needs to be 5 to 100 seconds.

The VC value is a factor that indicates the workability of ultra-hardened concrete. The measurement of the VC value is usually performed as described above.
In the case of concrete with Gmax exceeding 40 mm, the concrete is sifted through a 40 mm sieve and tested with concrete 40 mm below.In the measurement of the test quality, coarse aggregate of 40 mm or more is extracted in advance in the concrete mix. And kneading to measure the VC value.

If the VC value is less than 5 seconds, the concrete undulates and cannot be compacted with a roller or the like. If the VC value exceeds 100 seconds, it becomes difficult to compact and conversely, it tends to become a junk. Especially
10-80 seconds is preferred.

Dump trucks are convenient for transporting the ultra-compacted concrete of the present invention (hereinafter referred to as “concrete concrete”) mixed and kneaded as described above. A method of compacting with a vibrating roller or the like is possible.

<Example> Hereinafter, the present invention will be further described with reference to examples.

Example 1 Denki Kagaku Kogyo Co., Ltd., ordinary Portland cement 100
Using the composition shown in Table 1, the amount of cement was changed with respect to parts by weight, and concrete for 30 to 50 l was kneaded for 90 seconds with a forced kneading mixer. The coarse aggregate used was from Himekawa, Niigata Prefecture. In the case of Gmax80mm, aggregate of 40mm or more was extracted and kneaded. Gmax of 80mm is crushed (specific gravity 2.78),
Crushed stone (specific gravity 2.68) was used for Gmax 25mm, and river sand (specific gravity 2.65) was used for fine aggregate.

After kneading, the strength and heat of hydration ΔT were measured in a room at 20 ° C. to evaluate the filling property. The test specimen was molded 90 minutes after kneading.

[Materials used]

Ca aluminate-a: CA. Partly amorphous, Blaine 4,000 ± 2
00cm ² / g anhydrous: hydrofluoric acid generated by-product anhydrous, brane 5,000
0 ± 200 cm ² / g Water reducing agent-j: Daiichi Kogyo Seiyaku Co., Ltd., trade name “Cell Flow 110P”, main component, alkyl allyl sulfonate, standard type 〃 −k: Showa Denko Corporation, trade name “ Melment F-10 ", main component, sulfonated melamine condensate, standard type II-1: Nisso Master Builders Co., Ltd.
Product name "Pozzolith No.8 IMP", main component, lignin sulfonate, standard type [Measurement of VC value] On a shaking table (3,000 vpm, amplitude 1.0 mm), φ24 × 20
After fixing a 15 cm concrete container into 15 layers of concrete and dividing it into three layers, striking it with a piercing rod 35 times to lighten the top surface, setting a transparent plastic disc and a 20 kg weight, and starting to apply vibration The time (seconds) from when the mortar overflows at any one place through the small hole in the disk is defined as the VC value.

[Measurement of strength]

 The bending or compression strength was measured in the usual way.

The specimen was prepared by placing the formwork on a table vibe, placing half concrete, and applying pressure while attaching a tamper to the tip of a hammer drill while applying vibration.

(Measurement of heat of hydration)

In a special container, pack 10 l of concrete with a table vibe to obtain an adiabatic temperature rise curve.

(Evaluation of filling property)

The filling property was evaluated as good when no junk was observed at the end of the test piece, and evaluated as poor when no junk was observed at the center and slightly at the end.

As can be seen from Table 1, the unit cement amount is 50 kg / m ³
When the amount is less than 400 kg / m ³ , the strength is reduced, and when the amount exceeds 400 kg / m ³ , the concrete becomes a round dango during kneading and cannot be kneaded.
Also, the heat of hydration of this concrete was
The temperature drops by about 10 ° C within the range that does not lower the strength. Also experiment
Experiment No.1−
No. 9 has an extremely high flexural strength at the initial stage, and a very large effect on the 28-day compressive strength.

Example 2 The same procedure as in Example 1 was carried out except that the concrete of Experiment No. 1-17 was used, and the type, amount, and amount of anhydrous Ca aluminate having the composition shown in Table 2 were changed. Was measured. The results are shown in Table-2. The VC value is 40 ± 10 seconds.

[Materials used]

Ca aluminate -b: c ₁₂ A _7, most amorphous, -c: C ₁₂ A _7, crystalline, -d: C ₃ A, crystalline, -e: C ₄ AF, crystalline, -f : CA, crystalline, −g: C ₄ A ₃ , crystalline, −h: C ₁₁ A ₇ CaF ₂ , crystalline, −i: C ₃ A ₃ CaF ₂ , crystalline Lime, bauxite, red iron oxide, anhydrous hydrofluoric acid, and fluorite were used to prepare the respective compositions. Ca aluminate
d, e, and -g were fired in a silicon knit furnace at 1,450 ° C, and -h in 1,300 ° C, and cooled in air. Ca aluminates -a to -c, -f, and -i were fired in an electric furnace of 100 KVA. 1,650 ℃
, And gradually cooled in a mold, crystallized, and blown off with air to become amorphous, thereby obtaining clinker.

In the obtained clinker, it was confirmed by X-ray diffraction that each type of Ca aluminate was mainly produced.

The brain value of Ca aluminate is 4,000 ± 200cm ² /
Adjusted to g.

 Other materials used are the same as in the first embodiment.

From Table 2, it can be seen that when the present concrete is used, a high bending strength is obtained in the initial stage, and in the comparative example, the strength is slow to develop or the construction is impossible due to a quick connection.

Example 3 It carried out similarly to Example 2 at 30 degreeC and 5 degreeC using the composition shown in Table-3. The results are shown in Table-3.

[Materials used]

Water reducing agent-m: Kao Corporation, trade name "Miti 150R", main component, alkyl allyl sulfonate, delayed type 〃 -n: Kao Corporation, trade name "Mity HS", main component, alkyl allyl sulfone Acid salt, acceleration type Accelerator: NaNO ₃ , KNO ₃ , Ca (NO ₃ ) ₂ , Mg (NO ₃ ) ₂ , Ca
(NO ₂ ) ₂ , Na thiosulfate, Na rhodate, Ca formate, Wako Junyaku Co., Ltd., first class reagent The other materials used are the same as in Example 2.

[Measurement of amount of helicopter]

15 ^w × 30 ^l × 6 ^h (cm) Lunch box-shaped form using table vibe and tamper, filling the mold, when it reaches the material age, combine these 6 pieces and rotate so that the sanding surface is on the inside Set on a drum, enclose 25 φ1.9 x 40 (mm) sill pep in it, rotate at 88 rpm while showering 20 l / min of water in the center of the drum, and perform a 4 hour pick-up test After carrying out, the weight of the sword helicopter per unit area was measured.

In the case of 5 ° C, as a cement, Denki Kagaku Kogyo Co., Ltd.
Early strength Portland was used.

In addition, in the sand helicopter test, the surface that has undergone drying (the concrete-implanted surface) and the back surface that has not been dried are cut with a mold, and the test is performed. The hydration reaction of that portion is stopped, and it is determined that the strength has decreased. Material age is 7
Day.

As is clear from Table-3, in Experiments Nos. 3-1 and 3-2, the curing speed is slow, so that they are susceptible to drying, and there is a large difference in the amount of sharpness between the front surface and the back surface.

<Effects of the Invention> The following effects can be obtained by using the present concrete.

1. In order to obtain the same strength, the amount of cement can be reduced and the heat of hydration can be reduced.

2. High strength can be obtained early and absolutely high even at 28 days old.

3. By controlling the setting and hardening, drying before hardening can be reduced, and a marked decrease in wear resistance can be suppressed.

Claims (1)

(57) [Claims] 1. 100 parts by weight of cement, 0.1 to 4 parts by weight of calcium aluminate, 1 to 8 parts by weight of anhydrous gypsum, a water reducing agent and an aggregate as main components, and a unit cement amount of 50 to 400 kg / m ³ ,
Unit water is an 60~110kg / m ^3, and, VC value 5-10
Ultra-hardened concrete characterized by being 0 seconds.