JP2019052523A - Concrete pavement and concrete pavement construction method - Google Patents

Abstract

To provide a concrete pavement and the like having a large bending strength at a long-term material age, a small fatigue degree, and a long service life even in a region where the annual mean air temperature is high.SOLUTION: A concrete pavement of the present invention includes at least fly ash, Portland cement, a water reducing agent, a find aggregate, and a coarse aggregate which satisfy all of the following conditions (a) through (d): (a) fly ash having a Blaine specific surface area of 2,500 to 6,000 cm/g; (b) fly ash quantity reduction of 5 mass% or less following heating the fly ash at 975±25°C for 15 min; (c) fly ash having an SiOcontent of 50 mass% or more; and (d) fly ash having a mass ratio of (NaO+0.658×KO)/(MgO+SO+TiO+PO+MnO) of 0.2 to 1.0 (the unit for the previous formula is mass%).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a concrete pavement having a high bending strength at a long-term age, a low fatigue level, and a long service life even in an area where the annual average temperature is high.

In concrete pavement in Japan, blast furnace cement type B, ordinary Portland cement, etc. have been used in consideration of durability and economy. However, in recent years, as a result of adjusting the mixing ratio and fineness of slag to increase the initial strength, the temperature rise of concrete using blast furnace cement is higher than that of concrete using ordinary Portland cement, and the size and size of the pavement plate There have been reports of cases in which the durability of concrete pavement deteriorates and cracks occur when the environmental conditions, particularly when the outside air temperature is high or when the outside air temperature changes greatly (Non-Patent Document 1). Therefore, in a high temperature environment, concrete pavement using blast furnace cement requires measures to suppress cracking.
In addition, although blast furnace cement has a characteristic that long-term strength development is high, in order for concrete pavement using blast furnace cement to exhibit this characteristic, sufficient wet curing is necessary.

Pavement Committee Pavement Design and Construction Subcommittee Book, Concrete Pave Book Guide 2016, p. 84, published by Japan Road Association, March 2016

  Accordingly, an object of the present invention is to provide a concrete pavement having a high bending strength at a long-term age, a low fatigue level, and a long service life even in an area where the annual average temperature is high.

  Therefore, the inventor diligently studied concrete pavement that can achieve the above object, and found that concrete pavement including fly ash or the like that satisfies a specific condition can achieve the above object and completed the present invention. That is, this invention is concrete pavement etc. which have the following structures.

[1] A concrete pavement including at least fly ash, Portland cement, water reducing agent, fine aggregate, and coarse aggregate that satisfy all the following conditions (a) to (d).
(A) The fly ash has a Blaine specific surface area of 2500 to 6000 cm ² / g.
(B) The mass reduction rate of fly ash after heating the fly ash at 975 ± 25 ° C. for 15 minutes is 5 mass% or less. (C) The SiO ₂ content in the fly ash is 50 mass% or more. (D) Fly The mass ratio of (Na ₂ O + 0.658 × K ₂ O) / (MgO + SO ₃ + TiO ₂ + P ₂ O ₅ + MnO) in ash is 0.2 to 1.0 (however, the chemical formula in the above formula) The unit of is mass%.)
[2] The concrete pavement according to the above [1], wherein the total content of the fly ash and Portland cement is 100% by mass, and the fly ash content is 10 to 50% by mass.
[3] The concrete pavement according to [1] or [2], wherein the fly ash further satisfies the following condition (5).
(5) The lattice volume of quartz in fly ash is 113.5 to 114.5 ^{３ 3} (however, the lattice volume is a value obtained using a Rietveld analysis method.)
[4] The concrete pavement according to any one of [1] to [3], which is used in an environment having an environmental temperature (an average temperature around the concrete) of 15 ° C. or higher.
[5] The concrete pavement according to any one of [1] to [4], wherein a part or all of the aggregate is limestone aggregate.
[6] After a kneaded mixture containing at least fly ash, Portland cement, water reducing agent, fine aggregate, coarse aggregate, and water satisfying the following conditions (a) to (d) is spread and compacted A concrete pavement construction method that is cured and constructed.
(A) The fly ash has a Blaine specific surface area of 2500 to 6000 cm ² / g.
(B) The mass reduction rate of fly ash after heating the fly ash at 975 ± 25 ° C. for 15 minutes is 5 mass% or less. (C) The SiO ₂ content in the fly ash is 50 mass% or more. (D) Fly The mass ratio of (Na ₂ O + 0.658 × K ₂ O) / (MgO + SO ₃ + TiO ₂ + P ₂ O ₅ + MnO) in ash is 0.2 to 1.0 (however, the chemical formula in the above formula) The unit of is mass%.)

  The concrete pavement of the present invention has a high bending strength at a long-term age, a low fatigue level, and a long service life even in an area where the annual average temperature is high.

(A) Relationship between bending strength and design age of concrete pavement using sandstone coarse aggregate at an ambient temperature of 27 ° C, (B) Relationship between fatigue level and design age, and (C) Service life and design age It is a figure which shows the relationship of age. (A) Relationship between flexural strength and design age of concrete pavement using sandstone coarse aggregate at an ambient temperature of 20 ° C, (B) Relationship between fatigue level and design age, and (C) Service life and design age It is a figure which shows the relationship of age. (A) Relationship between bending strength and design material age of concrete pavement using limestone coarse aggregate at an ambient temperature of 27 ° C, (B) Relationship between fatigue level and design material age, and (C) Service life and design material It is a figure which shows the relationship of age. (A) Relationship between bending strength and design age of concrete pavement using limestone coarse aggregate at ambient temperature of 20 ° C, (B) Relationship between fatigue level and design age, and (C) service life and design material It is a figure which shows the relationship of age.

First, the concrete pavement of the present invention will be described.
1. Concrete pavement As described above, the concrete pavement of the present invention is a concrete pavement including at least fly ash, Portland cement, water reducing agent, fine aggregate, and coarse aggregate that satisfy all the following conditions (a) to (d). .
(A) The fly ash has a Blaine specific surface area of 2500 to 6000 cm ² / g.
(B) The mass reduction rate of fly ash after heating the fly ash at 975 ± 25 ° C. for 15 minutes is 5 mass% or less. (C) The SiO ₂ content in the fly ash is 50 mass% or more. (D) Fly The mass ratio of (Na ₂ O + 0.658 × K ₂ O) / (MgO + SO ₃ + TiO ₂ + P ₂ O ₅ + MnO) in ash is 0.2 to 1.0 (however, the chemical formula in the above formula) The unit of is mass%.)

(1) In the fly ash and Portland cement fly ash Blaine specific surface area of 2500cm less than ² / g, and reduces the strength development of the concrete, exceeds 6000 cm ² / g, high becomes useful life fatigue of concrete pavement In addition to reduction, fly ash having a brain specific surface area exceeding 6000 cm ² / g is difficult to obtain. In addition, this brane specific surface area becomes like this. Preferably it is 2700-5000 cm < ² > / g, More preferably, it is 2900-4000 cm < ² > / g.
On the other hand, if the mass reduction rate of fly ash after heating the fly ash at 975 ± 25 ° C. for 15 minutes exceeds 5% by mass, the strength development of the concrete decreases. The mass reduction rate is preferably 0.5 to 4.5% by mass, more preferably 0.7 to 4.3% by mass, and still more preferably 1.0 to 1.0% from the viewpoint of availability and strength development. It is 4.0 mass%.
The content of fly ash SiO ₂ is less than 50 wt%, strength development of the concrete is reduced. The content of SiO ₂ is preferably 51 to 70% by mass, more preferably 52 to 65% by mass, from the viewpoint of availability and strength development.
Furthermore, when the mass ratio of (Na ₂ O + 0.658 × K ₂ O) / (MgO + SO ₃ + TiO ₂ + P ₂ O ₅ + MnO) in fly ash is less than 0.2, the environmental temperature of concrete (concrete When the temperature of the surroundings of the concrete becomes high (for example, 27 ° C or higher), the strength develops, and when the temperature exceeds 1.0, the environmental temperature of the concrete increases (for example, 27 ° C or higher). The fatigue level of concrete pavement increases and the service life decreases. In addition, this ratio becomes like this. Preferably it is 0.25-0.8, More preferably, it is 0.28-0.7, More preferably, it is 0.3-0.6.

  Further, the Portland cement is selected from ordinary Portland cement, early-strength Portland cement, moderately hot Portland cement, and low heat Portland cement as defined in R 5210 “Portland cement” of Japanese Industrial Standard (hereinafter “JIS”). 1 type or more is mentioned. Among these, the Portland cement is preferably ordinary Portland cement and / or early-strength Portland cement from the viewpoint of improving the strength development of the concrete.

  In the present invention, the fly ash content is 10 to 50% by mass, where the total of fly ash and Portland cement is 100% by mass. If the fly ash content is less than 10% by mass, the fatigue level of the concrete pavement increases and the useful life decreases. If it exceeds 50% by mass, the strength development of the concrete decreases. In addition, the content rate of this fly ash becomes like this. Preferably it is 12-40 mass%, More preferably, it is 14-35 mass%.

The fly ash usually contains 5 to 25% by mass of quartz, and the lattice volume of quartz in the fly ash used in the present invention is a value obtained by using a Rietveld analysis method, preferably 113. 5-114.5 cm ³ . If the quartz lattice volume is within this range, the fatigue level of the concrete pavement can be lowered and the service life can be extended when the environmental temperature of the concrete is high (for example, 27 ° C. or higher). In addition, the lattice volume of quartz is more preferably 113.6 to 114.4 ^{３ 3} , and further preferably 113.7 to 114.3 ^{３ 3} .
The Rietveld analysis of quartz in fly ash is based on the fly ash X-ray diffraction pattern. For example, Bruker's analysis software (Topas ver. 2.1) and crystal structure data (ICDD number) of 331161 (Quartz) are used. Can be used.

The total unit amount of fly ash and Portland cement is preferably 300 to 410 kg per 1 m ³ of concrete. When the unit amount is within this range, strength development, fluidity, workability, etc. are high. The unit amount is more preferably 310 to 400 kg per 1 m ³ of concrete, and further preferably 320 to 390 kg per 1 m ³ of concrete.

(2) Water reducing agent The water reducing agent used in the present invention is one or more selected from water reducing agents, AE water reducing agents, high performance water reducing agents, and high performance AE water reducing agents specified in JIS A 6204 “Chemical admixture for concrete”. Is mentioned. In addition, the water reducing agent includes at least one selected from polycarboxylic acid, naphthalene sulfonic acid formaldehyde condensate, melamine sulfonic acid formaldehyde condensate, lignin sulfonic acid, and salts thereof, in terms of a water reducing component.
The amount of the water reducing agent added is preferably 0.1 to 4 parts by mass (B × 0.1 to 4%) with respect to 100 parts by mass in total of fly ash and Portland cement. When the added amount is within this range, the workability of the concrete and the medium-long term strength development are good. The added amount is more preferably 0.15 to 3 parts by mass (B × 0.15 to 3%), further preferably 0.2 to 2 with respect to 100 parts by mass in total of the fly ash and Portland cement. It is a mass part (Bx0.2-2%). The “B” means a binder (a mixture of fly ash and Portland cement).

(3) Fine aggregate The fine aggregate used in the present invention is one selected from river sand, mountain sand, land sand, sea sand, crushed sand, dredged sand, slag fine aggregate, limestone fine aggregate, and lightweight fine aggregate. The above is mentioned. In addition to natural aggregate, recycled aggregate can be used as the fine aggregate.
The unit amount of fine aggregate is preferably 550 to 800 kg per 1 m ³ of concrete. When the unit amount is within this range, the fluidity and workability of the concrete are good. The unit amount is more preferably 600 to 750 kg per 1 m ³ of concrete.

(4) Coarse aggregate The coarse aggregate used in the present invention includes one or more selected from gravel, crushed stone, slag coarse aggregate, limestone coarse aggregate, and lightweight coarse aggregate. As the coarse aggregate, similar to the fine aggregate, regenerated aggregate can be used in addition to natural aggregate.
The unit amount of the coarse aggregate is preferably 950 to 1250 kg per 1 m ³ of concrete. If the unit amount is within this range, the fluidity and workability of the concrete are high. The unit amount is more preferably 1000 to 1200 kg per m ³ of concrete.

  In the concrete pavement of the present invention, if part or all of the aggregate is made of limestone aggregate, the useful life of the concrete pavement is greatly improved. Here, “a part of the aggregate is limestone aggregate” means that only the fine aggregate or only the coarse aggregate is limestone aggregate, or a part of each of the fine aggregate and the coarse aggregate. Is made into limestone aggregate.

(5) Water The water used in the present invention can be used as long as it does not adversely affect the physical properties of concrete such as strength and fluidity. Examples include tap water, sewage treated water, and fresh concrete supernatant. It is done.
The unit amount of water is preferably 100 to 200 kg per 1 m ³ of concrete. If the unit amount is within this range, the fluidity and workability of the concrete are high. The unit amount is more preferably 130 to 180 kg per 1 m ^{3 of the} concrete.
The concrete pavement of the present invention includes, in addition to the essential components, blast furnace slag powder, anhydrous gypsum powder, hemihydrate gypsum powder, dihydrate gypsum powder, limestone powder, quartz powder, silica fume, An expansion material, a shrinkage reducing agent, a setting retarder, an air amount adjusting agent, and the like can be included.

  The concrete pavement of the present invention is used in an environment where the environmental temperature (average annual temperature around the concrete) is preferably 15 ° C. or higher because the flexural strength in the long-term age is high. The ambient temperature is more preferably 20 ° C. or higher, further preferably 23 ° C. or higher, and particularly preferably 25 ° C. or higher.

2. Concrete pavement construction method The concrete pavement construction method of the present invention includes at least fly ash, Portland cement, water reducing agent, fine aggregate, coarse aggregate, and water that satisfy all of the conditions (a) to (d). In this method, the kneaded material is spread and compacted, and then cured and applied. Specifically, after kneading concrete with a biaxial forced kneading mixer, etc., the kneaded material is spread with a rake, a rake with a vibrator, a scoop, etc., and the required compacting device / machine such as a vibrator or tamper After finishing with rough finish with a simple finisher, finish with a float or trowel and cure. Examples of the curing include, but are not limited to, air curing using an aqueous curing agent, heating curing using a curing sheet, and steam curing.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples.
1. Table 1 shows the materials used and Table 2 and Table 4 (above, the environmental temperature is 27 ° C) and Table 3 and Table 5 (above, the ambient temperature is 20 ° C). Yes.) In addition, fly ash FA1 in Table 1 satisfies all the conditions (a) to (d), but fly ash FA2 does not satisfy the conditions (b) and (c).

2. Concrete Kneading and Evaluation (1) Concrete Kneading According to the blending shown in Tables 2 and 3, each material was put all at once into a biaxial forced kneading mixer and kneaded for 90 seconds.
(2) Evaluation item (A) Bending strength The bending strength of each concrete was measured according to JIS A1106.
(B) Fatigue degree Fatigue degree was calculated according to the theoretical design method shown in the pavement design manual (Japan Road Association), with each concrete being a plain concrete pavement with a plate thickness of 25 cm and a joint spacing of 10 m. Specifically, as main design conditions, the design life was 40 years, the roadbed reaction force coefficient (k ₇₅ ) was 100 MPa / m, and the reliability was 90%. The fatigue curve used was verified by the actual performance of Japanese concrete pavements. The travel position distribution is paved with wide enough shoulders, with 4 lanes, large vehicle traffic ratio in the suburbs, and temperature conditions with small temperature differences. Measured values were used for the bending strength and static elastic modulus of concrete. The static elastic modulus was measured according to JIS A 1149 “Testing method of static elastic modulus of concrete”.
(C) Service life The service life was calculated by the following formula.
Service life = Design service life (40 years) / Fatigue degree These results are shown in FIGS.

As shown in FIGS. 1 to 4, the concrete using the fly ash FA1 that satisfies all the conditions (a) to (d) has an environmental temperature of 27 ° C. and 20 ° C. compared to the concrete using the fly ash FA2. Long-term bending strength is great. Moreover, the concrete pavement using the fly ash FA1 has a lower fatigue level and a longer service life than the concrete pavement using the fly ash FA2.
In addition, concrete (Figs. 3 and 4) using limestone aggregate for all coarse aggregates has a longer service life than concrete using sandstone coarse aggregate (Figs. 1 and 2) for all coarse aggregates. long.

Claims (6)

Concrete pavement including at least fly ash, Portland cement, water reducing agent, fine aggregate, and coarse aggregate that satisfy all of the following conditions (a) to (d).
(A) The fly ash has a Blaine specific surface area of 2500 to 6000 cm ² / g.
(B) The mass reduction rate of fly ash after heating the fly ash at 975 ± 25 ° C. for 15 minutes is 5 mass% or less. (C) The SiO ₂ content in the fly ash is 50 mass% or more. (D) Fly The mass ratio of (Na ₂ O + 0.658 × K ₂ O) / (MgO + SO ₃ + TiO ₂ + P ₂ O ₅ + MnO) in ash is 0.2 to 1.0 (however, the chemical formula in the above formula) The unit of is mass%.)   The concrete pavement according to claim 1, wherein a content of the fly ash is 10 to 50% by mass, where a total of the fly ash and Portland cement is 100% by mass. The concrete pavement according to claim 1 or 2, wherein the fly ash further satisfies the following condition (5).
(5) The lattice volume of quartz in fly ash is 113.5 to 114.5 ^{３ 3} (however, the lattice volume is a value obtained using a Rietveld analysis method.)   The concrete pavement according to any one of claims 1 to 3, which is used in an environment having an environmental temperature (an average temperature around the concrete) of 15 ° C or higher.   The concrete pavement according to any one of claims 1 to 4, wherein a part or all of the aggregate is limestone aggregate. A kneaded mixture containing at least fly ash, Portland cement, water reducing agent, fine aggregate, coarse aggregate, and water that satisfies all of the following conditions (a) to (d) is spread and compacted, and then cured. The concrete pavement construction method.
(A) The fly ash has a Blaine specific surface area of 2500 to 6000 cm ² / g.
(B) The mass reduction rate of fly ash after heating the fly ash at 975 ± 25 ° C. for 15 minutes is 5 mass% or less. (C) The SiO ₂ content in the fly ash is 50 mass% or more. (D) Fly The mass ratio of (Na ₂ O + 0.658 × K ₂ O) / (MgO + SO ₃ + TiO ₂ + P ₂ O ₅ + MnO) in ash is 0.2 to 1.0 (however, the chemical formula in the above formula) The unit of is mass%.)

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