JP2019112276A - Concrete and manufacturing method therefor - Google Patents

Abstract

To provide concrete that can suppress dilatation even under low temperature environment while containing a polymer for cement admixture, and meet required hardness when setting.SOLUTION: The concrete contains a hydraulic material, a polymer for cement admixture, a setting retarder and aggregate. The hydraulic material includes calcium aluminate and gypsum, and in the hydraulic material, a content of AlOis 7 mass% to 25 mass% based on the total mass of hydraulic material, the total of content of AlOand content of SOis 12 to 30 mass%, and a mass ratio between the content of SOand the content of AlO(SOcontent/AlOcontent) is 0.6 to 1.1.SELECTED DRAWING: None

Description

  The present invention relates to concrete and a method of manufacturing the same.

  In emergency repair work, for example, road repair work, a hydraulic composition is used in which strength development can be obtained in a short time in order to release the road. In such hydraulic compositions, hydraulic materials are used as quick-hardening cements and admixtures. Moreover, the hydraulic composition which added the polymer to these materials, and considered quick-hardening, water shielding, durability, etc. is also proposed (patent documents 1 and 2).

JP, 2014-58437, A JP, 2009-184867, A

  However, when used in a low temperature environment, conventional quick-setting hydraulic compositions expand when contacted with water in a stage where sufficient curing is not obtained or in a state where hydration reaction is delayed. There was a possibility of causing a decrease in strength. In particular, when the polymer for cement mixing is mixed in consideration of the durability, the setting and hydration tend to be delayed, and the possibility of occurrence of the above phenomenon may be increased.

  Therefore, an object of the present invention is to provide a concrete which contains a polymer for cement mixing, which can suppress expansion even in a low temperature environment and can satisfy the required strength at the time of hardening.

In order to solve such problems, the present inventors now use calcium aluminates and gypsum, and also use a hydraulic material having Al ₂ O ₃ content and SO ₃ content in a predetermined range for cement admixture By using a concrete containing a polymer, a setting retarder and an aggregate, it is possible to obtain an unexpected finding that expansion can be suppressed even in a low temperature environment, and concrete that can satisfy the required strength can be obtained. The The present invention has been made based on such findings.

That is, the present invention is as follows.
[1] A concrete comprising a hydraulic material, a polymer for mixing with cement, a setting retarder and an aggregate,
The hydraulic material comprises calcium aluminates and gypsum, and in the hydraulic material, based on the total mass of the hydraulic material,
Al ₂ O ₃ content was 7 wt% to 25 wt%,
The total amount of content of Al ₂ O ₃ and SO ₃ content is 12 to 30 wt%, and the mass ratio of _Al 2 _{O 3} content in the SO ₃ content (SO ₃ content / _Al 2 _{O 3} containing Concrete), the amount is 0.6-1.1.
[2] The concrete according to [1], wherein the hydraulic material further includes portland cement or mixed cement.
[3] The concrete according to [1] or [2], wherein the cement mixing polymer comprises a styrene butadiene based polymer.
[4] The concrete according to any one of [1] to [3], wherein expansion strain at 28 days of material age at 5 ° C. in water is 500 × 10 ^-6 or less.
[5] The concrete according to [4], which has a compressive strength of 20 N / mm ² or more at a material age of 150 minutes.
[6] A method of producing concrete,
(A) A hydraulic material containing calcium aluminates and gypsum,
Based on the total mass of hydraulic material
Al ₂ O ₃ content was 7 wt% to 25 wt%,
The total amount of content of Al ₂ O ₃ and SO ₃ content is 12 to 30 wt%, and the mass ratio of _Al 2 _{O 3} content in the SO ₃ content (SO ₃ content / _Al 2 _{O 3} containing Providing a hydraulic material having an amount of 0.6 to 1.1;
(B) A method for producing concrete comprising mixing the above-mentioned hydraulic material, polymer for mixing with cement, a setting retarder, aggregate and a raw material containing water to obtain concrete.

  According to the present invention, it is possible to provide a concrete which can suppress expansion even in a low temperature environment while containing a polymer for cement mixing, and can satisfy the required strength at the time of hardening.

  Hereinafter, the present invention will be described in detail. The following embodiment is an example for explaining the present invention, and it is not the meaning which limits the present invention only to this embodiment. The present invention can be practiced in various forms without departing from the scope of the invention. In addition, all the documents referred to in this specification, and the publication gazette, patent gazette, and other patent documents shall be incorporated in the present specification as a reference.

<Concrete>
The concrete of the present invention comprises (A) a calcium aluminate and gypsum and a hydraulic material having an Al ₂ O ₃ content and an SO ₃ content in a predetermined range, and (B) a polymer for mixing with cement ( By including C) a setting retarder and (D) aggregate, expansion can be suppressed even in a low temperature environment, and the required strength at the time of curing can be satisfied. Therefore, even in a low temperature environment, the concrete of the present invention can be suitably used for emergency repair work or a place requiring short-time strength.

The concrete of the present invention comprises, as described above, a hydraulic material, a polymer for cement admixture, a setting retarder and aggregate. Each component will be described below. In addition, in this specification, "unit quantity (kg / m < ³ >)" means the usage-amount of each raw material used when producing the concrete of 1 m < ³ >. Moreover, in the present specification, "concrete" also includes "mortar".

[Hydraulic material]
Hydraulic materials used in the present invention include calcium aluminates and gypsum. Further, the hydraulic material, based on the total weight of the water-hardening material, a content of _Al 2 _{O 3} is 7 wt% to 25 wt%, the total amount of content of _Al 2 _{O 3} and SO ₃ content of 12 a 30% by weight and _Al 2 _{O 3} content of the mass ratio of the SO ₃ content (SO ₃ content / content of _Al 2 _{O 3)} is 0.6 to 1.1.

As calcium aluminates, various ones including CaO and Al ₂ O ₃ can be used. For example, for calcium aluminates, when CaO is indicated by C and Al ₂ O ₃ is indicated by A, C ₃ A, C ₂ A, C ₁₂ A ₇ , C ₅ A ₃ , CA, C ₃ A ₅ or CA Crystalline calcium aluminate or mineral calcium aluminate having a mineral composition represented as ₂ etc., indicated as C ₁₁ A ₇ · CaF _{2 in} which halogen is dissolved or substituted in calcium or calcium cement. Calcium haloaluminate containing calcium fluoroaluminate etc., calcium sulfoaluminate such as auin (C ₃ A ₃ · CaSO ₄ ), and SiO ₂ , Fe ₂ O ₃ , MgO, K ₂ O, Na ₂ O, and the like It includes those in which Li ₂ O or TiO _{2 and the} like are in solid solution or in combination. Among them, crystalline or amorphous calcium aluminate is preferred in view of strength development in a low temperature environment.

The gypsum is not particularly limited, but various gypsums such as gypsum dihydrate, hemihydrate gypsum and anhydrite can be used. Among these, anhydrous gypsum is preferred. The gypsum may be mixed with the ground material of the intumescent fired product with a mixer or the like, or the gypsum and the expanded fired product may be mixed and ground. Since gypsum is a mineral having calcium sulfate (CaSO ₄ ) as a main component, the SO ₃ content in the hydraulic material can be adjusted by adjusting the content of gypsum.

Other than the above-mentioned calcium aluminates and gypsum, as a raw material contained in the hydraulic material, Portland cement, mixed cement and the like can be mentioned. Portland cement, tricalcium silicate (3CaO · SiO _2), dicalcium silicate (2CaO · SiO _2), calcium aluminate _{(3CaO · Al 2 O 3)} , calcium alumino ferrite _{(4CaO · Al 2 O 3 ·} Fe ₂ O ₃ ), and calcium sulfate (CaSO ₄ .2H ₂ O). The mixed cement is a cement in which blast furnace granulated slag, fly ash, and a siliceous mixed material are mixed in portland cement. Examples of portland cement that can be used in the present invention include ordinary portland cement, early strength portland cement, moderate heat portland cement, low temperature portland cement, etc. As mixed cement, blast furnace cement, fly ash cement, silica cement, etc. It can be mentioned. Raw materials contained in hydraulic materials other than these calcium aluminates and gypsum may be added to the hydraulic material before mixing other components, or hydraulic materials containing calcium aluminates and gypsum May be added separately after mixing with other components.

Hydraulic material of the present invention, based on the total weight of the hydraulic material, a content of _Al 2 _{O 3} is 7 wt% to 25 wt%, the total amount of content of _Al 2 _{O 3} and SO ₃ content of 12 a 30% by weight and _Al 2 _{O 3} content of the mass ratio of the SO ₃ content (SO ₃ content / content of _Al 2 _{O 3)} is 0.6 to 1.1. By setting the composition range in this way, the concrete containing the hydraulic material of the present invention can ensure the required characteristics at the time of curing even in a low temperature environment.

The Al ₂ O ₃ content in the hydraulic material can be adjusted mainly by the blending amount of Al ₂ O ₃ -containing raw materials such as calcium aluminates and portland cement. Al ₂ O ₃ content, based on the total weight of the hydraulic material, a 7 wt% to 25 wt%. By setting the content to 7% by mass or more, the initial strength development can be sufficiently ensured, and by setting the content to 25% by mass or less, the usable time can be controlled within a suitable range. . Further, _Al 2 _{O 3} content is preferably 8 wt% to 14 wt%, more preferably 10 wt% to 14 wt%.

The total amount of Al ₂ O ₃ content and SO ₃ content in the hydraulic material can be adjusted by the compounding amount of calcium aluminates, gypsum, portland cement, etc., and it is 12 to 12 based on the total mass of the hydraulic material It is 30% by mass. If the total amount of the Al ₂ O ₃ content and the SO ₃ content is 12% by mass or more, the decrease in strength development of the concrete can be suitably prevented, and expansion for compensating for the crack A sufficient amount can also be secured. Further, by setting the total amount of the Al ₂ O ₃ content and the SO ₃ content to 30% by mass or less, the amount of expansion becomes too large, or abnormal expansion (delayed expansion) of concrete occurs in a low temperature environment. Can be suitably prevented. 15 mass% or more is preferable, and, as for the lower limit of the total amount of Al ₂ O ₃ content and SO ₃ content, 17 mass% or more is more preferable. Moreover, 28 mass% or less is preferable, and, as for the upper limit, 27 mass% or less is more preferable. As components other than Al ₂ O ₃ and SO ₃ in the hydraulic material, calcium aluminates, gypsum and CaO derived from cement, SiO ₂ derived from cement and the like can be mentioned.

The mass ratio of the Al ₂ O ₃ content to the SO ₃ content in the hydraulic material (SO ₃ content / Al ₂ O ₃ content) is adjusted by the amount of calcium aluminates, gypsum, portland cement, etc. It can be 0.6 to 1.1. If the mass ratio of the Al ₂ O ₃ content to the SO ₃ content is 0.6 or more, it is possible to ensure a sufficient expansion amount of the concrete for compensating for the crack. Moreover, if it is 1.1 or less, it can prevent that the amount of concrete expansions in a low temperature environment becomes large too much. The lower limit of _Al 2 _{O 3} content in weight ratio of the SO ₃ content is preferably 0.65 or more, more preferably 0.7 or more. The upper limit of the mass ratio of _Al 2 _{O 3} content in the SO ₃ content is preferably 1.0 or less, more preferably 0.95 or less.

Polymer for cement mixing
The concrete of the present invention comprises a polymer for cement mixing. Here, the polymer for cement mixing is a generic name of polymer dispersion and re-emulsion type powder resin to be mixed and used with them for the purpose of modifying cement mortar and concrete, and defined by JIS A 6203. Specifically, as polymers for mixing with cement, acrylic acid ester polymers, acrylic styrene polymers, styrene butadiene (SBR) polymers, vinyl acetate polymers, ethylene vinyl acetate polymers, vinyl acetate / versatric acid vinyl ester polymers A polymer, ethylene vinyl alcohol (EVA) based polymer, vinyl acetate / vinyl versatate / acrylic ester based polymer can be used, but it is not limited thereto. These cement miscible polymers may be either commercially available in the form of polymer dispersions or commercially available as re-emulsifiable powder resins. Among these, styrene butadiene based polymers are particularly preferred. The content of the polymer for cement mixing is preferably 2 to 20 parts by mass, and more preferably 4 to 16 parts by mass with respect to 100 parts by mass of the hydraulic material, from the viewpoint of securing bending strength and adhesion strength.

[Settlement retarder]
The concrete of the present invention contains a setting retarder. The setting retarder is not particularly limited as long as it is used as a setting retarder for mortar or concrete. For example, citric acid, tartaric acid, gluconic acid, oxycarboxylic acid such as heptonic acid or a salt thereof, phosphate, oxalic acid Or salts thereof and the like. The content of the retarder is preferably 0.05 to 2.0 parts by mass, and more preferably 0.1 to 1.5 parts by mass with respect to 100 parts by mass of the hydraulic material, from the viewpoint of securing pot life and preventing strength development delay. Part is preferred.

[aggregate]
The concrete of the present invention comprises aggregate. The aggregate is not particularly limited, and any of fine aggregate and coarse aggregate which are used in ordinary mortar and concrete production can be used. Examples of fine aggregate and coarse aggregate include river sand, sea sand, mountain sand, crushed sand, lime sand, artificial fine aggregate, slag fine aggregate, regenerated fine aggregate, silica sand, river gravel, land gravel, crushed stone, Limestone aggregate, artificial coarse aggregate, slag coarse aggregate, regenerated coarse aggregate, etc. may be mentioned.

[Other components]
The concrete of the present invention may contain various admixtures (agents) as needed, as long as the effects of the present invention are not impaired. As the admixture (agent), for example, a water reducing agent, an AE agent, an antifoaming agent, a foaming agent, a waterproofing agent, an antirust agent, an expanding agent, a shrinkage reducing agent, a thickener, a water retention agent, a pigment, a water repellent, Anti-whitening agents, fibers, inorganic fine powders and the like can be mentioned.

[Blended amount based on unit amount (kg / m ³ )]
The blending amount on a unit amount basis of the concrete of the present invention is preferably 300 to 600 kg / m ³ of hydraulic material, 100 to 200 kg / m ³ of water, and 20 to 60 kg / m ³ of polymer for mixing with cement ³ (solid content), the fine aggregate is 700 to 900 kg / m ³ , and the coarse aggregate is 800 to 1000 kg / m ³ . Other optional components such as the above-mentioned admixtures (agents) may be added, as desired.

[Characteristics of concrete]
The concrete of the present invention preferably has an expansion strain of 500 * 10 <^-6> or less at a material age of 28 days at 5 [deg.] C. in water. As a result, even in a low temperature environment, good concrete can be obtained without causing a decrease in strength due to abnormal expansion. The expansion strain can be measured in accordance with JIS A 1129.

Furthermore, the concrete of the present invention preferably has a compressive strength of 20 N / mm ² or more at a material age of 150 minutes. Thereby, quick-hardening concrete excellent in initial strength is obtained. The compressive strength can be measured in accordance with JIS A 1108.

The pot life of the concrete of the present invention is preferably 30 minutes or more. The pot life is preferably long from the viewpoint of securing the construction time of concrete, but is preferably 90 minutes or less in order to obtain a compressive strength of 20 N / mm ² or more at a material age of 150 minutes. The usable time is the time from the start of kneading of concrete to the state where it can be cast, and can be measured by confirming the time-dependent change of slump by the concrete slump test method of JIS A 1101. By setting the usable time to 30 minutes or more, sufficient construction time can be secured. The pot life of the concrete can be adjusted by adjusting the amount of the setting retarder to be mixed.

The concrete of the present invention can suppress the expansion strain under a low temperature environment, so it can suppress the strength reduction due to the expansion, and can obtain a concrete with good initial strength development even under a low temperature environment . Therefore, the concrete of the present invention can be used as rapid setting concrete for low temperature environment. In the present specification, "for low temperature environment" refers to those which show sufficient setting time and initial strength development even in a low temperature environment such as 10 ° C. or less, and can suppress expansion strain. Specifically, the usable time of concrete in a 5 ° C. environment is 30 minutes or more, and the compressive strength (N / mm ² ) of concrete (curing condition: 5 ° C.) is 20 N / mm ² at 150 minutes of age. The above is shown. Furthermore, it shows that the expansion strain at 28 days of material age at 5 ° C. in water curing is 500 × 10 ⁻⁶ or less.

  By using the concrete of the present invention, good fast-hardening concrete can be obtained, so the concrete of the present invention can be used for emergency repair work on roads and the like.

  Hardening of the concrete of the present invention can be carried out by any method, but, for example, the constituent materials of the concrete may be kneaded, and the kneaded material may be poured into a mold or the like and then cured.

<Method of manufacturing concrete>
The concrete of the present invention is a hydraulic material containing (A) calcium aluminates and gypsum, and the content of Al ₂ O ₃ is 7% by mass to 25% by mass on the basis of the total mass of the hydraulic material, the total amount of content of Al ₂ O ₃ and SO ₃ content is 12 to 30 wt%, and the mass ratio of _Al 2 _{O 3} content in the SO ₃ content (SO ₃ content / _Al 2 _{O 3} containing Preparing a hydraulic material having an amount of 0.6 to 1.1, and (B) mixing (kneading the raw material including the hydraulic material, the polymer for cement admixture, the setting retarder, the aggregate and water ) To obtain concrete, and manufacturing. The mixing method is not particularly limited, and, for example, general-purpose mixers such as tilting mixers, pan-type mixers, 2-axis mixers, grout mixers, Hobart mixers, and omni mixers can be used. These mixing methods can also be used when preparing mortar and concrete. The hydraulic material may be prepared to have the above-mentioned composition before mixing other components, and addition of materials other than calcium aluminates and gypsum when mixing with other components You may prepare by.

  EXAMPLES The present invention will next be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

(Preparation of hydraulic material)
Using ordinary portland cement (manufactured by Pacific Cement Co., Ltd.), calcium aluminates (sample product), and gypsum (manufactured by Central Glass Co., Ltd.), hydraulic materials were prepared to have the chemical components shown in Table 1. At that time, the Al ₂ O ₃ content and the SO ₃ content in each raw material are measured by a method based on a fluorescent X-ray analysis method of cement specified in JIS R 5204 (Fluorescent X-ray analyzer: manufactured by RIGAKU Co., Ltd. Based on the obtained values, the blending amounts of the respective raw materials were adjusted so as to be the chemical components shown in Table 1. The ordinary portland cement, calcium aluminates and gypsum were prepared so that the mass ratio would be approximately 7: 3. As calcium aluminates, calcium aluminate containing calcium sulfoaluminate (CSA) in formulation No. 1, calcium fluoroaluminate (CFA) in No. 2 and calcium aluminate as the main ingredient in other formulations (CA) used. All calcium aluminates are crystalline, and their Al ₂ O ₃ content and SO ₃ content are 55% by mass and 13% by mass, respectively, and 47% by mass and 0.4% by mass of CFA, respectively. The mass% and CA were 53 mass% and 0.3 mass%. The plaster used anhydrite.

(Preparation of concrete)
Formulation No. The hydraulic materials obtained in 1 to 14 and polymer for cement mixing, setting retarder and aggregate (fine aggregate, coarse aggregate) are prepared to have the composition shown in Table 2, and are mixed with water using a concrete mixer And produced concrete of each composition.

A styrene-butadiene rubber-based polymer emulsion (solid content 45%: Table 1 describes solid content, manufactured by Pacific Materials Co., Ltd.) was used as a polymer for cement mixing. A citric acid based retarder was used as a setting retarder. The setting retarder was added to the hydraulic material in an amount of 0.12% by mass, and adjusted so that the pot life was 30 minutes or more. The fine aggregate used Kakegawa fine sand (density: 2.54 g / cm ³ ), and the coarse aggregate used Sakuragawa aggregate (density: 2.65 g / cm ³ ).

(Evaluation test)
The compressive strength and expansion strain of various concretes obtained were evaluated. The specific evaluation was performed by the following method.
(1) Compressive strength Compressive strength is based on JIS A 1108, and cures a concrete specimen under 5 ° C environment. Material age 150 minutes is 5 ° C sealed curing, material age 28 days is 5 ° C strength in water curing It was measured.
(2) Expansion strain Expansion strain was measured according to JIS A 1129 except that demolding was performed at 24 hours of material age and measurement of the base length was changed from 7 days of material age to 24 hours. Thereafter, the expansion strain was measured while curing the obtained concrete specimen in water at 5 ° C.

(Evaluation test results)
The evaluation test results are shown in Table 3. In Examples (Nos. 1 to 6) in which the chemical components of the hydraulic material fall within the predetermined range, the expansion strain at 28 ° C. material age at 5 ° C. is 500 × 10 ⁻⁶ or less, and the amount of expansion even in a low temperature environment And the compressive strength at a material age of 150 minutes was 20 N / mm ² or more, and it was found that a concrete having good initial strength development was obtained.

On the other hand, content of _Al 2 _{O 3,} out of the at least one of the specified range of the content of _Al 2 _{O 3} and SO ₃ total amount of content, content of _Al 2 _{O 3} mass ratio of the SO ₃ content blended In (Nos. 7 to 14), the compressive strength of material for 150 minutes did not reach 20 N / mm ² or the expansion strain at 28 days of material increased to 500 × 10 ⁻⁶ or more.

Claims (6)

A concrete comprising a hydraulic material, a polymer for cement admixture, a setting retarder and aggregate,
The hydraulic material comprises calcium aluminates and gypsum, and in the hydraulic material, based on the total mass of the hydraulic material,
Al ₂ O ₃ content was 7 wt% to 25 wt%,
The total amount of content of Al ₂ O ₃ and SO ₃ content is 12 to 30 wt%, and the mass ratio of _Al 2 _{O 3} content in the SO ₃ content (SO ₃ content / _Al 2 _{O 3} containing Concrete), the amount is 0.6-1.1.   The concrete according to claim 1, wherein the hydraulic material further comprises portland cement or mixed cement.   The concrete according to claim 1, wherein the cement mixing polymer comprises a styrene butadiene based polymer. The concrete according to any one of claims 1 to 3, wherein the expansion strain at a material age of 28 days in water curing at 5 ° C is 500 × 10 ^-6 or less. Compressive strength at age of 150 minutes is 20 N / mm ² or more, concrete according to claim 4. A method of producing concrete,
(A) A hydraulic material containing calcium aluminates and gypsum,
Based on the total mass of hydraulic material
Al ₂ O ₃ content was 7 wt% to 25 wt%,
The total amount of content of Al ₂ O ₃ and SO ₃ content is 12 to 30 wt%, and the mass ratio of _Al 2 _{O 3} content in the SO ₃ content (SO ₃ content / _Al 2 _{O 3} containing Providing a hydraulic material having an amount of 0.6 to 1.1;
(B) A method for producing concrete comprising mixing the above-mentioned hydraulic material, polymer for mixing with cement, a setting retarder, aggregate and a raw material containing water to obtain concrete.