JP2013100202A - Mortar composition for repair - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mortar composition in which the resistance of an initial crack is improved, the flow down is controlled (extension of working hours), the decrease of an expansive power is few even if stored for the long period of time, and further the storage stability is excellent without using a special package material.SOLUTION: The mortar composition for repair includes: a Portland cement; an expansive additive; a polymer; and a fine aggregate, wherein the expansive additive is obtained by heat-treating a clinker or a clinker grinding material containing free lime, a hydraulic compound, and anhydrous gypsum under the carbon dioxide atmosphere to generate calcium carbonate, the expansive additive is 2-10 parts in 100 parts of the binder consisting of the Portland cement and the expansive additive, the polymer is 1-20 parts and the fine aggregate is 50-250 parts based on 100 parts of the binder, and further the mortar composition for repair includes: a shrinkage reducing agent; fibers; and a water reducing agent.

Description

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

  Concrete structures may deteriorate due to salt damage, neutralization, freezing and thawing, and chemical corrosion, which may cause cracks and floats on the surface. As countermeasures, there is a construction in which a deteriorated portion is confirmed by a hammering inspection or the like, removed by an electric pick, an air pick, a water jet, or the like, and newly repaired with a repair member. In small-scale repair work with a small repair cross section, cross-section repair is often performed by kneading polymer cement mortar and applying a trowel (see Patent Documents 1 and 2).

When repairing with a trowel or the like, a material excellent in workability such as ease of application and adhesion of the mortar to be used is preferred. Therefore, as described in Patent Documents 1 and 2, for the purpose of imparting appropriate stickiness and anti-sag properties to mortar, materials containing inorganic fine powders such as fly ash and silica fume are used.
In addition, polymer cement mortar provides durability by suppressing the permeability of carbon dioxide, chloride ions and water by hardening the hardened structure by mixing with the polymer, but it cannot be completely blocked. . In particular, cracks may occur at the level of several months due to the influence of drying shrinkage caused by evaporation of moisture. In order to solve this, a shrinkage reducing agent is also blended (see Patent Document 3), but in some cases, the setting is significantly delayed in a low temperature environment.

On the other hand, an expansion material is used for the purpose of compensating for the shrinkage of the cement, suppressing the occurrence of cracking, and maintaining the adhesion performance with the structure. Examples of the expansion material include 3CaO.3Al ₂ O ₃ .CaSO ₄ (auin), calcium sulfoaluminate-based (hereinafter referred to as “auin-based expansion material”) mainly composed of CaSO ₄ and CaO, and free lime as the main component. In addition to the lime-based (hereinafter referred to as lime-based expanding material), there is an expanding material containing free lime-hydraulic material-gypsum.

  Cement, aggregate, expansion material, drying shrinkage reducing agent, polymer is used to reduce shrinkage of mortar / concrete due to the synergistic effect of the expansion material and shrinkage reducing agent (see Patent Document 4), cement, expansion material, There has been proposed a polymer cement composition containing a re-emulsifying powder resin, an aggregate, a fiber material, a shrinkage reducing agent, a water reducing agent, and an antifoaming agent. (See Patent Document 5)

  However, when the cement composition containing the expansion material is stored beyond the quality assurance period, the expansion performance may deteriorate due to moisture entering from the outside. There was a risk that the adhesion performance would decrease. Furthermore, the expansion material used for the purpose of compensating for the long-term shrinkage may cause initial cracks due to the plastic shrinkage unless it is sufficiently cured in the initial stage.

  Therefore, a cement premix composition comprising cement, a lime-based expansion material, and a binder mainly composed of a water reducing agent as a method for delaying deterioration of cement premix products due to storage (deterioration of mortar properties, deterioration of expansion performance). Cement premix products in which things are packed in polyethylene bags have been proposed. (See Patent Document 6)

  According to this method, although the quality assurance period of the cement premix composition is extended, it is necessary to use a special packaging material, and in order to improve the manufacturing efficiency at the time of packaging, pinholes and slits are added to the packaging bag. It was necessary to apply special processing to the packing material, such as putting

In addition, when the conventional expansion material is stored for a long time in a high temperature and high humidity environment, the expansion performance is deteriorated. There has been proposed a method for improving the storage stability by heat-treating an expanding material in a carbon dioxide atmosphere to generate calcium carbonate. (See Patent Document 7)

Although it has been shown that this expandable material can be used in combination with a water reducing agent, a fluidizing agent, an antifoaming agent, a shrinkage reducing agent, a polymer emulsion, fibers, and other additives in addition to aggregates, specific use The amount is not shown and the effect was not suggested for any other expansion performance.

JP 2001-322858 A JP 2003-89565 A JP 2003-55018 A JP 2008-31006 A JP 2005-82416 A Japanese Patent No. 3939135 International Publication No. 2010/143506 Pamphlet

  The present invention is intended to solve the above-mentioned problems, and improves resistance to initial cracks, suppresses flow-down (extension of working time), and has little decrease in expansion performance even after long-term storage. Provided is a mortar composition having excellent storage stability without using a special packaging material.

That is, the present invention comprises (1) a portland cement, an expansion material, a polymer and a fine aggregate, and the expansion material contains free lime, a hydraulic compound, and anhydrous gypsum, or a clinker or a clinker pulverized product obtained by carbon dioxide. It is an expansion material obtained by heat-treating in an atmosphere to produce calcium carbonate. Among 100 parts of a binding material composed of Portland cement and an expansion material, the expansion material is 2 to 10 parts, and the polymer is 1 20 parts, mortar composition for repair having 50 to 250 parts of fine aggregate, (2) Further, 1 to 8 parts of shrinkage reducing agent for 100 parts of binder, (1) repair mortar composition (3) Further, 0.05 to 0.7 parts of fibers are contained with respect to 100 parts of the binder (1) or (2) the mortar composition for repair, and (4) further contains a water reducing agent. (1) to ( Either repair mortar composition) is.

The mortar composition for repair according to the present invention improves the resistance to initial cracks, reduces the deterioration of expansion performance even when stored for a long period of time, suppresses the flow down (extends the working time), and uses a special packaging material. Even if it is not used, there are effects such as excellent storage stability.

Hereinafter, the present invention will be described in detail.
Parts and% used in the present invention are based on mass unless otherwise specified.

The cement used in the present invention is not particularly limited, and normal, early strength, very early strength, low heat, and moderate heat Portland cement, and blast furnace slag, fly ash, or silica are added to these Portland cements. Examples thereof include various mixed cements, eco-cement, white cement, super-hard cement, filler cement mixed with limestone fine powder and the like.

The polymer used in the present invention is, for example, a polymer for cement admixture specified in JIS A 6203, such as polymer dilversion in which fine particles of polymer are dispersed in water, rubber latex and resin emulsion. This refers to re-emulsifying powder resin obtained by drying a stabilizer added, etc., improving durability such as neutralization, salt damage, frost damage, etc., mortar adhesion strength, bending strength, tensile strength It is used for the purpose of improving strength characteristics.
For example, rubber latex such as acrylonitrile-butadiene rubber, styrene-butadiene rubber, chloroprene rubber, and natural rubber, ethylene-vinyl acetate copolymer, polyacrylic ester, vinyl acetate vinyl versatate copolymer, and styrene-acrylic Examples include acid ester copolymers, acrylic ester copolymers represented by acrylonitrile / acrylic acid esters, epoxy resins, liquid polymers represented by unsaturated polyester resins, and the like. Mixtures can be used.

The amount of the polymer of the present invention used is preferably 1 to 20 parts, more preferably 3 to 10 parts in terms of solid content, with respect to 100 parts of a binder composed of cement and an expansion material. If it is less than 1 part, the durability improvement effect is small, and if it exceeds 20 parts, strength development may be affected.

The expansion material used in the present invention is obtained by heat-treating clinker or clinker pulverized material containing free lime, hydraulic compound, and anhydrous gypsum in a carbon dioxide atmosphere to generate calcium carbonate.
It is preferred that free lime, hydraulic compound, anhydrous gypsum and calcium carbonate contain particles present in the same particle.

The expansion material of the present invention is a clinker or clinker pulverized material obtained by appropriately mixing and heat-treating CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, SiO ₂ raw material, and CaSO ₄ raw material with carbon dioxide gas. Is obtained.
The free lime referred to in the present invention is usually called f-CaO.
Table In the hydraulic compound referred to in the present invention, Auin represented by _{3CaO · 3Al 2 O 3 · CaSO} 4, 3CaO · SiO 2 (C 3 S for short) and 2CaO · _{SiO 2 (C} 2 S for short) Calcium silicate, 4CaO.Al ₂ O ₃ .Fe ₂ O ₃ (abbreviated as C ₄ AF), 6CaO.2Al ₂ O ₃ .Fe ₂ O ₃ (abbreviated as C ₆ A ₂ F), 6CaO.Al ₂ O Calcium ferrite such as calcium aluminoferrite represented by ₃ · Fe ₂ O ₃ (abbreviated as C ₆ AF), 2CaO · Fe ₂ O ₃ (abbreviated as C ₂ F), and one or two of them It is preferable to include the above. The form of calcium carbonate contained in the expansion material of the present invention is not particularly limited.

The CaO feed include such as limestone or slaked lime, as the _Al 2 _{O 3} raw material include such as bauxite and aluminum residual ash, etc. _Fe 2 _{O 3} copper Karami and commercial iron oxide as a raw material, as SiO ₂ raw material Includes silica, and examples of the CaSO ₄ raw material include dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum.
These raw materials may contain impurities, but this is not a problem as long as the effects of the present invention are not impaired. Examples of impurities include MgO, TiO ₂ , ZrO ₂ , MnO, P ₂ O ₅ , Na ₂ O, K ₂ O, Li ₂ O, sulfur, fluorine, and chlorine.

  Although the heat processing method of the clinker used for the expansion material of this invention is not specifically limited, It is preferable to bake at the temperature of 1100-1600 degreeC using an electric furnace, a kiln, etc., and 1200-1500 degreeC is more preferable. . If it is less than 1100 ° C., the expansion performance is not sufficient, and if it exceeds 1600 ° C., anhydrous gypsum may decompose.

  It is preferable that the ratio of each mineral contained in the clinker used for the expansion material of the present invention is in the following range. The content of free lime is preferably 10 to 70 parts, more preferably 40 to 60 parts, in 100 parts of clinker. As for content of a hydraulic compound, 10-50 parts are preferable in 100 parts of clinker, and 20-30 parts are more preferable. The content of anhydrous gypsum is preferably 1 to 50 parts and more preferably 20 to 30 parts in 100 parts of clinker. Outside the above range, the amount of expansion may become extremely large and the compression strength may decrease, or the amount of expansion may decrease.

  The mineral content can be confirmed by a conventional analysis method. For example, the pulverized sample can be applied to a powder X-ray diffractometer to confirm the produced mineral and analyze the data by the Rietveld method to quantify the mineral. Further, based on the identification result of chemical components and powder X-ray diffraction, the amount of minerals can also be obtained by calculation.

The treatment conditions of carbon dioxide gas for preparing the expansion material of the present invention are preferably in the following ranges.
The flow rate of carbon dioxide gas to the carbonation treatment container is preferably 0.01 to 0.1 L / min per 1 L of the volume of the carbonation treatment container. If it is less than 0.01 L / min, it may take time to carbonize the clinker, and even if it is increased to 0.1 L / min or more, further improvement in the carbonation treatment rate cannot be obtained, which is uneconomical. This condition is a condition when a crucible is used as a carbonation treatment container, the crucible is left in an electric furnace and carbon dioxide gas is allowed to flow, and the clinker and carbon dioxide gas are reacted by other methods. This is not the case.
It is preferable that the temperature of a carbonation processing container shall be 200-800 degreeC. If it is less than 200 ° C., the carbonation reaction of the clinker may not proceed, and if it is 800 ° C. or more, even if it is once changed to calcium carbonate, the decarbonation reaction occurs again, and calcium carbonate may not be generated.
In addition, carbonation of a clinker may carbonize an unpulverized clinker as it is, or may pulverize and then carbonize the clinker. The carbonation treatment container referred to in the present invention is not particularly limited, as long as the clinker and carbon dioxide gas can be brought into contact with each other and reacted, and an electric furnace or a fluidized bed heating furnace may be used, or the clinker is pulverized. It can be a mill.

The proportion of calcium carbonate is preferably 0.5 to 10 parts, more preferably 1 to 5 parts, in 100 parts of clinker. If the composition ratio of each mineral is not within the above range, excellent expansion performance, initial compressive strength, and storage stability may not be obtained.
The content of calcium carbonate can be quantified from a change in weight accompanying decarboxylation of calcium carbonate by a differential thermal balance (TG-DTA), differential thermal calorimetry (DSC), or the like.

The expansion material of the present invention preferably contains particles in which free lime, a hydraulic compound, anhydrous gypsum, and calcium carbonate are present in the same particle.
Whether or not free lime, hydraulic compound, anhydrous gypsum, and calcium carbonate are present in the same particle can be confirmed by an electron microscope or the like. Specifically, the expansion material is embedded in resin, surface treatment is performed with an argon ion beam, the structure of the particle cross section is observed, and elemental analysis is performed to confirm that calcium carbonate is present in the same particle. can do.

Fineness of the expansion material of the present invention is preferably 2000~9000cm ² / g in Blaine specific surface area, 3000~6000cm ² / g is more preferable. If it is less than 2000 cm ² / g, it expands over a long period of time and the hardened body structure is broken, and if it exceeds 9000 cm ² / g, the expansion performance may be lowered, the fluidity may be lowered, or the flow down may be increased.

  Although the usage-amount of the expansion material of this invention changes with mixing | blending of repair material, it is not specifically limited, Usually, 2-10 parts are preferable in 100 parts of binders which consist of cement and an expansion material, 4- 8 parts is more preferable. If it is less than 2 parts, sufficient expansion performance may not be obtained, and if it exceeds 10 parts, it may overexpand and may cause expansion cracks in the cured product.

The shrinkage reducing agent used in the present invention prevents the unreacted moisture from being lost and suppresses the drying shrinkage of the cement hydrate. Specifically, the shrinkage reducing agent is an alcohol-based, lower alcohol alkylene oxide derivative. Organic compounds having surface activity such as a system, glycol, glycol ether / amino alcohol derivative, and polyether can be used.
The amount of the shrinkage reducing agent used is preferably 1 to 8 parts with respect to 100 parts of the binder composed of cement and an expansion material. If the amount is less than 1 part, the shrinkage reduction effect may not be sufficient. If the amount exceeds 8 parts, not only the cost increases, but also the fluidity at the time of freshness may decrease, or the setting delay or strength may be reduced.

The fibers used in the present invention improve crack resistance and bending strength. Examples of the fiber include, but are not particularly limited to, polymer fibers such as vinylon fiber, propylene fiber, and nylon fiber, and inorganic fibers represented by steel fiber, glass fiber, and carbon fiber.
The amount of fibers used is preferably 0.05 to 0.7 part, more preferably 0.08 to 0.5 part with respect to 100 parts of cement mortar. If it is less than 0.05 part, the effect of improving the bending strength may not be exhibited, and if it exceeds 0.7 part, the fluidity of the mortar may be adversely affected. The length of the fiber is preferably 15 mm or less in view of the beauty of the iron finish surface.

The water reducing agent used in the present invention is not particularly limited, and is a general term for those having a dispersing action and air entraining action on cement, improving fluidity and increasing strength, and specifically, naphthalenesulfonic acid-based water reducing agents. Agent, melamine sulfonic acid-based water reducing agent, lignin sulfonic acid-based water reducing agent, and polycarboxylic acid-based water reducing agent can be used. Either water or powder can be used as the water reducing agent. When used as a powder, powder is preferred.
The amount of water reducing agent used is not particularly limited. Although there are differences in the water reduction rate depending on the type of water reducing agent and the appropriate amounts are different, usually 0.05 to 1.0 part in terms of solid content is preferable with respect to 100 parts of the binder composed of cement and expansion material. If it is less than 0.05 part, fluidity may not be sufficient, and if it exceeds 1.0 part, material separation may occur.

In the present invention, an antifoaming agent can be further used. An antifoaming agent can be used for the purpose of adjusting moderate air entrainment. The types of antifoaming agents include polyether defoamers such as alkylene oxide adducts of higher fatty acids, ethylene oxide adducts of glycols, silicone defoamers such as dimethyl silicone, and trialkyl phosphate deodorants such as tributyl phosphate. There are foaming agents.

The amount of the antifoaming agent used in the present invention is preferably 0.001 to 0.5 part, more preferably 0.003 to 0.1 part, with respect to 100 parts of the binder composed of cement and an expansion material. If it is less than 0.001 part, the defoaming effect is small, and even if it exceeds 0.5 part, the defoaming effect reaches its peak and may be uneconomical.

Examples of the fine aggregate used in the present invention include commonly used river sand, sea sand, crushed sand, silica sand, lightweight aggregate, and the like, and one or more of them can be used in combination. Yes, these dry sands are preferred when used as premixed products.
The maximum particle size of the fine aggregate is preferably 2 mm or less. If it is more than that, workability at the time of iron finishing may be impaired, and the finished surface may feel rough.
The amount of fine aggregate used is preferably 50 to 250 parts with respect to 100 parts of the binder. If it exceeds 250 parts, strength may be insufficient or workability may be impaired.

The amount of kneading water used in the present invention is not particularly limited, but is usually preferably 25 to 50% and more preferably 30 to 45% in terms of water / binder ratio. Outside this range, kneading may be difficult, and material separation or strength reduction may occur.

Furthermore, as additives (agents), thickeners, rust inhibitors, antifreeze agents, and setting modifiers, cement hardeners, clay minerals such as bentonite, ion exchangers such as zeolite, siliceous fine powder, carbonic acid One or more of calcium, calcium hydroxide, gypsum, and calcium silicate can be used as long as the object of the present invention is not substantially inhibited.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

"Experiment 1"
The CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, SiO ₂ raw material, CaSO ₄ raw material are blended so as to have the mineral ratio shown in Table 1, mixed and pulverized, and then heat treated at 1350 ° C. to synthesize clinker. Then, it was pulverized to 3000 cm ² / g with a Blaine specific surface area using a ball mill. 25 g of this pulverized product is put in an alumina crucible and set in an electric furnace, and the flow rate of carbon dioxide gas is reacted at 0.05 L / min per 1 L of electric furnace volume, at a firing temperature of 600 ° C. for 1 hr, to produce generated calcium carbonate The amount was quantified to obtain an expansion material. In addition, carbon dioxide treatment was performed under the same conditions as before clinker pulverization, and then an expanded material pulverized to a Blaine specific surface area of 3000 cm ² / g was also used (Experiment No. 1-8).

Using this expansive material, in 100 parts of a binder composed of cement and expansive material, 6 parts of the expansive material, 200 parts of aggregate and 100 parts of the polymer are uniformly mixed in a V-type blender. did.
In a room at 20 ° C., 42 parts of water was added to the repairing mortar composition, and the mixture was kneaded with a mortar mixer to form cement mortar. The results are shown in Table 1.
Furthermore, the same experiment was conducted on the repair cement composition subjected to the accelerated storage test.
In addition, as a comparison, calcium carbonate powder was mixed with an expansion material (experiment No. 1-9 to 11) in which clinker was not pulverized without carbon dioxide treatment, and expansion material in which clinker was pulverized without carbon dioxide treatment. A similar experiment was performed on the expansion material (Experiment No. 1-12).

(Materials used)
CaO raw material: Limestone Al ₂ O ₃ raw material: Bauxite Fe ₂ O ₃ raw material: Iron oxide SiO ₂ raw material: Silica CaSO ₄ raw material: Dihydrate gypsum Carbonate gas: Commercial cement: Normal Portland cement, Commercial fine aggregate: Limestone crushed sand Maximum particle size 1.2mm
Polymer: Acrylic-vinyl acetate-vinyl versatate copolymer Commercially available calcium carbonate powder: Commercially available, 200-mesh product

(Test method)
Mineral composition: Obtained by calculation based on the chemical composition and the identification result of powder X-ray diffraction.
Amount of calcium carbonate produced: Quantified from the change in weight associated with decarboxylation at 500 to 750 ° C. on a differential thermal balance (TG-DTA).
Mineral distribution in the expanded material particles: The expanded material is put into a silicon container, the epoxy resin is poured and cured, and the cured product is cross-sectional processed with an ion beam processing machine (SM-09010, manufactured by JEOL), and SEM- It confirmed with the EDS analyzer.
Length change rate: The length change rate up to 28 days of material age was measured according to the test method of JIS A 1171 polymer cement mortar.
Compressive strength: The compressive strength at the age of 28 days was measured according to the test method of JIS A 1171 polymer cement mortar.
Accelerated storage test: 25kg of repair mortar composition is packed in a packing material in which a high-density polyethylene sheet with a thickness of 20μm is attached to the interior of a triple kraft paper, sealed and sealed in a 35 ° C, 90% RH room for 1 month. Remained.

  According to Table 1, when comparing Experiment No.1-4 and Experiment No.1-12, the mineral content is the same, but the mixture with calcium carbonate has a higher shrinkage after accelerated storage. . This means that the presence of calcium carbonate particles alone has no effect on the improvement of storage stability, and by treating the clinker with carbon dioxide gas, a calcium carbonate film layer is formed on the clinker surface, which causes expansion. It can be inferred that the storage deterioration of the contributing minerals is suppressed.

"Experimental example 2"
The experiment was performed in the same manner as in Experimental Example 1 except that the expansion ratio 2 used in Experiment No. 1-4 was used and the addition rate was changed as shown in Table 2. The results are shown in Table 2.

According to Table 2, it can be seen that the rate of change in length decreases as the addition rate of the expansion material is increased, and shows a shrinkage compensation effect even after accelerated storage.

"Experiment 3"
Experimental Example 1 except that the expansion ratio used in Experiment No.1-4 was changed, and the addition rate of the polymer was changed as shown in Table 2, and the adhesion strength, compressive strength, and neutralization depth were measured. The same was done. The results are shown in Table 3.

(Test method)
Adhesion strength: Primer (ethylene-vinyl acetate emulsion) is applied to a sandblasted concrete plate 30 x 30 x 6 cm thick with a brush to a thickness of 150 g / m2, and repair mortar is applied to a thickness of 2 cm. The surface of the iron was finished to make a test specimen. After 28 days of age, the core was cut with a high speed cutter to the ground concrete part with a coring and drilled, and a special drawing jig was attached and measured with a Kenken-type adhesion tester. The specimen was cured at a temperature of 20 ° C., a humidity of 60%, and the adhesion area per specimen was 1600 mm ² .
Neutralization depth: compliant with JIS A 1171.

  According to Table 3, it can be seen that by adding 4 to 15 parts of the polymer, the adhesion strength is improved, the neutralization depth is also reduced, and the neutralization resistance is improved. In particular, when the polymer is 4 to 10 parts, the adhesion strength and the neutralization resistance are remarkably improved.

"Experimental example 4"
It was carried out in the same manner as in Experimental Example 1 except that a commercially available expansion material was processed and the fluidity and neutralization depth were measured. The results are shown in Table 3.

(Materials used)
Commercial expansion material A: 50 parts of free lime, 12 parts of Auin, 5 parts of calcium aluminoferrite (4CaO.Al ₂ O ₃ .Fe ₂ O ₃ ), 3 parts of calcium silicate (2CaO.SiO ₂ ), 30 parts of anhydrous gypsum.
Commercially available expandable material B: free lime 52 parts, calcium alumino ferrite _{(4CaO · Al 2 O 3 ·} Fe 2 O 3) 4 parts of calcium silicate (2CaO · _SiO 2) 10 parts of calcium silicate (3CaO · _SiO 2) 12 parts 20 parts anhydrous gypsum.

(Test method)
Flowability: Table flow value according to JIS-R5201

As shown in Table 4, when the expansion material is treated with CO ₂ , the flow down is reduced, and even when the commercial product is treated with CO ₂ , the increase in shrinkage due to storage is small, and the neutralization depth is the same as before accelerated storage. The value of the degree is shown, and it can be seen that the storage stability is improved. The reason for the improvement in neutralization resistance (storage stability) is that the digestion by hydration is delayed due to the formation of a calcium carbonate film layer around f-CaO in the clinker by the CO ₂ treatment. Further, it is considered that CO ₂ attack due to carbonation curing was slowed by further neutralization.

“Experimental Example 5”
Experimental example, except that a commercially available expansion material A and the expansion material of Experiment No. 4-2 in which it was treated with CO ₂ were used, the amount of polymer was changed as shown in Table 5, and the initial crack resistance was measured. 1 was performed. The results are shown in Table 5.

Initial crack resistance: 30 × 40 × 30 cm sandblasted concrete board with primer (ethylene-vinyl acetate emulsion) brushed to 150 g / m ² , in a constant temperature room at 30 ° C.-40% RH Then, the repair mortar was applied to a thickness of 2 cm, and the surface was troweled to obtain a test specimen. From 2 hours after the casting, the material was left for 24 hours while applying wind with a blower and checked for cracks.

According to Table 5, it can be seen that the initial crack resistance is improved by using a CO ₂ -treated expansion material and a polymer in combination.

"Experimental example 6"
Table 5 shows the carbon dioxide-treated product of the expandable material 2 with a fineness of 3000 cm ² / g used in Experiment No. 1-4 and the commercial expandable material A used in Experiment No. 4-1, in 100 parts of binder. Except having used the shrinkage reducing agent shown, it carried out similarly to Experimental example 1, and performed the length change rate and the crack confirmation test. The results are shown in Table 6.

(Materials used)
Shrinkage reducing agent: polyoxyalkylene derivative, commercially available product

(Test method)
Crack confirmation test: A specimen was prepared in a constant temperature room at 20 ° C.-80% RH according to JHS432 5.1 Crack Resistance Test Method. After moving to a constant temperature room of 30 ° C.-40% RH at 48 hours of age, it was left until the age of 28 days while blowing air with a blower and checked for cracks.

From Table 6, it can be seen that by using 1 to 8 parts of the shrinkage reducing agent together with the expansion material, the rate of change in length is reduced, and the shrinkage reducing effect is exhibited. In particular, when the shrinkage reducing agent is 3 to 8 parts, the rate of change in length is extremely small, and further, a high compressive strength is maintained.

"Experimental example 7"
Performed in the same manner as in Experimental Example 1 except that 5 parts in 100 parts of the binder and the fibers and water reducing agents shown in Table 7 were used for the expansion material 2 having a fineness of 3000 cm ² / g used in Experiment No. 1-4. The fluidity of the mortar (Experimental Example 4) and the bending toughness were measured. The results are shown in Table 7.

(Materials used)
Fibers: Vinylon fiber, fiber length 6 mm, fiber diameter 0.027 mm, convergence type, commercial water reducing agent: naphthalene sulfonic acid, commercial product, powder

(Test method)
Bending toughness: JCSE-G 552-2010 The bending toughness of steel fiber reinforced concrete and the bending toughness test method (draft) were measured, and the bending toughness at 28 days of age was measured.

From Table 7, the addition of 0.05 to 0.7 parts of fibers improves the bending toughness, while the addition of 0.01 to 0.50 parts of water reducing agent improves the fluidity. Recognize.

  By adopting the repair mortar composition of the present invention, the flow down is suppressed (extension of work time), the resistance to initial cracks is improved, and even when stored for a long time, the mortar physical properties are almost the same as immediately after production. It has excellent effects such as not impairing the product value, and can be widely used in the civil engineering and construction fields.

Claims (4)

It contains Portland cement, expansion material, polymer and fine aggregate, and the expansion material is a clinker or clinker pulverized product containing free lime, hydraulic compound, and anhydrous gypsum, and heat-treated in a carbon dioxide atmosphere. It is an expansion material obtained, and in 100 parts of a binder made of Portland cement and an expansion material, the expansion material is 2 to 10 parts, the polymer is 1 to 20 parts per 100 parts of the binding material, and the fine aggregate is 50 -250 parts of mortar composition for repair characterized by the above-mentioned. Furthermore, the repair mortar composition of Claim 1 which contains 1-8 parts of shrinkage reducing agents with respect to 100 parts of binders. Furthermore, the repair mortar composition of Claim 1 or 2 which contains 0.05-0.7 part of fibers with respect to 100 parts of binders. Furthermore, the mortar composition for repair of any one of Claims 1-3 containing a water reducing agent.