Rapid-hardening mortar composition for use on sloped surfaces and rapid-hardening mortar for use on sloped surfaces

Abstract

To provide a quick-hardening mortar composition for constructing a slope surface, which has fluidity for easy pumping and filling without material separation in repairing or newly constructing a large section with a gradient, and can secure a slope and finish plastering after the filling.SOLUTION: A quick-hardening mortar composition for constructing a slope surface includes: a binder comprising cement, inorganic sulfate and calcium aluminate; a fine aggregate; a water reducing agent; and fibers. The water reducing agent contains at least one water reducing agent selected from the group consisting of a naphthalenesulfonic acid-based water reducing agent, a lignin sulfonic acid-based water reducing agent and a melamine-based water reducing agent. The content of the polycarboxylic acid-based water reducing agent is less than 0.08 pts.mass based on 100 pts.mass of the binder, and the content of the fine aggregate is 110-270 pts.mass based on 100 pts.mass of the binder.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rapid-hardening mortar composition for use on inclined surfaces and a rapid-hardening mortar for use on inclined surfaces. [Background technology]

[0002] Recently, cementitious repair materials have been used in civil engineering and construction work to repair and reinforce concrete structures that have deteriorated due to various factors. Examples of cementitious cross-section repair materials include plastering mortar for small cross-section repairs, pourable filling mortar for large cross-section repairs where formwork can be installed, and sprayable mortar for large cross-section repairs where formwork cannot be installed.

[0003] On the other hand, for repair and new construction work on roads, railways, etc., there are restrictions on the period of closure due to construction, so quick-hardening mortar is often used for emergency repair work and nighttime work.

[0004] Examples of such materials include an ultra-rapid-hardening, non-shrinkage grout material (see Patent Document 1), which is highly fluid and can be poured and filled into large cross sections; and a rapid-hardening polymer cement mortar composition (see Patent Document 2), which is easy to work with and can be applied uniformly with a trowel and can be used to repair small cross sections; the rapid-hardening polymer cement mortar composition contains cement, polymer, fine aggregate, ultra-rapid-hardening clinker, gypsum, and a setting regulator; the ultra-rapid-hardening clinker is a CaO-Al2O3-based ultra-rapid-hardening clinker that contains a carbonate component. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-021160 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-218415 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in repair, renovation, and construction work on earthen floors and walkways with a 2-3% slope as a rainwater treatment measure, high-flow mortar cannot be used, even on large scales, due to the risk of sagging. Instead, plastering mortar is poured and the slope is adjusted using a trowel. In other words, there is no mortar that can be poured in large quantities over large cross sections at once, which requires time and effort and results in low construction efficiency. Therefore, there is a need for mortar that can be poured in large quantities using pumping, while still maintaining a slope and allowing for plastering after pouring. However, achieving both high fluidity for pumping and hardness for plastering are contradictory properties, making it difficult to achieve both. Furthermore, as mortar becomes more fluid, it is more susceptible to material separation, which can be a problem during use.

[0007] Therefore, an object of the present invention is to provide a fast-setting mortar composition for use on sloped surfaces, which does not separate into materials, can be easily pumped even in repair or new construction work on large cross sections involving slopes, has fluidity that allows filling, and can ensure a slope after filling and allow for a plastering finish, and a fast-setting mortar for use on sloped surfaces. [Means for solving the problem]

[0008] As a result of thorough investigation into the above-mentioned problems, the inventors have discovered that by using a specific type of water-reducing agent and adjusting the content of fine aggregate, it is possible to obtain a fast-setting mortar composition for use on inclined surfaces and a fast-setting mortar for use on inclined surfaces that have appropriate fluidity to enable both pumping and plastering.

[0009] That is, the present invention is represented by the following [1] to [7]. [1] A fast-setting mortar composition for use on sloped surfaces, comprising cement, a binder consisting of inorganic sulfates and calcium aluminates, fine aggregate, a water-reducing agent, and fibers, wherein the water-reducing agent comprises at least one water-reducing agent selected from the group consisting of naphthalene sulfonic acid-based water-reducing agents, lignin sulfonic acid-based water-reducing agents, and melamine-based water-reducing agents, the content of the polycarboxylic acid-based water-reducing agent being less than 0.08 parts by mass per 100 parts by mass of the binder, and the content of the fine aggregate being 110 to 270 parts by mass per 100 parts by mass of the binder. [2] The rapid-hardening mortar composition for application to sloped surfaces according to [1], wherein the mass ratio of inorganic sulfate to calcium aluminates ([calcium aluminate content (parts by mass)] / [inorganic sulfate content (parts by mass)]) is 1.5 to 2. [3] The sloped surface application method according to [1] or [2], wherein the content of at least one water-reducing agent selected from the group consisting of naphthalene sulfonic acid-based water-reducing agents, lignin sulfonic acid-based water-reducing agents, and melamine-based water-reducing agents is 0.01 to 1 part by mass per 100 parts by mass of the binder. work Fast-hardening mortar composition for concrete. [4] The sloped surface application method according to any one of [1] to [3], further comprising a shrinkage reducing agent. work Fast-hardening mortar composition for concrete. [5] A sloped surface application method according to any one of [1] to [4], which is used for pumping. work Fast-hardening mortar composition for concrete. [6] The sloped surface construction method according to any one of [1] to [5]. work and water, wherein the content of the water is 30 to 50 parts by mass relative to 100 parts by mass of the binder. work Fast-hardening mortar. [7] The sloped surface application method according to [6], wherein the 0 stroke flow value is 110 to 150 mm and the 15 stroke flow value is 160 to 260 mm. work Fast-hardening mortar. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a fast-setting mortar composition for use on sloped surfaces and a fast-setting mortar for use on sloped surfaces that do not separate and can be easily pumped even in repair or new construction work on large cross-sections involving slopes, have fluidity that allows filling, and can ensure a slope after filling and be finished by plastering. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, one embodiment of the present invention will be described in detail.

[0012] In this specification, the term "inclined surface" refers to a construction surface that has an incline (gradient of more than 0%). The gradient (%) of the incline is not particularly limited, but the gradient is preferably 1% to 8%, more preferably 1% to 5%, and even more preferably 1.5% to 4%.

[0013] The rapid-hardening mortar composition for use on inclined surfaces of this embodiment contains cement, a binder made of inorganic sulfates and calcium aluminates, fine aggregate, a water-reducing agent, and fibers.

[0014] In the fast-hardening mortar composition for use on inclined surfaces of this embodiment, the binder is composed of three components: cement, inorganic sulfate, and calcium aluminate.

[0015] Various cements can be used, including various types of Portland cement such as ordinary, early strength, extra early strength, low heat, and medium heat, as well as ecocement and rapid hardening cement. Ordinary Portland cement and early strength Portland cement are preferred because they can be pumped and troweled, do not delay setting time, make it easy to control the usable time, and easily obtain appropriate fluidity. One type of cement may be used alone, or two or more types may be used in combination.

[0016] The inorganic sulfate is not limited as long as it can elute sulfate ions and react with aluminum ions to form ettringite. Examples of inorganic sulfates include calcium sulfate, sodium sulfate, magnesium sulfate, and lithium sulfate. One type of inorganic sulfate may be used alone, or two or more types may be used in combination. Among the inorganic sulfates, calcium sulfate is preferred from the viewpoint of easily improving strength development. Examples of calcium sulfate include gypsums such as anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. As the gypsums, anhydrous gypsum is preferred from the viewpoint of further improving strength development. The Blaine specific surface area of ​​the gypsums is 4000 to 10000 cm from the viewpoint of easily obtaining rapid hardening and strength development. 2 / g, and 5000 to 9000 cm 2 / g, and more preferably 5500 to 8500 cm 2 / g is more preferred.

[0017] The content of the inorganic sulfate is preferably 2 to 25 parts by mass, more preferably 3 to 20 parts by mass, and even more preferably 4 to 15 parts by mass, relative to 100 parts by mass of the binder. When the content of the inorganic sulfate is within the above range, good fluidity and usable life are easily ensured, and excellent strength development is likely to occur.

[0018] Calcium aluminates are classified as C3A, C2A, C, where CaO is C, Al2O3 is A, Na2O is N, Fe2O3 is F, and SiO2 is S. 12 Calcium aluminate with a mineral composition indicated as A7, CA, or CA2, calcium aluminoferrite indicated as C4AF, calcium aluminate with halogen as a solid solution or substituted, C3A3·CaF2, and C 11 Calcium haloaluminates, including calcium fluoroaluminates, such as A7·CaF2, calcium sodium aluminates, such as C8NA3 and C3N2A5, calcium lithium aluminates, CA, CA2, C 12A general term for alumina cements whose main components are A7, C2AS, etc., and calcium sulfoaluminates expressed as C3A3·CaSO4, etc. Alumina cement is preferred as calcium aluminates. Calcium aluminates can be crystalline, amorphous, or a mixture of amorphous and crystalline. Calcium aluminates can be used alone or in combination of two or more. The fineness of calcium aluminates is preferably 3000 cm2 in Blaine specific surface area, from the viewpoint of further improving early strength development. 2 / g or more, and 2 / g or more. The fineness of calcium aluminates is preferably 8000 cm2 in terms of Blaine specific surface area. 2 / g or less is preferable.

[0019] The content of calcium aluminates is preferably 5 to 45 parts by mass, more preferably 8 to 40 parts by mass, and even more preferably 10 to 35 parts by mass, relative to 100 parts by mass of the binder. When the content of calcium aluminates is within the above range, it is easy to achieve both rapid curing and usable life, and it is easy to achieve excellent strength development.

[0020] The mass ratio of the inorganic sulfate to the calcium aluminates ([calcium aluminate content (parts by mass)] / [inorganic sulfate content (parts by mass)]) is preferably 1.5 to 2, and more preferably 1.7 to 1.9. When the mass ratio of the inorganic sulfate to the calcium aluminates is within the above range, it is easy to obtain an appropriate fluidity that allows both pumping and trowel finishing, and the compressive strength is further improved.

[0021] Examples of fine aggregate include river sand, silica sand, crushed sand, kansui stone, limestone sand, and slag aggregate. Of these, it is preferable to use silica sand, limestone sand, etc., adjusted to a particle size that does not contain fine powder or coarse aggregate. One type of fine aggregate may be used alone, or two or more types may be used in combination. It is preferable to use fine aggregate with a particle size of 5 mm or less (passing through a 5 mm sieve), which is commonly used.

[0022] The particle size of the fine aggregate is not particularly limited and can be adjusted within the required particle size range. The particle size of the fine aggregate can be determined based on the coarse particle ratio specified in JIS A 1102:2014 "Sieving Test Method for Aggregates." From the viewpoint of achieving better fluidity and suppressing bleeding when made into mortar, the coarse particle ratio of the fine aggregate is preferably 1 to 4, more preferably 1.5 to 3.8, and most preferably 1.8 to 3.5.

[0023] The content of fine aggregate is 110 to 270 parts by mass per 100 parts by mass of binder. If the content of fine aggregate is outside this range, the fluidity sufficient for both pumping and troweling may not be obtained, material separation may occur, and workability may be reduced. The content of fine aggregate is preferably 120 to 250 parts by mass, more preferably 130 to 220 parts by mass, and even more preferably 140 to 200 parts by mass per 100 parts by mass of binder. If the content of fine aggregate is within the above range, it is easy to obtain an appropriate fluidity sufficient for both pumping and troweling, and workability is further improved.

[0024] The water-reducing agent includes at least one selected from the group consisting of naphthalenesulfonic acid-based water-reducing agents, ligninsulfonic acid-based water-reducing agents, and melamine-based water-reducing agents. Examples of the water-reducing agent include high-performance water-reducing agents, high-performance air-entraining water-reducing agents, air-entraining water-reducing agents, and superplasticizers. Examples of such water-reducing agents include those specified in JIS A 6204:2011 "Chemical admixtures for concrete." One type of water-reducing agent may be used alone, or two or more types may be used in combination.

[0025] The content of the water-reducing agent is preferably 0.01 to 1 part by mass, more preferably 0.02 to 0.8 parts by mass, and even more preferably 0.03 to 0.7 parts by mass, per 100 parts by mass of binder. When the content of the water-reducing agent is within the above range, it is easy to obtain an appropriate fluidity that allows for both pumping and trowel finishing. The content of the polycarboxylic acid-based water-reducing agent in the rapid-setting mortar composition for sloped surface application of this embodiment is less than 0.08 parts by mass per 100 parts by mass of binder. If the content of the polycarboxylic acid-based water-reducing agent is 0.08 parts by mass or more, the fluidity becomes too high, resulting in material separation or sagging when used on sloped surfaces, making trowel finishing impossible. The content of the polycarboxylic acid-based water-reducing agent is preferably 0.05 parts by mass or less, more preferably 0.02 parts by mass or less, per 100 parts by mass of binder. It is even more preferable that the polycarboxylic acid-based water-reducing agent is substantially absent.

[0026] Examples of fibers include organic fibers such as vinylon fibers, polypropylene fibers, nylon fibers, and acrylic fibers; steel fibers; and inorganic fibers such as glass fibers. From the viewpoint of better dispersibility, the fibers are preferably organic fibers, and vinylon fibers and polypropylene fibers are more preferred. One type of fiber may be used alone, or two or more types may be used in combination.

[0027] The length of the fibers is preferably 1 to 30 mm, more preferably 1.5 to 20 mm, and even more preferably 2 to 15 mm. If the length of the fibers is within the above range, the dispersibility of the materials during mortar mixing is further improved.

[0028] The content of the fibers is preferably 0.01 to 5 parts by mass, more preferably 0.03 to 3 parts by mass, and even more preferably 0.05 to 2 parts by mass, relative to 100 parts by mass of the binder. If the content of the fibers is within the above range, material dispersibility during mortar mixing is maintained, and durability, primarily crack resistance, is further improved.

[0029] The fast-hardening mortar composition for application on inclined surfaces of this embodiment may contain a hardening accelerator. Examples of hardening accelerators include alkali metal carbonates. The alkali metal carbonate is not particularly limited as long as it is a carbonate of an alkali metal (an element of Group 1 of the periodic table excluding hydrogen atoms). Among the alkali metal carbonates, lithium carbonate, sodium carbonate, and potassium carbonate are preferred from the viewpoint of further promoting strength development. One hardening accelerator may be used alone, or two or more may be used in combination.

[0030] The content of the curing accelerator is preferably 0.1 to 2 parts by mass, more preferably 0.2 to 1.5 parts by mass, and even more preferably 0.3 to 1.2 parts by mass, relative to 100 parts by mass of the binder. If the content of the curing accelerator is within the above range, the initial strength development will be even better.

[0031] The fast-hardening mortar composition for inclined surface construction of this embodiment may contain a set retarder. Examples of set retarders include organic acids or salts thereof, such as citric acid, gluconic acid, malic acid, and tartaric acid; boric acid, borates such as sodium borate, phosphates, and inorganic salts, such as alkali metal bicarbonates; and sugars. Among these, citric acid, citrates, tartaric acid, and tartrates are preferred. The set retarder may be in the form of a powder or a liquid (for example, an aqueous solution, emulsion, or suspension). One type of set retarder may be used alone, or two or more types may be used in combination.

[0032] The content of the setting retarder is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.8 parts by mass, and even more preferably 0.08 to 0.5 parts by mass, relative to 100 parts by mass of the binder. If the content of the setting retarder is within the above range, it is easier to ensure a longer pot life.

[0033] The fast-setting mortar composition for inclined surface construction of this embodiment may contain a shrinkage-reducing agent. Examples of shrinkage-reducing agents that can be used include polyoxyalkylene compounds, polyether compounds, and alkylene oxide compounds. Specific examples of shrinkage-reducing agents include polyoxyethylene alkylaryl ethers, polypropylene glycols, lower alcohol alkylene oxide adducts, glycol ether aminoalcohol derivatives, polyethers, polyoxyalkylene glycols, ethylene oxide methanol adducts, ethylene oxide propylene oxide polymers, phenyl ethylene oxide polymers, cycloalkylene ethylene oxide polymers, and dimethylamine ethylene oxide polymers. One type of shrinkage-reducing agent may be used alone, or two or more types may be used in combination.

[0034] The content of the shrinkage reducing agent is preferably 0.1 to 5 parts by mass, more preferably 0.3 to 3 parts by mass, and even more preferably 0.5 to 2 parts by mass, relative to 100 parts by mass of the binder. If the content of the shrinkage reducing agent is within the above range, drying shrinkage after hardening can be suppressed and durability can be further improved without causing almost any delay in setting.

[0035] The fast-setting mortar composition for slope construction of this embodiment may contain various admixtures (materials) within the range that does not impair the effects of the present invention. Examples of admixtures (materials) include expansive additives, cement polymers, antifoaming agents, foaming agents, waterproofing agents, rust inhibitors, water retention agents, pigments, water repellents, anti-efflorescence agents, blast furnace slag powder, stone powder, earth mineral powder, slag powder, fly ash, silica fume, inorganic fillers, and volcanic ash.

[0036] The method for producing the fast-hardening mortar composition for inclined surface construction of this embodiment is not particularly limited, and for example, it can be produced by mixing the above-mentioned materials using a mixer such as a gravity mixer such as a V-type mixer or a tilting concrete mixer, a Henschel mixer, a jet mixer, a ribbon mixer, or a paddle mixer.

[0037] The rapid-setting mortar composition for inclined surface construction of this embodiment can be mixed with water to prepare a rapid-setting mortar for inclined surface construction, and the water content can be adjusted appropriately depending on the application. The water content is preferably 30 to 50 parts by mass, more preferably 33 to 48 parts by mass, and even more preferably 35 to 45 parts by mass, per 100 parts by mass of binder. If the water content is within the above range, it is easy to obtain an appropriate fluidity that allows for pumping and trowel finishing, and workability is further improved.

[0038] The rapid-setting mortar for inclined surface construction of this embodiment can be prepared using the same mixing equipment as that used for ordinary rapid-setting mortar compositions, and is not particularly limited. Examples of mixing equipment include a mortar mixer, a grout mixer, a hand mixer, a tilting mixer, and a twin-screw mixer.

[0039] The sloped surface of this embodiment work The fast-setting mortar for application preferably has a 0-shot flow value of 110 to 150 mm and a 15-shot flow value of 160 to 260 mm, more preferably a 0-shot flow value of 120 to 148 mm and a 15-shot flow value of 180 to 250 mm, and even more preferably a 0-shot flow value of 125 to 148 mm and a 15-shot flow value of 195 to 245 mm. If the 0-shot flow value is 110 or more and the 15-shot flow value is 160 or more, pumping tends to be easy, and if the 0-shot flow value is 150 mm or less and the 15-shot flow value is 260 mm or less, the occurrence of material separation of the mortar is easily suppressed, and adjustment of the fast-setting mortar for application to sloped surfaces by trowel finishing tends to be easy.

[0040] The fast-setting mortar composition for sloped surfaces and the mortar produced by the composition of this embodiment have a moderate fluidity that allows for easy spreading while maintaining a moderate hardness, and are resistant to material separation. Therefore, they can be used for both pumping into large cross sections and troweling for plastering finishes, and they do not sag even on sloped surfaces. Therefore, the fast-setting mortar composition for sloped surfaces and the mortar produced by the composition of this embodiment can be suitably used for repair, renovation, and construction work on sloped earthen floors, walkways, and the like. The construction method is not particularly limited, and options include pumping the composition to the work site and finishing with a trowel, filling recesses with a trowel, or filling and smoothing the surface with a vibrator or the like, followed by finishing with a trowel. [Example]

[0041] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0042] The materials used in the examples are as follows: Cement: Ordinary Portland cement Inorganic sulfate: anhydrous gypsum (blaine specific surface area: 7000 cm 2 / g) Calcium aluminate: Alumina cement (main component: CA) Fine aggregate: Silica sand (adjusted to a coarse grain ratio of 2.0 to 3.0) Water reducing agent A: Naphthalene sulfonic acid water reducing agent Water-reducing agent B: Melamine sulfonic acid-based water-reducing agent Water reducing agent C: Lignosulfonic acid-based water reducing agent Water reducing agent D: Polycarboxylic acid-based high-performance water reducing agent Fiber: Nylon fiber (fiber length 5 mm) Hardening accelerator: sodium carbonate Set retarder: citric acid Powder shrinkage reducers: alkylene oxide adducts of lower alcohols.

[0043] [Experimental Example 1] <Production of rapid-hardening mortar composition> Each material was charged into a Henschel mixer in the proportions shown in Table 1 and mixed for 6 minutes to produce a fast-hardening mortar composition. In Table 1, the numerical values ​​for each material are shown in parts by mass, where the binder consisting of cement, inorganic sulfate, and calcium aluminate is taken as 100 parts by mass.

[0044] <Manufacturing of fast-hardening mortar> The produced rapid-setting mortar composition and water were mixed for 90 seconds using a basket-type high-speed hand mixer (1000 rpm) to prepare a rapid-setting mortar. The mixing ratio of water is shown in Table 1.

[0045] [Table 1]

[0046] <Evaluation of fresh properties of fast-hardening mortar> The produced fast-hardening mortars (Invention Products 1 to 7, Reference Products 1 to 4) were evaluated for fresh consistency, usable time, material separation resistance, and workability. The evaluation test methods are shown below. [Consistency] The fast-hardening mortar was filled into a cement paste container (flow cone) according to JIS R5201:1997 "Physical Testing Methods for Cement," and the table flow value after the container was lifted (0-hit flow value) and the table flow value after 15 hits of drop vibration (15-hit flow value) were measured. In assessing fluidity, in addition to being able to be pumped and filled, the fluidity was evaluated as being such that a gradient could be secured with a trowel finish after filling. Those that met the flow value of 110 to 150 mm for 0 strokes and 160 to 260 mm for 15 strokes were rated as good, those that did not meet the above criteria were rated as poor, and those that showed separation in the material separation resistance test described below were rated as separated. [Pot life] 300ml of quick-hardening mortar was placed in a 350ml plastic cup, and the plastic cup was transferred three times every five minutes to check the fluidity. The point at which the mortar gelled and lost its fluidity (the point at which the mortar could no longer be poured out when the plastic cup was turned upside down) was taken as the pot life. The pot life was set as an index of whether the mixture could be maintained for 30 minutes or more after mixing, from the perspective of maintaining the workability required for pumping. [Material separation resistance] Resistance to material separation was assessed by checking the presence or absence of aggregate separation in the mixed rapid-hardening mortar by touch. If the rapid-hardening mortar was not uniform and the feel of fine aggregate was clearly visible on the bottom of the container, it was rated as × (aggregate separation present), and if the rapid-hardening mortar was uniform and the feel of fine aggregate was not visible on the bottom of the container, it was rated as ○ (no aggregate separation). [Workability] Quick-hardening mortar was poured into a wooden formwork measuring 30cm long x 30cm wide x 15cm high, and the quick-hardening mortar was leveled with a trowel so that the gradient was roughly 2%. When the usable time was up and the surface of the quick-hardening mortar had begun to harden, the mortar was leveled again with the trowel to achieve a 2% gradient. As an index of workability, a good trowel finish and the gradient could be adjusted were marked with an O, and sagging or the gradient could not be adjusted were marked with an X.

[0047] Table 2 shows the evaluation results of fresh properties. The rapid-hardening mortars of the examples all had a zero-pump flow value of 129-146 mm and a 15-pump flow value of 187-240 mm immediately after mixing, confirming that they had fluidity that allowed them to be easily pumped. Regarding workability, the rapid-hardening mortar poured into the formwork could be easily leveled with a trowel and the gradient adjusted. Furthermore, it was confirmed that the usable time of each mortar could be maintained for 30 minutes or more.

[0048] [Table 2]

[0049] [Experimental Example 2] <Evaluation of hardening properties of mortar> The compressive strength of the hardened mortars (Invention Products 1 to 7, Reference Products 1 and 2) was measured and evaluated. The evaluation test methods are as follows. [Compression strength] Compressive strength was measured in accordance with JIS R5201:1997 "Physical Testing Methods for Cement." As an index of fast-hardening mortar, short-term strength was measured at 3 and 24 hours. Curing was carried out in air in a test room at 20°C and 60% RH until each age was reached.

[0050] The compressive strength measurement results are shown in Table 3. The specimen of the example had a compressive strength of 12 N / mm at 3 hours. 2 It has a short-term strength development of 20N / mm at 24 hours. 2 The above strength development was confirmed.

[0051] [Table 3]

[0052] [Experimental Example 3] <Evaluation of pumpability and crack resistance of fast-hardening mortar> The pumpability and crack resistance of the fast-hardening mortar were confirmed using the present invention products 1, 3 and 4. The test method is as follows. [Pumpability] Using fast-setting mortar mixed in a pan mixer, it was pumped using a squeeze grout pump through 20 m of a 1.5-inch pressure-resistant hose, and the table flow value and material separation resistance of the fast-setting mortar emerging from the hose tip were confirmed in the same manner as in Example 1. As an index of pumpability, if the 0-shot flow value of the fast-setting mortar emerging from the hose tip after pumping was within the range of 110 to 150 mm and the 15-shot flow value was within the range of 160 to 260 mm, it was evaluated as ○ (good pumpability), and if it was outside the range, it was evaluated as × (poor pumpability). [Crack resistance] In accordance with NEXCO Test Method 432-2006, "Test Method for Shotcrete Mortar for Repairing Cross Sections," fast-hardening mortar was poured into a triangular steel formwork (75mm x 75mm x 6mm x 1000mm) with D13 rebar welded to the bottom of the steel formwork, and the occurrence of cracks 28 days after molding was confirmed. Curing was carried out in a test room with a room temperature of 20±3°C and a relative humidity of 60±10%.

[0053] Table 4 shows the evaluation results of the pumpability and crack resistance of the rapid-hardening mortar. The flow values ​​after pumping of the product of the present invention were in the range of 139-145 mm at 0 shots and 212-222 mm at 15 shots, confirming good pumpability without blockage or material separation. Furthermore, no cracks occurred in the test specimens of the product of the present invention, confirming good crack resistance.

[0054] [Table 4]

Claims

1. The concrete comprises a binder made of cement, calcium sulfate, and alumina cement, a fine aggregate, a water-reducing agent, and fibers, The water-reducing agent includes at least one water-reducing agent selected from the group consisting of a naphthalene sulfonic acid-based water-reducing agent, a lignosulfonic acid-based water-reducing agent, and a melamine-based water-reducing agent, The content of the polycarboxylic acid-based water-reducing agent is less than 0.08 parts by mass per 100 parts by mass of the binder, The content of the calcium sulfate is 6 to 25 parts by mass relative to 100 parts by mass of the binder, The content of the alumina cement is 8 to 45 parts by mass relative to 100 parts by mass of the binder, The fast-hardening mortar composition for application to sloped surfaces, wherein the content of the fine aggregate is 110 to 270 parts by mass per 100 parts by mass of the binder.

2. The rapid-hardening mortar composition for slope construction according to claim 1, wherein the mass ratio of the calcium sulfate to the alumina cement ([the content of the alumina cement (parts by mass)] / [the content of the calcium sulfate (parts by mass)]) is 1.5 to 2.

3. The fast-hardening mortar composition for inclined surface construction according to claim 1 or 2, wherein the content of the at least one water-reducing agent selected from the group consisting of naphthalene sulfonic acid-based water-reducing agents, lignin sulfonic acid-based water-reducing agents, and melamine-based water-reducing agents is 0.01 to 1 part by mass relative to 100 parts by mass of the binder.

4. The fast-hardening mortar composition for use on inclined surfaces according to any one of claims 1 to 3, further comprising a shrinkage reducing agent.

5. The fast-hardening mortar composition for slope construction according to any one of claims 1 to 4, which is used for pumping.

6. A method for constructing a sloping surface comprising the rapid-hardening mortar composition for sloped surfaces according to any one of claims 1 to 5 and water, The fast-hardening mortar for slope surface application, wherein the content of the water is 30 to 50 parts by mass per 100 parts by mass of the binder.

7. The fast-hardening mortar for slope construction according to claim 6, wherein the 0-stroke flow value is 110 to 150 mm and the 15-stroke flow value is 160 to 260 mm.

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