Mortar composition and method of using the same

Abstract

To provide a mortar composition that has proper flowability under a high-temperature environment, and expresses excellent strength in a short time.SOLUTION: A mortar composition contains cement, high-tensile fiber, quick-hardening material, retarder, and water-reducing agent. When the unit quantity of the quick-hardening material for 1 m3 of the mortar composition is A[kg / m3], the unit quantity of the retarder is B[kg / m3], and the unit quantity of the water-reducing agent is C[kg / m3], A is 100-180 kg / m3, B is 3-15 kg / m3, C is 5-35 kg / m3, A / B is 14.0-29.5, and C / B is 1.8-5.2.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a mortar composition and a method of using the same.

Background Art

[0002] As a road repair material, a cement composite material containing reinforcing fibers is known. For example, in Patent Document 1, a construction method is proposed in which ultra-high strength fiber-reinforced concrete produced by kneading reinforcing fibers, fine aggregate, water reducing agent, shrinkage reducing agent, defoaming agent, and water is placed on the joint surface. According to this construction method, it is stated that the hardened body can be made thinner because the strength of the hardened body is higher than that of conventional repair materials.

[0003] In Patent Document 2, as a repair material used for repairing roads, bridges, etc., a cement paste obtained by adding water, water reducing agent, defoaming agent, thixotropic agent, and rapid hardening agent to a binder composed of cement, silica fume, and limestone filler, and a cement-based repair material obtained by mixing reinforcing fibers is proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, the demand for repairing the floor slabs of highways has been increasing. Since repairs need to be carried out systematically, a technology is required that can temporarily reduce highway damage and continue highway operation until the repair turn comes. As such a technology, a material that has strength, toughness, and durability sufficient to suppress cracks without applying a waterproofing agent, and that exhibits appropriate fluidity during construction and excellent strength development in a short time in order to shorten the closure period of repair work is considered effective. For example, since highways have cross slopes and longitudinal slopes, repair work can be carried out smoothly by using a material that has excellent strength development in a short time and appropriate fluidity.

[0006] However, even a mortar composition that has suitable fluidity in winter may not necessarily have appropriate fluidity in summer, and in that case, there is a concern that repair work cannot proceed smoothly. Also, appropriate fluidity and strength development in a short time may be required not only for sloped highways but also for the repair and coating of various structures. Therefore, the present invention provides a mortar composition that has appropriate fluidity even in a high-temperature environment and excellent strength development in a short time in various scenarios such as the repair of sloped highways, as well as the repair and coating of structures such as roads, bridges, port structures, river structures, and underground structures. Further, the present invention provides a method of using a mortar composition that can smoothly perform repair work even in a high-temperature environment in similar scenarios.

Means for Solving the Problems

[0007] In one aspect, the present invention includes cement, high-tensile fibers, a rapid hardening agent, a retarder, and a water reducing agent. When the unit amount of the rapid hardening agent per 1 m 3 of the mortar composition is A [kg / m 3 , the unit amount of the retarder is B [kg / m 3 , and the unit amount of the water reducing agent is C [kg / m 3 , A is 100 to 180 kg / m 3 , B is 3 to 15 kg / m 3 , and C is 5 to 35 kg / m 3Provided is a mortar composition wherein A / B is 14.0 to 29.5 and C / B is 1.8 to 5.2.

[0008] The above mortar composition includes, together with high-tensile fibers, a rapid-hardening material, a retarder, and a water-reducing agent. The rapid-hardening material, the retarder, and the water-reducing agent are contained in predetermined amounts, and the ratio of the rapid-hardening material to the retarder (A / B) and the ratio of the water-reducing agent to the retarder (C / B) are each within a predetermined range. Thus, by containing these three components in a well-balanced manner, the fluidity of the mortar composition during construction can be kept within an appropriate range even in a high-temperature environment. Also, since the fluidity is within an appropriate range, the workability is excellent, the filling property is improved, and the strength development property in a short time is also excellent. That is, the above mortar composition contains, together with high-tensile fibers, a rapid-hardening material, a retarder, and a water-reducing agent in a well-balanced manner, and thus has appropriate fluidity in a high-temperature environment and excellent strength development property in a short time. Note that "under a high-temperature environment" in this specification means an environment where the air temperature is 20°C or higher.

[0009] The mineral composition of the cement preferably has a C3S content of 25.0 to 75.0% by mass, a C3A content of less than 4.0% by mass, and a residue on a 45-μm sieve of the cement of less than 25.0% by mass. Thereby, fluidity and strength development property in a short time can be achieved at a higher level.

[0010] The high-tensile fibers preferably include at least one fiber selected from the group consisting of metal fibers, carbon fibers, aramid fibers, PP fibers, PVA fibers, PE fibers, glass fibers, nylon fibers, and PBO fibers. Thereby, a mortar hardened body having sufficiently high strength and durability can be formed.

[0011] The tensile strength of the high-tensile fibers is 100 to 10000 N / mm 2 and the aspect ratio of the high-tensile fibers is 40 to 250, and the unit amount of the high-tensile fibers is preferably 10 to 500 kg / m 3 By including such high-tensile fibers, the toughness and tensile strength of the mortar hardened body can be made sufficiently high.

[0012] The above mortar composition further contains fine aggregate and inorganic fine powder, and the Blaine specific surface area of the inorganic fine powder is preferably 3000 to 5000 cm 2 / g. Thereby, the fluidity of the mortar composition can be further increased. The Blaine specific surface area of the inorganic fine powder in this specification can be measured using the Blaine air permeability apparatus described in JIS R 5201:1997.

[0013] The above mortar composition preferably further contains silica fume. The average particle size of the silica fume is preferably 0.05 to 2.0 μm. The unit amount of silica fume per 1 m 3 of the above mortar composition is preferably 30 to 350 kg / m 3 Thereby, the compressive strength of the hardened body of the mortar composition and the fluidity of the mortar composition can be further increased.

[0014] The above mortar composition is preferably used for road repair in an environment of 20°C or higher. In such an environment, the above mortar composition has appropriate fluidity and excellent strength development properties. Therefore, it has excellent workability and reliability.

[0015] In one aspect, the present invention provides a method of using a mortar composition, which includes a step of repairing a road using any of the above mortar compositions, and placing the mortar composition on the road in a high-temperature environment of 20°C or higher. In this method of use, a mortar composition having appropriate fluidity during construction is used even in a high-temperature environment. Therefore, according to this method of use, the road repair work can be smoothly performed even in a high-temperature environment of 20°C or higher.

[0016] In the above usage method, it is preferable to have a step of adjusting at least one blending ratio selected from the group consisting of quick-setting materials, retarders, and water reducers according to the temperature. The fluidity of the mortar composition varies greatly according to the temperature. By having the above step, the properties of the mortar composition can be adjusted to an appropriate range according to the temperature.

Advantages of the Invention

[0017] According to the present invention, it is possible to provide a mortar composition having appropriate fluidity even in a high-temperature environment and excellent strength development in a short time. In addition, it is possible to provide a method of using a mortar composition capable of smoothly performing repair work even in a high-temperature environment.

Brief Description of the Drawings

[0018]

Figure 1

Modes for Carrying Out the Invention

[0019] Hereinafter, an embodiment of the present invention will be described. However, the following embodiments are examples for explaining the present invention and are not intended to limit the present invention to the following contents.

[0020] A mortar composition according to an embodiment includes cement, high-tensile fibers, quick-setting materials, retarders, and water reducers.

[0021] The mineral composition of the cement may be, for example, a C3S content of 25.0 to 75.0% by mass and a C3A content of less than 4.0% by mass. The C3S content is preferably 40.0 to 73.0% by mass, more preferably 48.0 to 70.0% by mass, and still more preferably 50.0 to 68.0% by mass. The C3A content is preferably less than 2.7% by mass, more preferably less than 2.3% by mass. The lower limit of the C3A content is not particularly limited and may be, for example, 0.1% by mass. By having such a mineral composition, it is possible to sufficiently increase the fluidity while sufficiently increasing the compressive strength of the mortar hardened body.

[0022] The C2S content is preferably 9.5 to 40.0% by mass, more preferably 10.0 to 35.0% by mass, and still more preferably 12.0 to 30.0% by mass. The C4AF content is preferably 9.0 to 18.0% by mass, more preferably 10.0 to 15.0% by mass, and still more preferably 11.0 to 15.0% by mass. By having such a mineral composition, it is possible to sufficiently increase the fluidity while sufficiently increasing the compressive strength of the mortar hardened body.

[0023] The above mineral composition is a value calculated by the following Bogue formula. Each chemical component of the cement used in the Bogue formula can be measured in accordance with JIS R 5202:2010 "Chemical Analysis Method for Cement".

[0024] C3S content = (4.07×CaO) - (7.60×SiO2) - (6.72×Al2O3) - (1.43×Fe2O3) - (2.85×SO3) C2S content = (2.87×SiO2) - (0.754×C3S) C3A content = (2.65×Al2O3) - (1.69×Fe2O3) C4AF content = 3.04×Fe2O3

[0025] The residue on a 45-μm sieve of the cement may be, for example, less than 25.0% by mass, preferably less than 20.0% by mass, more preferably less than 18.0% by mass, and still more preferably less than 16.0% by mass. The residue on the 45-μm sieve may be 0% by mass or may be 1.0% by mass or more. If the particle size of the cement is within the above range, high compressive strength can be ensured. Further, since the mortar composition containing such cement has appropriate viscosity, sufficient dispersibility can be ensured even if high-tensile fibers are contained. The residue on the 45-μm sieve of the cement can be measured in accordance with the standard test method of the Cement Association, JCAS K-02, "Test method for fineness of cement by 45-μm wire sieve".

[0026] The Blaine specific surface area of the cement is preferably 2500-4800 cm 2 / g, more preferably 2800-4000 cm 2 / g, still more preferably 3000-3600 cm 2 / g, and particularly preferably 3100-3500 cm 2 / g. When the Blaine specific surface area of the cement is too small, the strength of the mortar composition tends to be low, and when it is too large, the fluidity at a low water-cement ratio tends to decrease. The Blaine specific surface area of the cement can be measured in accordance with JIS R 5201:1997, "Physical test methods for cement".

[0027] The unit amount of cement per 1 m 3 of the mortar composition may be 700-1100 kg / m 3 or may be 750-1000 kg / m 3 .

[0028] The high-tensile fiber contains at least one kind of fiber selected from the group consisting of metal fiber, carbon fiber, aramid fiber, PP (polypropylene) fiber, PVA (polyvinyl alcohol) fiber, PE (polyethylene) fiber, glass fiber, nylon fiber, and PBO (polyparaphenylene benzobisoxazole) fiber. Examples of the metal fiber include steel fiber, stainless fiber, and amorphous alloy fiber. The tensile strength of the high-tensile fiber is preferably 100 to 10000 N / mm 2 and more preferably 500 to 5000 N / mm 2 and still more preferably 2000 to 3000 N / mm 2 and particularly preferably 2000 to 2500 N / mm 2 The aspect ratio (fiber length / fiber diameter) of the high-tensile fiber is preferably 40 to 250, more preferably 50 to 200, and still more preferably 60 to 170. By including such high-tensile fibers, the toughness and tensile strength of the mortar hardened body can be sufficiently increased.

[0029] The fiber diameter of the high-tensile fiber may be, for example, 0.05 to 1.20 mm. The fiber length of the high-tensile fiber may be 3 to 60 mm. The unit amount of the high-tensile fiber is preferably 10 to 500 kg / m 3 and more preferably 50 to 300 kg / m 3 and still more preferably 100 to 200 kg / m 3 and even more preferably 120 to 180 kg / m 3 and may be.

[0030] The rapid hardening material is an admixture that promotes the strength development of the mortar composition, and examples thereof include a mixture of calcium aluminate and inorganic sulfate. Such a rapid hardening material contains Al2O3, CaO, and SO3 as chemical components. As a commercially available product, for example, Befoam (registered trademark) manufactured by Denka Co., Ltd. can be used.

[0031] If the content of the quick-setting material is too small, the mortar composition cannot develop sufficient strength in a short time. On the other hand, if the content is excessive, hardening progresses too rapidly in a short time, the filling property decreases, and sufficient strength cannot be developed. Also, the fluidity decreases and the workability deteriorates. Therefore, from the perspective of obtaining a mortar composition that has appropriate fluidity even under high-temperature environments and is excellent in strength development in a short time, the unit amount A [kg / m 3 of the quick-setting material per 1 m of the mortar composition 3 is 100 to 180 kg / m 3 . The lower limit of the unit amount A [kg / m 3 of the quick-setting material is preferably 110 kg / m 3 , more preferably 120 kg / m 3 , and even more preferably 130 kg / m 3 . The upper limit of the unit amount A [kg / m 3 of the quick-setting material is preferably 170 kg / m 3 , more preferably 160 kg / m 3 , and even more preferably 150 kg / m 3 .

[0032] The retarder is an admixture also called a setting regulator or a setting retarder and has the effect of delaying the initial hardening of the mortar composition. Examples of retarders include lignin sulfonic acid, silicofluoride, or those mainly composed of alkali carbonate and citric acid. As commercial products, for example, Setter D-300 manufactured by Dencal Co., Ltd. can be used.

[0033] If the content of the retarder is too small, hardening is promoted too rapidly in a short time, the filling property decreases, and sufficient strength cannot be developed. Also, the fluidity decreases and the workability deteriorates. On the other hand, if the content of the retarder becomes excessive, the flow becomes small, the workability decreases, and there is a tendency that the target strength cannot be obtained in a short time. From the perspective of ensuring a mortar composition that has appropriate fluidity under high-temperature environments and is excellent in strength development in a short time, the unit amount B [kg / m 3 of the retarder per 1 m of the mortar composition 3 is 3 to 15 kg / m 3is as follows. The lower limit of the unit amount B [kg / m 3 of the retarder is preferably 4 kg / m 3 and more preferably 5 kg / m 3 is as follows. The lower limit of the unit amount B [kg / m 3 of the retarder is preferably 12 kg / m 3 and more preferably 10 kg / m 3 is as follows.

[0034] As the water reducing agent, those having an action of improving the fluidity of the mortar composition can be used, such as lignin-based, naphthalene sulfonic acid-based, amino sulfonic acid-based, polycarboxylic acid-based water reducing agents, high performance water reducing agents, and high performance AE water reducing agents. From the viewpoint of improving the fluidity of the mortar composition, the water reducing agent is preferably a polycarboxylic acid-based one. Such a water reducing agent can form a steric hindrance between cement clinkers to improve the fluidity of the mortar composition.

[0035] If the content of the water reducing agent is too small, the fluidity of the mortar composition decreases and the workability deteriorates. On the other hand, if the content of the water reducing agent becomes excessive, material separation occurs and the mortar composition cannot exhibit sufficient strength. From the viewpoint of obtaining a mortar composition having appropriate fluidity under a high temperature environment and excellent strength development in a short time, the unit amount C [kg / m 3 of the water reducing agent per 1 m of the mortar composition 3 is 5 to 35 kg / m 3 is as follows. The lower limit of the unit amount C [kg / m 3 of the water reducing agent per 1 m of the mortar composition 3 is preferably 7 kg / m 3 and more preferably 9 kg / m 3 and even more preferably 11 kg / m 3 is as follows. The upper limit of the unit amount C [kg / m 3 of the water reducing agent is preferably 28 kg / m 3 and more preferably 26 kg / m 3 and even more preferably 25 kg / m 3 is as follows.

[0036] As described above, the mortar composition of the present embodiment contains a quick-setting material, a retarder, and a water reducer as admixtures. The ratio (A / B) of the unit amount A of the quick-setting material to the unit amount B of the retarder is 14.0 to 29.5. The upper limit of the ratio (A / B) is preferably 29.0, more preferably 28.0. Thereby, it is possible to suppress the rapid hardening of the mortar composition and improve the workability. The lower limit of the ratio (A / B) is preferably 15.0, more preferably 17.0. Thereby, the strength development property of the mortar composition in a short time can be made sufficiently high. Further, when placed on a road or the like having a cross slope and / or a longitudinal slope, it is possible to sufficiently suppress the mortar composition from flowing too much.

[0037] The ratio (C / B) of the unit amount C of the water reducer to the unit amount B of the retarder is 1.8 to 5.2. The upper limit of the ratio (C / B) is preferably 4.0, more preferably 3.5. Thereby, the fluidity of the mortar composition can be sufficiently ensured. The lower limit of the ratio (C / B) is preferably 1.9. Thereby, even if the amount of water added is reduced, the excellent fluidity of the mortar composition can be sufficiently maintained.

[0038] The ratio (A / C) of the unit amount A of the quick-setting material to the unit amount C of the water reducer is 13.0 or less, preferably 12.0 or less, more preferably 11.5 or less. Thereby, it is possible to suppress the rapid hardening of the mortar composition, ensure the fluidity, and improve the workability. The ratio (A / C) is preferably 4.0 or more, more preferably 5.0 or more. Thereby, the strength development property of the mortar composition in a short time can be made sufficiently high.

[0039] The mortar composition of the present embodiment contains a quick-setting material, a retarder, and a water reducer as admixtures in a well-balanced manner. Therefore, even in a high-temperature environment, it has appropriate fluidity during construction and is excellent in strength development property in a short time. For this reason, it is particularly useful for, for example, repair applications of highways where good workability and strength development in a short time are required.

[0040] In addition to the above-mentioned admixture, the mortar composition of this embodiment may contain inorganic fine powder and fine aggregate. Examples of the inorganic fine powder include limestone powder, silica powder, and crushed stone powder. The inorganic fine powder may be a fine powder obtained by pulverizing and / or classifying limestone powder, silica powder, crushed stone powder, etc. The inorganic fine powder may be blended for the purpose of supplementing the fine particles of the fine aggregate. The Blaine specific surface area of the inorganic fine powder is preferably 3000~5000 cm 2 / g, more preferably 3200~4700 cm 2 / g, and even more preferably 3400~4600 cm 2 / g. By containing such inorganic fine powder, the fluidity of the mortar composition can be further improved. The unit amount of the inorganic fine powder per 1 m 3 of the mortar composition is preferably 100~300 kg / m 3 , more preferably 150~250 kg / m 3 .

[0041] Examples of the fine aggregate include river sand, land sand, sea sand, crushed sand, silica sand, limestone aggregate, blast furnace slag fine aggregate, ferronickel slag fine aggregate, copper slag fine aggregate, and electric furnace oxidized slag fine aggregate. The fine aggregate may have a particle size that completely passes through a 10 mm sieve and 85 mass% or more passes through a 5 mm sieve. The particle diameter of the fine aggregate measured in accordance with JIS A 1102:2014 is preferably 5.0 mm or less, and the coarse grain ratio is preferably 2.0~2.5. The fine particle content of the fine aggregate measured in accordance with JIS A 1103:2014 is preferably 9% or less. The unit amount of the fine aggregate per 1 m 3 of the mortar composition is preferably 600~1050 kg / m 3 , more preferably 700~1000 kg / m 3 , and even more preferably 800~980 kg / m 3 . The fine aggregate may be prepared by mixing a plurality of fine aggregates having different particle sizes.

[0042] The total unit amount of the fine aggregate and the inorganic fine powder per 1 m 3 of the mortar composition is preferably 800~1200 kg / m 3and more preferably 900 to 1150 kg / m 3 and even more preferably 1000 to 1100 kg / m 3 .

[0043] The mortar composition of this embodiment may contain silica fume. Silica fume is a by-product obtained by collecting dust in the exhaust gas generated during the production of metallic silicon, ferrosilicon, or fused zirconia. Silica fume mainly contains amorphous SiO2 that dissolves in an alkaline solution. The average particle diameter of silica fume is preferably 0.05 to 2.0 μm, more preferably 0.10 to 1.5 μm, and even more preferably 0.18 to 0.28 μm. By using such silica fume, it is possible to sufficiently increase the compressive strength of the mortar hardened body while maintaining appropriate fluidity of the mortar composition.

[0044] The content of silica fume based on cement is preferably 3 to 30% by mass, more preferably 5 to 20% by mass, and even more preferably 8 to 18% by mass. Also, the unit amount of silica fume per 1 m 3 of the mortar composition is preferably 30 to 350 kg / m 3 and more preferably 50 to 250 kg / m 3 and even more preferably 100 to 140 kg / m 3 .

[0045] The mortar composition of this embodiment may contain water. The unit water amount per 1 m 3 of the mortar composition is preferably 150 to 280 kg / m 3 and more preferably 180 to 250 kg / m 3 and even more preferably 190 to 230 kg / m 3 . From the viewpoint of achieving appropriate fluidity, the water-to-binder ratio is preferably 10 to 30% by mass, more preferably 15 to 25% by mass. The binder includes cement, silica fume, and a quick-setting material.

[0046] The mortar composition may, if necessary, contain at least one selected from an expansion agent, an antifoaming agent, a shrinkage reducing agent, a thickening agent, glass fiber, organic fiber, synthetic resin powder, polymer emulsion, and polymer dispersion, in addition to the above-described components. The expansion agent is commercially available, and for example, an ettringite-lime composite type or a lime type can be used. The unit amount of the expansion agent per 1 m 3 of the mortar composition is preferably 1 to 50 kg / m 3 , more preferably 2 to 40 kg / m 3 , still more preferably 5 to 30 kg / m 3 . The expansion agent is included in the binder.

[0047] Examples of the antifoaming agent include special nonionic compound type surfactants, polyalkylene derivatives, hydrophobic silica, polyether type, etc. The unit amount of the antifoaming agent per 1 m 3 of the mortar composition is preferably 0.1 to 20 kg / m 3 , more preferably 0.5 to 10 kg / m 3 , still more preferably 1 to 5 kg / m 3 .

[0048] When the mortar composition of the present embodiment is used in a high-temperature environment where the temperature is 20°C or higher, it has appropriate fluidity and excellent strength development in a short time. For example, the fluidity can be evaluated by the mortar 0-slump flow. The mortar 0-slump flow of the mortar composition is preferably 120 mm or more, more preferably 140 mm or more, and still more preferably 150 mm or more. Such a mortar composition is excellent in filling property during placement, so it has excellent workability and can sufficiently increase the compressive strength. The mortar 0-slump flow of the mortar composition is preferably 300 mm or less, more preferably 250 mm or less. With such a mortar composition, for example, when there is a transverse gradient and / or a longitudinal gradient at the placement location, it is possible to suppress the mortar composition from flowing down immediately downward. Therefore, the workability is excellent. Note that the mortar 0-slump flow in this specification is a value measured under the condition of no drop in accordance with JIS R 5201:1997 "Methods of Physical Tests for Cement".

[0049] The strength development property in a short time can be evaluated, for example, by the compressive strength at the age of 3 hours. The compressive strength of the mortar composition at the age of 3 hours is preferably 20 N / mm 2 or more, more preferably 24 N / mm 2 or more. The compressive strength can be measured by preparing a 5 cm × 10 cm cylindrical specimen with reference to JIS A 1132:2006 "Method of Making Specimens for Strength Test of Concrete" and performing a compressive strength test with reference to JIS A 1108:2006 "Method of Compressive Strength Test of Concrete".

[0050] The mortar composition may be used in an environment where the temperature is 20°C or higher, 25°C or higher, or 30°C or higher. In particular, the upper limit of the temperature is not limited and may be, for example, 40°C or lower. The use of the mortar composition is not particularly limited and may be, for example, for repair materials or coating materials. Specifically, it may be used as a repair material or coating material for roads (expressways), bridges, port structures, river structures, and underground structures, etc. Since the mortar composition is excellent in workability and excellent in initial strength development property, it can be suitably used for the repair of expressways that require construction in a short period of time.

[0051] For the manufacturing method of the mortar composition, all raw materials may be simultaneously blended, mixed, and prepared, or only some of the raw materials may be pre-mixed, and then the remaining raw materials may be simultaneously or sequentially blended, mixed, and prepared. For example, the raw materials other than water may be blended and mixed, water may be added to the powdery mixture, and it may be put into a mixer and kneaded to prepare the mortar composition. As the mixer used for kneading, a mortar mixer, a forced kneader, a pan mixer, a grout mixer, etc. can be used. Note that the above manufacturing method is an example, and it may be manufactured by a manufacturing method other than the above.

[0052] The method of using the mortar composition according to one embodiment includes a step of repairing a road using the mortar composition. The mortar composition can be the mortar composition according to the above embodiment. Therefore, the description content of the above mortar composition can be applied to this method of use. Also, the description content of this method of use can be applied to the description of the above mortar composition. In the above step, the mortar composition is placed on the road in an environment where the temperature is 20°C or higher. The road is preferably an expressway that requires short-term construction. The above step may be performed in an environment where the temperature is 25°C or higher, or 30°C or higher. From the viewpoint of maintaining good workability, the above step is preferably performed in an environment where the temperature is 40°C or lower.

[0053] In the above method of use, it is preferable to have a step of adjusting at least one blending ratio selected from the group consisting of a quick-setting material, a retarder, and a water reducing agent according to the temperature at which the mortar composition is used before the above step. The fluidity of the mortar composition varies greatly depending on the temperature. Therefore, for example, based on the measured value of the temperature, the blending ratio (unit amount) of the quick-setting material, the retarder, and the water reducing agent can be determined, and the mortar composition can be prepared so as to have the blending ratio (unit amount). By having such a step, the properties of the mortar composition can be adjusted so as to have an optimal fluidity corresponding to the temperature.

[0054] As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above embodiments at all.

Examples

[0055] The content of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[0056] [Preparation of Mortar Composition] In order to prepare the mortar compositions of each Example and each Comparative Example, the raw materials shown below were prepared.

[0057] (1) Cement The chemical components of the cement were measured in accordance with JIS R 5202:2010 "Methods of Chemical Analysis of Cement", and the mineral composition was calculated by the above-mentioned Bogue formula. Also, the 45-μm sieve residue of the cement was measured in accordance with the standard test method of the Cement Association JCAS K-02 "Test Method for Powder Fineness of Cement by 45-μm Mesh Sieve", and the Blaine specific surface area of the cement was measured in accordance with JIS R 5201:1997 "Physical Test Methods of Cement". The results were as shown in Table 1.

[0058]

Table 1

[0059] (2) Silica fume (SF) Silica fume was prepared. The average particle size of this silica fume was 0.24 μm. This average particle size was determined by the following procedure. First, using a laser diffraction / scattering particle size distribution measuring device (manufactured by Horiba, Ltd., trade name "LA-950V2"), the particle size distribution of this silica fume was measured. Based on the measurement results, a particle size - cumulative passing percentage curve was calculated, and the particle size at which the cumulative passing percentage became 50% by volume was determined from the particle size - cumulative passing percentage curve. This particle size was taken as the average particle size.

[0060] (3) Fine aggregate Silica sand (produced in Tochigi Prefecture, particle size: 5.0 mm or less, fine particle content: 0.62%, coarse particle ratio: 2.35) was prepared.

[0061] (4) Inorganic fine powder Limestone fine powder (density: 2.71 g / cm 3 , Blaine specific surface area: 4570 cm 2 / g) was prepared.

[0062] (5) Quick-hardening material As the quick-hardening material, Befoam (registered trademark) manufactured by Denka Co., Ltd. was prepared. The analysis results of the chemical components of this quick-hardening material were as shown in Table 2.

[0063]

Table 2

[0064] (6) Retarder As the retarder, Setter D-300 (trade name) manufactured by Dencal Co., Ltd. was prepared. (7) Water reducing agent As the water reducing agent, a polycarboxylic acid-based high-performance water reducing agent (solid content concentration: 25% by mass) was prepared. (8) Defoaming agent As the defoaming agent, a special nonionic compound type surfactant was prepared. Figure 1 shows the 1H-NMR spectrum measured using an NMR measuring device (manufactured by BRUKER, trade name "AVANCE") after dissolving this defoaming agent in heavy methanol. The molar ratios of the structural units of polyoxypropylene (hereinafter abbreviated as "POP"), polyoxyethylene (hereinafter abbreviated as "POE"), and the alkyl chain, which are the structural units of the defoaming agent, were calculated based on the integral value of the signal derived from the methyl group in POP. Among these, the molar ratio of POE to POP was calculated by subtracting the integral value of the signal derived from the hydrocarbon group other than the methyl group of POP that appears near 3.5 ppm and the integral value of the signal derived from the hydrocarbon group of POE from the integral value of the signal derived from the hydrocarbon group other than the methyl group of POP. Table 3 shows the molar ratios of the structural units of POP, POE, and the alkyl chain in the defoaming agent. 1 1H-NMR spectrum. The molar ratios of the structural units of polyoxypropylene (hereinafter abbreviated as "POP"), polyoxyethylene (hereinafter abbreviated as "POE"), and the alkyl chain, which are the structural units of the defoaming agent, were calculated based on the integral value of the signal derived from the methyl group in POP. Among these, the molar ratio of POE to POP was calculated by subtracting the integral value of the signal derived from the hydrocarbon group other than the methyl group of POP that appears near 3.5 ppm and the integral value of the signal derived from the hydrocarbon group of POE from the integral value of the signal derived from the hydrocarbon group other than the methyl group of POP. Table 3 shows the molar ratios of the structural units of POP, POE, and the alkyl chain in the defoaming agent.

[0065]

Table 3

[0066] (9) Expansive agent As the expansive agent, an ettringite-lime composite expansive agent manufactured by Dencal Co., Ltd. was prepared. (10) High-tensile fiber As the high-tensile fiber, steel fiber (manufactured by Tokyo Seitetsu Co., Ltd., trade name "CW9416", density: 7.87 g / cm 3 , fiber diameter: 0.16 mm, fiber length: 13 mm, aspect ratio: 81.25, tensile strength: 2200 N / mm 2 ) was prepared. (11) As the mixing water (W), tap water was prepared.

[0067] (Examples 1-1 to 1-8, Comparative Examples 1-1 to 1-25) Under the environment of 20°C ambient temperature, the above raw materials were compounded at the ratios shown in Table 4 to prepare a mortar composition. The mixing was carried out using a Hobart mixer. Cement, silica fume, inorganic fine powder, defoaming agent, expansion agent, and fine aggregate were dry-mixed for 30 seconds, then water and high-performance water reducer were added and mixed for 5 minutes. Thereafter, a retarder was added and mixed for 1 minute, and steel fibers were added and further mixed for 2 minutes. Furthermore, a rapid hardening material was added and mixed for 1 minute. The units of the numerical values in Table 4 are kg / m 3 and represent the mass (unit amount) per 1 m 3 of the mortar composition.

[0068] (Examples 2-1 to 2-11) Under the environment of 25°C ambient temperature, the above raw materials were compounded at the ratios shown in Table 4 to prepare a mortar composition. The mixing was carried out in the same manner as in Example 1-1. The units of the numerical values in Table 4 are kg / m 3 and represent the mass (unit amount) per 1 m 3 of the mortar composition.

[0069] (Examples 3-1 to 3-11, Comparative Examples 3-1, 3-2) Under the environment of 30°C ambient temperature, the above raw materials were compounded at the ratios shown in Table 5 to prepare a mortar composition. The mixing was carried out in the same manner as in Example 1-1. The units of the numerical values in Table 5 are kg / m 3 and represent the mass (unit amount) per 1 m 3 of the mortar composition.

[0070] (Examples 4-1 to 4-12, Comparative Examples 4-1 to 4-3) Under the environment of 35°C ambient temperature, the above raw materials were compounded at the ratios shown in Table 5 to prepare a mortar composition. The mixing was carried out in the same manner as in Example 1-1. The units of the numerical values in Table 5 are kg / m 3 and represent the mass (unit amount) per 1 m 3 of the mortar composition.

[0071] (Examples 5-1 to 5-13) In an environment with a temperature of 40°C, a mortar composition was prepared by mixing the above raw materials at the ratios shown in Table 5. The mixing was carried out in the same manner as in Example 1-1. The units of the numerical values in Table 5 are kg / m 3 and indicate the mass (unit amount) per 1 m 3 of the mortar composition.

[0072]

Table 4

[0073]

Table 5

[0074] [Evaluation of Mortar Composition] (1) Fresh Properties The zero-slump flow of the mortar immediately after remixing in each temperature environment of the mortar compositions prepared in each example and each comparative example was measured. The zero-slump flow of the mortar was measured under the condition of no dropping in accordance with JIS R 5201:1997 "Methods of Physical Tests for Cement". The measurement results were as shown in the column of "Flow Value" in Tables 6 and 7.

[0075] (2) Strength Test Cylindrical specimens of 5 cm × 10 cm were prepared with reference to JIS A 1132:2006 "Method of Making Specimens for Strength Test of Concrete", and the compressive strength in each temperature environment was measured with reference to JIS A 1108:2006 "Method of Compressive Strength Test for Concrete". The measurement results at the ages of 3 hours, 7 days, and 28 days are shown in Tables 6 and 7. Tables 6 and 7 also show the water / binder ratio, the ratio of the rapid-hardening material to the retarder (A / B), the ratio of the water-reducing agent to the retarder (C / B), and the ratio of the rapid-hardening material to the water-reducing agent (A / C).

[0076]

Table 6

[0077]

Table 7

[0078] As shown in Table 6 and Table 7, the values of the slump flow of the mortar for each example were in the range of 123 to 291 mm, and it was confirmed that the mortar had appropriate fluidity even under high-temperature environments. Also, the compressive strength at 3 hours of age was 24 N / mm 2 or more, and it was confirmed that the mortar had excellent strength development in a short time.

[0079] Table 8 extracts and shows the data of Examples 1-2 and 2-6, and Examples 3-9 and 4-6 among the examples shown in Tables 4 to 7, where the air temperatures are different from each other and the formulations are similar.

[0080]

Table 8

[0081] As shown in Table 8, it was confirmed that even when the formulations were substantially the same, the values of the slump flow of the mortar changed greatly when the air temperatures were different. Therefore, it can be said that it is preferable to adjust the formulation ratio according to the temperature environment during construction.

Industrial Applicability

[0082] According to the present invention, it is possible to provide a mortar composition having appropriate fluidity under high-temperature environments and excellent strength development in a short time. Also, it is possible to provide a method of using a mortar composition capable of smoothly performing repair work under high-temperature environments.

Claims

**Claim 1**: A cement having a mineral composition with a C₃S content of 40.0 to 75.0% by mass and a C₃A content of less than 4.0% by mass, and a 45-μm sieve residue of less than 25.0% by mass, silica fume with an average particle diameter of 0.05 to 2.0 μm, inorganic fine powder with a Blaine specific surface area of 3000 to 5000 cm² / g, fine aggregate, high-strength fiber, accelerating agent, retarder, and water reducer, wherein the unit amount of the cement per 1 m³ of the mortar composition is 700 to 1100 kg / m³, the unit amount of the silica fume is 100 to 140 kg / m³, the unit amount of the inorganic fine powder is 150 to 250 kg / m³, the unit amount of the fine aggregate is 600 to 1050 kg / m³, and the unit amount of the high-strength fiber is 120 to 180 kg / m³, per 1 m of the mortar composition ３ When the unit amount of the quick-setting material is A [kg / m ３ , the unit amount of the retarder is B [kg / m ３ , and the unit amount of the water reducer is C [kg / m ３ , A is 110 to 170 kg / m ３ , B is 4 to 12 kg / m ３ , C is 9 to 35 kg / m ３ and A / B is 14.0 to 29.5, C / B is 1.8 to 5.2, a mortar composition.

2. The C ３ mortar composition according to Claim 1, wherein the content of A is less than 2.7% by mass. **Claim 3** The high-strength fiber according to claim 1 or 2, wherein the high-strength fiber contains at least one fiber selected from the group consisting of metal fiber, carbon fiber, aramid fiber, PP fiber, PVA fiber, PE fiber, glass fiber, nylon fiber, and PBO fiber. **Claim 4** The tensile strength of the high-strength fiber is 100 to 10,000 N / mm ２ , and the aspect ratio of the high-strength fiber is 40 to 250. The mortar composition according to any one of claims 1 to 3. **Claim 5** The mortar composition according to any one of claims 1 to 4, wherein the average particle diameter of the silica fume is 0.18 to 0.28 μm. **Claim 6**: The mortar composition according to any one of claims 1 to 5, further comprising an antifoaming agent, wherein the unit amount of the antifoaming agent per 1 m³ of the mortar composition is 0.1 to 20 kg / m³. **Claim 7** The mortar composition according to any one of claims 1 to 6, which is used for road repair in an environment of 20°C or higher. **Claim 8** A method for using a mortar composition, comprising a step of repairing a road using the mortar composition according to any one of claims 1 to 7, wherein the mortar composition is placed on the road in an environment of 20°C or higher.

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