JP2018065708A - Concrete composition for pavement, and cured body of concrete for pavement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a concrete composition for pavement or the like, which is excellent in workability, development of initial strength, suppression of initial crack, and durability, and high in material separation resistance during construction.SOLUTION: The present invention provides a concrete composition for pavement, which at least includes binder comprising the following constituent of (A) to (D), coarse aggregate, fine aggregate, water, and water-reducing agent, with water-binder ratio of 10 to 37%. The constituent includes: (A) a pozzolanic fine powder that has a BET specific surface area of 15 to 25 m/g of 0.5 to 27.5 mass %; (B) fly ash that has a Blaine ratio surface area of 2500 to 10000 cm/g of 1.0 to 45.0 mass %; (C) anhydrous gypsum that has a Blaine ratio surface area of 3000 to 12000 cm/g of 0.5 to 20.0 mass %; and (D) portland cement or conventional ecological cement of 50.0 to 90.0 mass % (where, the sum of percentage content of (A) to (D) is 100 mass %).SELECTED DRAWING: None

Description

  The present invention is a concrete composition for paving that has excellent workability, initial strength development, suppression of initial cracking, durability, and high material separation resistance during construction, and hardening of paving concrete using the composition. About the body.

  Paving concrete and paving asphalt are used as paving materials for highways, arterial roads, and residential roads. Among these, asphalt for paving is relatively easy to paving, and the period from the start of paving to the opening of traffic is short, but it is inferior in durability to concrete for paving, and rubbing is likely to occur on the road surface. On the other hand, paving concrete is more durable than paving asphalt, and rubbing is less likely to occur on the road surface. In addition, the road surface of paving concrete is bright, so drivers are less likely to feel fatigue even at night. In addition to the road paving, the concrete for paving has these advantages, such as paving for heavy loads such as airports, harbors, factory sites, etc. and paving for light loads such as passages, and concrete floor boards such as bridges. There are a wide range of applications such as thickening concrete for the purpose of reinforcing steel.

  However, the concrete for pavement may be fatigued due to the temperature difference inside the concrete or the stress due to the wheel load of the vehicle, and may crack. And if cracks occur in the concrete for paving, it will be repaired using fresh concrete for paving, but this repair work takes (i) placing and curing concrete, and (ii) paving work. There is a problem that the period from the start of traffic to the opening of traffic is long, and (iii) the treatment of the concrete removed by cracking is troublesome. Therefore, there is a demand for concrete for paving that has a longer concrete life and can reduce the frequency of repairs.

  Therefore, from this point of view, concrete for paving has been proposed in which a mixture containing cement, fine pozzolanic powder, fine aggregate having a predetermined particle size, a water reducing agent, and water is cured (Patent Document 1). . However, the concrete for paving is excellent in workability, bending strength and compressive strength after 28 days of age, and the concrete has a long life, but is inferior in the initial strength development of about 1 day of age. Therefore, the problem of shortening the period from the start of paving work to the opening of traffic has not been solved. Moreover, depending on the curing method, initial cracks may occur, and suppression of initial cracks is also desired.

JP 2001-207402 A

Cement Association, Cement / Concrete No.282, issued on August 1, 1969, pages 22-29

  Then, an object of this invention is to provide the concrete composition etc. for pavement etc. which are excellent in construction property, the expression of initial strength, suppression of an initial crack, and durability, and high material separation resistance at the time of construction.

  As a result of intensive studies to solve the above problems, the present inventor has identified a pozzolanic fine powder having a specific BET specific surface area, a fly ash having a specific brain surface area, an anhydrous gypsum having a specific brain surface area, and a cement. Concrete pavement comprising a hardened body of a cement composition for pavement containing at least a binder, a coarse aggregate, a fine aggregate, water, and a water reducing agent, and a water binder ratio within a specific range. Has found that the object can be achieved, and has completed the present invention. That is, the present invention is a concrete composition for paving having the following configuration.

[1] A binder, a coarse aggregate, a fine aggregate, water, and a water reducing agent including the following constituents (A) to (D) are contained at least, and the water binder ratio is 10 to 37%. Concrete composition for paving.
(A) Pozzolanic fine powder having a BET specific surface area of 15 to 25 m ² / g: 0.5 to 27.5% by mass
(B) Fly ash having a Blaine specific surface area of 2500 to 10000 cm ² / g: 1.0 to 45.0% by mass
(C) Anhydrous gypsum having a Blaine specific surface area of 3000 to 12000 cm ² / g: 0.5 to 20.0% by mass
(D) Portland cement or ordinary eco-cement: 50.0-90.0% by mass
(However, the total content of (A) to (D) is 100% by mass.)
[2] The concrete composition for paving according to [1], further comprising an antifoaming agent.
[3] A cured concrete for paving, which is obtained by curing the concrete composition for paving according to [1] or [2].
[4] The cured concrete for paving according to the above [3], wherein the bending strength per day of material age is 3.47 N / mm ² or more.

  The hardened concrete for paving using the concrete composition for paving of the present invention is excellent in workability, initial strength development, suppression of initial cracking, durability, and high material separation resistance during construction.

It is a figure which shows an example of the steel constrained formwork used for the initial stage crack test of the concrete of this invention.

As described above, the present invention contains at least a binder, a coarse aggregate, a fine aggregate, water, and a water reducing agent containing the components (A) to (D), and has a specific water binder ratio. A concrete composition for paving, and a hardened concrete for paving.
Hereinafter, the binder, the coarse aggregate, the fine aggregate, water, and the water reducing agent contained in the concrete composition for paving of the present invention and the hardened concrete for paving will be described in detail.

1. Binder (1) Constituent Component of Binder The binder used in the present invention is (A) a pozzolanic fine powder having a BET specific surface area of 15 to 25 m ² / g, and (B) a brane specific surface area of 2500 to 10,000 cm ² / g. Fly ash (C), (C) anhydrous gypsum having a specific surface area of 3000 to 12000 cm ² / g, and (D) Portland cement or eco-cement as constituents. Next, description will be made separately for each component.

(A) Pozzolanic fine powder Pozzolanic fine powder is not a hydraulic substance alone, but if calcium hydroxide is present, it is a substance that reacts in water to form an insoluble gel and hardens.
The pozzolanic fine powder used in the present invention is selected from, for example, silica fume, silica dust, fly ash (classified and / or pulverized), slag, volcanic ash, silica sol, and precipitated silica 1 More than a seed. Among these, silica fume and silica dust are preferable because their average particle diameter is 1 μm or less and they do not need to be pulverized. In addition, a ball mill, a rod mill, etc. can be used for the grinding | pulverization means for preparing the powder used by this invention including a pozzolanic fine powder.
Moreover, the BET specific surface area of this pozzolanic fine powder is 15-25 m < ² > / g, Preferably it is 17-23 m < ² > / g, More preferably, it is 18-22 m < ² > / g. When the specific surface area is out of the range of 15 to 25 m ² / g, strength development and durability may be lowered, and workability of the concrete composition for paving may be lowered.

(B) Fly ash Examples of the fly ash used in the present invention include fly ash for concrete defined in JIS A 6201. Among these, type I or type II fly ash is preferable.
The fineness of fly ash is usually a brane specific surface area of 2500 to 10000 cm ² / g, preferably 2700 to 9000 cm ² / g, more preferably 2800 to 8000 cm ² / g. When the specific surface area is less than 2500 cm ² / g, the strength development of the concrete for paving is low, and when it exceeds 10,000 cm ² / g, it is difficult to suppress initial cracks and the durability may be lowered.

(C) Anhydrous gypsum The anhydrous gypsum used in the present invention includes natural anhydrous gypsum and regenerated anhydrous gypsum obtained by heat treating gypsum waste such as gypsum board.
Further, the powder of the anhydrous gypsum is usually Blaine specific surface area of 3000~12000cm ² / g, preferably from 4000~10000cm ² / g. If the specific surface area is less than 3000 cm ² / g, the strength developability of the cured body is low, and if it exceeds 12000 cm ² / g, the labor of grinding increases and the cost increases, and it becomes difficult to suppress initial cracks, In addition, durability may be reduced.

(D) Portland cement or ordinary ecocement The cement used in the present invention is Portland cement or ordinary ecocement. Examples of the Portland cement include one or more selected from ordinary Portland cement, early-strength Portland cement, ultra-early strong Portland cement, moderately hot Portland cement, low heat Portland cement, and sulfate-resistant Portland cement. Among these, ordinary Portland cement, early-strength Portland cement, and ultra-early strong Portland cement can exhibit strength in the initial stage, and moderately hot Portland cement has high chemical resistance and long-term strength.
The content ratios of 3CaO · SiO ₂ and 3CaO · Al ₂ O _{3 in} the Portland cement or ordinary eco-cement are preferably 45 to 80% by mass and 4 to 20% by mass, more preferably 50 to 75% by mass, respectively. % And 5 to 15% by mass. If the content ratios of 3CaO · SiO ₂ and 3CaO · Al ₂ O ₃ are out of the range of 45 to 80% by mass and 4 to 20% by mass, respectively, the strength development property of the concrete for paving may be lowered. .
In addition, in this invention, you may use the fly ash cement prescribed | regulated to JISR 5213 "fly ash cement" instead of the fly ash and Portland cement which comprise the said binder.

(2) Content of each component in the binder Next, the content of each component in the binder will be described.
(A) Pozzolanic fine powder The content of the pozzolanic fine powder is 0.5 to 27.5 mass%. When the content of the pozzolanic fine powder is less than 0.5% by mass, the workability, the material separation resistance during construction, and the long-term strength are reduced. In addition to a decrease in strength, it may be difficult to suppress initial cracking. The content is preferably 1.0 to 20.0% by mass.

(B) Fly ash The content of fly ash is 1.0 to 45.0 mass%. If the fly ash content is less than 1.0% by mass, the workability and long-term strength are reduced. If the fly ash content exceeds 45.0% by mass, the initial strength and durability are reduced. It may be difficult to suppress the above. The content is preferably 2.0 to 35.0% by mass.

(C) Anhydrous gypsum The content of anhydrous gypsum is 0.5 to 20.0 mass%. If the content of anhydrous gypsum is less than 0.5% by mass, the initial strength will be deteriorated and it may be difficult to suppress initial cracking. If it exceeds 20.0% by mass, the workability and long-term strength will be increased. This reduces the expression and durability of. The content is preferably 1.5 to 15.0% by mass.

(D) Portland cement or ordinary ecocement The content of the cement is 50.0-90.0% by mass. When the cement content is less than 50% by mass, the strength development and durability of the concrete for paving are reduced. When it exceeds 90.0% by mass, the workability and durability are reduced. It may be difficult to prevent material separation and control initial cracking. In addition, this content rate becomes like this. Preferably it is 55.0-90.0 mass%, More preferably, it is 60.0-85.0 mass%.
However, the total content of the above (a) to (d) is 100% by mass.

In the present invention, the amount of the unit binder is preferably 300 to 1200 kg / m ³ , more preferably 400 from the viewpoint of improving the strength development and durability of the concrete for paving concrete and suppressing the initial crack. ˜800 kg / m ³ .

Next, materials for the concrete for concrete for paving other than the binder will be described.
2. Coarse aggregate The coarse aggregate used in the present invention is not particularly limited, and examples thereof include one or more selected from gravel, crushed stone, slag coarse aggregate, and lightweight coarse aggregate. In the present invention, the coarse aggregate bulk volume is preferably 0.45 m ³ / m ³ or more, from the viewpoints of improving the strength development and durability of the hardened concrete for paving, and suppressing initial cracks, and the like. preferably from 0.50~0.75m ³ / ^{m 3.}
In addition, the unit coarse aggregate amount is preferably 600 to 1300 kg / m ³ , more preferably 700 to 1200 kg, from the viewpoints of workability at the time of placing the concrete composition for paving, strength development of the hardened body, and the like. / M ³ .

3. Fine aggregate The fine aggregate used in the present invention is not particularly limited. For example, one or more kinds selected from river sand, mountain sand, land sand, sea sand, crushed sand, dredged sand, slag fine aggregate, and lightweight fine aggregate. Is mentioned. These coarse aggregates and fine aggregates can use natural aggregates as well as recycled aggregates.
In addition, the unit fine material amount is preferably 40 to 1200 kg / m ³ , more preferably 80 to 1100 kg / m, from the viewpoints of workability at the time of placing the concrete composition for paving, strength development of the cured body, and the like. m is ^3.

4). Water The water used in the present invention is not particularly limited, and tap water, sludge water, or the like can be used. Further, the water binder ratio (W / B: 100 × mass of water / mass of binder) is 10 to 37%, preferably 12 to 35%. If the water binder ratio is less than 10%, the workability deteriorates, and it becomes difficult to suppress initial cracking. If it exceeds 37%, the strength of the hardened concrete for paving, durability, and materials for construction In some cases, it may be difficult to reduce separation and to suppress initial cracking.
Further, the unit water amount is preferably 100 to 200 kg / m ³ , more preferably 110 to 150 kg / m ³ from the viewpoint of workability at the time of placing the concrete composition for paving, durability of the cured body, and the like. is there.

5. Water reducing agent The water reducing agent used in the present invention is a lignin sulfonate-based, naphthalene sulfonate-based, melamine sulfonate-based or polycarboxylate-based water reducer, AE water reducer, high-performance water reducer, or high A performance AE water reducing agent is mentioned. Among these, a high performance water reducing agent or a high performance AE water reducing agent is preferable from the viewpoint of the strength development of the concrete for concrete for paving. Further, the blending amount of the water reducing agent is preferably 0.5 to 4.0 parts by mass with respect to 100 parts by mass of the binder from the viewpoint of the workability of the concrete composition for paving and the strength development of the cured body. Preferably it is 0.8-3.6 mass parts, More preferably, it is 1.2-3.2 mass parts.

6). Arbitrary component (1) Defoamer The concrete composition for paving of this invention can contain an antifoamer from viewpoints, such as the intensity | strength expression property of the concrete hardening body for pavements. Commercially available products can be used as the antifoaming agent, and the blending amount of the antifoaming agent is preferably 0.1 parts by mass or less, more preferably 100 parts by mass or less with respect to 100 parts by mass of the binder. Is 0.05 parts by mass or less. The air content of the concrete composition for paving of the present invention is preferably 4% or less, more preferably 3% or less, and still more preferably 2% or less, from the viewpoint of strength development and durability.

(2) Blast furnace slag powder, etc. In addition to the above materials (components), the concrete composition for paving of the present invention includes blast furnace slag powder, coal ash powder, quartz powder, expansion material, pigment, shrinkage reducing agent, and thickener. 1 or more types selected from can be included. The blending amount of blast furnace slag powder, coal ash powder, quartz powder, expansion material, and pigment is preferably 10 parts by mass or less, more preferably 5 parts by mass or less with respect to 100 parts by mass of the binder, And the compounding quantity of a thickener becomes like this. Preferably it is 5 mass parts or less with respect to 100 mass parts of binders, More preferably, it is 3 mass parts or less.

7). Hardened concrete for pavement (1) Flexural strength The hardened concrete for pavement of the present invention is 3.47 N / mm ² or more, preferably the design standard strength of concrete for pavement, necessary for opening traffic at the age of one day. A bending strength (initial bending strength) of 4.5 N / mm ² or more can be exhibited. Further, paving concrete cured product of the present invention, in the age of 28 days after 8.5 N / mm ² or more, preferably capable of expressing 9.5 N / mm ² or more flexural strength (long-term flexural strength).

(2) compressive strength further paving concrete cured product of the present invention, 20 N / mm ² or more in a day the age, preferably capable of expressing 30 N / mm ² or more compression strength (initial compressive strength). Further, paving concrete cured product of the present invention, 110~135N / mm ² at an age of 28 days after, preferably capable of expressing the compressive strength of 125~135N / mm ² (prolonged compressive strength).

(3) Production of hardened concrete for pavement The hardened concrete for pavement of the present invention is prepared by kneading the above materials with a biaxial forced kneading mixer or the like, and then mixing the kneaded product (composition) with a rake or a vibratory rake. Lay it out with a scoop, compact it with the necessary compacting equipment and machines such as vibrators and tampers, rough finish it with a simple finisher, etc., and finish it with a float or a trowel. Examples of the curing method include air curing, warm curing using a curing sheet, and steam curing, but are not limited thereto.

As described above, the hardened concrete for paving of the present invention can exhibit a bending strength of 3.47 N / mm ² or more necessary for opening traffic at an early stage, and therefore can open traffic early after starting the paving work. . Moreover, since the hardened concrete for paving of the present invention is excellent in long-term strength development, suppression of initial cracking, and durability, rubbing or the like hardly occurs and the life of the pavement can be greatly extended.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples.
1. Materials used (1) Pozzolanic fine powder (SF): Silica fume, BET specific surface area 20 m ² / g
(2) Fly ash (FA): Blaine specific surface area 3800 m ² / g
(3) Natural anhydrous gypsum (GS): Blaine specific surface area 4000 m ² / g
(4) Portland cement (C): Normal Portland cement (manufactured by Taiheiyo Cement)
(5) Fine aggregate (G): Mountain sand from Ichihara City, Chiba Prefecture (actual volume ratio 64.2%)
(6) Aggregate (S): Crushed stone 6 from Sakuragawa City, Ibaraki Prefecture (actual volume ratio 60.7%)
(7) Polycarboxylic acid-based high-performance water reducing agent (PC): Product name Mighty 3000H [registered trademark] (manufactured by Kao Corporation)
(8) Antifoaming agent (DF): trade name Master Air 404 [registered trademark] (manufactured by BASF Japan)
(9) Water (W): Tap water, but the symbols in parentheses after each material correspond to the symbols in Table 1.

2. Manufacture of concrete According to the concrete mix shown in Table 1, each material was put into a biaxial forced-kneading mixer all at once, and then kneaded for 2 minutes to produce concrete. In all Examples and Comparative Examples, the amount of polycarboxylic acid-based high-performance water reducing agent added is 1.8 parts by mass with respect to 100 parts by mass of the binder, and the amount of antifoaming agent added is 100 parts by mass of the binder. It is 0.01 mass part with respect to it. And the air quantity of concrete was 2% or less in all the Examples and the comparative examples.
In Comparative Examples 1 and 7, the water binder ratio is outside the above range, in Comparative Examples 2 and 6, the cement content is outside the above range, and Comparative Examples 3 to 5 are pozzolanic fine powder, fly ash, natural anhydrous It does not contain any plaster.

3. Test items evaluated The test items evaluated using the kneaded concrete are as follows (1) to (5).
(1) Workability (workability)
In accordance with a shaking table type consistency test (JSCE-F501) of paving concrete, the degree of settlement of the kneaded concrete was measured to evaluate the workability.
(2) Separation resistance In order to evaluate the separation resistance during the construction of concrete, a drop separation test was performed using the kneaded concrete. Specifically, using the test apparatus shown in FIG. 4 on page 23 of Non-Patent Document 1, a certain amount of concrete is dropped on the top of the square weight, and the schematic diagram shown in FIG. 5 on page 24 of Non-Patent Document 1. as calculated and coarse aggregate content in the concrete part of the a spread over a certain distance, from the ratio of the mass of the original concrete (G _a), the separation factor using the following equation (1) did.
In the schematic diagram, the part A is regarded as a part where the separation is remarkable, and the part B is regarded as a part where the separation does not occur. Further, it is evaluated that the smaller the separation factor, the greater the separation resistance.
Separation factor _{= (G A -G O) ×} M A / (M A + M B + M C) ··· (1)
However, in formula (1),
G _A is the coarse aggregate in the portion of A, represents the weight ratio concrete,
G _O represents the coarse aggregate of the original concrete, the weight ratio concrete,
M _A , M _B , and M _C represent the mass of concrete in the portions A, B, and C, respectively.
(3) Initial cracks After making a concrete plate using the constrained crack form shown in FIG. 1 and the kneaded concrete, the plate was in mid-September, the weather was sunny, and the temperature was about 25 ° C. Exposure to the outdoors and the presence of cracks were evaluated in the evening of the next day.
(4) Initial bending strength A 10 × 10 × 40 cm specimen was prepared using the kneaded concrete, and the bending strength at one day of age was measured according to JIS A 1106 “Concrete Bending Test Method”. .
(5) Relative kinematic modulus A 100 × 100 × 30 cm concrete plate was prepared using the kneaded concrete and installed in a site where vehicles pass. When three months have passed since the preparation of the concrete plate, and when one year has passed since the concrete plate was installed, a core was taken from the concrete plate, and the primary resonance frequency was measured using the core. The relative dynamic elastic modulus was obtained.
The test results are shown in Table 2.

4). Test results As shown in Table 2,
(1) The degree of settlement is 20.4 to 24.5 in Comparative Examples 1, 2, and 4, which is large, whereas in Examples 1 to 12, it is 8.2 to 19.1. Is small and has excellent workability.
(2) In Comparative Examples 3, 5, and 7, the separation factors were 12.3 × 10 ⁻³ , 10.2 × 10 ⁻³ , and 11.6 × 10 ⁻³ , respectively. In 1 to 12, the separation is small and the separation resistance is high in all examples, 5.3 × 10 ^{−3 to} 8.9 × 10 ⁻³ .
(3) While initial cracks occurred in Comparative Examples 1, 2, and 4, none occurred in Examples 1-12.
(4) The bending strength is as low as 2.0 to 3.1 MPa in Comparative Examples 3 and 5 to 7, whereas it is 3.9 to 5.3 MPa in Examples 1 to 12 and is necessary for early traffic release. Since it is 3.47 MPa or more, the initial strength development is excellent.
(5) The relative dynamic elastic modulus is as low as 84 to 93% in Comparative Examples 1, 2, 4, and 7, whereas it is as high as 96 to 100% in Examples 1 to 12, and is excellent in durability.

Claims (4)

Concrete for pavement containing at least a binder, a coarse aggregate, a fine aggregate, water, and a water reducing agent including the following components (A) to (D), and having a water binder ratio of 10 to 37%. Composition.
(A) Pozzolanic fine powder having a BET specific surface area of 15 to 25 m ² / g: 0.5 to 27.5% by mass
(B) Fly ash having a Blaine specific surface area of 2500 to 10000 cm ² / g: 1.0 to 45.0% by mass
(C) Anhydrous gypsum having a Blaine specific surface area of 3000 to 12000 cm ² / g: 0.5 to 20.0% by mass
(D) Portland cement or ordinary eco-cement: 50.0-90.0% by mass
(However, the total content of (A) to (D) is 100% by mass.)   Furthermore, the concrete composition for pavement of Claim 1 containing an antifoamer.   A hardened concrete for paving, which is obtained by hardening the concrete composition for paving according to claim 1 or 2. The concrete hardening body for pavements of Claim 3 whose bending strength of material age 1 day is 3.47 N / mm < ² > or more.

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