JP5221014B2 - Low shrink mortar composition - Google Patents

Description

  The present invention relates to a mortar composition mainly used in the civil engineering and construction fields.

Cracks that occur in mortar used in civil engineering and construction work include cracks that occur due to surface temperature drop and wind at the stage of hardening, cracks that occur due to self-shrinkage due to cement hydration, There are cracks caused by significant heat of hydration when repaired at large locations, cracks due to drying shrinkage that occurs when the moisture gradually dissipates after curing, and moisture escapes.
Conventionally, a drying shrinkage reducing agent has been used as a measure for preventing cracking due to drying shrinkage of mortar. For example, alkylene oxide adduct of lower alcohol having 1 to 4 carbon atoms (Patent Document 1), block or random compound of ethylene oxide and propylene oxide (Patent Document 2), alkyl oxide adduct of phenol or alkylphenol (Patent Document 3) Further, alkyl oxide adducts of bisphenol (Patent Document 4), ethylene oxide and propylene oxide adducts (Patent Document 5) and the like are known as chain hydrocarbons.
Japanese Patent Publication No. 56-51148 Japanese Patent Publication No. 1-53214 Japanese Examined Patent Publication No. 62-10947 Japanese Patent Publication No. 5-40714 JP 2001-163653 A

However, conventional drying shrinkage reducing agents are not sufficient in performance, and there is also a problem that strength development in low temperature properties is delayed. In addition, the drying shrinkage reducing agent combining a compound having a polyoxyalkylene group formed by copolymerization of ethylene oxide and propylene oxide and a compound having oxyethylene does not cause a decrease in the strength of the cured product, and is effective. Although it is known to suppress drying shrinkage (Patent Document 6), there is no description regarding neutralization suppression or strength development in low temperature properties.
JP 2003-171155 A

Moreover, as a technique for blending a drying shrinkage reducing agent into a material for repairing and suppressing drying shrinkage, for example, a spraying material (Patent Document 7) in which a specific polyoxyalkylene derivative is blended in a polymer cement mortar, or a certain specific There is known a spraying material or the like in which aluminate, carbonate, or aluminum sulfate is mixed as a rapid setting agent with mortar containing the polyoxyalkylene derivative (Patent Documents 8 and 9). There is no description about the low-temperature properties.
JP 2004-203699 A Japanese Patent Laying-Open No. 2005-082432 JP 2005-104826 A

Furthermore, a technique is known in which a setting accelerator such as a silicate or an organic carboxylic acid metal salt is blended for the purpose of improving the low-temperature properties when a specific polyoxyalkylene derivative is used (Patent Documents 10 and 11). ).
Japanese Patent Laying-Open No. 2005-089227 Japanese Patent Laying-Open No. 2005-089228

  The present invention provides a low-shrinkage mortar composition that not only significantly reduces drying shrinkage but also has a neutralization-inhibiting effect and good low-temperature properties by using a specific drying-shrinkage reducing agent or the like.

That is, this invention takes the following structures.
(1) Alumina cement, aggregate, expanded material, and a ratio of 10 to 90% by mass of component A represented by general formula (1) and 10 to 90% by mass of component B represented by general formula (2) The expansion shrinkage agent is 1 to 10 parts by mass with respect to 100 parts by mass of the alumina cement, and the dry shrinkage reduction agent is 0.1 to 10 parts by mass with respect to 100 parts by mass of the alumina cement. A low shrinkage mortar composition characterized by being a part .
General formula (1) HO {(AO) _a (C ₂ H ₄ O) _b } -H
However, AO represents an oxyalkylene group having 3 and / or 4 carbon atoms, a and b are 1 ≦ a and 1 ≦ b, respectively, and 2 ≦ (a + b) ≦ 30 and 0.4 ≦ a / b. A random adduct or a block adduct may be used.
General formula (2) R'O (A'O) _{n '} -H
However, R ′ represents an alkyl group having 2 to 8 carbon atoms, A′O represents an oxyalkylene group having 2 and / or 3 carbon atoms, and n ′ represents 1 to 10.
(2) The low shrinkage mortar composition according to (1), wherein the drying shrinkage reducing agent is a liquid.
(3) One or more inorganic powders selected from slag, silica fume, and fly ash are contained , and the inorganic powder is 1 to 20 parts by mass with respect to 100 parts by mass of the alumina cement. (1) or ( 2) The low shrinkage mortar composition .
(4) The low-shrink mortar composition according to any one of (1) to (3) , comprising a polymer dispersion, wherein the polymer dispersion is 20 parts by mass or less in terms of solid content with respect to 100 parts by mass of the alumina cement. object.
(5) It contains fibers, and the fibers are 0.02 to 2 parts by mass with respect to 100 parts by mass in total of alumina cement and aggregate or alumina cement, inorganic powder and aggregate. (1) to (4 ) Any of the low shrink mortar compositions.
(6) The low shrinkage mortar composition according to any one of (1) to (5) , comprising a setting accelerator, wherein the setting accelerator is 1 part by mass or less with respect to 100 parts by mass of the alumina cement .
(7) The low shrinkage mortar composition according to any one of (1) to (6), which contains an antifoaming agent.

  The present invention is a low-shrinkage mortar composition that not only significantly reduces drying shrinkage but also has a neutralization-inhibiting effect and good low-temperature properties due to a dry-shrinkage-reducing agent having a composition different from that of conventional dry-shrinkage-reducing agents. A thing is obtained.

  Hereinafter, the present invention will be described in detail.

The alumina cement used in the present invention is obtained from a clinker pulverized product containing monocalcium aluminate as a main mineral. For example, alumina cement 1 or alumina cement 2 can be used. The fineness of the alumina cement is preferably 2000 to 8000 cm ² / g in terms of hydration activity. Moreover, the particle size of the alumina cement is adjusted, and particles having a particle diameter of 5 μm or less and less than 30% by mass are preferable because shrinkage when cured is reduced.

The aggregate used in the present invention is not particularly limited as long as it can be used for ordinary mortar, natural aggregate such as river sand, river gravel, land sand, land gravel, crushed sand, sea sand, Fly ash balloons, aggregates made by firing from obsidian, ceramic balloons, shirasu balloons, lightweight aggregates made by firing from waste glass, and heavy aggregates with a specific gravity of 3.0 g / cm ³ or more It can also be used. Examples of the heavy aggregate include non-ferrous smelted slag aggregates that collectively refer to electric furnace oxidation period slag-based aggregates, ferronickel slag, ferrochrome slag, copper slag, zinc slag, lead slag, and the like.

The dry shrinkage reducing agent of the present invention is characterized by combining the component A represented by the general formula (1) and the component B represented by the general formula (2).
The component A is represented by the general formula (1) HO {(AO) _a (C ₂ H ₄ O) _b } -H. AO represented by the general formula (1) represents an oxyalkylene group having 3 and / or 4 carbon atoms. Carbon number 3 represents an oxypropylene group, and carbon number 4 represents an oxybutylene group. When AO has 5 or more carbon atoms and is mixed with cement, homogenization due to mixing cannot be expected, and the effect of reducing drying shrinkage is reduced. When AO is a copolymer of an oxypropylene group and an oxybutylene group, random addition or block addition may be used. a and b respectively represent 1 ≦ a and 1 ≦ b, and 2 ≦ (a + b) ≦ 30 and 0.4 ≦ a / b. Preferably, 12 ≦ (a + b) ≦ 30. Further, 1 ≦ a / b ≦ 10 is more preferable, and 1 ≦ a / b ≦ 5 is more preferable. When a and b are out of this range, when mixed with cement, air entrainment is increased, strength is reduced, and drying shrinkage reduction effect may be reduced. The combination of (AO) and (C ₂ H ₄ O) may be a random adduct or a block adduct.
The B component is represented by the general formula (2) R′O (A′O) _{n ′} -H. R represented by the general formula (2) represents an alkyl group having 2 to 8 carbon atoms, for example, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, n- Pentyl group, isopentyl group, n-hexyl group, isohexyl group, n-heptyl group, isoheptyl group, n-octyl group, and isooctyl group are represented, and n-butyl group, isobutyl group, and t-butyl group are preferable, and n-butyl group Groups are more preferred. A′O represents an oxyalkylene group having 2 and / or 3 carbon atoms. Carbon number 2 represents an oxyethylene group, and carbon number 3 represents an oxypropylene group. n represents 1 to 10, and when A′O is two or more oxyalkylene groups, the polymerization form of the oxyethylene group and oxypropylene group is not particularly limited, and random copolymerization, block copolymerization, random copolymerization / Block copolymerization. If n exceeds 10, the effect of reducing drying shrinkage is reduced, so 10 or less is preferable, and 1 to 5 is more preferable.

  The blending ratio of the A component and the B component of the drying shrinkage reducing agent of the present invention is preferably 10 to 90% by mass for the A component and 10 to 90% by mass for the B component. When the component A is less than 10% by mass or more than 90% by mass, a sufficient composite effect cannot be obtained and the drying shrinkage reduction effect is reduced. On the other hand, if the component A is less than 10% by mass, the strength expression may not be improved.

  0.1-10 mass parts is preferable with respect to 100 mass parts of alumina cement, and, as for the usage-amount of the drying shrinkage reducing agent of this invention, 0.5-5 mass parts is more preferable. If the amount is less than 0.1 parts by mass, the effect is small, and if it exceeds 10 parts by mass, strength development may be affected.

  The drying shrinkage reducing agent of the present invention may be solid or liquid, but the liquid state is more uniform when mixed with alumina cement or sand.

  The method for mixing the drying shrinkage reducing agent of the present invention may be added and mixed when kneaded with water at the construction site, or may be premixed in dry mortar in advance. In the case of adding at the site, since the work of weighing occurs, it is better to premix in advance in consideration of the simplification of the work.

The expandable material used in the present invention is used to exhibit a mortar shrinkage inhibiting effect, and a synergistic effect can be expected by using it together with the dry shrinkage reducing agent of the present invention.
The type of the expansion material is not particularly limited, and commercially available materials can be used. For example, an ettringite expansion material, a lime-based expansion material, a lime-ettringite composite expansion material, and the like can be given. Two or more of these may be mixed and used.

  1-10 mass parts is preferable with respect to 100 mass parts of alumina cement, and, as for the usage-amount of the expansion material of this invention, 2-8 mass parts is more preferable. When the amount is less than 1 part by mass, a sufficient synergistic effect of suppressing shrinkage cannot be expected, and when the amount exceeds 10 parts by mass, the expansion is too large and the strength may be lowered.

  The polymer dispersion used in the present invention is, for example, a polymer for cement admixture defined in JIS A 6203, which improves durability such as neutralization, salt damage, frost damage, etc., adhesion strength of mortar, bending Used to improve strength properties such as strength and tensile strength. For example, rubber latex such as acrylonitrile-butadiene rubber, styrene-butadiene rubber, chloroprene rubber, and natural rubber, ethylene-vinyl acetate copolymer, polyacrylic acid ester, vinyl acetate vinyl versatate copolymer, and styrene-acrylic Examples include acid ester copolymers, acrylic ester copolymers typified by acrylonitrile / acrylic acid esters, epoxy resins, liquid polymers typified by unsaturated polyester resins, and the like. Mixtures can be used.

  The amount of the polymer dispersion of the present invention is preferably 1 to 20 parts by mass, more preferably 3 to 15 parts by mass in terms of solid content with respect to 100 parts by mass of the alumina cement. If it is less than 1 part by mass, the effect of improving durability is small, and if it exceeds 20 parts by mass, the strength development may be affected.

  The inorganic powder used in the present invention is at least one selected from slag, silica fume, and fly ash, and is used for the purpose of preventing sagging and improving various durability.

  1-20 mass parts is preferable with respect to 100 mass parts of alumina cement, and, as for the usage-amount of the inorganic powder of this invention, 3-15 mass parts is more preferable. If it is less than 1 part by mass, the effect of preventing dripping is small, and if it exceeds 20 parts by mass, strength development may be reduced.

  The fiber used in the present invention is used for the purpose of improving the sagging of mortar or imparting the effect of preventing cracks before curing. The type of fiber is not particularly limited, and any of inorganic fibers and polymer fibers can be used. Examples of the inorganic fibers include rock wool melted and blown from fly ash, slag, basalt and the like, melt-spun fibers, glass fibers, steel fibers, and the like. Examples of the polymer fiber include vinylon fiber, polypropylene fiber, polyethylene fiber, nylon fiber, and acrylic fiber.

  The amount of the fiber of the present invention is preferably 0.02 to 2 parts by mass, and 0.05 to 1 part by mass with respect to 100 parts by mass in total of the alumina cement and the aggregate or the alumina cement, the inorganic powder and the aggregate. More preferred. If it is less than 0.02 parts by mass, the effect of suppressing cracking is small, and if it exceeds 2 parts by mass, it is difficult to ensure adequate mortar fluidity.

  The setting accelerator used in the present invention controls the curing time, and is used particularly in a low temperature environment. Sodium such as carbonic acid, bicarbonate, sulfuric acid, silicic acid, phosphoric acid, nitric acid, and nitrous acid. Examples thereof include salts, potassium salts and lithium salts, lithium salts of organic acids such as stearic acid, lactic acid and citric acid, and clay minerals containing lithium. Clay minerals containing lithium are preferred from the viewpoint of easy adjustment of the curing time.

  The use amount of the setting accelerator of the present invention is preferably 0.01 to 1 part by mass and more preferably 0.05 to 0.5 part by mass with respect to 100 parts by mass of the alumina cement. If the amount is less than 0.01 parts by mass, the setting acceleration effect is small, and if it exceeds 1 part by mass, the setting time may be shortened and workability may be deteriorated.

  The antifoaming agent used in the present invention is used for the purpose of adjusting moderate air entrainment. The types of antifoaming agents include: polyether oxide defoamers such as alkylene oxide adducts of higher fatty acids, glycol oxide oxide adducts, silicone defoamers such as dimethyl silicone, and trialkyl phosphate deodorants such as tributyl phosphate. There are foaming agents.

  0.001-0.5 mass part is preferable with respect to 100 mass parts of alumina cement, and, as for the usage-amount of the antifoamer of this invention, 0.003-0.1 mass part is more preferable. If it is less than 0.001 part by mass, the defoaming effect is small, and even if it exceeds 0.5 part by mass, the defoaming effect reaches its peak and may be uneconomical.

  Various admixtures can be added to the low shrinkage mortar composition of the present invention as long as the performance is not adversely affected. For example, AE water reducing agent, high performance AE water reducing agent, fluidizing agent, rust preventive agent, antifreeze agent, setting modifier, clay mineral, thickener, antibacterial agent and the like can be mentioned.

  The construction method using the low shrinkage mortar composition of the present invention is not particularly limited. The plastering method, spraying method, and grout method used in repair work can be used. For example, it can be used as a surface covering material for smoothing a cross-sectional repair after removing a missing portion or a deteriorated portion, a non-land portion, and the like. What is necessary is just to adjust using the amount of water, various admixtures, etc. in the mortar property suitable for each construction method.

  Examples will be described below.

  Dry shrinkage reducing agent 2 comprising 200 parts by mass of aggregate (sand) with respect to 100 parts by mass of alumina cement, and a mixture of 50 parts by mass (A) as component A and 50 parts by mass as component B (B) shown in Table 1. As shown in Table 2, parts by mass and an expanding material were added to prepare a low shrinkage mortar composition. 45 parts by mass of water was added to 100 parts by mass of the low shrinkage mortar composition, and the mixture was kneaded with a mortar mixer. About the obtained mortar, after curing, compression strength ratio, drying shrinkage reduction ratio, and neutralization depth were measured. In Comparative Examples (Experiment No. 1-1 to Experiment No. 1-5), no drying shrinkage reducing agent was added to the mortar. The results are shown in Table 2.

(Materials used)
Alumina cement: manufactured by Denki Kagaku Kogyo Co., Ltd., Alumina cement No. 1 expansion material: manufactured by Denki Kagaku Kogyo Co., CSA # 20
Sand: Made of Tokai Ritec Co., Ltd., equal amounts of No. 5, 6 and 7 dredged sand, maximum particle size 1.2mm
Water: tap water drying shrinkage reducing agent: a mixture of 50 parts by mass (b) shown in Table 1 and 50 parts by mass (b) shown in Table 2

(Test method)
Compressive strength ratio: The obtained mortar was packed in a 4 × 4 × 16 cm mold and cured in air in a room at a temperature of 20 ° C. and a humidity of 60%. The material age at that time is 1 day and 28 days. Further, it was cured in the air in a room at a temperature of 5 ° C. and a humidity of 60%. The material age at that time is 1 day and 28 days. The measurement of compressive strength was based on JIS R5201. The compressive strength ratio was expressed in% as the measured compressive strength value of the mortar containing the drying shrinkage reducing agent of the present invention / the measured compressive strength value of the mortar without adding the drying shrinkage reducing agent at each age.
Drying shrinkage reduction ratio: JIS A 1129-3 mortar and concrete length change test method, according to dial gauge method, temperature change at a temperature of 20 ° C and humidity of 60%, based on a material age of 2 days and after 30 days of material age Was measured. The drying shrinkage reduction ratio was expressed in% as a measured change in length of a mortar containing a dry shrinkage reducing agent of the present invention after 30 days of age / a measured change in length of a mortar without addition of a dry shrinkage reducing agent.
Neutralization depth: measured in accordance with JIS A 1171.

  From Table 2, it can be seen that the low shrinkage mortar composition of the present invention has good compressive strength at room temperature and low temperature, and remarkably reduces drying shrinkage. Moreover, it turns out that it has the outstanding neutralization inhibitory effect.

  In Experiment No. 1-8 of Example 1, Example 1 except that the types (Tables 1 and 3) and the blending ratios of the components A and B of the drying shrinkage reducing agent were changed as shown in Table 4. The same was done. The results are shown in Table 4.

  From Table 4, it can be seen that the low shrinkage mortar composition of the present invention has good compressive strength at room temperature and low temperature, and remarkably reduces drying shrinkage. Moreover, it turns out that it has the outstanding neutralization inhibitory effect.

  The experiment was conducted in the same manner as in Example 1 except that the amount of the drying shrinkage reducing agent used in Experiment No. 1-8 of Example 1 was changed as shown in Table 5. The results are shown in Table 5.

  From Table 5, it can be seen that the low shrinkage mortar composition of the present invention has good compressive strength at room temperature and low temperature, and remarkably reduces drying shrinkage. Moreover, it turns out that it has the outstanding neutralization inhibitory effect.

  In Experiment No. 1-8 of Example 1, Example 1 except that the amount of polymer dispersion (converted to solid content) was changed as shown in Table 6 with respect to 100 parts by mass of alumina cement. The same was done. The results are shown in Table 6.

(Materials used)
Polymer dispersion: made by Erotex, re-emulsifying powder styrene-acrylic resin

  From Table 6, it can be seen that the low shrinkage mortar composition of the present invention has a more excellent neutralization inhibitory effect by further reducing the drying shrinkage by adding the polymer dispersion.

  In Experiment No. 1-8 of Example 1, with respect to 100 parts by mass of alumina cement, the amount of inorganic powder used was changed as shown in Table 7 and the sagging resistance was evaluated. The same was done. The results are shown in Table 7.

(Materials used)
Inorganic powder: Silica fume, commercial product, BET specific surface area 10 m ² / g

(Test method)
Sagging resistance: The surface of a concrete lithographic plate having a length of 30 cm, a width of 30 cm and a thickness of 6 cm was moistened, mortar was applied at a thickness of 2 cm, and the adhesion state after 24 hours was observed. If it was not abnormal, it was rated as ○, and if it got stuck or slipped off, it was marked as ×. The test was conducted in a room at a temperature of 20 ° C. and a humidity of 60%.

  From Table 7, it can be seen that the low shrinkage mortar composition of the present invention has good sagging resistance by adding inorganic powder.

  In Experiment No. 1-8 of Example 1, the amount of fibers used was changed as shown in Table 8 with respect to 100 parts by mass of the alumina cement and sand, and the sagging resistance was changed in the same manner as in Example 5. The measurement was performed in the same manner as in Example 1 except that the crack resistance before curing of the mortar was measured. The results are shown in Table 8.

(Materials used)
Fiber: Kuraray Co., Ltd., vinylon fiber, fiber length 6 mm, fiber diameter 26 μm

(Test method)
Crack resistance before curing: It was placed on a concrete flat plate having a width of 30 cm, a length of 30 cm and a thickness of 6 cm so as to have a thickness of 1 cm. Specimens that were completed pouring, the humidity 60%, at a temperature of 5 ℃, was confirmed cracks situation after one day in a state that rely on the wind of the wind speed 1~3m in sending wind machine. If there was no occurrence of cracks, it was rated as ◯. If there were fine cracks or 2 or less, Δ, and if 3 or more, it was marked as ×.

  From Table 8, it can be seen that the low shrinkage mortar composition of the present invention has good sagging resistance and crack resistance by adding fibers.

  In Experiment No. 1-8 of Example 1, the amount of setting accelerator used was changed as shown in Table 9 with respect to 100 parts by mass of alumina cement, and the curing properties at low temperature (5 ° C.) were evaluated. Except that, the same procedure as in Example 1 was performed. The results are shown in Table 9.

(Materials used)
Setting accelerator: manufactured by Elementis Japan, Benton OC, lithium-containing clay mineral (hectorite), lithium content 1% by mass

(Test method)
Curing property at low temperature: In a thermostatic chamber at 5 ° C., mortar was placed in a 4 × 4 × 16 cm mold, and its curing time (when it was not depressed by pressing with a finger) was measured.

  From Table 9, it can be seen that the low shrinkage mortar composition of the present invention is remarkably improved in curability at low temperatures by adding a setting accelerator.

  In Experiment No. 1-8 of Example 1, with respect to 100 parts by mass of alumina cement, the amount of defoaming agent used was changed as shown in Table 10, and the unit volume mass of mortar was measured. Performed as in Example 1. The results are shown in Table 10.

(Materials used)
Antifoaming agent: polyether antifoaming agent, commercial product

(Test method)
Unit volume mass: Measured according to JIS A 1171.

  From Table 10, it can be seen that the low shrinkage mortar composition of the present invention increases the unit volume mass when the antifoaming agent is added, further reduces the drying shrinkage, and has a more excellent neutralization inhibiting effect. .

  The present invention not only significantly reduces drying shrinkage, but also has a neutralization-inhibiting effect, and a low-shrinkage mortar composition with good low-temperature properties can be obtained, so it is particularly applicable to civil engineering and construction fields, such as repair work. it can.

Claims (7)

Aluminium cement, aggregate, expanded material, and a dry composition comprising 10 to 90% by mass of component A represented by general formula (1) and 10 to 90% by mass of component B represented by general formula (2). It contains a shrinkage reducing agent, the expansion material is 1 to 10 parts by mass with respect to 100 parts by mass of the alumina cement, and the dry shrinkage reducing agent is 0.1 to 10 parts by mass with respect to 100 parts by mass of the alumina cement. A low shrinkage mortar composition characterized by the above.
General formula (1) HO {(AO) _a (C ₂ H ₄ O) _b } -H
However, AO represents an oxyalkylene group having 3 and / or 4 carbon atoms, a and b are 1 ≦ a and 1 ≦ b, respectively, and 2 ≦ (a + b) ≦ 30 and 0.4 ≦ a / b. A random adduct or a block adduct may be used.
General formula (2) R'O (A'O) _{n '} -H
However, R ′ represents an alkyl group having 2 to 8 carbon atoms, A′O represents an oxyalkylene group having 2 and / or 3 carbon atoms, and n ′ represents 1 to 10. The low shrinkage mortar composition according to claim 1, wherein the drying shrinkage reducing agent is a liquid. The inorganic powder selected from slag, silica fume, and fly ash is contained, and the inorganic powder is 1 to 20 parts by mass with respect to 100 parts by mass of the alumina cement. Low shrink mortar composition. The low-shrinkage mortar composition according to any one of claims 1 to 3, comprising a polymer dispersion, wherein the polymer dispersion is 20 parts by mass or less in terms of solid content with respect to 100 parts by mass of the alumina cement. And also contains a fiber, is 0.02 to 2 parts by weight per 100 parts by weight of fibers of alumina cement and aggregate or alumina cement and inorganic powder and aggregate, any of the preceding claims 1 The low shrinkage mortar composition according to Item. The low shrinkage mortar composition according to any one of claims 1 to 5, comprising a setting accelerator, wherein the setting accelerator is 1 part by mass or less with respect to 100 parts by mass of the alumina cement. The low shrinkage mortar composition according to any one of claims 1 to 6, comprising an antifoaming agent.