Method for manufacturing a high-strength mortar composition for shotcrete containing oyster shells as fine aggregate and method for manufacturing a concrete product using mortar composition manufactured thereof

Abstract

The present invention provides a method for manufacturing a high-strength mortar composition for shotcrete, comprising the steps of: preparing crushed oyster shells by washing and naturally drying oyster shells and then crushing them; preparing a first mixture by first mixing Portland cement, metakaolin, powdered fluidizing agent, defoaming agent, and powdered resin; preparing a second mixture by second mixing the first mixture and the crushed oyster shells; preparing a third mixture by third mixing the second mixture and polyester fibers; and preparing a fourth mixture by fourth mixing the third mixture and nylon fibers.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a high-strength mortar composition used in a shotcrete method that includes oyster shells as fine aggregate and additionally includes reinforcing fibers, and a method for manufacturing a concrete product using the mortar composition manufactured therefrom. Background Technology

[0002] Mortar, used in the construction industry for various tasks such as floor finishing or tiling, has evolved from a form where sand and cement were mixed directly on-site to a dry form where mortar for various uses is premixed in a factory and can be used by simply adding water on-site.

[0003] The raw materials used in such dry mortar can be broadly classified into cement and fine aggregate (sand), and depending on the intended use, water reducers, fluidizers, thickeners, etc., may be additionally mixed in.

[0004] While cement, the primary mixing ingredient for dry mortar, is supplied stably by major domestic cement companies and supplementary mixing materials maintain a stable supply structure within the market, the supply structure for fine aggregate is unstable due to regional imbalances between supply and demand. For these fine aggregates, sand meeting legal standards must be used to ensure structural stability in construction. Sand is generally extracted from rivers; however, with the expansion of the construction market, extraction volumes are gradually decreasing. Consequently, securing suitable sand is difficult, leading to increased manufacturing costs, and the use of substandard sand can adversely affect the physical properties of concrete. Furthermore, issues regarding natural and environmental destruction caused by indiscriminate extraction are emerging. Accordingly, there are attempts to replace fine aggregate with other natural materials and incorporate them into dry mortar compositions.

[0005] Concrete structures require continuous maintenance through repair and reinforcement. In particular, the demand for repair and reinforcement increases when issues regarding materials, construction, and structure interact in combination with natural environmental factors. Furthermore, since the repair and reinforcement of concrete structures must be carried out quickly and urgently, considering the degree of concrete deterioration and limited traffic control conditions, rapid setting is required as a critical performance characteristic for mortar compositions used for repair and reinforcement. Therefore, it is necessary to introduce methods capable of controlling cracks during construction or various repair techniques for concrete structures. Crack control methods involve incorporating various fibers capable of reducing crack formation into concrete during pouring or installing wire mesh inside the concrete structure. Crack repair methods involve removing existing deteriorated concrete and using polymer cement mortar, which incorporates polymers into cement materials to improve physical performance, strength, and durability.

[0006] Oyster shells, which make up about 70% of the total weight of oysters, amount to approximately 300,000 tons annually in Korea, but technology for processing them in large quantities is currently lacking. Only 50% of the generated amount is recycled, and the remainder is mostly landfilled or illegally stockpiled, causing secondary environmental pollution such as foul odors, pest infestations, and water pollution from leachate. Therefore, it is urgent to find recycling methods.

[0007] Accordingly, there is a demand for a method to manufacture a mortar composition that can completely prevent cracks occurring in concrete structures by using oyster shells as fine aggregate in the manufacture of the mortar composition, and to supplement the rapid hardening properties of the mortar composition by additionally adding reinforcing fibers. Furthermore, there is a demand for a method to manufacture a mortar composition suitable for shotcrete use that includes oyster shells as fine aggregate and additionally includes reinforcing fibers. Prior art literature

[0008] Korean Registered Patent No. 10-2320968 The problem to be solved

[0009] The problem that the present invention aims to solve is to provide a method for manufacturing a high-strength mortar composition suitable for shotcrete that does not cause a decrease in concrete strength by using oyster shells and reinforcing fibers in the manufacture of a mortar composition to increase waterproofing performance and strengthen water resistance. means of solving the problem

[0010] To solve the above problem, the present invention provides a method for manufacturing a high-strength mortar composition for shotcrete, comprising the steps of: preparing crushed oyster shells by washing and naturally drying oyster shells and then crushing them; preparing a first mixture by first mixing Portland cement, metakaolin, powdered fluidizing agent, defoaming agent, and powdered resin; preparing a second mixture by second mixing the first mixture and the crushed oyster shells; preparing a third mixture by third mixing the second mixture and polyester fibers; and preparing a fourth mixture by fourth mixing the third mixture and nylon fibers. Effects of the invention

[0011] By recycling oyster shells through the method for manufacturing a high-strength mortar composition for shotcrete according to the present invention, environmental problems can be solved, and a high-strength mortar composition for shotcrete can be provided that offers high waterproofing performance and water resistance and helps improve concrete strength. In addition, the high-strength mortar composition for shotcrete according to the present invention can be utilized for concrete repair using a shotcrete construction method and can be used to manufacture high-strength concrete products. Brief explanation of the drawing

[0012] FIG. 1 is a schematic diagram of a method for manufacturing a high-strength mortar composition for shotcrete according to one embodiment of the present invention. Specific details for implementing the invention

[0013] Hereinafter, various embodiments of the present invention are described with reference to the accompanying drawings. The present invention is not limited to specific embodiments and should be understood to include various modifications, equivalents, and / or alternatives of the embodiments of the present invention. In relation to the description of the drawings, similar reference numerals may be used for similar components.

[0014] In this document, expressions such as "have," "can have," "include," or "can include" refer to the existence of the relevant feature (e.g., numerical values, functions, actions, or components, etc.) and do not exclude the existence of additional features.

[0015] In this document, expressions such as “A or B,” “at least one of A or / and B,” or “one or more of A or / and B” may include all possible combinations of items listed together. For example, “A or B,” “at least one of A and B,” or “at least one of A or B” may refer to cases including (1) at least one A, (2) at least one B, or (3) both at least one A and at least one B.

[0016] As used in this document, the expression "configured to" may be replaced, depending on the context, with, for example, "suitable for," "having the capacity to," "designed to," "adapted to," "made to," or "capable of." The term "configured to" does not necessarily mean "specifically designed to."

[0017] The terms used in this document are used merely to describe specific embodiments and are not intended to limit the scope of other embodiments. Singular expressions may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as generally understood by those skilled in the art described in this document. Terms used in this document that are defined in general dictionaries may be interpreted as having the same or similar meaning as they have in the context of the relevant technology, and are not to be interpreted in an ideal or overly formal sense unless explicitly defined in this document. In some cases, even terms defined in this document may not be interpreted to exclude the embodiments of this document.

[0018] The embodiments disclosed in this document are presented for the purpose of explaining and understanding the disclosed technical content and are not intended to limit the scope of the invention. Accordingly, the scope of this document should be interpreted to include all modifications or various other embodiments based on the technical concept of the invention.

[0019] Hereinafter, preferred embodiments of the present invention will be described in detail. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0020] Therefore, it should be understood that the configurations of the embodiments described in this specification are merely some of the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, and that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0021] Throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0022] The present invention will be described in detail below.

[0024] A method for manufacturing a high-strength mortar composition for shotcrete according to one embodiment of the present invention may include the steps of: preparing crushed oyster shells by washing and naturally drying oyster shells and then crushing them; preparing a first mixture by first mixing Portland cement, metakaolin, powdered fluidizing agent, defoaming agent, and powdered resin; preparing a second mixture by second mixing the first mixture and the crushed oyster shells; preparing a third mixture by third mixing the second mixture and polyester fibers; and preparing a fourth mixture by fourth mixing the third mixture and nylon fibers.

[0025] The step of preparing crushed oyster shells by washing, naturally drying, and then crushing the oyster shells is intended to remove salt and impurities from the oyster shells and to dry and powder them. The oyster shells are high-calcium materials containing 95 wt% or more of CaCO3 and small amounts of SiO2 and Al2O3. By crushing and applying them as fine aggregates, they are mixed with Portland cement. The CaCO3 component has a positive effect on improving potential hydraulic properties and compressive strength, while the SiO2 and Al2O3 components participate in the hydration reaction of Portland cement to help improve compressive strength.

[0026] In the step of preparing crushed oyster shells by washing, drying, and then crushing the oyster shells, the crushed oyster shells may be crushed to have a particle size smaller than 0.1 mm, which is the maximum particle size of Portland cement. The particle size of the crushed oyster shells may be 0.01 to 0.1 mm. If the particle size of the crushed oyster shells is less than the above numerical range, the amount of water required during the process of mixing the crushed oyster shells with Portland cement, etc. becomes too large, making it difficult to increase compressive strength; if it exceeds the above numerical range, it does not mix well with Portland cement, etc., making it difficult to achieve high strength and unsuitable for the shotcrete method.

[0027] The step of preparing crushed oyster shells by washing, air-drying, and then crushing the oyster shells may further include a calcination processing step of heating the oyster shells to a temperature of 500 to 800°C before crushing them after washing and air-drying. Preferably, the temperature may be 600 to 700°C. The heating is intended to increase the degree of calcium oxide formation of the calcium carbonate (CaCO3) component of the oyster shells and to provide a structure that is more stable against shrinkage and expansion caused by thermal shock as a porous inorganic material.

[0028] The step of preparing crushed oyster shells by washing and naturally drying the oyster shells and then crushing them may further include a process of heating the oyster shells to a temperature of 500°C to 800°C before crushing them after washing and naturally drying, followed by a calcination processing process, and then crushing the oyster shells that have undergone the calcination processing process into a powder form, and then filtering them using 10 standard sieves so that oyster shell powder of 0.1 mm or less passes through, and filtering them using 20 standard sieves so that oyster shell powder of 0.01 mm or more remains.

[0029] As a result, after undergoing all processes of washing, calcination treatment, grinding, and filtering, powdered oyster shells with a particle size of 0.01 to 0.1 mm are obtained, and it is desirable to use this resulting product in a mixture with Portland semant, metakaolin, powder fluidizing agent, defoaming agent, and powder resin.

[0030] The first step of preparing the mixture, which involves primary mixing of the above Portland cement, metakaolin, powder fluidizing agent, defoaming agent, and powder resin, is to mix them in order to increase the durability, strength, and water resistance of the mortar composition.

[0031] The above Ordinary Portland Cement (OPC) is a main component serving as the base of a mortar composition. It is used in a powdered form by adding gypsum to clinker, which is a sintered clinker formed by sufficiently mixing raw materials containing lime, silica, alumina, and iron oxide—the main components of Portland cement—in appropriate proportions, and then melting a portion of the mixture. Although the above Portland Cement is a material with excellent durability, metakaolin may be mixed in to supplement its water resistance. The above Ordinary Portland Cement (OPC) can be implemented by applying the product example of 'Union Type 1 Portland Pure White Cement'.

[0032] The above meta-kaolin is a raw material produced by heating kaolinite in air to a temperature of 550 to 600°C. It suppresses the problem of reduced corrosion resistance and durability that occurs when the amount of Ca(OH) present in concrete increases, and increases the overall durability and strength of the mortar composition by causing silicon dioxide (SiO2) to react with calcium hydroxide (Ca(OH)2) to form calcium silicate hydrate. In addition, meta-kaolin is a material used to improve waterproofing performance and water resistance by filling the pores through the complementary porous characteristics of oyster shells, which are used as a 100% replacement for fine aggregate. The above meta-kaolin can be implemented by applying the product example of 'MetaStar® 501'.

[0033] The above powder fluidizing agent is mixed to increase the strength of the mortar composition by controlling the water absorption rate. The above powder fluidizing agent can be used as a product example of 'Peramin® CONPAC 149S'.

[0034] The above-mentioned defoaming agent is intended to reduce the increase in air volume caused by the generation of entrained air. As the above defoaming agent, mineral oil-based defoaming agents such as kerosene, paraffin, mineral oil, ethanol synthetic oil, etc.; oil-based defoaming agents such as animal and vegetable oils, sesame oil, castor oil and their alkylene oxide adducts, etc.; fatty acid-based defoaming agents such as oleic acid, stearic acid and their alkylene oxide adducts, etc.; fatty acid ester-based defoaming agents such as glycerin monoricinoleate, alkenyl succinic acid fluid, sorbitol monolaurate, sorbitol trioleate, natural wax, etc.; oxyalkylene-based defoaming agents such as polyoxyalkylenes, (poly)oxyalkyl ethers, acetylene ethers, (poly)oxyalkylene alkyl phosphate esters, (poly)oxyalkylene alkylamines, (poly)oxyalkylenamides, etc.; alcohol-based defoaming agents such as octyl alcohol, hexadecyl alcohol, acetylene alcohol, glycols, etc.; amide-based defoaming agents such as polyamine acrylates, etc.; tributyl phosphate, One or more selected from the group consisting of phosphate ester-based defoaming agents such as sodium octyl phosphate, metal soap-based defoaming agents such as aluminum stearate and calcium oleate, dimethyl silicone oil, silicone paste, silicone emulsion, organically modified polysiloxane (polyorganosiloxane such as dimethylpolysiloxane), and silicone-based defoaming agents such as fluorosilicone oil may be used, but are not limited thereto. The above defoaming agent can be implemented by applying the product example of 'AGITAN® P 8850'.

[0035] The above powder resin is a dispersion material produced by spray-drying a liquid resin, and is a component that becomes a safe liquid resin when dispersed in water. It can adjust water absorption to an appropriate level and significantly improve water resistance by filling the numerous pores caused by the porous characteristics of crushed oyster shells having a particle size of 0.01 to 0.1 mm, such as metakaolin.

[0036] In the first mixture preparation step of first mixing the above Portland cement, metakaolin, powdered fluidizing agent, defoaming agent, and powdered resin, the weight ratio of the above Portland cement, metakaolin, powdered fluidizing agent, defoaming agent, and powdered resin may be 1 : 0.05 to 0.1 : 0.01 to 0.3 : 0.001 to 0.02 : 0.05 to 0.2. If the metakaolin content is below the above numerical range, when the mortar composition is applied to concrete, the amount of Ca(OH) present in the concrete cannot be controlled, which may increase the corrosion resistance of the concrete and reduce its durability, and if it exceeds the above numerical range, the hydration reactivity becomes excessive, which may degrade the physical properties. If the content of the powdered fluidizing agent is below the above numerical range, it is impossible to control the absorption rate of crushed oyster shells, which have a high absorption rate, which may result in a decrease in the durability and strength of the mortar composition; if it exceeds the above numerical range, clumping of the composition may occur, and if used in the shotcrete method, it may cause clogging of the transfer pump or the inlet of the shotcrete gun. If the content of the defoaming agent is below the above numerical range, sufficient fine air cannot be generated within the concrete to which the composition is applied, which may result in a decrease in durability; if it exceeds the above numerical range, the individual components may not mix well, which may cause a decrease in durability and strength. If the content of the powdered resin is below the above numerical range, the water resistance of the mortar composition may decrease; if it exceeds the above numerical range, it may lead to an increase in product price due to the high unit cost of the product, and may cause material separation by increasing the curing time of the concrete product to which the composition is applied.

[0037] The second mixture preparation step, which involves secondarily mixing the first mixture and the crushed oyster shells, is intended to enhance the water resistance and durability of the mortar composition by mixing the crushed oyster shells as fine aggregate.

[0038] In the second mixture preparation step in which the first mixture and the crushed oyster shell are mixed secondarily, the weight ratio of the first mixture to the crushed oyster shell may be 1:0.5 to 1. If the crushed oyster shell is less than the above numerical range, the manufacturing cost may increase because the fine aggregate mixed with Portland cement must be replaced with a sand component, and if it exceeds the above numerical range, the water absorption rate increases due to the porous crushed oyster shell, which may reduce the durability or strength of the composition.

[0039] The third mixture preparation step, which involves mixing the second mixture and polyester fibers a third time, is performed to improve tensile strength and increase the stability of the structure even when the composition is used in plain concrete that does not contain reinforcing steel.

[0040] The above polyester fiber may be one or more selected from the group consisting of liglycolyte (PGA), polyglycolide (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polyethylene adipice (PEA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and Vectran. Additionally, the above polyester fiber may be replaced with glass fiber.

[0041] The above polyester fibers may have an average length of 10 mm or less, preferably 7 mm or less, and more preferably 3 mm or less. The above polyester fibers may be used to match the average length of the nylon fibers to be mixed later. The purpose of adjusting the average length of the above polyester fibers as described above is to control the clogging of the shotcrete gun when spraying the mortar composition using the shotcrete gun later.

[0042] In the third mixture preparation step in which the second mixture and polyester fibers are mixed for the third time, the weight ratio of the second mixture to the polyester fibers may be 1:0.0005 to 0.002. If the content of the polyester fibers is below the above numerical range, the tensile strength cannot be improved, and if it exceeds the above numerical range, it is difficult to release moisture, which may reduce the durability of the concrete to which the mortar composition is applied.

[0043] The fourth step of preparing the mixture, which involves mixing the third mixture and nylon fibers a fourth time, can increase the water resistance of the mortar composition and, when applied together with polyester fibers, can greatly help in enhancing the strength of the concrete. Since nylon fibers have partial negative charges on N or O within their molecules, they interact electrostatically with the H of water molecules, which have partial positive charges, thereby strengthening the bonding strength with cement.

[0044] In the fourth mixture preparation step in which the third mixture and nylon fibers are mixed for the fourth time, the average length of the nylon fibers may be 0.1 to 5 mm. Preferably, the average length of the nylon fibers may be 0.1 to 3 mm. If the average length of the nylon fibers is less than the above numerical range, the nylon fibers cannot effectively exert their effect and thus cannot affect the enhancement of concrete strength, and if it exceeds the above numerical range, clumping may occur when the mixture is subsequently injected and sprayed into a shotcrete gun, causing the inlet to become clogged.

[0045] In the fourth mixture preparation step in which the third mixture and nylon fibers are mixed for the fourth time, the weight ratio of the third mixture to the nylon fibers may be 100:0.5 to 5. If the content of the nylon fibers is below the above numerical range, plastic shrinkage cracks cannot be reduced, and if it exceeds the above numerical range, mixing with other components is not performed well, which may cause clumping and lead to a problem where the workability of the composition is reduced.

[0046] According to another embodiment of the present invention, a high-strength mortar composition for shotcrete is provided, manufactured by any one of the above manufacturing methods.

[0047] The above high-strength mortar composition for shotcrete may include one or more selected from the group consisting of Portland cement, metakaolin, powdered fluidizing agent, defoaming agent, powdered resin, crushed oyster shell, polyester fiber, and nylon fiber.

[0048] The above high-strength mortar composition for shotcrete may comprise, based on 100 parts by weight of Portland cement, 8 to 9 parts by weight of metakaolin, 1 to 30 parts by weight of powdered fluidizer, 0.3 to 1 part by weight of defoamer, 5 to 20 parts by weight of powdered resin, 50 to 150 parts by weight of crushed oyster shells, 0.05 to 0.2 parts by weight of polyester fiber, and 0.7 to 2 parts by weight of nylon fiber. If the metakaolin is included in an amount less than the above numerical range, the amount of Ca(OH) present in the concrete cannot be controlled when the mortar composition is applied to concrete, which may result in increased corrosion resistance of the concrete and reduced durability; if included in an amount exceeding the above numerical range, the hard hydration reactivity becomes excessive, which may degrade physical properties. If the above powder fluidizing agent is included below the above numerical range, it is impossible to control the absorption rate of crushed oyster shells, which have a high absorption rate, which may result in a decrease in the durability and strength of the mortar composition; if included above exceeding the above numerical range, clumping of the composition may occur, and if used in the shotcrete method, it may cause clogging of the transfer pump or the inlet of the shotcrete gun. If the above defoaming agent is included below the above numerical range, sufficient fine air cannot be generated within the concrete to which the composition is applied, which may result in a decrease in durability; if included above exceeding the above numerical range, the mixing of each component is not properly achieved, which may cause a decrease in durability and strength. If the above powder resin is included below the above numerical range, the waterproofing performance of the mortar composition may decrease; if included above exceeding the above numerical range, it may lead to an increase in product price due to the high unit cost of the product, and may cause material separation by increasing the curing time of the concrete product to which the composition is applied.If the above crushed oyster shells are included in an amount less than the above numerical range, the fine aggregate mixed with Portland cement must be replaced with a sand component, which may increase the manufacturing cost; if included in an amount exceeding the above numerical range, the absorption rate increases due to the porous crushed oyster shells, which may reduce the durability or strength of the composition. If the above polyester fibers are included in an amount less than the above numerical range, tensile strength cannot be improved, and if included in an amount exceeding the above numerical range, it is difficult to release moisture, which may reduce the durability of the concrete to which the mortar composition is applied. If the above nylon fibers are included in an amount less than the above numerical range, plastic shrinkage cracks cannot be reduced, and if included in an amount exceeding the above numerical range, mixing with other components is not achieved well, which may cause clumping and lead to a decrease in the workability of the composition.

[0049] According to another embodiment of the present invention, a shotcrete construction method is provided using a high-strength mortar composition for shotcrete manufactured by any one of the above manufacturing methods.

[0050] A shotcrete construction method using the above-described high-strength mortar composition for shotcrete may include the step of injecting the above-described high-strength mortar composition for shotcrete into a mortar transfer pump; and the step of spraying the composition moved by the transfer pump using a shotcrete gun.

[0051] In the step of injecting the above high-strength mortar composition for shotcrete into the mortar transfer pump, the flow rate of the mortar composition transfer pump may be 2.5 to 3.0 tons / hour.

[0052] In the step of spraying the composition moved by the above transfer pump using a shotcrete gun, the average diameter of the shotcrete gun may be 10 to 20 mm, and preferably 15 mm. If the average diameter of the shotcrete gun is less than the above numerical range, the composition cannot be sprayed smoothly, and if it exceeds the above numerical range, the spraying of the composition is not even, so when applied to a concrete wall or product, it may clump or not be sprayed uniformly, which may cause a decrease in durability and a decrease in water resistance and waterproofing performance.

[0053] In the step of spraying the composition moved by the above transfer pump using a shotcrete gun, an air compressor and a regulator can be additionally used for spraying. The air compressor can be a device having at least 5 horsepower, and the regulator can be connected to the air compressor to spray at a constant pressure of 4 to 5 bar.

[0054] The present invention will be described in more detail below through examples. These examples are intended solely to explain the present invention more specifically, and it will be obvious to those skilled in the art that the scope of the present invention is not limited by these examples according to the gist of the present invention.

[0056] Examples and Comparative Examples

[0057] Example 1

[0058] Oyster shells were washed, air-dried, and then crushed to prepare crushed oyster shells with a particle size of 0.01 to 0.1 mm (S1).

[0059] A first mixture was prepared by mixing 100g of Portland cement, 8g of metakaolin, 10g of powdered fluidizing agent, 1g of defoaming agent, and 1g of powdered resin (S2).

[0060] A second mixture was prepared by mixing 100g of the first mixture with 70g of crushed oyster shells prepared in step S1 (S3).

[0061] A third mixture was prepared by mixing 100g of the second mixture with 0.1g of polyester fiber (S4).

[0062] A final mortar composition was prepared by mixing 100g of the above third mixture with 2g of nylon fiber (S5).

[0063] Example 2

[0064] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 3g of metakaolin was mixed in step S2 of Example 1.

[0065] Example 3

[0066] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 5g of metakaolin was mixed in step S2 of Example 1.

[0067] Example 4

[0068] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 10g of metakaolin was mixed in step S2 of Example 1.

[0069] Example 5

[0070] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 15g of metakaolin was mixed in step S2 of Example 1.

[0071] Example 6

[0072] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 0.07g of defoaming agent was mixed in step S2 of Example 1.

[0073] Example 7

[0074] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 0.1g of defoaming agent was mixed in step S2 of Example 1.

[0075] Example 8

[0076] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 2g of defoaming agent was mixed in step S2 of Example 1.

[0077] Example 9

[0078] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 3g of defoaming agent was mixed in step S2 of Example 1.

[0079] Example 10

[0080] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 30g of crushed oyster shells was mixed in step S3 of Example 1.

[0081] Example 11

[0082] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 50g of crushed oyster shells was mixed in step S3 of Example 1.

[0083] Example 12

[0084] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 100g of crushed oyster shells was mixed in step S3 of Example 1.

[0085] Example 13

[0086] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 120g of crushed oyster shells was mixed in step S3 of Example 1.

[0087] Example 14

[0088] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 0.4g of nylon fiber was mixed in step S5 of Example 1.

[0089] Example 15

[0090] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 0.5g of nylon fiber was mixed in step S5 of Example 1.

[0091] Example 16

[0092] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 5g of nylon fiber was mixed in step S5 of Example 1.

[0093] Example 17

[0094] A final mortar composition was prepared by carrying out the same procedure as in Example 1, except that 6g of nylon fiber was mixed in step S5 of Example 1.

[0095] Comparative Example 1

[0096] A final mortar composition was prepared in the same manner as in Example 1, except that in step S1 of Example 1, oyster shells were crushed to prepare crushed oyster shells with a particle size of 10 mm.

[0097] Comparative Example 2

[0098] A final mortar composition was prepared in the same manner as in Example 1, except that crushed oyster shells were not mixed in step S3 of Example 1.

[0099] Comparative Example 3

[0100] A final mortar composition was prepared in the same manner as in Example 1, except that nylon fibers were not mixed in step S5 of Example 1.

[0102] Experimental Example 1

[0103] The mortar compositions of Examples 1 to 17 and Comparative Examples 1 to 2 were mixed with water, placed in a mixer, mixed and stirred for 5 minutes to form concrete test specimens, and a compressive strength measurement test was performed on the concrete test specimens in accordance with KS F 2405. The results are shown in Table 1.

[0104] division Compressive strength (kgf / cm²) 2 ) 4 hours later 12 hours later 24 hours later 7 days later 28 days later Example 1 352 408 478 501 520 Example 2 301 320 362 398 434 Example 3 312 342 365 403 445 Example 4 322 353 373 412 457 Example 5 330 365 389 420 480 Example 6 280 316 347 398 413 Example 7 292 320 354 400 430 Example 8 299 345 374 419 459 Example 9 301 320 359 382 440 Example 10 281 301 320 348 372 Example 11 290 320 337 369 402 Example 12 301 340 367 382 429 Example 13 320 328 376 440 502 Example 14 332 360 387 450 478 Example 15 354 372 402 465 479 Example 16 374 384 430 478 500 Example 17 379 390 445 486 513 Comparative Example 1 290 301 320 336 356 Comparative Example 2 280 290 302 329 346 Comparative Example 3 302 345 364 385 398

[0106] Experimental Example 2

[0107] The mortar compositions of Examples 1 to 17 and Comparative Examples 1 to 2 were mixed with water, put into a mixer, mixed and stirred for 5 minutes to form concrete test specimens, and an adhesive strength measurement test was performed on the concrete test specimens in accordance with KS F 2762, and the measurement results are shown in Table 2 below.

[0108] division Adhesive strength (kgf / cm²) 2 ) 3 hours later 12 hours later 24 hours later 7 days later 28 days later Example 1 20 25 28 30 32 Example 2 15 17 18 24 28 Example 3 17 18 21 22 29 Example 4 17 17 20 22 29 Example 5 19 20 20 23 28 Example 6 13 14 15 20 26 Example 7 14 16 20 22 26 Example 8 15 17 19 21 27 Example 9 18 19 20 26 29 Example 10 11 12 16 18 19 Example 11 12 15 16 19 23 Example 12 14 18 19 22 24 Example 13 18 20 23 26 27 Example 14 10 13 16 19 25 Example 15 13 15 19 22 24 Example 16 14 16 20 21 25 Example 17 18 18 19 23 26 Comparative Example 1 15 15 17 18 20 Comparative Example 2 14 14 15 16 19 Comparative Example 3 13 14 16 20 20

[0110] Experimental Example 3

[0111] The mortar compositions of Examples 1 to 17 and Comparative Examples 1 to 2 were mixed with water, fed into a mixer, mixed and stirred for 5 minutes to form concrete test specimens, and water resistance was evaluated by measuring the time it took for surface deformation (cracks, blisters, etc.) to occur in the concrete test specimens in hot water at 120°C, and the results of measuring the waterproofing performance are shown in Table 3 below.

[0112] Water resistance (hr) Example 1 900 Example 2 650 Example 3 680 Example 4 720 Example 5 740 Example 6 780 Example 7 790 Example 8 792 Example 9 800 Example 10 560 Example 11 580 Example 12 780 Example 13 790 Example 14 650 Example 15 670 Example 16 790 Example 17 800 Comparative Example 1 320 Comparative Example 2 460 Comparative Example 3 480

Claims

Claim 1 A step of preparing crushed oyster shells by washing, naturally drying, and crushing oyster shells; a step of preparing a first mixture by first mixing Portland cement, metakaolin, powdered fluidizing agent, defoaming agent, and powdered resin; a step of preparing a second mixture by second mixing the first mixture and the crushed oyster shells; a step of preparing a third mixture by third mixing the second mixture and polyester fibers; A method for manufacturing a high-strength mortar composition for shotcrete, comprising a step of preparing a fourth mixture by mixing the third mixture and nylon fibers a fourth time, wherein, in the step of preparing crushed oyster shells by washing and naturally drying the oyster shells and then crushing them, the crushed oyster shells have a particle size of 0.01 to 0.1 mm, in the step of preparing a first mixture by mixing the Portland cement, metakaolin, powdered fluidizing agent, defoaming agent, and powdered resin a first time, the weight ratio of the Portland cement, metakaolin, powdered fluidizing agent, defoaming agent, and powdered resin is 1 : 0.05 to 0.1 : 0.01 to 0.3 : 0.001 to 0.02 : 0.05 to 0.2, in the step of preparing a second mixture by mixing the first mixture and the crushed oyster shells a second time, the weight ratio of the first mixture to the crushed oyster shells is 1 : 0.5 to 1, and the second mixture is mixed with polyester fibers a third time. A method for manufacturing a high-strength mortar composition for shotcrete, wherein in the third mixture manufacturing step, the weight ratio of the second mixture to the polyester fiber is 1:0.0005 to 0.

002. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 A high-strength mortar composition for shotcrete manufactured by the manufacturing method of claim 1.

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