JP6639608B2 - Highly durable mortar, highly durable concrete, and method of manufacturing high durable mortar - Google Patents

Description

  The present invention relates to a highly durable mortar, a highly durable concrete, and a method for producing a highly durable mortar.

  In recent years, there is an increasing need to extend the life of reinforced concrete (RC) structures from the viewpoints of financial tightness of the national and local governments and stable operation of infrastructure. The main causes of the aging of RC structures include salt damage and neutralization. These deteriorations impair the performance of RC structures by causing deterioration factors (chloride ions and carbon dioxide) to penetrate into concrete and promote corrosion of reinforcing steel. In addition, there are various causes of deterioration of RC structures, such as cracks caused by drying shrinkage of concrete and damage to concrete caused by frost damage.

  In order to produce highly durable concrete, a method of replacing a part of cement with an admixture is well known. For example, it is known that when blast furnace slag fine powder is used, resistance to neutralization is reduced, but chloride penetration resistance is improved. Further, it is known that the use of fly ash has the effects of improving chloride penetration resistance and reducing drying shrinkage, although the resistance to neutralization and the initial compressive strength up to a material age of about 28 days are reduced. Have been.

Other admixtures include silica fume. Silica fume is fine particles containing SiO ₂ as a main component and having a large specific surface area. Non-Patent Document 1 reports that chloride permeation resistance is improved when blast furnace slag fine powder and silica fume are used in combination. It is said that the mechanism of the chloride permeation resistance improvement is that the concrete composition is densified by the incorporation of silica fume.

Another less common admixture, although less common than silica fume, is metakaolin. Metakaolin is a fine particle containing SiO ₂ or Al ₂ O ₃ as a main component, and has a large specific surface area, though not as large as silica fume. According to Non-Patent Document 2, when artificial pozzolan containing metakaolin is used in combination with blast furnace slag fine powder, although resistance to neutralization is reduced as compared with blast furnace cement, improvement in chloride penetration resistance and compressive strength, It is reported that an effect of reducing drying shrinkage is observed, and the mechanism is said to be due to densification of the concrete composition.

Further, a method has been proposed in which diethylene glycol, gypsum, activated silica, and a pozzolanic substance are used as an admixture to obtain a seawater-resistant cement composition (Patent Document 1). In Patent Literature 1, it is considered that prevention of leaching of Ca (OH) ₂ is necessary to improve seawater resistance (chloride permeation resistance) and corrosion resistance, and thus the generation of Ca (OH) ₂ is suppressed from an early age. The main objective is to use active silica and pozzolanic substances that consume Ca (OH) ₂ during hydration, and further suppress the generation of Ca (OH) _{2 by} the effect of diethylene glycol. In the seawater-resistant cement composition of Patent Document 1, although the compressive strength decreases with an increase in the amount of diethylene glycol added, it has been reported that the amount of Ca (OH) ₂ decreases and the chloride penetration resistance improves. I have.

JP-A-11-278895

Kohei Majima, Shinichi Kawahara, Michio Kikuchi, Tatsuhiko Saeki, "Salt Penetration Resistance of Cement-Based Hardened Body Using Blast Furnace Slag Fine Powder and Silica Fume", Cement and Concrete Transactions, No. 66, pp. 146-64. 452-459, 2012 Kohei Eguchi, Koji Takewaka, Akinobu Yamaguchi, Kodai Kudoku, "Quality improvement effect of artificial pozzolan aiming at high durability of blast furnace cement concrete", Annual Journal of Concrete Engineering, Vol.33, No.1, pp. 761-766, 2011

  However, the method of replacing a part of cement with an admixture as described above has two trade-offs: for example, if chloride penetration resistance is improved, resistance to neutralization is reduced. Improve performance such as chloride penetration resistance, resistance to neutralization, suppression of drying shrinkage, resistance to frost damage, compressive strength, or improve any performance without lowering other performance There was no concrete admixture.

In the method of replacing a part of cement with an admixture, a particular problem is resistance to neutralization. Generally, the amount of Ca contained in a concrete admixture is smaller than that of cement. When the amount of Ca is large, the amount of Ca (OH) _2, which is a hydrate that is a main factor against neutralization, increases, so that the amount of Ca is closely related to the resistance to neutralization. If the amount of Ca is small, it is inevitable that the resistance to neutralization is reduced. Therefore, the use of the admixture generally lowers the resistance to neutralization.

  The present invention relates to a highly durable mortar capable of achieving a sufficiently high level of chloride penetration resistance, drying shrinkage suppression, resistance to frost damage and compressive strength while maintaining sufficient resistance to neutralization, and It is an object of the present invention to provide a method for producing concrete and highly durable mortar containing the same.

  The present inventors have conducted intensive studies and, as an admixture for replacing a part of cement, have found that it is useful to achieve the above object in combination with silica fume and metakaolin, thereby completing the present invention. Reached.

  That is, the present invention is a highly durable mortar containing a binder, silica fume, metakaolin, water, fine aggregate, and a chemical admixture, wherein the binder comprises cement, and 100 parts by mass of the binder. , And 1-15 parts by mass of metakaolin, and the ratio (B / A) of the mass B of water to the total mass A of the binder, silica fume and metakaolin (B / A) is 0.30-0. A highly durable mortar of 65 is provided. According to the high-strength mortar, all of the chloride penetration resistance, drying shrinkage suppression, resistance to frost damage and compressive strength can be achieved at sufficiently high levels while sufficiently maintaining the resistance to neutralization. The method for producing a highly durable mortar includes a step of mixing a binder, silica fume, metakaolin, and fine aggregate to obtain a mixture, and a step of adding water and a chemical admixture to the mixture and kneading the mixture.

  Regarding the main cause of the above effect, the present inventors have found that by using silica fume and metakaolin in combination, the concrete structure is highly densified, whereby the resistance to neutralization can be sufficiently achieved even with a small amount of Ca. It is speculated that in addition to this, chloride permeation resistance, suppression of drying shrinkage, resistance to frost damage and compressive strength can all be achieved at sufficiently high levels.

From the viewpoint of achieving the effects of the present invention more stably and at a higher level, it is preferable to use the metakaolin that satisfies the following conditions. In addition, "Brain specific surface area" means the value measured according to JIS R5201-1997 "Physical test method of cement". "BET specific surface area" means a value measured by a BET multipoint method using BELSORP-mini II (trade name) manufactured by Bell Japan Co., Ltd.
· SiO ₂ amount of 40 to 60 mass%
· _Al 2 _{O 3} content 40 to 50 wt%
・ Brain specific surface area 15000-40000cm ² / g
-BET specific surface area: 50,000 to 250,000 cm ² / g

  The binder may be made of Portland cement and blast furnace slag fine powder, and may contain 30 to 60 parts by mass of blast furnace slag fine powder with respect to 100 parts by mass of binder. By using such a binder, the effect of improving the chloride permeation resistance by the blast furnace slag fine powder is exhibited.

  The present invention provides a highly durable concrete containing the above-mentioned highly durable mortar and coarse aggregate. That is, the highly durable concrete of the present invention contains a binder, water, silica fume, metakaolin, fine aggregate, coarse aggregate, and a chemical admixture, the binder contains cement, and the binder 100 1 to 15 parts by mass of silica fume and 1 to 15 parts by mass of metakaolin with respect to parts by mass, and the ratio (B / A) of water mass B to total mass A of binder, silica fume and metakaolin is 0.20 to 0.20. 0.65. According to the high-strength concrete, it is possible to achieve a sufficiently high level of chloride penetration resistance, suppression of drying shrinkage, resistance to frost damage, and compressive strength while sufficiently maintaining resistance to neutralization.

The unit amount (the amount contained in 1 m ³ of concrete) of the component constituting the highly durable concrete may be in the following range.
・ Portland cement 150-450 kg / m ³
・ Blast furnace slag fine powder 100-300kg / m ³
・ Water 130 to 200 kg / m ³
・ Silica fume 5-40kg / m ³
・ Metakaolin 5-40 kg / m ³
・ Fine aggregate 500 to 1500 kg / m ³
・ Coarse aggregate 500 to 1500 kg / m ³

  According to the present invention, while maintaining sufficient resistance to neutralization, high durability mortar capable of achieving a sufficiently high level of chloride penetration resistance, drying shrinkage suppression, resistance to frost damage, and compressive strength. And a method for producing a concrete and a highly durable mortar containing the same.

<Highly durable mortar>
The highly durable mortar according to the present embodiment includes a binder, silica fume, metakaolin, water, fine aggregate, and a chemical admixture.

(Binder)
Examples of the binder include portland cement, blast furnace slag fine powder, and blast furnace cement. Examples of the Portland cement include ordinary Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, low-heat Portland cement, moderate-heat Portland cement, and sulfate-resistant Portland cement. One of these may be used alone, or two or more may be used in combination.

The Blaine specific surface area of Portland cement is preferably 2500 to 4800 cm ² / g, more preferably 2800 to 4000 cm ² / g, still more preferably 3000 to 3600 cm ² / g, and particularly preferably 3200 to 3500 cm ² / g. . If the Blaine specific surface area of Portland cement is less than 2500 cm ² / g, the strength of the cured product of the highly durable mortar tends to decrease, and if it exceeds 4800 cm ² / g, the fluidity at a low water cement ratio tends to decrease. .

The blast furnace slag fine powder is obtained by crushing granulated blast furnace slag. Fineness of the ground granulated blast furnace slag is preferably 500~5000cm ² / g, more preferably 3800~5000cm ² / g, and more preferably 4200~5000cm ² / g, particularly preferably 4500～5000Cm ² / G.

  From the viewpoint of improving chloride penetration resistance, it is preferable to use a binder composed of Portland cement and blast furnace slag fine powder. In this case, the content of the blast furnace slag fine powder with respect to 100 parts by mass of the binder is preferably 30 to 60 parts by mass, more preferably 34 to 56 parts by mass, and still more preferably 38 to 52 parts by mass, particularly Preferably it is 42 to 48 parts by mass. When the content of the blast furnace slag fine powder is less than 30 parts by mass (the content of Portland cement is more than 70 parts by mass), the effect of improving chloride permeation resistance tends to be thin, and the content of the blast furnace slag fine powder Is more than 60 parts by mass (the content of Portland cement is less than 40 parts by mass), the compressive strength and the resistance to neutralization tend to decrease.

(Silica fume)
Silica fume is a by-product obtained by collecting dust in exhaust gas generated when producing metal silicon, ferrosilicon, electrofused zirconia, or the like. The main component of silica fume is amorphous SiO ₂ that dissolves in an alkaline solution, and its content is about 90 to 98% by mass. By using such silica fume, high compressive strength, high tensile strength and high fluidity of the highly durable mortar can be secured.

The brane specific surface area of silica fume is preferably from 10,000 to 30,000 cm ² / g, more preferably from 11,000 to 28,000 cm ² / g, and still more preferably from 12,000 to 28,000 cm ² / g, from the viewpoints of the microfiller effect and the improvement of reactivity and the securing of fluidity. ２６26000 cm ² / g, particularly preferably 13000 to 24000 cm ² / g. From the same viewpoint, the BET specific surface area of the silica fume is preferably 50,000 to 250,000 cm ² / g, more preferably 100,000 to 240000 cm ² / g, still more preferably 120,000 to 230,000 cm ² / g, and particularly preferably. 140,000 to 220,000 cm ² / g.

  In the highly durable mortar according to the present embodiment, the silica fume content based on 100 parts by mass of the binder is 1 to 15 parts by mass, preferably 2 to 12 parts by mass, more preferably 3 to 10 parts by mass. And more preferably 4 to 8 parts by mass. If the silica fume content is less than 1 part by mass, chloride penetration resistance, drying shrinkage suppression, resistance to frost damage and the effect of improving compressive strength tend to be thin, and if it exceeds 15 parts by mass, the desired fresh properties In addition, it becomes difficult to secure the fluid (flowability, air amount, etc.), and the resistance to neutralization tends to decrease.

(Metakaolin)
Metakaolin is a powder obtained by calcining kaolin minerals. The main components of metakaolin are SiO ₂ and Al ₂ O ₃ . The content of SiO ₂ in metakaolin is preferably 40 to 60% by mass, and more preferably 49 to 54% by mass. The content of Al ₂ O ₃ in metakaolin is preferably 40 to 50% by mass, and more preferably 42 to 47% by mass. Metakaolin contains trace amounts of Fe ₂ O ₃ and TiO ₂ as components other than SiO ₂ and Al ₂ O ₃ . By using such metakaolin, high compressive strength, high tensile strength and high fluidity of the highly durable mortar can be secured.

The specific surface area of the metakaolin is preferably from 15,000 to 40,000 cm ² / g, more preferably from 19000 to 38000 cm ² / g, and still more preferably from 23,000 to 23,000 g, from the viewpoint of improving the microfiller effect and the reactivity and ensuring the fluidity. ３５35000 cm ² / g, particularly preferably 25,000 to 33000 cm ² / g. From the same viewpoint, the BET specific surface area of metakaolin is preferably 50,000 to 250,000 cm ² / g, more preferably 100,000 to 200,000 cm ² / g, still more preferably 120,000 to 180,000 cm ² / g, and particularly preferably. 130,000 to 170,000 cm ² / g.

  In the highly durable mortar according to the present embodiment, the metakaolin content based on 100 parts by mass of the binder is 1 to 15 parts by mass, preferably 2 to 12 parts by mass, more preferably 3 to 10 parts by mass. And more preferably 4 to 8 parts by mass. If the content of metakaolin is less than 1 part by mass, chloride penetration resistance, drying shrinkage suppression, resistance to frost damage and the effect of improving compressive strength tend to be thin, and if it exceeds 15 parts by mass, predetermined fresh properties In addition, it becomes difficult to secure the fluid (flowability, air amount, etc.), and the resistance to neutralization tends to decrease.

  In the highly durable mortar according to the present embodiment, the total amount of silica fume and metakaolin with respect to 100 parts by mass of the binder is preferably 2 to 30 parts by mass, more preferably 4 to 24 parts by mass, and still more preferably It is 6 to 20 parts by mass, particularly preferably 8 to 16 parts by mass.

(water)
As the water, tap water, distilled water, deionized water, or the like may be used. The mass ratio of water to the binder (water / binder) is preferably 0.21 to 0.70, more preferably 0.23 to 0.68, and even more preferably 0.25 to 0.66. And particularly preferably 0.27 to 0.63. When the mass ratio is less than 0.21, it tends to be difficult to secure predetermined fresh properties (fluidity, air amount, etc.) and moldability, and when it exceeds 0.70, the compressive strength and durability decrease. Tend to.

  In the highly durable mortar according to this embodiment, the ratio (B / A) of the mass B of water to the total mass A of the binder, silica fume, and metakaolin is 0.20 to 0.65, preferably 0.22 to 0.65. 0.63, more preferably 0.24 to 0.60, even more preferably 0.25 to 0.55. If this ratio is less than 0.20, it tends to be difficult to ensure predetermined fresh properties (fluidity, air amount, etc.) and moldability, and if it exceeds 0.65, the compressive strength and durability are reduced. There is a tendency.

(Fine aggregate)
As the fine aggregate, river sand, land sand, sea sand, crushed sand, silica sand, limestone aggregate, blast furnace slag fine aggregate, copper slag fine aggregate, electric furnace oxidized slag fine aggregate, and the like can be used in combination. From the viewpoint of the fluidity of the mortar slurry, the fine aggregate preferably includes particles having a particle size of 0.15 mm or less, preferably 70 to 98% by mass, more preferably 72 to 97% by mass, and still more preferably 75 to 96% by mass. Including. The fine aggregate includes a particle group having a particle size of 0.15 mm or less in the above range, and a particle group having a particle size of 0.075 mm or less, preferably 16 to 80% by mass, more preferably 20 to 75% by mass, and Preferably, it contains 25 to 70% by mass. The method for preparing the fine particles is not particularly limited. For example, the fine particles can be prepared by mixing two or more kinds of fine aggregates having different particle sizes.

(Chemical admixture)
Examples of the chemical admixture include a water reducing agent, an AE agent, an antifoaming agent, a shrinkage reducing agent, a setting accelerator, a setting retarder, and a thickener. One of these may be used alone or a plurality of them may be used in combination depending on the required performance.

  As the water reducing agent, a lignin-based, naphthalene sulfonic acid-based, aminosulfonic acid-based, polycarboxylic acid-based water reducing agent, a high performance water reducing agent, a high performance AE water reducing agent, and the like can be used. From the viewpoint of ensuring fluidity at a low water cement ratio, it is preferable to use a polycarboxylic acid-based water reducing agent, a high-performance water reducing agent or a high-performance AE water reducing agent as the water reducing agent, and a polycarboxylic acid-based high performance water reducing agent. It is more preferable to use The amount of the water reducing agent in the highly durable mortar according to the present embodiment is preferably 0.5 to 2.0 parts by mass, more preferably 0.5 to 2.0 parts by mass, based on 100 parts by mass of the total amount of the binder, silica fume and metakaolin. To 1.5 parts by mass, more preferably 0.5 to 1.0 parts by mass.

  Examples of the defoaming agent include special nonionic compounding surfactants, polyalkylene derivatives, hydrophobic silica, polyethers, and the like. The compounding amount of the defoaming agent in the highly durable mortar according to the present embodiment is preferably 0.002 to 0.020 parts by mass, more preferably 0.1 to 100 parts by mass, based on 100 parts by mass of the total amount of the binder, silica fume and metakaolin. 003 to 0.015 parts by mass, more preferably 0.004 to 0.010 parts by mass, particularly preferably 0.005 to 0.008 parts by mass.

<Production method of highly durable mortar>
The method for producing a highly durable mortar according to the present embodiment is not particularly limited, but water or a part or all of the materials other than the chemical admixture is previously mixed, and then water and the chemical admixture are added. Mix in the mixer. The mixer used for kneading the mortar is not particularly limited, and a mortar mixer, a twin-screw kneading mixer, a pan-type mixer, a grout mixer, or the like can be used.

Unit amount of the components constituting the high durability mortar (amount contained in the mortar 1 m ³⁾ may be set to the following range.
・ Portland cement 250-750kg / m ³
・ Blast furnace slag fine powder 150-500kg / m ³
・ Water 200-350kg / m ³
・ Silica fume 8 to 65 kg / m ³
・ Metakaolin 8-65 kg / m ³
· Fine aggregate 800~2500kg / ^{m 3}

Unit amount of Portland cement as described above is preferably 250~750kg / ^{m 3,} more preferably from 270~720kg / ^{m 3,} more preferably from 290~680kg / ^{m 3,} particularly preferably 300~650kg / ^{m 3.}

As described above, the unit amount of the blast furnace slag fine powder is preferably 150 to 500 kg / m ³ , more preferably 180 to 470 kg / m ³ , still more preferably 220 to 440 kg / m ³ , and particularly preferably 250 to 440 kg / m ^3. ４００400 kg / m ³ . When the unit amount of the blast furnace slag fine powder is less than 150 kg / m ³ , the effect of improving chloride permeation resistance tends to be thin, and when it exceeds 500 kg / m ³ , the compressive strength and the resistance to neutralization are reduced. It tends to decrease.

As described above, the unit amount of water is preferably 200 to 350 kg / m ³ , more preferably 220 to 330 kg / m ³ , still more preferably 240 to 310 kg / m ³ , and particularly preferably 260 to 290 kg / m ^3. m is ^3.

Unit amount of silica fume as described above preferably 8~65kg / ^{m 3,} more preferably from 14~60kg / ^{m 3,} more preferably from 20~55kg / ^{m 3,} particularly preferably 25～50Kg / m is ^3. If the unit amount of silica fume is less than 8 kg / m ^3, the chloride penetration resistance, drying shrinkage suppression, the effect of improving the resistance and compressive strength against frost injury is tend to become thinner and more than 65 kg / m ^3, a predetermined It becomes difficult to ensure fresh properties (fluidity, amount of air, etc.), and the resistance to neutralization tends to decrease.

As described above, the unit amount of metakaolin is preferably from 8 to 65 kg / m ³ , more preferably from 14 to 60 kg / m ³ , still more preferably from 20 to 55 kg / m ³ , and particularly preferably from 25 to 50 kg / m ^3. m is ^3. If the unit amount of metakaolin is less than 8 kg / m ^3, the chloride penetration resistance, drying shrinkage suppression, the effect of improving the resistance and compressive strength against frost injury is tend to become thinner and more than 65 kg / m ^3, a predetermined It becomes difficult to ensure fresh properties (fluidity, amount of air, etc.), and the resistance to neutralization tends to decrease.

As described above, the unit amount of the fine aggregate is preferably 800 to 2500 kg / m ³ , more preferably 900 to 2200 kg / m ³ , still more preferably 950 to 1800 kg / m ³ , and particularly preferably 1000 to 2000 kg / m ^3. It is 1500 kg / m ³ .

<Highly durable concrete>
Concrete may be prepared by combining a suitable amount of coarse aggregate with the mortar composition according to the present embodiment. The amount of coarse aggregate and the amount of water may be changed as appropriate according to the target compressive strength, toughness, and target slump. As the coarse aggregate, gravel, crushed stone, limestone aggregate, blast furnace slag coarse aggregate, electric furnace oxidized slag coarse aggregate, and the like can be used. Further, a coarse aggregate that remains on a 5 mm sieve at 85% by mass or more is more preferable.

The unit amount of the component constituting the highly durable concrete (the amount contained in 1 m ³ of concrete) may be in the following range.
・ Portland cement 150-450 kg / m ³
・ Blast furnace slag fine powder 100-300kg / m ³
・ Water 130 to 200 kg / m ³
・ Silica fume 5-40kg / m ³
・ Metakaolin 5-40 kg / m ³
・ Fine aggregate 500 to 1500 kg / m ³
・ Coarse aggregate 500 to 1500 kg / m ³

As described above, the unit amount of Portland cement is preferably 150 to 450 kg / m ³ , more preferably 170 to 420 kg / m ³ , still more preferably 190 to 380 kg / m ³ , and particularly preferably 200 to 350 kg. / ^{m 3.}

As described above, the unit amount of the blast furnace slag fine powder is preferably 100 to 300 kg / m ³ , more preferably 120 to 280 kg / m ³ , still more preferably 140 to 260 kg / m ³ , and particularly preferably 150 to 260 kg / m ^3. ２５０250 kg / m ³ . When the unit amount of the blast furnace slag fine powder is less than 100 kg / m ³ , the effect of improving chloride permeation resistance tends to be thin, and when it exceeds 300 kg / m ³ , the compressive strength and the resistance to neutralization are reduced. It tends to decrease.

As described above, the unit amount of water is preferably 130 to 200 kg / m ³ , more preferably 140 to 190 kg / m ³ , still more preferably 145 to 185 kg / m ³ , and particularly preferably 150 to 180 kg / m ^3. m is ^3.

As described above, the unit amount of silica fume is preferably 5 to 40 kg / m ³ , more preferably 8 to 35 kg / m ³ , still more preferably 12 to 30 kg / m ³ , and particularly preferably 15 to 25 kg / m ^3. m is ^3. If the unit amount of silica fume is less than 5 kg / m ^3, the chloride penetration resistance, drying shrinkage suppression, the effect of improving the resistance and compressive strength against frost injury is tend to become thinner and more than 40 kg / m ^3, a predetermined It becomes difficult to ensure fresh properties (fluidity, amount of air, etc.), and the resistance to neutralization tends to decrease.

As described above, the unit amount of metakaolin is preferably 5 to 40 kg / m ³ , more preferably 8 to 35 kg / m ³ , still more preferably 12 to 30 kg / m ³ , and particularly preferably 15 to 25 kg / m ^3. m is ^3. If the unit amount of metakaolin is less than 5 kg / m ^3, the chloride penetration resistance, drying shrinkage suppression, the effect of improving the resistance and compressive strength against frost injury is tend to become thinner and more than 40 kg / m ^3, a predetermined It becomes difficult to ensure fresh properties (fluidity, amount of air, etc.), and the resistance to neutralization tends to decrease.

As described above, the unit amount of the fine aggregate is preferably 500 to 1500 kg / m ³ , more preferably 530 to 1300 kg / m ³ , still more preferably 560 to 1100 kg / m ³ , and particularly preferably 600 to 1100 kg / m ^3. a 900kg / ^{m 3.}

As described above, the unit amount of the coarse aggregate is preferably 500 to 1500 kg / m ³ , more preferably 600 to 1400 kg / m ³ , still more preferably 700 to 1300 kg / m ³ , and particularly preferably 800 to 1300 kg / m ^3. It is 1200 kg / m ³ .

  According to the highly durable mortar and the highly durable concrete according to the above embodiment, all of the chloride penetration resistance, drying shrinkage suppression, resistance to frost damage and compressive strength, while sufficiently maintaining the resistance to neutralization. To a sufficiently high level.

Hereinafter, the present invention will be described in detail with reference to examples.
[1. Materials used]
The following materials were used.
(1) Cement, ordinary Portland cement (density 3.16 g / cm ³ , manufactured by Ube Mitsubishi Cement Co., Ltd.)
Blast furnace slag fine powder (density 2.90 g / cm ³ , CaO amount 41.9% by mass, SiO ₂ amount 31.6% by mass, Al ₂ O ₃ amount 14.0% by mass, SO ₃ amount 1.7% by mass , Blaine specific surface area 4760 cm ² / g, JIS A 6206 blast furnace slag fine powder 4000 equivalent, manufactured by Ube Industries, Ltd.)
(2) Admixture / silica fume (density 2.22 g / cm ³ , SiO ₂ content 94.5% by mass, Blaine specific surface area 16100 cm ² / g, BET specific surface area 218000 cm ² / g, manufactured by EFACO)
-Metakaolin (density 2.50 g / cm ³ , SiO ₂ amount 51.6 mass%, Al ₂ O ₃ amount 44.8 mass%, Blaine specific surface area 30300 cm ² / g, BET specific surface area 159000 cm ² / g, manufactured by BASF)
(3) Fine aggregate / sea sand A (density 2.59 g / cm ³ , coarse grain ratio 2.66, produced in Fukuoka Prefecture)
・ Sea sand B (density 2.57 g / cm ³ , coarse grain ratio 2.97, Fukuoka Prefecture)
・ Crushed sand (density 2.68 g / cm ³ , coarse grain ratio 2.71; hard sandstone, Fukuoka Prefecture)
(4) Coarse aggregate / crushed stone (maximum size 20 mm, density 2.70 g / cm ³ , coarse grain ratio 6.64, hard sandstone, Yamaguchi Prefecture)
(5) Chemical admixture-Trade name: Mighty 21VS, high-performance water reducing agent, manufactured by Kao Corporation-Trade name: micro air 404, air flow regulator, manufactured by BASF Japan Co., Ltd. (6) Mixing water and tap water

[2. Concrete mix]
Table 1 shows the compositions of the concretes Nos. 1 to 18 using the above materials.
In the table, ordinary Portland cement is described as N, blast furnace slag fine powder as BFS, silica fume as SF, metakaolin as MK, unit water amount as W, unit cement amount as C, and unit binder as B. In addition, the formulation No. In 2 to 15, 17 and 18, the mass ratio of blast furnace slag fine powder / (normal Portland cement + blast furnace slag fine powder) is constant at 45%, which corresponds to blast furnace cement B type. Notated as BB.

Formulation No. In Nos. 4 to 6, 8 to 12, 14, and 15, the substitution ratio of silica fume and metakaolin is represented by a mass ratio (%) in the compound name. In 7, 13, 16 to 18, the substitution amount is represented by a unit amount (kg / m ³ ) in the compound name.

  Formulation No. In Sea Nos. 1 to 6, 8 to 12, 14, and 15, sea sand A was used. In 7, 13, 16 to 18, sea sand B was used. Although it is sea sand of the same locality, the particle size is different. In Nos. 1 to 6, 8 to 12, 14, and 15, the volume ratio of sea sand to crushed sand was 8: 2. In 7, 13, 16 to 18, the volume ratio of sea sand to crushed sand was 4: 6.

[3. Concrete preparation and test method]
(1) Mixing of concrete Mixing No. shown in Table 1 The mixing of the concretes Nos. 1 to 18 was performed in the following procedure. That is, fine aggregate, coarse aggregate, cement, and an admixture were put into a horizontal biaxial forced kneading mixer, kneaded for 30 seconds, and then water (including an admixture) was added and kneaded for 120 seconds.
(2) Fresh properties of concrete About 1-18, as a property test of fresh concrete, the slump and air volume were measured. Table 2 shows the results. The slump test was performed in accordance with JIS A1101 “Slump test method for concrete”. Further, the air amount was 2.0% or less.

(3) Curing of concrete specimens Curing of concrete specimens was carried out by steam curing in the early stage of material age. After pre-heating at 20 ° C. for 4 hours, the temperature was raised at a rate of 10 ° C./hr, maintained at 60 ° C. for 3 hours, and lowered at a rate of 10 ° C./hr. After one day of material age, they were cured in the air in a constant temperature room at 20 ° C.
(4) Diffusion Coefficient Measurement Test The apparent diffusion coefficient of chloride ions is measured in accordance with JSCE-G 572-2003 "Test method for apparent diffusion coefficient of chloride ions in concrete by immersion" (draft). I went. Both ends of a cylindrical specimen having a diameter of 10 cm and a height of 20 cm were cut by 2.5 cm to a height of 15 cm, and the surfaces other than the casting surface were sealed with silicon and epoxy resin, and then immersed in a 10% aqueous sodium chloride solution. The concrete was taken out periodically, cut out in the depth direction, and the amount of chloride ions in the concrete was measured according to JIS A1154, and the apparent diffusion coefficient was calculated.
The measurement of the effective diffusion coefficient of chloride ions was carried out in accordance with JSCE-G571-2010 "Method for testing effective diffusion coefficient of chloride ions in concrete by electrophoresis" (draft). A 5.0 cm disk-shaped specimen was cut out from the center of a cylindrical specimen having a diameter of 10 cm and a height of 20 cm, and after sealing the circumferential surface with an epoxy resin, a vacuum saturation treatment was performed, and the specimen was saturated with water. . The test specimen was placed in an electric cell, and a constant DC voltage of 15 V was applied between the electrodes. Chloride on the anode side (0.5 mol / L NaCl aqueous solution) and on the cathode side (0.3 mol / L NaOH aqueous solution) The ion concentration and the like were measured over time to calculate the effective diffusion coefficient.
(5) Compressive strength test Compressive strength at the age of 28 days was measured according to JIS A1108 “Test method for compressive strength of concrete”.
(6) Length change test The drying shrinkage strain was measured according to JIS A1129-2 "Method for measuring length change of mortar and concrete". However, the base age of the drying start material age and length change was one day of material age.
(7) Accelerated neutralization test According to JIS A1153 “Test method for accelerated neutralization of concrete”, the depth of neutralization was measured.
(8) Freeze-thaw test The relative dynamic elastic modulus was measured in accordance with JIS A1148 “Test method for freeze-thaw concrete”. However, only for the freeze-thaw test, the air amount was set to 4.5 to 6.0%.

[4. Test results]
Table 3 shows the apparent diffusion coefficient and effective diffusion coefficient of chloride ions in the salt water immersion for one month and three months, and Table 4 shows the compressive strength and other durability test results.

Here, Comparative Examples 1 to 3 are reference concretes using a binder equivalent to ordinary Portland cement or blast furnace cement B, and the water binder ratio (W / B) was partially changed. Comparative Examples 4 to 9 are concrete in which silica fume is replaced by 3 to 25% by mass, and Comparative Examples 10 to 15 are concrete in which metakaolin is replaced by 3 to 25% by mass. Examples 1 to 3 are concretes in which the replacement of 20 kg / m ³ mass of silica fume and the replacement of 20 kg / m ³ mass of metakaolin are combined, and the water binder ratio (W / B) was partially changed.

[5. Evaluation]
From Table 3, comparing the apparent diffusion coefficient and the effective diffusion coefficient at 1 month and 3 months with salt water immersion for each base binder (equivalent to ordinary Portland cement or blast furnace cement B type), In comparison, the apparent diffusion coefficient of chloride ions in the examples is a small value, and the examples are excellent in chloride permeation resistance.

  From Table 4, comparing the compressive strengths at the age of 28 days, the compressive strengths of the examples are all larger than those of the comparative examples, and the examples are superior in the compressive strength.

  When comparing the drying shrinkage strains during the drying period of 6 months, the drying shrinkage strains of the examples are all smaller than those of the comparative examples, and the examples are excellent in suppressing the drying shrinkage.

  The neutralization depth in the accelerated neutralization period of 3 months is compared for each base binder. As compared with Comparative Example 2, the neutralization depth of Example 2 was almost the same between the formulations based on the binder equivalent to the blast furnace cement B type. In addition, the neutralization depth of Example 1 was slightly larger than that of Comparative Example 1 between the compositions based on ordinary Portland cement. Therefore, the resistance to neutralization of the example is almost the same as that of the comparative example.

  Comparing the relative dynamic elastic moduli at the end of 300 cycles of freezing and thawing, the values of Comparative Examples 1, 2, and 7 are greatly reduced from 100%, whereas the values are not changed from 100% in Examples. The embodiment is excellent in resistance to frost damage.

From the above, it was confirmed that the concrete of this example is a highly durable concrete having excellent chloride penetration resistance, compressive strength, drying shrinkage suppression, resistance to frost damage, and resistance to neutralization does not decrease. it can. This is because the concrete structure is extremely densified by using silica fume and metakaolin together as an admixture.

Claims (6)

A highly durable mortar containing a binder , silica fume, metakaolin, water, fine aggregate, a water reducing agent, and an antifoaming agent ,
Wherein the binder is a cement,
Comprises 3-5 parts by weight 3 to 5 parts by mass comprises and the metakaolin the silica fume relative to the binder 100 parts by weight,
Wherein the ratio of the mass B of the water binding material and the silica fume to the total weight A of the metakaolin (B / A) is Ri der 0.30 to 0.65,
The compounding amount of the water reducing agent is 0.5 to 2.0 parts by mass based on 100 parts by mass of the total amount of the binder, the silica fume, and the metakaolin.
The highly durable mortar Ru from 0.002 to 0.020 parts by der amount of defoamer on the total amount 100 parts by weight of the said silica fume and the binder metakaolin. 1m ³ inside
250-750 kg of Portland cement,
200-350kg of water,
8 to 65 kg of silica fume,
8-65 kg of metakaolin,
The highly durable mortar according to claim 1, comprising 800 to 2500 kg of fine aggregate. A highly durable mortar according to claim 1 or 2,
Coarse aggregate,
High durability concrete including. 1m ³ inside
150-450 kg of Portland cement,
130-200kg of water,
5-40 kg of silica fume,
5-40 kg of metakaolin,
500-1500 kg of fine aggregate,
4. The highly durable concrete according to claim 3, comprising 500 to 1500 kg of coarse aggregate. A method for producing a highly durable mortar according to claim 1 or 2,
Step of mixing the binder, silica fume, metakaolin and fine aggregate to obtain a mixture,
Adding water, a water reducing agent and an antifoaming agent to the mixture and kneading,
And a method for producing a highly durable mortar. A method for producing highly durable concrete according to claim 3 or 4,
A step of mixing a binder, silica fume, metakaolin, fine aggregate and coarse aggregate to obtain a mixture,
Adding water, a water reducing agent and an antifoaming agent to the mixture and kneading,
And a method for producing highly durable concrete.