JP2018184328A - Concrete with high fluidity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide concrete of high fluidity with a reduced unit cement content.SOLUTION: Concrete with high fluidity contains cement, water, aggregate, a thickener, and a high-performance AE water-reducing agent. The thickener includes water-soluble cellulose ether, an antifoaming agent, and a gum. The high-performance AE water-reducing agent has a water-reducing rate of 18% or more in accordance with JISA6204. The concrete has a water cement ratio of 46.1% or more and 65% or less, and a slump flow of 35 cm or more and 75 cm or less. Preferably, the slump flow is 55 cm or more and 50 cm or less, and the 500 mm flow reaching time is 3-15 seconds.SELECTED DRAWING: None

Description

  The present invention relates to concrete with high fluidity.

  Highly fluid concrete obtained by adding an admixture to commonly used concrete (ordinary concrete) is known. High fluidity concrete includes what are called high fluidity concrete and medium fluidity concrete obtained by adding an admixture (water reducing agent) in a different composition from ordinary concrete.

  Since the high fluidity concrete has a high fluidity of a slump flow of about 50 to 70 cm, the concrete itself can pass through the gaps of the reinforcing bar structure and can be uniformly filled to every corner of the formwork. Therefore, since the compacting work at the time of concrete construction (work which gives vibration by the vibrator to the concrete poured into the mold) can be omitted, the workability is remarkably improved.

  Moreover, since the medium fluidity concrete has a high fluidity of about slump flow 35 to 50 cm, the fluidity and the filling property to the reinforcing bar structure are higher than that of ordinary concrete, and the compacting operation can be simplified.

JP 2012-116671 A

  However, high fluid concrete and medium fluid concrete need to increase the unit cement amount (powder amount) more than ordinary concrete in order to ensure material separation resistance commensurate with high fluidity.

For example, the unit cement amount of ordinary concrete used in the general civil engineering field is 300 kg / m ³ or less, whereas high fluid concrete requires a unit cement amount of 500 kg / m ³ or more, for example.

Moreover, a one-pack type high-performance AE water reducing agent containing a thickening component is known as an admixture. However, even when such a high-performance AE water reducing agent is added, the unit cement amount is 400 kg / m ³ or more for high fluid concrete, and the unit cement amount is 350 kg / m ³ or more for medium fluid concrete. .

  That is, the conventional high-fluidity concrete and medium-fluidity concrete have a large unit cement amount, and thus the ratio of the unit water amount to the unit cement amount (water cement ratio) becomes small. Moreover, when the amount of unit cement increases, the hydration calorific value of cement increases, and cracks and the like are likely to occur when the concrete is hardened. Furthermore, the material cost of concrete increases due to the increase in the amount of unit cement.

  An object of this invention is to provide the concrete with high fluidity | liquidity which suppressed the amount of unit cement.

To achieve the above object, the present invention provides a highly flowable concrete containing cement, water, aggregate, thickener, and high-performance AE water reducing agent, wherein the thickener is a water-soluble cellulose ether. The high-performance AE water reducing agent includes an antifoaming agent and gums, and the water reduction rate specified in JIS A 6204 is 18% or more, and the water cement ratio is 46.1% or more and 65% or less, The slump flow is not less than 35 cm and not more than 75 cm.
Further, the highly fluid concrete of the present invention has a filling height of 30 cm or more (obstruction: rank 2) as defined in the 2012 Standard Specification for Concrete [Construction], the slump flow is 55 cm or more and 75 cm or less, and It is preferable that the high flow concrete has a flow arrival time of 500 mm for 3 to 15 seconds.
Alternatively, the high fluidity concrete of the present invention has a filling height of 28 cm or more (obstruction: rank 3) defined by the East, Middle and West Japan Expressway Tunnel Construction Management Guidelines, and the slump flow is 35 cm or more and 50 cm. The following medium fluidity concrete is preferable.
Moreover, it is preferable that the unit water amount of the water is 185 kg or less per 1 m ³ of the highly fluid concrete.

  According to the highly fluid concrete of the present invention, the unit cement amount can be suppressed.

== Embodiment ==
This embodiment relates to concrete with high fluidity containing cement, water, aggregate, thickener, and high-performance AE water reducing agent. In the present embodiment, high fluidity concrete includes high fluidity concrete (self-filling concrete) and medium fluidity concrete.

  High fluidity concrete is concrete having a filling height of 30 cm or more (obstruction: rank 2) as defined in the 2012 Standard Specification for Concrete (Construction), and a slump flow of 55 cm or more and 75 cm or less. In addition, the high fluidity concrete has a 500 mm flow arrival time of 3-15 seconds as defined in the 2012 Standard Specification for Concrete [Construction], and the bleeding rate based on JIS A 1123 is equal to or less than that of ordinary concrete. It is preferable. The high-fluid concrete is used for a structure adopting a reinforced concrete structure (RC structure), for example.

  On the other hand, medium-fluid concrete refers to concrete having a filling height of 28 cm or more (obstruction: rank 3) specified in the East, Middle and West Japan Highway Tunnel Construction Management Guidelines and a slump flow of 35 cm to 50 cm. . Moreover, it is preferable that the medium fluidity concrete has a bleeding rate based on JIS A 1123 equal to or less than that of ordinary concrete. Medium fluidity concrete is used, for example, as tunnel lining concrete.

[Cement, water, aggregate]
As the cement, water, and aggregate, various materials used in normal concrete production can be used.

  The cement is, for example, Portland cement (ordinary Portland cement, early-strength Portland cement, moderately hot Portland cement, etc.) or mixed cement (blast furnace cement, fly ash cement, etc.). The water is, for example, tap water or “water other than tap water” shown in JIS A5308.

The water cement ratio in the highly fluid concrete according to the present embodiment is 46.1% or more and 65% or less. For example, when the unit water amount in concrete with high fluidity is 175 kg per 1 m ^{3 of} concrete, the unit cement amount in concrete with high fluidity is 269 kg to 380 kg per 1 m ^{3 of} concrete.

The unit water amount per 1 m ^{3 of} concrete is preferably 175 kg or less in the civil engineering field, and 185 kg or less is preferable in the construction field.

  Aggregates include coarse aggregates and fine aggregates.

The coarse aggregate is crushed stone, river gravel, mountain gravel, land gravel and the like. The fine aggregate is land sand, river sand, mountain sand, quartz sand, crushed sand and the like. The unit amount of the coarse aggregate with respect to concrete with high fluidity according to the present embodiment is preferably 700 kg to 1100 kg per 1 m ³ of concrete. The unit amount of fine aggregate with respect to concrete with high fluidity according to the present embodiment is preferably 700 kg to 1100 kg per 1 m ³ of concrete. In addition, in the concrete standard specification [construction edition] established in 2012, the standard for the minimum amount of cement when using aggregate with a coarse aggregate size of 40 mm is 250 kg / m ³ or more. The standard of the minimum cement amount when using the material is 270 kg / m ³ or more.

[Thickener]
A thickener is used to increase the viscosity of highly fluid concrete and suppress material separation. The addition amount of the thickener is preferably 15 to 250 g per 1 m ³ of concrete. The thickener according to the present embodiment includes a water-soluble cellulose ether, an antifoaming agent, and gums.

  The water-soluble cellulose ether is nonionic, and is capable of suppressing material separation of concrete with high fluidity, improving durability by reducing bleeding, and reducing variation in strength and quality. Alkyl cellulose, hydroxyalkyl cellulose, Hydroxyalkyl alkyl cellulose is preferred.

  As the alkyl cellulose, DS is preferably 1.0-2.2, more preferably 1.2-2.0 methylcellulose, and DS is preferably 1.0-2.2, more preferably 1.2-2. 0.0 ethylcellulose and the like. As the hydroxyalkyl cellulose, MS is preferably 0.1 to 3.0, more preferably 0.5 to 2.8 hydroxyethyl cellulose, and MS is preferably 0.05 to 3.3, more preferably 0.1. -3.0 hydroxypropyl cellulose etc. are mentioned. As the hydroxyalkylalkyl cellulose, DS is preferably 1.0 to 2.2, more preferably 1.2 to 2.0, MS is preferably 0.05 to 0.6, more preferably 0.10 to 0. .5 hydroxyethyl methylcellulose, DS is preferably 1.0-2.2, more preferably 1.2-2.0, MS is preferably 0.05-0.6, more preferably 0.10-0 .5 hydroxypropyl methylcellulose, DS is preferably 1.0-2.2, more preferably 1.2-2.0, MS is preferably 0.05-0.6, more preferably 0.10-0 .5 hydroxyethyl ethyl cellulose.

  Here, DS represents the degree of substitution (degree of substitution) and is the number of alkoxy groups present per glucose ring unit of cellulose. MS represents the number of moles of substitution (molar substitution), and per cellulose glucose ring unit. Is the average number of moles of hydroxyalkoxy groups added to.

  As a method for measuring the degree of substitution of the alkyl group and the number of moles of substitution of the hydroxyalkyl group, it is determined by converting values that can be measured by the substitution degree analysis method for hypromellose (hydroxypropylmethylcellulose) described in the 17th revised Japanese Pharmacopeia. Can do.

  The aqueous solution viscosity of 2% by mass or 1% by mass of the water-soluble cellulose ether is preferably 30 (2% by mass) to 30 (2% by mass) at 20 rpm in a BH viscometer from the viewpoint of giving a predetermined viscosity to concrete. 1,000 (1% by mass) mPa · s, more preferably 80 (2% by mass) to 25,000 (1% by mass) mPa · s, and even more preferably 350 (2% by mass) to 20,000 mPa · s (1 Mass%). The viscosity of the water-soluble cellulose ether was measured with a 2% by mass aqueous solution at 50,000 mPa · s or less, and with a 1% by mass aqueous solution when the viscosity was higher than that.

  The addition amount of the water-soluble cellulose ether is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, and further preferably 0.1 to 5% by mass with respect to the high-performance AE water reducing agent. is there.

  Antifoaming agents are oxyalkylene-based, silicone-based, alcohol-based, mineral oil-based, fatty acid-based, fatty acid ester-based, etc. in terms of stabilization of water-soluble cellulose ether when a high-performance AE water reducing agent and a thickener are mixed. Is used.

  Examples of the oxyalkylene antifoaming agent include polyoxyalkylenes such as (poly) oxyethylene (poly) oxypropylene adducts; diethylene glycol heptyl ether, polyoxyethylene oleyl ether, polyoxypropylene butyl ether, polyoxyethylene polyoxy (Poly) oxyalkylene alkyl ethers such as propylene 2-ethylhexyl ether, higher alcohols having 8 or more carbon atoms and oxyethyleneoxypropylene adducts to secondary alcohols having 12 to 14 carbon atoms; polyoxypropylene phenyl ether; (Poly) oxyalkylene (alkyl) aryl ethers such as polyoxyethylene nonylphenyl ether; 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 2,5-di Acetylene ethers obtained by addition polymerization of alkylene oxide to acetylene alcohol such as til-3-hexyne-2,5-diol and 3-methyl-1-butyn-3-ol; diethylene glycol oleate, diethylene glycol laurate, ethylene (Poly) oxyalkylene fatty acid esters such as glycol distearate; (poly) oxyalkylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan trioleate; sodium polyoxypropylene methyl ether sulfate (Poly) oxyalkylene alkyl (aryl) ether sulfate esters such as sodium polyoxyethylene dodecylphenol ether sulfate; ) (Poly) oxyalkylene alkyl phosphoric acid esters such as polyoxyethylene stearyl phosphate ester; polyoxyethylene such as polyoxyethylene lauryl amine (poly) oxyalkylene alkyl amines; polyoxyalkylene amides.

  Examples of the silicone antifoaming agent include dimethyl silicone oil, silicone paste, silicone emulsion, organically modified polysiloxane (polyorganosiloxane such as dimethylpolysiloxane), fluorosilicone oil, and the like.

  Examples of the alcohol-based antifoaming agent include octyl alcohol, 2-ethylhexyl alcohol, hexadecyl alcohol, acetylene alcohol, glycols and the like.

  Examples of the mineral oil-based antifoaming agent include kerosene and liquid paraffin.

  Examples of the fatty acid antifoaming agent include oleic acid, stearic acid, and alkylene oxide adducts thereof.

  Examples of the fatty acid ester-based antifoaming agent include glycerin monoricinoleate, alkenyl succinic acid derivative, sorbitol monolaurate, sorbitol trioleate, natural wax and the like.

  The addition amount of the antifoaming agent is preferably 0.001 to 16% by mass, more preferably 0.002 to 10% by mass with respect to the high performance AE water reducing agent. As described above, by adding more antifoaming agent (usually 5 to 10% by mass with respect to the water-soluble cellulose ether) necessary to suppress the foaming of the water-soluble cellulose ether, stabilization against salting out increases. Can do. The reason for this is presumed that some component (surfactant) in the antifoaming agent is adsorbed and stabilized on the surface of the salted out water-soluble cellulose ether.

  Like the antifoaming agent, the gums are effective in stabilizing the water-soluble cellulose ether, and it is preferable to use one type or two or more types of gums selected from dieutan gum, welan gum, xanthan gum, and gellan gum.

  Dieutan gum is composed of D-glucose, D-glucuronic acid, D-glucose and L-rhamnose, and two L-rhamnose. For example, KELCO-CRETE DG-F (CP Kelco) can be used. .

  Welan gum has a structure in which L-rhamnose or L-mannose side chain is bound to a main chain in which D-glucose, D-glucuronic acid and L-rhamnose are bound at a ratio of 2: 2: 1. For example, CP KELCO K1A-96 (CP Kelco) can be used.

  Similar to cellulose, xanthan gum has a β-1,4 bond of D-glucose in the main chain and two mannose and one glucuronic acid in the side chain. For example, KELZAN (Sanki Co., Ltd.) can be used.

  Gellan gum is a heteropolysaccharide having four sugars as repeating units in which D-glucose, D-glucuronic acid, and L-rhamnose are bound at a ratio of 2: 1: 1. For example, KELCOGEL AFT (CP Kelco) can be used.

  The gums may be added in any form of powder or aqueous solution, but welan gum, xanthan gum and gellan gum are preferably added in an aqueous solution from the viewpoint of stabilizing the water-soluble cellulose ether.

  The addition amount of gums is preferably 0.005 to 2% by mass, more preferably 0.01 to 1% by mass, and further preferably 0.1 to 1% by mass with respect to the high-performance AE water reducing agent in the case of Dieutan gum. 0.8% by mass. In the case of welan gum, xanthan gum, and gellan gum, it is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, and further preferably 0.5 to 8% by mass with respect to the high-performance AE water reducing agent. .

[High-performance AE water reducing agent]
A high performance AE water reducing agent is used to disperse cement particles, increase the fluidity of concrete, and maintain the slump flow. As the high-performance AE water reducing agent, a known one can be used, and preferably a liquid polycarboxylic acid-based water reducing agent. The high-performance AE water reducing agent according to the present embodiment has a water reduction rate (hereinafter sometimes referred to as “water reduction rate”) defined by JIS A 6204 of 18% or more.

  The amount of the high-performance AE water reducing agent added is preferably 0.5 to 2.5% by weight of the unit cement amount.

[Other admixtures]
The highly fluid concrete according to the present embodiment may contain a general AE water reducing agent or an air amount adjusting agent (AE agent or antifoaming agent) as an admixture. The air amount adjusting agent is used for securing a predetermined amount of air to concrete having high fluidity and obtaining durability of the concrete. In addition, the concrete having high fluidity may contain a drying shrinkage reducing agent or an expansion material.

[Manufacturing method of highly fluid concrete]
The highly fluid concrete according to the present embodiment can be manufactured according to the same manufacturing method as that of general concrete.

  For example, concrete with high fluidity can be produced by first kneading the aggregate and cement first, then adding an admixture (thickener, high-performance AE water reducing agent, etc.) and water, and further kneading. Concrete with high fluidity can be produced in advance as ready-mixed concrete, or can be produced immediately before use at an actual site.

  The thickener and the high-performance AE water reducing agent may be mixed in advance. Or after manufacturing the base concrete into which other than the admixture is added, the admixture may be added and kneaded at an appropriate timing.

  The amount of cement, water, aggregate, thickener, and high-performance AE water reducing agent should be adjusted as appropriate within the range where high fluidity concrete satisfying the definition of high fluidity concrete and medium fluidity concrete can be obtained. Is possible. However, the water cement ratio in the highly fluid concrete according to the present embodiment is adjusted to be 46.1% or more and 65% or less.

== Example ==
[Materials used]
Table 1 shows the materials used in the examples or comparative examples.

In all the examples and all the comparative examples, as the cement (C), ordinary Portland cement (density 3.16 g / cm ³ ) manufactured by Taiheiyo Cement was used. For fine aggregate (S), land sand from Kisarazu City, Chiba Prefecture (surface dry density 2.61 g / cm ³ , water absorption 1.80%, coarse grain rate 2.46, actual rate 66.0%) is used. It was. Coarse aggregate (G) is crushed stone from Ome-shi, Tokyo (category: crushed stone 2005, surface dry density 2.65 g / cm ³ , water absorption 0.75%, coarse particle rate 6.62, actual rate 59.7. %) Was used. Water (W) was tap water (density 1.00 g / cm ³ ).

  On the other hand, as an admixture, an AE water reducing agent (WR), a high performance AE water reducing agent (SP1 to SP3), an air amount adjusting agent (AE agent: AE1, antifoaming agent: AE2), and a thickener (VMA) are appropriately used. It was.

  Specifically, the AE water reducing agent (WR) is a master pozzolith (registered trademark) No. 1 manufactured by BASF Japan. 70 was used. High-performance AE water reducing agents are Master Grenium (registered trademark) SP-8SV (water reduction rate 18%. SP1) manufactured by BASF Japan, and Floric (registered trademark) SF500S (water reduction rate 18%, manufactured by Floric Co., Ltd.). One of SP2) and Tupol HP-11 (water reduction rate 19%, SP3) manufactured by Takemoto Yushi Co., Ltd. was used. Master air 775S manufactured by BASF Japan was used as the air amount adjuster (AE agent: AE1), and master air 404 manufactured by BASF Japan was used as the air amount adjuster (antifoaming agent: AE2).

  As the thickeners (VMA1 and VMA2), an agent manufactured by Shin-Etsu Chemical Co., Ltd. was used. This thickener is composed of 62.5% by mass of water-soluble cellulose ether, 18.75% by mass of antifoaming agent, and 18.75% by mass of xanthan gum. Hydroxypropyl methylcellulose is used as the water-soluble cellulose ether. In VMA1, DS: 1.76, MS: 0.15, and a 2% by mass aqueous solution viscosity at 20 ° C. is 31,500 mPa · s at 20 rpm of a BH viscometer. s was used. In VMA2, DS: 1.5, MS: 0.21, and a 1 mass% aqueous solution viscosity at 20 ° C. of 15,400 mPa · s at 20 rpm of a BH type viscometer was used. In addition, about an antifoamer and a xanthan gum, the case where VAM1 is used and the case where VMA2 is used are the same. Specifically, the antifoaming agent is SN deformer 14HP, manufactured by San Nopco, an oxyalkylene antifoaming agent. Xanthan gum is KELZAN manufactured by Sanki Co., Ltd.

[Composition of materials used]
Table 2 shows the composition of the materials used in the examples and comparative examples.

  Examples 1-7 differ in water cement ratio (W / C). The water cement ratio of Example 1 is 65.0%, the water cement ratio of Example 2 is 60.0%, the water cement ratio of Example 3 is 58.7%, and the water of Example 4 The cement ratio is 51.5%, the water cement ratio of Example 5 is 48.6%, the water cement ratio of Example 6 is 47.5%, and the water cement ratio of Example 7 is 46.%. 1%.

  Examples 8-10 differ in the timing which throws a thickener and a high performance AE water reducing agent. Example 8 is an example in which a thickener and a high-performance AE water reducing agent were added during production. Example 9 is an example in which a thickener and a high-performance AE water reducing agent mixed in advance were added during production. Example 10 is an example in which a material other than a thickener and a high-performance AE water reducing agent is kneaded to produce base concrete, and then a thickener and a high-performance AE water reducing agent are added.

In Examples 11 to 13, the unit water amount is different. Example 11 is the unit water amount is 185 kg / ^{m 3,} Example 12, the unit water amount is 165 kg / ^{m 3,} Example 13, the unit water amount is 155 kg / ^{m 3.}

Examples 14-17 differ in the addition amount of a thickener. Example 14 is an example in which 30 g of thickener was added per 1 m ^{3 of} concrete. Example 15 is an example in which 120 g of thickener was added per 1 m ^{3 of} concrete. Example 16 is an example in which 200 g of thickener was added per 1 m ^{3 of} concrete. Example 17 is an example in which 250 g of thickener was added per 1 m ^{3 of} concrete.

  Examples 18 and 19 are examples using a high-performance AE water reducing agent of a different type from the other examples. Example 18 uses Floric SF500S as a high performance AE water reducing agent. Example 19 uses Tupol HP-11 as a high performance AE water reducing agent.

  Examples 20 and 21 and Examples 22 to 25 differ in water cement ratio. The water cement ratio of Example 20 is 65.0%, and the water cement ratio of Example 21 is 60.0%. On the other hand, the water cement ratio of Examples 22 to 25 is 55.0%.

  Moreover, Examples 22-25 change the addition amount of a high performance AE water reducing agent supposing the range (35 cm-50 cm) of the slump flow of medium fluidity concrete. In Example 22, an air amount adjusting agent (antifoaming agent: AE2) was not added.

  Moreover, about the kind of thickener, VMA2 was used in Examples 1-4, 8-10, 12-25, and VMA1 was used in Examples 5-7,11.

  The concrete obtained by the blending of Comparative Example 1 is a concrete (ordinary concrete) to which a thickener and a high-performance AE water reducing agent are not added.

  Comparative Examples 2 to 4 are concrete to which no thickener is added. Comparative Examples 2-4 differ in water cement ratio (W / C). The water cement ratio of Comparative Example 2 is 55.0%, the water cement ratio of Comparative Example 3 is 46.1%, and the water cement ratio of Comparative Example 4 is 35.0%.

  The target slump flow (slump flow after kneading after 5 minutes, cm) is 65 ± 10 cm in Examples 1 to 19, 42.5 ± 7.5 cm in Examples 20 to 25, and 12 in Comparative Example 1. It is ± 2.5 cm, and in Comparative Examples 2 to 4, it is 65 ± 10 cm.

[Production of concrete]
Concretes were prepared by kneading the materials shown in Table 2 together. For kneading, a forced biaxial kneading mixer with a nominal capacity of 60 L was used. The amount of kneading was 40 L per batch. In Examples 1 to 9, 11 to 25, and Comparative Examples 1 to 4, first, aggregate and cement were put into a mixer and kneaded for 10 seconds, and then admixture and water were added for 90 seconds. Concrete was produced by kneading. On the other hand, in Example 10, first, aggregate and cement were put into a mixer and kneaded for 10 seconds, and then AE water reducing agent (WR), air amount adjusting agent (AE1), and water were added. For 90 seconds. Then, the high performance AE water reducing agent (SP1) and the thickener (VMA) were added, and the concrete was produced by mixing for 60 seconds.

[Measurement of concrete]
With respect to the produced concrete, filling height (cm), slump flow (cm), 500 mm flow arrival time (seconds, excluding Examples 20 to 25 and Comparative Example 1), and bleeding rate (%) were measured. In addition, in each Example and the comparative example, it mix | blended and designed so that the air content might be 4.5 +/- 1.5% (range of the general air content of concrete).

  With respect to filling height, slump flow, and 500 mm flow arrival time, Examples 1 to 19 and Comparative Examples 1 to 4 were measured based on the provisions of 2012 Standard Specification for Concrete [Construction]. In addition, with respect to filling height and slump flow, Examples 20 to 25 were measured based on the rules of the East / Middle / West Japan Expressway Tunnel Construction Management Guidelines. In addition, about filling height, Examples 1-19 and Comparative Examples 1-10 are "failure: rank 2", and Examples 20-25 are "failure: rank 3".

  The bleeding rate was measured based on JIS A 1123.

[Measured value, judgment result]
Table 3 shows a determination result obtained by determining whether or not the produced concrete satisfies a predetermined condition based on the measurement value and the measurement value. Each measured value is a concrete value sampled at the time when 5 minutes have passed since the kneading.

  The determination results shown in Table 3 were made by (1) visual determination of the fresh state and (2) determination of whether the required performance of the highly fluid concrete shown in Table 4 is satisfied.

  (1) In the visual judgment of the fresh state, the state where the cement and the aggregate are uniformly distributed without separation and the appropriate material separation resistance is considered to be secured is “◯”. Is partly distributed in the center of the concrete, and the state where the water can be confirmed to bleed (bleeding) on the outer periphery and surface of the concrete is marked with “△”, and the material separation between the cement and the aggregate is remarkable, clearly the material The state in which it was determined that the separation resistance could not be secured was determined as “x”.

  (2) When judging whether or not the required performance of concrete with high fluidity shown in Table 4 is satisfied, the case where all the required performance is satisfied is set to “◯ (pass)”, and any one of the required performance is not satisfied Was judged as “× (failed)”.

  The required performance of the high-fluidity concrete shown in Table 4 is “filling height: 30 cm or more (obstruction: rank 2)”, “slump flow: 65 ± 10 cm ”and“ 500 mm flow arrival time: 3 to 15 seconds ”. Moreover, in this example, it was prescribed | regulated that the bleeding rate is equivalent to or lower than that of ordinary concrete (Comparative Example 1) as the required performance of the high fluidity concrete.

  In addition, the required performance of the medium-fluid concrete shown in Table 4 is “filling height: 28cm or more (obstacle: rank 3)”, “slump” as stipulated in the East, Middle and West Japan Highway Tunnel Construction Management Guidelines. Flow: 42.5 ± 7.5 cm ”. Moreover, in this example, it was prescribed | regulated that the bleeding rate is equivalent to or lower than normal concrete (comparative example 1) as the required performance of the medium fluidized concrete.

  It was judged that the concrete whose determination result of said (1) and (2) is "(acceptable)" is the target high fluidity concrete or medium fluidity concrete.

  As is clear from the results of Examples 1 to 7 and Comparative Examples 1 to 4, in the formulations of Examples 1 to 7, the water cement ratio is a large value of 46.1 to 65.0%. Even high fluidity concrete was obtained.

  On the other hand, also by the blending of Comparative Example 4, it was possible to obtain a concrete in which both of the determination results of (1) and (2) passed. However, in Comparative Example 4, the water cement ratio was as small as 35.0%.

That is, in the blends of Examples 1 to 7, the unit cement amount can be reduced (269 to 380 kg / m ³ ), while in the blend of Comparative Example 4, the unit cement amount is increased (500 kg / m ³ ). It became. As is clear from the results of Comparative Examples 2 and 3, in the blends of Comparative Examples 2 and 3, the higher the water-cement ratio (the smaller the unit cement amount), (1) and (2) The judgment result becomes worse.

Moreover, as is clear from the results of Examples 8 to 10, the timing for adding the thickener and the high-performance AE water reducing agent is not particularly limited in order to obtain highly fluid concrete. Further, as is clear from the results of Examples 11 to 13, the required performance as the high fluidity concrete is satisfied at least in the range where the unit water amount is 155 to 185 kg / m ³ . Moreover, as is clear from the results of Examples 14 to 17, the thickener is effective when added at least ³⁰ g to 250 g per 1 m ^{3 of} concrete. As is clear from the results of Examples 18 and 19, the high-performance AE water reducing agent is not limited to a specific agent as long as the water reduction rate is 18% or more.

  As described above, as is clear from the results of Examples 1 to 19, a thickener containing a water-soluble cellulose ether, an antifoaming agent, and gums, and a high-performance AE water reducing agent having a water reduction rate of 18% or more should be used. Thus, it became clear that a high fluidity concrete with a reduced unit cement amount can be obtained.

  Moreover, as is clear from the results of Examples 20 to 25, by adjusting the addition amount of the thickener and the high-performance AE water reducing agent described in the above embodiment, a medium-fluid concrete with a reduced unit cement amount is obtained. It became clear that

  The above-described embodiments, examples and comparative examples are presented as examples and do not limit the scope of the invention. The above configurations can be implemented in appropriate combination, and various omissions, replacements, and changes can be made without departing from the scope of the invention. The above-described embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof in the same manner as included in the scope and spirit of the invention.

Claims (4)

A highly flowable concrete containing cement, water, aggregate, thickener, and high performance AE water reducing agent,
The thickener includes a water-soluble cellulose ether, an antifoaming agent, and gums,
The high-performance AE water reducing agent has a water reduction rate defined in JIS A 6204 of 18% or more,
The water-cement ratio is 46.1% to 65%,
Highly fluid concrete with a slump flow of 35 cm to 75 cm.   The high-fluidity concrete has a filling height of 30 cm or more (obstruction: rank 2) as defined in the 2012 Standard Specification for Concrete (Construction), the slump flow is 55 cm to 75 cm, and a 500 mm flow arrival time. The high-fluidity concrete according to claim 1, wherein the high-fluidity concrete is 3 to 15 seconds.   The high-fluidity concrete has a filling height of 28 cm or more (obstruction: rank 3) specified by the East, Middle and West Japan Expressway Tunnel Construction Management Guidelines, and the slump flow is 35 to 50 cm. The concrete with high fluidity according to claim 1, wherein the concrete is concrete. 4. The highly fluid concrete according to claim 1, wherein a unit water amount of the water is 185 kg or less per 1 m ³ of the highly fluid concrete.