JP7777941B2 - Repair material, repair mortar composition and hardened body - Google Patents

Description

The present invention relates to a repair material, a repair mortar composition, and a hardened product.

Concrete structures deteriorate due to salt damage, neutralization, freezing and thawing, chemical corrosion, etc., and there is a risk of cracks or loosening on the surface. As a countermeasure, deteriorated areas are identified by hammering tests, etc., and then removed using electric picks, air picks, water jets, etc., and repair work is carried out to fill in the gaps with new repair materials.
In small-scale repair work where the repair cross section is small, cross section repair is often carried out by mixing polymer cement mortar and applying it with a trowel (see, for example, Patent Documents 1 and 2).

When repairing with a trowel or other method, materials that are easy to work with, such as rapid hardening, ease of mixing, and ability to be applied thickly, are required. To achieve this, materials that contain inorganic fine powders such as fly ash and silica fume, as described in Patent Documents 1 and 2, and materials that contain cellulose ethers, as described in Non-Patent Document 1 and Patent Documents 3 to 6, are used to give the mortar appropriate viscosity and resistance to sagging. Cellulose ethers increase viscosity and improve water retention, but they also have the problem of cracks occurring even after repair, necessitating re-repairs.

Furthermore, as in Patent Document 7, fibers have been proposed that have a self-healing effect that promotes the self-healing of cracks in hardened cement bodies, even if cracks occur in the hardened cement body. However, when mixed in, they have problems such as a decrease in fluidity, poor workability, and the self-healing effect takes time.

In addition, conventional repair materials have low fluidity, causing cracks to form in the hardened material, and even after cracks occur, they have a low self-healing effect, resulting in low long-term strength and wear resistance.

Japanese Patent Application Laid-Open No. 2001-322858 Japanese Patent Application Laid-Open No. 2003-89565 Japanese Patent Application Publication No. 11-349364 Japanese Patent Application Laid-Open No. 2000-103662 Japanese Patent Application Laid-Open No. 2000-128617 Japanese Patent Application Publication No. 06-219807 Japanese Patent Application Laid-Open No. 2017-222555

Edited by Shinji Nagatomo: New Applications and Markets of Water-Soluble Polymers, CMC Publishing, pp. 173-192, 1988

The present invention therefore aims to provide a repair material, repair mortar composition, and hardened product that have high fluidity, can enhance the self-healing effect, and become dense through natural carbonation, improving compressive strength and abrasion resistance.

The present invention has been made to solve the above-mentioned problems, and as a result of various efforts made by the inventors to solve the above-mentioned problems, they discovered that by adding a repair material admixture containing a specific non-hydraulic material, it is possible to further increase compressive strength and abrasion resistance, and improve durability, and have thereby completed the present invention. The gist of the present invention is as follows.
[1] A repair material comprising a grout admixture containing one or more non-hydraulic compounds selected from the group consisting of gamma-2CaO.SiO ₂ , 3CaO.2SiO ₂ , alpha-CaO.SiO ₂ , and calcium magnesium silicate, and cement, a polymer emulsion, fibers, and fine aggregate.
[2] The repair material according to [1], wherein the non-hydraulic compound contains Li, and the Li content in the non-hydraulic compound is 0.001 to 1.0 mass% in terms of oxide.
[3] The repair material according to any one of [1] to [2], wherein the amount of SO ₃ in the repair material is 0.5% by mass or more and 10.0% by mass or less, and the amount of MgO is 0.1% by mass or more and 3.0% by mass or less. Repair material.
[4] A repair material according to any one of [1] to [3], further containing an expanding agent.
[5] The repair material according to any one of [1] to [4], further comprising a hardening agent, wherein the hardening agent contains calcium aluminate, the calcium aluminate has a CaO/Al ₂ O ₃ molar ratio of 1.0 or more and 3.0 or less, and the content of the calcium aluminate is 2 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of the cement.
[6] A repair material described in any one of [1] to [5], wherein the content ratio of the fine aggregate is 40 parts by mass or more and 300 parts by mass or less per 100 parts by mass of the cement.
[7] A repair mortar composition containing the repair material according to any one of [1] to [6] and water.
[8] A hardened body obtained by using the repair mortar composition described in [7].

The present invention provides repair materials, repair mortar compositions, and hardened products that have high fluidity, can enhance the self-healing effect, and become dense through natural carbonation, improving compressive strength and abrasion resistance.

The present invention will be described in detail below.
In this specification, parts and mass % are based on mass unless otherwise specified.
The repair mortar composition as used herein is a general term for pastes containing no coarse aggregate and mortars containing fine aggregate.

The repair material of the present invention comprises a repair admixture containing one or more non-hydraulic compounds selected from the group consisting of γ-2CaO·SiO ₂ , 3CaO·2SiO ₂ , α-CaO·SiO ₂ , and calcium magnesium silicate, as well as cement, a polymer emulsion, fibers, and fine aggregate.

[Repair admixture]
<Non-hydraulic compound>
(γ-2CaO・SiO ₂ )
γ- _2CaO.SiO2 is known as a low-temperature phase of the compound expressed _as 2CaO.SiO2, and is completely different from the high-temperature phases α-2CaO.SiO2, α'- _2CaO.SiO2 , and _β - _2CaO.SiO2 . Although all of these are expressed as _2CaO.SiO2 , they have different crystal structures and densities.

(3CaO・2SiO ₂ )
_3CaO.2SiO2 is a mineral called rankinite, which is a pseudowollastonite containing CaO. It is a chemically stable mineral with no hydration activity, but has a strong effect in promoting carbonation.

(α-CaO・SiO ₂ )
α-CaO.SiO ₂ (α-type wollastonite) is known as a high-temperature phase among compounds expressed as CaO.SiO ₂ , and is completely different from the low-temperature phase β-CaO.SiO _2. Although both are expressed as CaO.SiO ₂ , they have different crystal structures and densities.

Naturally occurring wollastonite is a low-temperature phase of β- _CaO.SiO2 . β- _CaO.SiO2 has needle-like crystals and is used as an inorganic fibrous material such as wollastonite fiber, but it does not have the carbonation (salt) promoting effect of α- _CaO.SiO2 according to this embodiment.

(Calcium magnesium silicate)
Calcium magnesium silicate is a general term for CaO-MgO- _SiO2 compounds, but in this embodiment, merwinite, which is expressed as _{3CaO.MgO.2SiO2} ( _{C3MS2 )} , is preferred, as merwinite achieves a significant carbonation (salt) promotion effect.

The non-hydraulic compound may be one type or two or more types, but the Li content in the non-hydraulic compound is 0.001 to 1.0%, preferably 0.005 to 1.0%, more preferably 0.010 to 0.90%, and even more preferably 0.015 to 0.80%, calculated as oxide. When the Li content is 0.001% or more and 1.0% or less, calculated as oxide, a carbonation-promoting effect is obtained. The Li content calculated as oxide can be measured by the method described in the Examples.
When two or more non-hydraulic compounds are used, the Li content refers to the Li oxide content relative to the total of the two or more non-hydraulic compounds.

Among the above non-hydraulic compounds, γ- _2CaO.SiO2 is particularly preferred because it requires less energy to grind than other compounds due to the powdering phenomenon known as dusting that occurs during production, it has a significant effect of promoting carbonation over the long term, and when combined with blast furnace cement at a low water-binder ratio, it has a very significant effect of inhibiting carbonation.

The non-hydraulic compound according to this embodiment is obtained by blending a CaO raw material, a _SiO2 raw material, an MgO raw material, and a Li raw material in a predetermined molar ratio and then heat-treating the blend. Examples of CaO raw materials include calcium carbonate (e.g., limestone), calcium hydroxide (e.g., slaked lime), by-product slaked lime (e.g., acetylene-by-product slaked lime), and fine powder generated from waste concrete blocks. Examples of _SiO2 raw materials include silica stone, clay, and various siliceous dusts generated as industrial by-products, such as silica fume and fly ash. Examples of MgO raw materials include magnesium hydroxide, basic magnesium carbonate, and dolomite. Examples of Li raw materials include lithium carbonate. Note that if the CaO raw material, _SiO2 raw material, and MgO raw material contain Li, there is no need to add a Li raw material. In order to reduce non-energy-derived _CO2 emissions during heat treatment, one or more types of industrial by-products containing CaO can be used, such as by-product slaked lime, fine powder generated from waste concrete blocks, municipal waste incineration ash, and sewage sludge incineration ash. Among these, the use of by-product slaked lime, which contains fewer impurities than other industrial by-products, is more preferable.

Examples of by-product slaked lime include acetylene by-product slaked lime, such as by-product slaked lime produced in the acetylene gas production process using the calcium carbide method (there are wet and dry products depending on the acetylene gas production method), and by-product slaked lime contained in dust captured in the wet dust collection process of a calcium carbide electric furnace. By-product slaked lime contains, for example, 65 to 95% (preferably 70 to 90%) calcium hydroxide, 1 to 10% calcium carbonate, and 0.1 to 6.0% (preferably 0.1 to 3.0%) iron oxide. These proportions can be confirmed by X-ray fluorescence analysis and mass loss determined by differential thermogravimetric analysis (TG-DTA) (Ca(OH) ₂ : around 405°C to 515°C, CaCO ₃ : around 650°C to 765°C). The volume average particle size measured by laser diffraction/scattering is about 50 to 100 μm. Furthermore, the moisture content measured by the loss on drying method in JIS K 0068 "Method for measuring moisture content in chemical products" is preferably 10% or less. Furthermore, sulfur compounds such as CaS, Al ₂ S ₃ , and CaC ₂ ·CaS may be contained, but it is preferable that the content be 2% or less.

The aforementioned heat treatment at high temperatures of 1,000°C or higher can be carried out in, for example, a rotary kiln or electric furnace, although there are no particular limitations. The heat treatment temperature is not uniquely determined, but is typically in the range of approximately 1,000 to 1,800°C, and often in the range of approximately 1,200 to 1,600°C.

This embodiment can also use industrial by-products containing the non-hydraulic compounds mentioned above. In such cases, impurities will coexist. Examples of such industrial by-products include steelmaking slag.

The CaO raw material, _SiO2 raw material, and MgO raw material may contain impurities, but these do not pose a problem as long as they do not impair the effects of the present _invention . Specific examples of impurities include _Al2O3 , _Fe2O3 , _TiO2 , _MnO , _Na2O , _K2O , _S , _P2O5 , F, _B2O3 , and _chlorine . Coexisting compounds include free calcium oxide, calcium hydroxide, calcium aluminate, calcium aluminosilicate, calcium ferrite, calcium aluminoferrite, calcium phosphate, calcium borate, magnesium silicate, leucite (K ₂ O, Na ₂ O).Al ₂ O _{3.SiO 2 ,} spinel MgO.Al ₂ O ₃ , magnetite Fe ₃ O ₄ , and sulfur compounds such as the above-mentioned CaS, Al ₂ S ₃ , and CaC _2.CaS .

Of these impurities, the content of S (sulfur) in the non-hydraulic compound is preferably 1.0% or less, more preferably 0.7% or less, and even more preferably 0.5% or less, calculated as oxide ( _SO3 ). A content of 1.0% or less provides a sufficient carbonation (salt) promotion effect, and also allows the setting and hardening properties to be within an appropriate range. The S content calculated as oxide ( _SO3 ) can be measured by X-ray fluorescence analysis. Note that S (sulfur) may be present in the non-hydraulic compound in an amount of about 2% calculated as oxide.

In this repair admixture, the content of non-hydraulic compounds (when multiple types are included, the content is the total content) is preferably 65% or more, more preferably 70% or more, and even more preferably 75% or more. Note that hydraulic _2CaO.SiO2 other than γ- _2CaO.SiO2 can also be mixed in, up to a maximum of 35%.

The content of γ- _2CaO.SiO2 in this repair admixture is preferably 35% or more, more preferably 45% or more. There is no particular upper limit to the content of γ- _2CaO.SiO2 . Among steelmaking slags, electric furnace reduction-stage slag or stainless steel slag, which have a high content of γ- _2CaO.SiO2 , is preferred.

As chemical components, it is more preferable that the cement admixture contains 0.002 to 0.5 parts of Li ₂ O, 60 to 70 parts of CaO, 30 to 45 parts of SiO ₂ and 0.5 to 5 parts of Al ₂ O ₃ per 100 parts of the cement admixture.
Furthermore, as chemical components, the total amount of Li ₂ O, CaO, SiO ₂ and Al ₂ O ₃ is preferably 90 parts or more, and more preferably 95 to 100 parts, per 100 parts of the cement admixture.

Methods for quantifying the non-hydraulic compounds in this repair admixture include the Rietveld method using powder X-ray diffraction.

The Blaine specific surface area of this grout admixture is not particularly limited, but is preferably 1,500 cm ² /g or more, with the upper limit being preferably 8,000 cm ² /g or less. Of these, 2,000 to 6,000 cm ² /g is more preferred, and 4,000 to 6,000 cm ² /g is most preferred. A Blaine specific surface area of 2,000 cm ² /g or more provides good material separation resistance and a sufficient carbonation (salt) promotion effect. Furthermore, a Blaine specific surface area of 8,000 cm ² /g or less reduces the grinding power required for grinding, making it economical, and also inhibits weathering and reduces deterioration of quality over time.

[cement]
The cement used in the present invention is not particularly limited, and examples include various cements such as normal, early-strength, ultra-early-strength, low-heat, and moderate-heat cements, various mixed cements obtained by mixing these cements with blast furnace slag, fly ash, or silica fume, environmentally friendly cements (ecocement) made from municipal waste incineration ash or sewage sludge incineration ash, and commercially available fine particle cements. It is also possible to use various cements and mixed cements that have been finely powdered. Furthermore, cements prepared by increasing or decreasing the amount of components (such as gypsum) normally used in cements can also be used.
In the present invention, it is preferable to select ordinary Portland cement or high-early-strength Portland cement from the viewpoints of high fluidity, improved self-healing effect, increased compressive strength, and improved abrasion resistance.

From the viewpoints of production costs and strength development, the cement used in the present invention preferably has a Blaine specific surface area value of 2,500 cm ² /g or more and 7,000 cm ² /g or less, more preferably 2,750 cm ² /g or more and 6,000 cm ² /g or less, and even more preferably 3,000 cm ² /g or more and 4,500 cm ² /g or less.
The Blaine specific surface area value is determined in accordance with JIS R 5201 (physical testing method for cement).

[Polymer emulsion]
The polymer emulsion used in the present invention is not particularly limited, and examples thereof include rubber latexes such as acrylonitrile-butadiene rubber, styrene-butadiene rubber, chloroprene rubber, and natural rubber; resin emulsions such as ethylene-vinyl acetate copolymers, acrylic acid ester copolymers typified by polyacrylic acid esters, styrene-acrylic acid ester copolymers, and acrylonitrile-acrylic acid esters; and vinyl acetate-vinyl versatate copolymers.
The polymer comes in a re-emulsifiable powder form or a liquid form, and is used to improve adhesion to the substrate and the durability of the mortar.

The polymer emulsion content is preferably 1 to 15 parts by mass, more preferably 2 to 12 parts by mass, and even more preferably 3 to 10 parts by mass, in terms of solid content per 100 parts by mass of cement. Having the polymer emulsion content within the above range increases fluidity and improves the self-healing effect.

[fiber]
The fibers used in the present invention improve buildability and crack resistance.
The type of fiber is not particularly limited, but examples include polymer fibers such as vinylon fiber, propylene fiber, acrylic fiber, nylon fiber, and aramid fiber, and inorganic fibers such as steel fiber, glass fiber, carbon fiber, and fibers made by melt-spinning rocks such as basalt.

The fiber content is preferably 0.02 to 1.5 parts by mass, more preferably 0.03 to 1.2 parts by mass, and even more preferably 0.05 to 1.0 parts by mass, per 100 parts by mass of cement. Using a fiber content of 0.02 parts by mass or more can fully demonstrate the effect of improving sagging. Furthermore, a fiber content of 1.5 parts by mass or less can enhance fluidity and improve self-healing properties. From the perspective of the aesthetic appearance of the trowel-finished surface, the fiber length is preferably 15 mm or less, more preferably 12 mm or less, and even more preferably 10 mm or less. There is no particular lower limit to the fiber length, and it may be, for example, 1 mm or more.

[Fine aggregate]
The chemical components of the fine aggregate used in the present invention preferably have a CaO content of 85% by mass or more and a _SiO2 content of 0.2% by mass to 15% by mass. When the CaO content and the _SiO2 content are within the above ranges as chemical components of the fine aggregate, a repair material can be obtained that has high fluidity, excellent carbonation resistance, excellent bond strength to reinforcing bars, and excellent rust prevention.
The proportion of CaO is preferably 87% by mass or more, more preferably 89% by mass or more, and even more preferably 91% by mass or more. The upper limit of the proportion of CaO is not particularly limited, but is preferably 99% by mass or less, and more preferably 98.5% by mass or less.
The proportion of _SiO2 is preferably 0.25% by mass or more and 13% by mass or less, more preferably 0.3% by mass or more and 11% by mass or less, and even more preferably 0.4% by mass or more and 10% by mass or less.
In order to ensure that the chemical composition of the fine aggregate falls within the above and later-described ranges, silica sand, calcite, scapolite, a metamorphic rock, quartz, a igneous rock, potassium feldspar, and other rocks are mixed to prepare the fine aggregate. The chemical composition is confirmed by X-ray fluorescence analysis and adjusted to fall within the ranges specified in the present invention. The chemical composition of the fine aggregate used in the present invention is calculated in terms of oxides.

The fine aggregate used in this invention can be the same as that used in ordinary cement mortar and concrete. That is, river sand, crushed stone, crushed sand, lime sand, silica sand, colored sand, artificial lightweight aggregate, etc. can be used, and combinations of these are also possible. In particular, for applications aimed at increasing fluidity and achieving self-healing effects, the use of siliceous silica sand or lime sand is preferred, and the particle size of the fine aggregate is preferably JIS No. 6 to 8.

The content of fine aggregate is preferably 40 to 300 parts by mass, more preferably 45 to 275 parts by mass, and even more preferably 50 to 250 parts by mass, per 100 parts by mass of cement. Having the fine aggregate particle size within the above range ensures sufficient fluidity, self-healing effects, improved abrasion resistance, and low shrinkage.

[Li]
The repair admixture can further contain Li in the non-hydraulic compound, and the content can be 0.001 to 1.0 mass % in terms of oxide. It is presumed that Li promotes the formation of vaterite, a type of calcium carbonate, during the carbonation of C-S-H (calcium silicate hydrate), and that carbonation (salt) results in a denser hardened state, which is likely to increase strength, improve abrasion resistance, and reduce shrinkage.
Here, "Li is contained in the non-hydraulic compound" means that the non-hydraulic compound contains _Li2O as a chemical composition (its presence can be confirmed by ICP atomic emission spectroscopy), but _Li2O is not identified by X-ray diffraction measurement (no clear peak for _Li2O is observed), and does not simply mean that the non-hydraulic compound and the Li compound are physically mixed. This state can be obtained by mixing the respective raw materials and heat treating them at a high temperature of 1,000°C or higher. Each component will be explained below.

[ _SO3 and MgO]
The amounts of SO ₃ and MgO contained in the repair material can be adjusted, for example, by adding an admixture containing SO ₃ and MgO when preparing the repair material. The amounts of SO ₃ and MgO can also be measured by X-ray fluorescence spectroscopy (XRF).

The amount of _SO3 contained in the repair material in the present invention is preferably 0.5 mass% or more, more preferably 0.7 mass% or more, and even more preferably 0.8 mass% or more, from the viewpoint of increasing the fluidity of the repair material and improving the self-healing effect. Also, from the same viewpoint, the amount of _SO3 contained in the repair material is required to be 10.0 mass% or less, preferably 8.0 mass% or less, and even more preferably 6.0 mass% or less.

From the viewpoint of increasing the fluidity of the repair material and improving its self-healing effect, the amount of MgO contained in the repair material is preferably 0.1% by mass or more, more preferably 0.15% by mass or more, and even more preferably 0.2% by mass or more. From the same viewpoint, the amount of MgO contained in the repair material is preferably 3.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less.

[Expansive material]
The repair material of the present invention can further contain an expansive material. The expansive material used in the present invention is not particularly limited, and any material that generates expansive hydrates and suppresses bleeding can be used.
Known expansive materials include free lime, free magnesia, calcium ferrite, ettringite, lime, and ettringite-lime composites, and are not particularly limited, but from the viewpoint of long-term stability, those containing free lime are preferred. Examples of those containing free lime include free lime-anhydrous gypsum systems, free lime-hydraulic compound systems, and free lime-hydraulic compound-anhydrous gypsum systems.
Expansion materials and static crushing materials are commercially available from various companies, and representative examples include "Denka CSA#20" and "Denka Power CSA" manufactured by Denka Company Ltd., "Expan,""Hyperexpan,""N-EX," and "Blister" manufactured by Pacific Materials Corporation, and crushed products thereof.

The particle size of the expanding agent used in the present invention is not particularly limited, but a Blaine specific surface area value in the range of 2,000 cm ² /g to 25,000 cm ² /g is preferred, 2,200 cm ² /g to 15,000 ^{cm 2} /g is more preferred, and 2,400 cm ² /g to 10,000 cm ² /g is even more preferred. When the Blaine specific surface area value of the expanding agent is equal to or greater than the above lower limit, bleeding can be suppressed. Furthermore, when the Blaine specific surface area value of the expanding agent is equal to or less than the above upper limit, sufficient expandability can be obtained.

The content of the expansive agent used in the present invention is preferably 0.5 to 20 parts by mass, more preferably 1.0 to 18 parts by mass, and even more preferably 2 to 15 parts by mass, per 100 parts by mass of cement. When the content of the expansive agent is above the above lower limit, it becomes easier to achieve a crack suppression effect. When the content of the expansive agent is below the above upper limit, good strength development is achieved. When the content of the expansive agent is within the above range, it becomes easier to create a repair material that satisfies the effects of the present invention, i.e., a repair material that has increased fluidity, improved self-healing effects, and low shrinkage.

[Sudden hardwood]
The repair material of the present invention comprises a repair admixture containing one or more non-hydraulic compounds selected from the group consisting of γ-2CaO·SiO ₂ , 3CaO·2SiO ₂ , α-CaO·SiO ₂ , and calcium magnesium silicate, as well as cement, an expansive agent, a polymer emulsion, fibers, and fine aggregate, and may contain a rapid hardening agent in order to promote setting and increase strength in a short period of time.
The hardening accelerator used in the present invention is not particularly limited as long as it promotes setting and increases strength in a short period of time. Examples of hardening accelerators that promote setting include calcium salts of organic acids such as calcium formate, nitrates, sulfates, carbonates, thiocyanates, amines, maleic anhydride, silicates such as water glass, aluminum sulfate, and aluminum salts such as alum, calcium aluminate (calcium aluminate), and aluminates. Among these, aluminates are preferred from the viewpoint of strength development, and calcium aluminate (CA) is preferred. Calcium aluminate is more preferred from the viewpoint of improving strength development when used in combination with gypsum. The amount of gypsum used is preferably 80 to 250 parts by mass, more preferably 90 to 220 parts by mass, and even more preferably 100 to 200 parts by mass, per 100 parts by mass of calcium aluminate. Having a gypsum content above the above lower limit facilitates rapid hardening. Furthermore, when the gypsum content is equal to or less than the upper limit, the strength development and self-healing effect are good. When the gypsum content is within the above range, it is easy to obtain a repair material that improves the self-healing effect and satisfies the effects of the present invention.
Calcium aluminate is a general term for a substance with hydration activity, primarily composed of CaO and _Al2O3 , obtained by mixing calcia raw materials and _alumina raw materials, firing them in a kiln, or melting them in an electric furnace, and cooling them. Either crystalline or amorphous calcium aluminate can be used. It is a material with a fast setting time and high early strength development. Alumina cement is a typical example of calcium aluminate, and commercially available products are usually used. For example, Alumina Cement No. 1 and Alumina Cement No. 2 can be used. Among these, amorphous calcium aluminate, which is melted and then rapidly cooled, is preferred because it sets in a shorter time than alumina cement and subsequently develops high early strength.
Among calcium aluminates, the molar ratio of CaO to Al ₂ O ₃ (CaO/Al ₂ O ₃ molar ratio) is preferably 1.0 or more and 3.0 or less, and more preferably 1.7 or more and 2.5 or less. When the molar ratio is within the above range, the curing time can be further shortened and the early strength development can be improved.

In the present invention, the impurity content in calcium aluminate is preferably 15% by mass or less, more preferably 10% by mass or less, from the viewpoint of early strength development. Here, impurities refer to substances other than CaO and _Al2O3 . If the impurity content exceeds 15% by _mass , the curing process takes a long time and the material may not solidify at low temperatures. Typical examples of impurities include silicon oxide, magnesium oxide, and sulfur oxide. Other examples include organic substances, alkali metal oxides, alkaline earth metal oxides, titanium oxide, iron oxide, alkali metal halides, alkaline earth metal halides, alkali metal sulfates, and alkaline earth metal sulfates partially substituted or dissolved in CaO or _Al2O3 . However, the impurities are not limited to _these .

The vitrification ratio of the calcium aluminate used in the present invention is preferably 70% by mass or more, more preferably 90% by mass or more, in terms of reaction activity. If the vitrification ratio is less than 70% by mass, the initial strength development may decrease. The vitrification ratio of the calcium aluminate is preferably 70% by mass or more, more preferably 90% by mass or more, in terms of reaction activity. The vitrification ratio is determined by measuring the main peak area S of the crystalline mineral of a measurement sample in advance by powder X-ray diffraction, heating the sample at 1,000°C for 2 hours, followed by slow cooling at a cooling rate of (1 to 10°C)/min, and determining the main peak area _S of the crystalline mineral after heating by powder X-ray diffraction. Using these values of _S0 and S, the vitrification ratio _X is calculated using the following formula:
Vitrification rate _X (mass%) = 100 × (1 − S/S ₀ )
In terms of early strength development, the particle size of calcium aluminate is preferably a Blaine specific surface area value of 3,000 cm ² /g or more, more preferably 5,000 cm ² /g or more. When the particle size of calcium aluminate is equal to or greater than the above lower limit, the curing time is shortened, resulting in good early strength development and good self-healing performance.

The content of the hardening agent used in the present invention is preferably 1 to 30 parts by mass, more preferably 3 to 25 parts by mass, and even more preferably 5 to 20 parts by mass, per 100 parts by mass of cement. Furthermore, when calcium aluminate is used as the hardening agent, the content of calcium aluminate is preferably 2 to 20 parts by mass, more preferably 3 to 18 parts by mass, and even more preferably 4 to 15 parts by mass, per 100 parts by mass of cement. Having a hardening agent content above the lower limit above facilitates early hardening and crack suppression. Furthermore, having a hardening agent content below the upper limit above improves strength development. Having a hardening agent content within the above range facilitates improving the self-healing effect, resulting in a repair material that satisfies the effects of the present invention.

[Water reducing agent]
The water-reducing agent used in the present invention helps disperse each material and also plays a role in imparting fluidity to the mixed repair mortar.

The water-reducing agent used in the present invention is not particularly limited, and examples thereof include naphthalene-based water-reducing agents, melamine-based flow-through water-reducing agents, aminosulfonic acid-based water-reducing agents, and polycarboxylic acid-based water-reducing agents. One or more of these water-reducing agents can be used in the present invention.
Specific examples of water-reducing agents include naphthalene-based water-reducing agents such as "Leobuild SP-9 Series" manufactured by NMB Corporation, "Mighty 2000 Series" manufactured by Kao Corporation, and "Sunflow HS-100" manufactured by Nippon Paper Industries Co., Ltd. Melamine-based water-reducing agents such as "Sikament 1000 Series" manufactured by Sika Japan and "Sunflow HS-40" manufactured by Nippon Paper Industries Co., Ltd. Aminosulfonic acid-based water-reducing agents such as "Paric FP-200 Series" manufactured by Fujisawa Pharmaceutical Co., Ltd. Polycarboxylic acid-based water-reducing agents such as "Leobuild SP-8 Series" manufactured by NMB Corporation, "Darlex Super 100PHX" manufactured by Grace Chemicals, and "Chupol HP-8 Series" and "Chupol HP-11 Series" manufactured by Takemoto Oil & Fat Co., Ltd.
Powdered water-reducing agents are also available. Specific examples of naphthalene-based water-reducing agents include "Mighty 100" manufactured by Kao Corporation, "Sanyo Revellon P" manufactured by Sanyo Chemical Industries, Ltd., and "Celluflow 110P" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. Melamine-based water-reducing agents include "Melment F10M" manufactured by BASF Pozzolith. Polycarboxylic acid-based water-reducing agents include "Queenflow 750" manufactured by Mitsubishi Chemical Corporation and "CAD9000P" manufactured by Kao Corporation.

The content of the water-reducing agent is preferably 0.1 to 2 parts by mass, in terms of solids, per 100 parts by mass of cement, more preferably 0.2 to 1.8 parts by mass, and even more preferably 0.3 to 1.0 part by mass. By ensuring that the content of the water-reducing agent is at or above the lower limit, sufficient fluidity can be achieved. Furthermore, by ensuring that the content of the water-reducing agent is at or below the upper limit, material separation can be suppressed.

[Silica fine powder]
The repair material of the present invention can contain, in addition to cement, expansive agent, polymer emulsion, fiber, and fine aggregate, silica fine powder in order to improve strength development, acid resistance, ensure usable time, and improve dimensional stability.

Examples of the siliceous fine powder include latent hydraulic substances such as ground granulated blast furnace slag, fly ash, and pozzolanic substances such as silica fume, with silica fume being preferred.
Although there are no limitations on the type of silica fume, from the viewpoint of fluidity, it is more preferable to use silica fume containing 10% or less of _ZrO2 as an impurity or acidic silica fume. Acidic silica fume refers to silica fume that, when 1 g of silica fume is added to 100 cc of pure water and stirred, the supernatant liquid exhibits an acidic pH of 5.0 or less.

The fineness of the siliceous fine powder is not particularly limited, but typically, the Blaine value of granulated blast furnace slag and fly ash is in the range of 3,000 cm ² /g or more and 9,000 cm ² /g or less, and the BET specific surface area of silica fume is in the range of 20,000 cm ² /g or more and 300,000 cm ² /g or less.

The content of siliceous fine powder is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and even more preferably 3 to 10 parts by mass, per 100 parts by mass of cement. Having a content of siliceous fine powder above the lower limit mentioned above can improve strength development, enhance acid resistance, ensure usable life, and provide good dimensional stability. Furthermore, having a content of siliceous fine powder below the upper limit mentioned above can improve fluidity and enhance the self-healing effect.

[others]
In the present invention, one or more of the following may be used to the extent that they do not adversely affect performance: setting regulators, air-entraining agents, rust inhibitors, water repellents, antibacterial agents, colorants, antifreeze agents, finely divided limestone powder, finely divided slowly cooled blast furnace slag, admixtures such as sewage sludge incineration ash and its molten slag, municipal waste incineration ash and its molten slag, and pulp sludge incineration ash; antifoaming agents; thickeners; shrinkage reducing agents; clay minerals such as bentonite and sepiolite; and anion exchangers such as hydrotalcite.

In the repair material of the present invention, the method for mixing the materials is not particularly limited, and the materials may be mixed at the time of application, or some or all of the materials may be mixed in advance.
As the mixing device, any existing device such as a tilting mixer, an omni mixer, a Henschel mixer, a V-type mixer, or a Nauta mixer can be used.

The repair mortar composition of the present invention contains the repair material of the present invention and water, and is prepared by kneading the repair material and water.
The amount of mixing water in the present invention is not particularly limited, as it varies depending on the purpose and application of use and the content ratio of each material, but is preferably 10 to 70 parts by mass, more preferably 14 to 65 parts by mass, and even more preferably 16 to 60 parts by mass, per 100 parts by mass of repair material. By having the amount of mixing water equal to or greater than the above-mentioned lower limit, it is possible to prevent a decrease in fluidity and prevent the heat generation from becoming extremely large. Furthermore, by having the amount of mixing water equal to or less than the above-mentioned upper limit, it is possible to ensure strength development.

In the present invention, the method for mixing the repair material and water is not particularly limited, but it is preferable to use a hand mixer with a rotation speed of 900 rpm or more, a conventional mortar mixer, or a twin-screw forced mixer.

When mixing with a hand mixer or mortar mixer, it is preferable to first add a predetermined amount of water to a container such as a pail or mixer, then add the remaining repair mortar composition while rotating the mixer, and mix for at least 3 minutes. When mixing with a forced mixer, it is preferable to first add the repair mortar composition to the mixer, add the predetermined amount of water while rotating the mixer, and mix for at least 4 minutes. If the mixing time is shorter than the predetermined time, the repair mortar composition may not have the proper fluidity due to insufficient mixing.
The mixed repair mortar composition is usually applied using a plastering trowel or pumped to the application site using a squeeze-type mortar pump, and then sprayed using compressed air with a spray nozzle to form a hardened body using the repair mortar composition of the present invention.

The present invention will be further explained below based on experimental examples, but the present invention is not limited to these.

Experimental Example 1
A repair material was obtained by preparing a mixture containing 11.1 parts by mass of expansive material, 3.0 parts by mass of polymer emulsion, 0.1 parts by mass of fiber, and 0.5 parts by mass of water-reducing agent per 100 parts by mass of cement, and containing the repair admixture, rapid hardening material, and fine aggregate in the amounts shown in Table 1 per 100 parts by mass of cement. Next, the _SO3 content of the repair material was measured by X-ray fluorescence analysis, and the MgO content was also measured by X-ray fluorescence analysis. Taking these measured values into consideration, an SO3-containing admixture (material name: potassium sulfate) and an _MgO -containing admixture (material name: magnesium carbonate) were mixed so that the final repair material would have the _SO3 content and MgO content shown in Table 1 below, to prepare the repair material.
100 parts by mass of the resulting repair material was mixed with 15 parts by mass of water to prepare a repair mortar composition.
The prepared repair mortar compositions were tested for fluidity, self-healing effect, compressive strength, and abrasion resistance. The results are shown in Table 1.

<Materials used>
Cement: Ordinary Portland cement, Blaine value 3,450 cm ² /g
Expanding agent: CaO raw material, _{Al2O3 raw} material, _SiO2 raw material, and _CaSO4 raw material were mixed and crushed, and then fired at 1,200°C to synthesize clinker, which was then crushed in a ball mill to produce a Blaine specific surface area of 3,000 ^cm2 /g.
Polymer emulsion: Polyacrylate ester re-emulsified resin, commercially available product, moisture content 0.8%, density 0.5 g/mL
Fiber: Vinylon fiber, fiber length 6 mm, fineness 6.6 dtex, dry strength 1,850 N/mm ² , dry elongation 6.0%
- Water reducing agent: naphthalene-based water reducing agent, commercially available product (Dai-ichi Kogyo Seiyaku Co., Ltd. "Cellflow 110P")
Water: Tap water Fine aggregate: Lime sand, a mixture of 50% below 0.6 mm and 50% between 0.6 and 1.2 mm.
Repair admixture A: Li-containing gamma-2CaO.SiO ₂ . First-grade reagent calcium carbonate and first-grade reagent silicon dioxide were mixed in a molar ratio of 2:1, and then first-grade reagent lithium carbonate was mixed in so that the Li content of the mixture was 0.0005 to 1.1% (internal substitution) in terms of oxide (Li ₂ O). The mixed sample was heat-treated at 1,400°C for 2 hours and allowed to cool to room temperature. The cooled sample was pulverized to a Blaine specific surface area of 4,000 cm ² /g.
Repair admixture B: Li-containing α-CaO·SiO ₂ . First-grade reagent calcium carbonate and first-grade reagent silicon dioxide were mixed in a 1:1 molar ratio, and then first-grade reagent lithium carbonate was mixed in so that the Li content of the mixture was 0.0005 to 1.1% (internal substitution) in terms of oxide (Li ₂ O). The mixed sample was heat-treated at 1,500°C for 2 hours and allowed to cool to room temperature. The cooled sample was pulverized to a Blaine specific surface area of 4,000 cm ² /g.
Repair admixture C: β-2CaO·SiO ₂ . First-grade reagent calcium carbonate and first-grade reagent silicon dioxide were mixed in a molar ratio of 2:1. The mixed sample was heat-treated at 1,400°C for 2 hours, allowed to cool to room temperature, pulverized, and the same heat treatment repeated until the γ-2CaO·SiO ₂ peak was no longer observed by XRD. The Blaine specific surface area after the peak of only β-2CaO·SiO ₂ was observed was determined to be 4,000 cm ² /g.
Rapid hardening material A: Amorphous calcium aluminate prepared to contain 43% CaO and ₅₃ % _Al2O3 , melted and rapidly cooled in an electric furnace. The vitrification rate was 98% or more, the Blaine specific surface area was 6,050 ^cm2 /g, and 100 parts by mass of calcium aluminate was mixed with 150 parts by mass of gypsum. The CaO/ _{Al2O3 molar} ratio of the calcium aluminate was 1.5.
Accelerator B: Alumina cement No. 1, manufactured by Denka Co., Ltd. (CaO/Al ₂ O ₃ molar ratio of calcium aluminate: 1.0)
・Accelerator C: calcium formate, reagent ・Accelerator D: calcium nitrate, reagent

<Measurement items>
Flowability: Measured immediately after mixing using the JIS flow value in a 20°C environment in accordance with JIS A1171.
Self-healing effect: In accordance with JIS A6206, a 10 cm x 10 cm x 40 cm specimen of the repair material was prepared under rebar restraint conditions. After 56 days, a strain gauge was attached to the surface of the specimen and a bending test was performed. The bending test was terminated when a crack of 0.1 mm in width appeared. After that, the specimen was left to stand for 28 days under conditions of 98% relative humidity and 35°C, followed by 7 days under conditions of 60% relative humidity and 20°C. This cycle was repeated five times, and the percentage of the area where the cracks were closed (closed area/cracked area) was measured.
Compressive strength: In accordance with JSCE-G 505, specimens of the repair material were prepared in a Φ5 x 10 cm formwork, demolded after one day, and then cured in water at 20°C for up to 28 days. Then, natural carbonation was achieved by air-dry curing. The compressive strength was measured at 700 days.
Abrasion resistance: Repair material specimens were prepared in doughnut-shaped molds measuring 100mm diameter x 10mm, demolded after one day, and then cured in water at 20°C until the material was 28 days old, after which it was naturally carbonated by air-dry curing. At 700 days old, the specimens were subjected to a Taber abrasion test (weight loss method). The test conditions were a load of 1kg, an abrasion wheel H-22, and 1,000 cycles.
The measurement results are shown in Table 1 below.

From the results in Table 1, it was confirmed that, as shown in the examples, the inclusion of a repair admixture containing a specific non-hydraulic material can further enhance high fluidity and self-healing effects, as well as improve compressive strength and abrasion resistance.

The repair material of the present invention contains a specific non-hydraulic material, which allows for enhanced fluidity and self-healing effects. It also becomes dense through natural carbonation, providing a repair material, repair mortar composition, and hardened product with improved compressive strength and abrasion resistance, making it suitable for a wide range of applications, including civil engineering and construction.

Claims (7)

A repair material comprising a repair admixture containing one or more non-hydraulic compounds selected from the group consisting of γ-2CaO·SiO ₂ , 3CaO·2SiO ₂ , α-CaO·SiO ₂ , and calcium magnesium silicate, and cement, a polymer emulsion, fibers, and fine aggregate ,
The repair material, wherein the amount of SO ₃ in the repair material is 0.5% by mass or more and 10.0% by mass or less, and the amount of MgO in the repair material is 0.1% by mass or more and 3.0% by mass or less. The repair admixture comprises one or more non-hydraulic compounds selected from the group consisting of γ-2CaO·SiO ₂ , 3CaO·2SiO ₂ , α-CaO·SiO ₂ , and calcium magnesium silicate, as well as cement, a polymer emulsion, fibers, and fine aggregate;
The repair material contains Li in the non-hydraulic compound, and the Li content in the non-hydraulic compound is 0.001 to 1.0 mass % in terms of oxide. The repair material according to claim 1 or 2, further containing an expanding agent. It also contains rapid hardening materials,
The hardening agent contains calcium aluminate,
The calcium aluminate has a CaO/Al ₂ O ₃ molar ratio of 1.0 or more and 3.0 or less;
The repair material according to any one of claims 1 to 3, wherein the content of the calcium aluminate is 2 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the cement. The repair material described in any one of claims 1 to 4, wherein the content of the fine aggregate is 40 parts by mass or more and 300 parts by mass or less per 100 parts by mass of the cement. A repair mortar composition containing the repair material according to any one of claims 1 to 5 and water. A hardened body obtained using the repair mortar composition described in claim 6.