KR101246407B1 - Shotcrete composition including high strength accelerating amorphous calcium aluminate - Google Patents

Abstract

PURPOSE: A shotcrete composition including set accelerator agents of cement mineral for high intensity shotcrete is provided to reduce the thickness of shotcrete by satisfying early strength and long term intensity without using high-intensity blending material. CONSTITUTION: A shotcrete composition including set accelerator agents of cement mineral for high intensity shotcrete comprises cement 17-24 weight%, aggregate 64-74 weight%, water 6-12weight%, and high-intensity set accelerator agent 1-2 weight%. The set accelerator agent use powdery cement mineral system. The set accelerator agent comprises 12CaO·7Al2O3 powder 55-75 weight% which is the main raw material, calcium sulfo aluminate 0.1-10 weight%, a hardening accelerator 0.5-7weight%, an anhydrous gypsum 15-35 weight%, and micro powder pozzolan 5-10 weight%. A calcium sulfoaluminate steadily forms ettringite and enhances long term intensity when reacting with cement. Anhydrous gypsum enhances latter term hardening rate and compressive strength. Micropowder pozzolan enhances long term intensity, chemical resistance, and seawater resistance. [Reference numerals] (AA) High intensity cement mineral-based accelerating agent manufacturing process; (B1) A process - 12CaO, 7Al_2O_3 powder preparing process; (B10) A-9 process - melting process; (B11) A-10 process - impurity extracting process; (B12) A-11 process - water cooling process; (B13) A-12 process - clinker component intermediate inspecting process; (B14) A-13 process - clinker coarse grinding process; (B15) A-14 process - sorting process; (B16) A-15 process - work in process storage process; (B17) A-16 process - measuring process; (B18) A-17 process - fine grinding process; (B19) A-18 process - finely ground product intermediate inspecting process; (B2) A-1 process - ingredient inspecting process; (B20) A-19 process - 12CaO, 7Al_2O_3 powder packaging process; (B3) A-2 process - mixing process for generating seeds; (B4) A-3 process - alumina byproduct granulating process; (B5) A-4 process - alumina byproduct drying process; (B6) A-5 process - granulated alumina byproduct storage process; (B7) A-6 process - ingredient measuring process; (B8) A-7 process - measured ingredient mixing process; (B9) A-8 process - mixed ingredient injecting and fusing agent adding process; (C1) B process - high intensity accelerating agent manufacturing process; (C2) B-1 process - ingredient acceptance inspecting process; (C3) B-2 process - main ingredient and additive measuring process; (C4) B-3 process - mixing process; (C5) B-4 process - product storing process; (C6) B-5 process - product inspecting process; (C7) B-6 process - packaging process with paper bag, ton bag, and others

Description

Shotcrete composition comprising cement mineral filler for high strength shotcrete {Shotcrete Composition Including High Strength Accelerating Amorphous Calcium Aluminate}

The present invention relates to a shotcrete composition comprising a cement mineral filler for high-strength shotcrete for single-shell tunnel reinforcement lining, and more particularly to the use of a high-strength admixture previously added for high-strength shotcrete operations essential for single-shell tunnel reinforcement lining. The present invention relates to a shotcrete composition including a high-strength cement mineral quickener which is added to cement without any improvement in adhesion and accelerates strength development by rapid curing. The cement mineral quickener is melted in a melting furnace by mixing quicklime and alumina by-product. It consists of a mixture of calcium aluminate powder, calcium sulfoaluminate, hardening accelerator, anhydrous gypsum and fine powder pozzolane, which are prepared by a water cooling process and a pulverization process by spraying compressed air and water together to dry by quenching and quenching. Rust at high temperature State of the material is directed to a composition comprising a high strength shotcrete shotcrete mineral cement quick-setting admixture for using an amorphous mineral which the solid structure of the liquid when the instantly cooled.

Although shotcrete used in the construction of tunnels / underground spaces is the most important primary and permanent support material, the 28-day compressive strength standard of domestic shotcrete is about 21MPa. This is considerably lower than the 35 ~ 50MPa standard. Due to such low domestic strength standards, shotcrete has to be thickened for stabilization of tunnels / underground spaces.In addition, the current method of laying secondary concrete lining leads to a decrease in construction speed and an increase in construction cost, resulting in construction efficiency. . It is a factor that impedes economic efficiency.

Recently, many sites using shotcrete use unit cement amount of 460 ~ 480kg / ㎥, and high performance polycarboxylic acid-based fluidizing agent is applied to secure fluidity. Therefore, the water-cement ratio is reduced and the actual strength is higher than 25MPa compared with 21MPa, the design standard strength.

Recently, there is a movement in which high-strength shotcrete is reflected in the design at some sites in Korea, and for this purpose, an increase in the use of high-performance water reducing agents and a high-strength admixture are used or replaced.

However, the use of admixtures requires not only its own cost but also the installation of additional silos for the site application, which not only lowers the economic efficiency but also causes difficulties in quality control.

In addition, as the use of crushed sand instead of natural aggregates is increasing, it is difficult to produce stable high-strength shotcrete using only conventional fasteners.

As a high-strength admixture, fine powder admixtures such as silica fume, metakaolin and fly ash are used.

In terms of overseas technology development, high strength shotcrete and steel fiber reinforced shotcrete with compressive strength of 40 ~ 60 MPa are generally constructed in terms of replacement of secondary lining, long-term behavior and durability of shotcrete.

This is because the use of silica fume and high-performance water-reducing agent is common. Detailed guidance on the application of shotcrete, construction of shotcrete and quality control of high-performance materials, along with the development of equipment considering materials and construction characteristics, together with the systemization of high-quality shotcrete construction It is done.

Cement mineral-based fasteners using amorphous calcium aluminate minerals prepared by the water-cooling method, which is filed by the Applicant Patent No. 10-1074258, the cement mineral-based fastener is 50-70% by weight of calcium aluminate powder as a main raw material, and additives It is composed of a mixture of 10 to 25% by weight of sodium phosphate, 1 to 20% by weight of anhydrous gypsum, 5 to 15% by weight of hydrated lime and 1 to 10% by weight of sodium aluminate, and the calcium aluminate powder contains calcium oxide (CaO) 90 Water-cooling process that mixes 45-60% by weight of quicklime with more than% and 45-60% by weight of alumina raw material and melts it in the melting furnace to quench the water introduced into the cooler with compressed air the will of the calcium aluminate produced by the solid structure of the dried liquid to an amorphous powder after the grinding step, the alumina material is aluminum oxide (Al ₂ O ₃₎ also at least 80% Is a bauxite (Bauxite) or aluminum (Al ₂ O ₃₎ a by-product of alumina product containing at least 80% oxidation.

The compressive strength (MPa) is 1-day compressive strength (12 MPa, 7-day compression) when using 7-8% of cement mineral-based fastener using amorphous calcium aluminate mineral manufactured by water-cooling method published as Patent 10-1074258. Its strength is 27MPa, 28 days compressive strength 35MPa, which is superior to 21MPa based on 28 days compressive strength of domestic shotcrete, but it is less than 36MPa in USA and Japan and 35 ~ 50MPa in Europe. There was a problem of using a mixed material.

High performance admixture composition for improving the performance of shotcrete disclosed in Patent 10-1000258 and the shotcrete comprising the same is 5 to 20% by weight of metakaolin, 5 to 20% by weight calcium sulfoaluminate, anhydrous gypsum as admixture composition to be incorporated into the shotcrete 20 to 45% by weight, fly ash 30 to 50% by weight, 0.05 to 0.25% by weight reducing agent and 0.05 to 0.1% by weight thickener are uniformly mixed, as concrete shotcrete 5 to 20% by weight of metakaolin, calcium sulfoalumina 5 ~ 20 wt% Nate, 20 ~ 45 wt% Anhydrous gypsum, 30 ~ 50 wt% Fly Ash, 0.05 ~ 0.25 wt% Reducing Agent and 0.05 ~ 0.1 wt% Thickening Agent The compressive strength is more than 50MPa with 28 days of strength, but when using admixtures, it is not only the cost of its own but also additional silo installation for site application. Also called Quality Management follows this difficulty.

The present invention for solving the above problems is to upgrade the existing cement mineral filler to provide a shotcrete composition comprising a cement mineral filler for high-strength shotcrete that satisfies early strength and long-term strength without using a high-strength admixture .

The shotcrete composition including the high-strength shotcrete cement mineral fastener of the present invention is used as a temporary or permanent support for stabilizing the excavation section immediately after the excavation of the tunnel and underground space, 17 to 24% by weight cement, 64 to 74% by weight aggregate , 6 to 12% by weight of water, and 1 to 2% by weight of high strength fastener.

The high strength fastener is added to the concrete mixture to improve the adhesion and use a high-strength cement mineral powder type to accelerate the strength development by rapid curing.

The high strength fastener 55-75% by weight of 12CaO.7Al2O3 powder as a main raw material; 0.1 to 10% by weight of calcium sulfoaluminate which stably forms Ettringite and improves strength and durability in the long term upon reaction with cement; 0.5 to 7% by weight of a curing accelerator for promoting curing; 15-35% by weight of anhydrous gypsum to improve the late curing rate and compressive strength; It is composed of 5 to 10% by weight of fine powder pozzolanic to enhance the long-term strength, chemical resistance and seawater resistance by densifying the tissue.

The 12CaO.7Al2O3 powder is mixed with 45 to 60% by weight of quicklime and 45 to 60% by weight of alumina byproduct, and is quenched by spraying water with compressed air to the melt introduced into the cooler through a melting process of melting in a melting furnace. A powder of amorphous 12CaO.7Al2O3, which is a solid liquid, dried through the process, was pulverized to obtain a powder of 5000-7000 brain (cm2 / g).

The calcium sulfoaluminate has a powder degree of 4000 to 8000 brain (cm 2 / g).

The fine powder pozzolan uses silica fume, metakaolin, fly ash or blast furnace slag powder, and the curing accelerator uses at least one of lithium carbonate, sodium carbonate, magnesium sulfate, sodium sulfate or aluminum sulfate.

The shotcrete composition may further comprise 0.1 to 1.0% by weight of a high performance water reducing agent in order to improve the dispersibility, workability, solid resistance and high strength of the cement particles, the high performance water reducing agent is 20-30%, It is preferable to use an alkaaryl sulfonic acid type, a melamine polymarine resin sulfonic acid salt type, or a polycarbonate type.

The shotcrete composition may further be 1.4 ~ 2.4% by weight of steel fiber (Steel fiber) in order to improve the flexural toughness, crack restraint and impact resistance, the steel fiber 30 ~ 35mm in length, 0.5 ~ 0.7mm in diameter It is desirable to.

The quicklime is CaO 90.0% or more, SiO2 3.5% or less, MgO 2.0% or less, Fe2O3 1.5% or less, loss on ignition (Lg. Loss) 3.0% or less, and the alumina byproduct is Al2O3 80.0% or more, SiO2 10% or less, Na2O It is preferable that it is 5.0% or less and 3.0% or less of ignition loss (Lg. Loss).

The aggregate is composed of 55 to 65% by weight of the aggregate and 35 to 45% by weight of the coarse aggregate, the assembly rate of the fine aggregate is 2.3 to 3.1, the assembly rate of the coarse aggregate is 6 to 8.

The particle size of the fine aggregate is based on the nominal size of the sieve and the percent by weight of the sieve, from 10mm to 100%, from 5mm to 95 to 100%, from 2.5mm to 80 to 100%, from 1.2mm to 50 to 85%, from 0.6mm to 25 to 60%. , 0.3mm in 10 ~ 30%, 0.15mm in 2 ~ 10%, the coarse aggregate particle size is based on the nominal size of the sieve and the percentage of the passing weight of 13mm in 100%, 10mm in 85 ~ 100%, 2.5mm It is preferably made from 0 to 10%, 0 to 5% at 0.6mm.

The high-strength quick-setting admixture is high strength for producing the main ingredient of the 12CaO · 7Al ₂ O ₃ powder, a manufacturing process of A step, a high-strength quick-setting admixture by mixing the said 12CaO · 7Al ₂ O ₃ powder and the additives in the additive prepared in A process It is composed of B process, which is a manufacturing process of a fastener.

The present invention as described above can solve the problem to be solved of the shotcrete composition comprising a cement mineral-based fastener for high-strength shotcrete.

According to the shotcrete composition including the cement mineral filler for high-strength shotcrete of the present invention, it is possible to satisfy the early strength and the long-term strength without using a high-strength admixture, thereby reducing the thickness of the shotcrete.

In addition, there is no mixing path for mixing the concrete and the admixture can reduce the facility and simplify the construction.

In addition, the thickness of the shotcrete can be reduced to reduce the rebound amount, the curing time can be reduced, and the construction speed can be reduced, thereby reducing the construction cost and improving the construction efficiency and economic efficiency.

1 is a manufacturing process diagram of a high strength cement mineral filler according to the shotcrete composition including the high strength shotcrete cement mineral fillers of the present invention
Figure 2 is a hydration reaction process diagram of calcium sulfoaluminate according to the shotcrete composition comprising a cement mineral-based fastener for high-strength shotcrete of the present invention
Figure 3 is a graph comparing the compressive strength of the high-strength fastener of the present invention according to the shotcrete composition including the high-strength shotcrete cement mineral fillers of the present invention with other products

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In addition, the terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of the user, the operator, and the like. The definition of the present invention is a shotcrete including cement mineral filler for high-strength shotcrete according to the present invention. It should be made on the basis of the contents throughout this specification describing the "composition".

The shotcrete composition including the high-strength shotcrete cement mineral fastener of the present invention is used as a temporary or permanent support for stabilizing the excavation section immediately after the excavation of the tunnel and underground space, 17 to 24% by weight cement, 64 to 74% by weight aggregate , 6 to 12% by weight of water, and 1 to 2% by weight of high strength fastener.

The high strength fastener is added to the concrete mixture to improve the adhesion and use a high-strength cement mineral powder type to accelerate the strength development by rapid curing.

The high strength fastener 55-75% by weight of 12CaO.7Al2O3 powder as a main raw material; 0.1 to 10% by weight of calcium sulfoaluminate which stably forms Ettringite and improves strength and durability in the long term upon reaction with cement; 0.5 to 7% by weight of a curing accelerator for promoting curing; 15-35% by weight of anhydrous gypsum to improve the late curing rate and compressive strength; It is composed of 5 to 10% by weight of fine powder pozzolanic to enhance the long-term strength, chemical resistance and seawater resistance by densifying the tissue.

The 12CaO.7Al2O3 powder is mixed with 45 to 60% by weight of quicklime and 45 to 60% by weight of alumina byproduct, and is quenched by spraying water with compressed air to the melt introduced into the cooler through a melting process of melting in a melting furnace. A powder of amorphous 12CaO.7Al2O3, which is a solid liquid, dried through the process, was pulverized to obtain a powder of 5000-7000 brain (cm2 / g).

The calcium sulfoaluminate has a powder degree of 4000 to 8000 brain (cm 2 / g).

The fine powder pozzolan uses silica fume, metakaolin, fly ash or blast furnace slag powder, and the curing accelerator uses one or more of lithium carbonate, sodium carbonate, magnesium sulfate, sodium sulfate or aluminum sulfate.

The shotcrete composition may further comprise 0.1 to 1.0% by weight of a high performance water reducing agent in order to improve the dispersibility, workability, solid resistance and high strength of the cement particles, the high performance water reducing agent is 20-30%, It is preferable to use an alkaaryl sulfonic acid type, a melamine polymarine resin sulfonic acid salt type, or a polycarbonate type.

The shotcrete composition may further be 1.4 ~ 2.4% by weight of steel fiber (Steel fiber) in order to improve the flexural toughness, crack restraint and impact resistance, the steel fiber 30 ~ 35mm in length, 0.5 ~ 0.7mm in diameter It is desirable to.

The shotcrete composition may further comprise 0.3 to 0.7% by weight of polypropylene fiber in order to improve flexural toughness, crack restraint and impact resistance.

The quicklime is CaO 90.0% or more, SiO2 3.5% or less, MgO 2.0% or less, Fe2O3 1.5% or less, loss on ignition (Lg. Loss) 3.0% or less, and the alumina byproduct is Al2O3 80.0% or more, SiO2 10% or less, Na2O It is preferable that it is 5.0% or less and 3.0% or less of ignition loss (Lg. Loss).

The aggregate is composed of 55 to 65% by weight of the aggregate and 35 to 45% by weight of the coarse aggregate, the assembly rate of the fine aggregate is 2.3 to 3.1, the assembly rate of the coarse aggregate is 6 to 8.

The particle size of the fine aggregate is based on the nominal size of the sieve and the percent by weight of the sieve, from 10mm to 100%, from 5mm to 95 to 100%, from 2.5mm to 80 to 100%, from 1.2mm to 50 to 85%, from 0.6mm to 25 to 60%. , 0.3mm in 10 ~ 30%, 0.15mm in 2 ~ 10%, the coarse aggregate particle size is based on the nominal size of the sieve and the percentage of the passing weight of 13mm in 100%, 10mm in 85 ~ 100%, 2.5mm It is preferably made from 0 to 10%, 0 to 5% at 0.6mm.

The high-strength quick-setting admixture is high strength for producing the main ingredient of the 12CaO · 7Al ₂ O ₃ powder, a manufacturing process of A step, a high-strength quick-setting admixture by mixing the said 12CaO · 7Al ₂ O ₃ powder and the additives in the additive prepared in A process It is composed of B process, which is a manufacturing process of a fastener.

The step A includes a step A-1, which is a raw material inspection step of inspecting the appearance, composition, and loss of ignition of raw materials of quicklime and alumina by-products; A-2 process which is a mixing process which adds a binder to an alumina by-product and mixes in order to produce a seed; A-3 process, which is a process for making alumina byproduct into granules; A-4 process which is a drying process of removing the moisture of the alumina by-products; A step A-5 which is a granular alumina byproduct storage step of storing the dried granular alumina byproduct; A step A-6, which is a weighing step of measuring the stored quicklime and granular alumina byproducts at a predetermined ratio; A-7 process which is the mixing process which mixes measured quicklime and granular alumina by-product; A-8 process, which is a mixed raw material input and flux addition process which inputs the mixed raw material to an electric furnace, and adds the flux which helps melt the granular alumina by-product; A-9 process which is a melting process which melts the injected raw material at 1500-1700 degreeC in an electric furnace; Step A-10, which is an impurity extraction step of periodically extracting impurities from the electric furnace; A step A-11 which is a water cooling step of quenching by injecting compressed air and water together with the melt drawn into the rotary cooler through the melting step; A-12 process which is an intermediate | middle inspection process which examines the component of 12CaO.7Al2O3 clinker which went through the said A-11 process; Step A-13, which is a clinker coarsely crushing step of coarsely crushing a 12CaO.7Al2O3 clinker so that the particle size is less than 20% by 10 mm; A-14 process which is the sorting process of selecting co-crushed 12CaO.7Al2O3; A step A-15 which is a work-in-process storage step of storing coarse crushed 12CaO.7Al2O3 which has been screened after the step A-14; A-16 process which is a metering process which continuously measures to grind | store the coarse grinding 12CaO7Al2O3 stored finely; A-17 which is a fine grinding process which grind | pulverizes the measured coarse grinding 12CaO.7Al2O3 into a ball mill, and grind | pulverizes; An A-18 process, which is an intermediate inspection process for inspecting pulverized products; Consists of A-19 process, which is a packaging process for packaging 12CaO7Al2O3 powder as a raw material of a fastener.

The process B is a raw material acceptance test process of inspecting 12CaO.7Al2O3 powder as a main raw material, calcium sulfoaluminate, a curing accelerator, anhydrous gypsum and fine powder pozzolan as additives; A step B-2 which is a metering step of measuring 12CaO.7Al2O3 as a main raw material, calcium sulfoaluminate as an additive, a curing accelerator, anhydrous gypsum and fine powder pozzolan at a predetermined ratio; B-3 process which is the mixing process which mixes the measured main raw material and an additive; B-4 process which is a product storage process which stores the product which passed B-3 process; B-5 process which is a product inspection process which carries out product inspection; It consists of the B-6 process, which is a packaging process that is packed in a zone or ton bag.

Hereinafter, a preferred embodiment of the "shotcrete composition containing cement mineral-based fastener for high-strength shotcrete" according to the present invention will be described in detail.

The following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

1 is a manufacturing process diagram of a high strength cement mineral filler according to the shotcrete composition including a high strength shotcrete cement mineral filler according to the present invention, Figure 2 is a calcium alumina according to the shotcrete composition comprising a high strength shotcrete cement mineral filler Figure 3 is a process of hydration reaction of Nate, Figure 3 is a graph comparing the compressive strength of the high-strength fastener of the present invention according to the shotcrete composition comprising the high-strength shotcrete cement mineral fillers of the present invention.

The shotcrete composition of the present invention is composed of 17 to 24% by weight of cement, 64 to 74% by weight of aggregate, 6 to 12% by weight of water, and 1 to 2% by weight of high strength fastener.

The high strength fastener is added to the concrete mixture to improve the adhesion and use a high-strength cement mineral powder type to accelerate the strength development by rapid curing.

The high strength fastener 55-75% by weight of 12CaO.7Al2O3 powder as a main raw material; 0.1 to 10% by weight of calcium sulfoaluminate which stably forms Ettringite and improves strength and durability in the long term upon reaction with cement; 0.5 to 7% by weight of a curing accelerator for promoting curing; 15-35% by weight of anhydrous gypsum to improve the late curing rate and compressive strength; It is composed of 5 to 10% by weight of fine powder pozzolanic to enhance the long-term strength, chemical resistance and seawater resistance by densifying the tissue.

In the shotcrete composition, a key point of the present invention is to satisfy the early strength and the long-term strength without using a high-strength admixture.

The high strength fastener is added to the concrete mixture to improve the adhesion and use a high-strength cement mineral powder type to accelerate the strength development by rapid curing.

The high-strength fastener 55-75% by weight of amorphous 12CaO.7Al2O3 powder as a main raw material; Calcium Sulfo-Aluminate (4CaO · 3Al ₂ O ₃ · CaSO ₄ ) 0.1 ~ 10% by weight to stably form Ettringite and to improve strength and durability in the long term when reacting with cement Wow; 0.5 to 7% by weight of a curing accelerator for promoting curing; 15-35% by weight of anhydrous gypsum to improve the late curing rate and compressive strength; It consists of a 5 to 10% by weight fine powder pozzolanic mixture for densifying tissues to enhance organ strength, chemical resistance and seawater resistance.

The 12CaO.7Al2O3 powder is mixed with 40 to 60% by weight of quicklime and 40 to 60% by weight of alumina byproduct, and is quenched by spraying water with compressed air to the melt introduced into the cooler through a melting process of melting in a melting furnace. A powder of amorphous 12CaO.7Al2O3, which is a solid liquid, dried through the process, was pulverized to obtain a powder of 5000-7000 brain (cm2 / g).

In the high-strength fastener of the present invention, the calcium sulfoaluminate (4CaO · 3Al ₂ O ₃ · CaSO ₄ ), which is not added to the existing cement mineral filler, was added.

The calcium sulfo aluminate is widely applied to special cements and mortars such as cemented carbides and fast-hard cements, steels, repair materials, self-leveling materials, etc., due to the formation of ettringite minerals to exhibit roughness.

The calcium sulfoaluminate reacts with cement to produce various kinds of calcium aluminate hydrates (C ₂ AH ₈ , C ₃ AH ₆ , C ₄ AH ₁₉ ) and ettringite to quench the cement and provide excellent long-term strength. .

 The calcium sulfoaluminate meets gypsum and glass lime to rapidly form ettringite at the beginning of hydration, contributing to the initial reaction of cement, and continuously produces ettringite to minimize calcium hydroxide in the cement to minimize voids at the same time It has the advantage of improving strength and durability. However, because the fastening is rather low, a large amount of addition is required, and the condensation itself is slow.

Figure 2 shows the process of hydration of the calcium sulfoaluminate

The calcium sulfo aluminate (Calcium Sulfo-Aluminate, 4CaO · 3Al ₂ O ₃ · CaSO ₄ ) has a powder degree of 4000 to 8000 brain (cm 2 / g).

In addition, in the present invention, the fine powder pozzolan, which is not added to the existing cement mineral filler, was added.

The fine powder pozzolan uses silica fume, metakaolin, Fly Ash or blast furnace slag powder.

The fine powder pozzolan densifies the tissue by the pozzolanic reaction, exerts an excellent effect on enhancing the long-term strength, and has excellent chemical resistance and seawater resistance, thereby suppressing expansion and collapse of the specimen due to chlorine ion and sulfate in the marine environment.

The fine powder pozzolan has the greatest influence on the hydration of calcium silicate (C ₃ S) in the initial hydration of cement. For some pozzolanic materials, the surface of the pozzolanic material acts as a nucleus for the precipitation of CSH gels (Calcium Silicate Hydrate gel) from the pore fluid, which results in the initial hydration of calcium silicate (C ₃ S) (within one to several hours). In some cases, it is not promoted by the pozzolanic reaction. On the other hand, the Fly Ash by inhibiting the transition to the aluminate through the release of ions in a molar ratio of CaO / SiO ₂ of the "First Hydrates" the molar ratio of CaO / SiO ₂ of about 3 0.8 ~ 1.5 "Second Hydrate" C 3 S Delays the initial sign language.

Participation in the direct reaction of pozzolanic substances begins in earnest three to fourteen days after the hydration reaction begins. In general, Alite (the main mineral phase in cement based on C ₃ S) contained in cement at this time is about 70-80% reaction. Therefore, Si ions and Al ions eluted from the pozzolanic substance react with Ca ions contained in the pore solution present in the pores to form CSH phase and calcium aluminum hydrate, thereby making the structure of the cured body more dense.

The CSH phase produced by the pozzolanic reaction has a lower molar ratio of CaO / SiO ₂ than that of the CSH phase produced by the hydration of cement. However, the permeability is reduced by gradually filling the pores and suppressing the continuity of the pores. In addition, since the pozzolanic reaction is relatively slower than the hydration of cement, the hardened body in which a part of cement is replaced with pozzolanic material initially exhibits high permeability, but the permeability decreases as the reaction proceeds.

As a pozzolanic reaction, the reaction mechanism is gradually different from Ca (OH) ₂ produced when soluble components such as SiO ₂ and Al ₂ O ₃ eluted from the pozzolanic material are hydrated by C ₃ S, C ₂ S, etc. The reaction forms insoluble calcium silicate hydrate (CSH gel) or calcium aluminate hydrate (CAH gel), making the tissue more dense.

Hydration reaction between calcium silicate (C ₃ S) and pozzolanic material is shown below.

_{Ca (OH) 2 + (SiO} 2, Al 2 O 3) = 3 CaO · 2SiO 2 · 3H 2 O / 3 CaO · Al 2 O 3 · 6H 2 O

The curing accelerator may include at least one of lithium carbonate (Li ₂ CO ₃ ), sodium carbonate (Na ₂ CO ₃ ), magnesium sulfate (MgSO ₄ ), sodium sulfate (Na ₂ SO ₄ ), or aluminum sulfate (Al ₂ O ₃ SO ₄ ). use.

The quicklime should be at least 90.0% CaO, at most 3.5% SiO2, at most 2.0 MgO, at most 1.5% Fe2O3, and at most 3.0% of Lg. Loss.

The alumina by-product should be at least 80.0% Al ₂ O ₃ , 10% or less SiO ₂ , 5.0% or less Na ₂ O, 3.0% or less loss of ignition (Lg. Loss).

The high-strength fastener is a cement mineral-based fastener to reduce the alkali content to 1 ~ 4% to show a similar degree of irritation to the ordinary portland cement, so it is less toxic to the human body and can minimize environmental pollution. In addition, by forming a hydrated mineral called Ettringite in the long term, the hydrated structure of the hardened concrete becomes more dense, thus exhibiting strengths similar to or higher than those of the original concrete.

In addition, the high-strength fastener has a higher content of gypsum than conventional cement mineral-based fasteners. Gypsum has been known to act to control the coagulation mainly by Ettringite produced by the reaction with tricalcium aluminate (C ₃ A, 3CaOAl ₂ O ₃ ). Condensation control effect mechanism of the gypsum is in the particle surface of the C ₃ A ettringite (Ettringite) layer is formed by a layer C ₃ A, and then delays the hydrated silicate condensation of cement mainly calcium (C ₃ S, C of the ₂ S) by hydration. That is, the production of ettringite promotes the production of CSH gel, a major hydraulic compound of cement.

In addition, it is known that the cement composition plays an important role in the change of properties due to the content ratio of each component among CaO-Al ₂ O ₃ -SO ₃ three components. If the ettringite is formed before the cement hardened structure is formed, it shows rapidity, and when ettringite is concentrated at the time when the hardened cement is formed, it contributes to the strength of the hardened body.

 In addition, the reaction of producing ettringite from aluminate can effectively solidify water as compared to the hydration of silicates as shown in the following three chemical equations. Therefore, the free water in the matrix can be fixed to the crystal water, thereby making it possible to manufacture high-strength concrete due to the substantial reduction in the water-cement ratio.

From the beginning of the hydration hydrolysis of the C ₃ S it is promoted Ca ^{2 +} the amount of elution of the ions are the greater the reaction which produces the ettringite from C ₃ A is from hydrated initial than the hydration of silicates, such as three chemical reaction formula below Ethrinite is produced to fix a large amount of free water in the cement hardened body with crystal water to substantially reduce the water cement ratio, thereby expressing high strength.

a) C ₃ A + 3CaSO ₄ + 32H ₂ O → C3A ₃ CaSO ₄ 32H ₂ O

b) 2C ₃ S + 6H ₂ O → 3CaO ₂ SiO ₂ 3H ₂ O + 3Ca (OH) ₂

c) 2C ₂ S + 4H ₂ O → 3CaO ₂ SiO ₂ 3H ₂ O + Ca (OH) ₂

 Ettringite produced by the above reaction is filled with large pores of 1400Å or more with a large needle crystal of several μm, densifying the concrete structure, resulting in high strength in a short time, high freeze-melting resistance, and excellent condensation stability. do

As will be shown in Figure 1 wherein the high-strength quick-setting admixture is mixed with the main ingredient of the 12CaO · 7Al ₂ O ₃ powder manufacturing process the A step, the said 12CaO · 7Al ₂ O ₃ powder and the additives in the additive prepared in A process It is made of a high-density fastener manufacturing process for producing a high-strength fastener is composed of B process.

The step A includes a step A-1, which is a raw material inspection step of inspecting the appearance, composition, and loss of ignition of raw materials of quicklime and alumina by-products; A-2 process which is a mixing process which adds a binder to an alumina by-product and mixes in order to produce a seed; A-3 process, which is a process for making alumina byproduct into granules; A-4 process which is a drying process of removing the moisture of the alumina by-products; A step A-5 which is a granular alumina byproduct storage step of storing the dried granular alumina byproduct; A step A-6, which is a weighing step of measuring the stored quicklime and granular alumina byproducts at a predetermined ratio; A-7 process which is the mixing process which mixes measured quicklime and granular alumina by-product; A-8 process, which is a mixed raw material input and flux addition process which inputs the mixed raw material to an electric furnace, and adds the flux which helps melt the granular alumina by-product; A-9 process which is a melting process which melts the injected raw material at 1500-1700 degreeC in an electric furnace; Step A-10, which is an impurity extraction step of periodically extracting impurities from the electric furnace; A step A-11 which is a water cooling step of quenching by injecting compressed air and water together with the melt drawn into the rotary cooler through the melting step; A-12 process which is an intermediate | middle inspection process which examines the component of 12CaO.7Al2O3 clinker which went through the said A-11 process; Step A-13, which is a clinker coarsely crushing step of coarsely crushing a 12CaO.7Al2O3 clinker so that the particle size is less than 20% by 10 mm; A-14 process which is the sorting process of selecting co-crushed 12CaO.7Al2O3; A step A-15 which is a work-in-process storage step of storing coarse crushed 12CaO.7Al2O3 which has been screened after the step A-14; A-16 process which is a metering process which continuously measures to grind | store the coarse grinding 12CaO7Al2O3 stored finely; A-17 which is a fine grinding process which grind | pulverizes the measured coarse grinding 12CaO.7Al2O3 into a ball mill, and grind | pulverizes; An A-18 process, which is an intermediate inspection process for inspecting pulverized products; It consists of the detailed process of the A-19 process, which is a packaging process for packing 12CaO.7Al2O3 powder as a fastener raw material.

The A-1 process is a raw material inspection process for checking the appearance, composition and ignition loss of the raw material of quicklime and alumina by-products, the alumina by-product is SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , Check the content of TiO ₂ , Ignition Loss, Moisture and Grain size, and quicklime contains the content of CaO, Fe ₂ O ₃ , SiO ₂ , MgO and Ignition Loss and Grain Check your back.

As shown in Table 1, the quicklime is CaO 90.0% or more, SiO ₂ 3.5% or less, MgO 2.0% or less, Fe ₂ O ₃ 1.5% or less, loss on ignition (Lg. Loss) 3.0% or less, and the alumina byproduct is Al. It is preferable that they are at least 80.0% of ₂ O ₃ , at most 10% of SiO ₂ , at most 5.0% of Na ₂ O, and at most 3.0% of loss on ignition (Lg. Loss).

The A-1 process shall be carried out by the inspector of the quality assurance part and record the inspection record.

The A-2 process is a mixing process in which a binder is added to the alumina by-product to be mixed to create a seed, and the seed is mixed by adding and mixing a binder to the alumina by-product in powder form. Create

The A-3 process is a globular process to make the alumina byproduct into granules, and grows the seed (Seed) in a drum-type molding machine to grow granules having a size of 10 to 50 mm.

In the case of powder, it is scattered during the process, causing material loss and contamination, and floating on the inside of the electric furnace, which makes it difficult to smoothly melt and prolong the melting time.

The A-4 process is a drying process of removing the water of the alumina byproducts, and undergoes a drying process for a certain residence time in a rotary dryer maintained at 100 to 150 ° C. to remove water.

The temperature inside the rotary dryer maintains the proper temperature by adjusting the amount of oil input or the amount of feed of raw materials. The temperature in the dryer is adjusted by measuring the temperature of the bag filter inlet gas.

When the temperature of the bag filter inlet gas is 180 ° C. or higher, there is a possibility that the bag may be burned out or deteriorated.

The A-5 process is a granular alumina byproduct storage process for storing the dried granular alumina byproduct, and generally uses a ton bag, and may be stored in a vessel such as a tank, but the tank is damp. It is not used much because the lower part is cone type, so the raw material is not stagnant and the discharge is smooth.

The A-6 process is a weighing process for measuring the stored quicklime and granular alumina byproducts at a predetermined ratio, and the two raw materials for each batch according to the ingredients of the raw materials within the range of 40 to 60 wt% of quicklime and 40 to 60 wt% of alumina byproducts. Weigh to add up to 100%.

Each raw material should be weighed so that the chemical composition of 12CaO7Al ₂ O ₃ is 46.0 ± 2.0% of calcium oxide (CaO), 42.0% or more of aluminum oxide (Al ₂ O ₃ ), and 5.0% or less of SiO ₂ .

In other words, each weighing quantity should be determined by knowing the contents of calcium oxide (CaO) and aluminum oxide (Al ₂ O ₃ ), so the dose should be determined based on the inspection data of step A-1. Weigh using.

The A-7 process is a mixing process of mixing the measured quicklime and granular alumina by-products, and the mixed product coming up from the Vibrating Conveyor is lifted up by the Bucket Elevator to be stored as a weighing material storage container and put into the electric furnace. In order to facilitate the discharge, the weighing material storage container should be of a cone type at the bottom.

The A-8 process is a mixed raw material input and flux addition process in which the mixed raw material is added to the electric furnace and a flux to help melt the granular alumina byproduct is added. The solvent is added and mixed before the mixed raw material is added to the electric furnace. The mixed raw materials and the solvent are mixed again to be introduced into the electric furnace.

In the case of alumina by-products, there is a problem that melting is not better than that of conventional bauxite, and using graphite powder and aluminum powder having good electrical conductivity as a flux, 3 to 6% of the weight of alumina by-product is added to make melting smooth. to be.

The A-9 process is a melting process of melting the injected raw material at 1500 ~ 1700 ℃ in the electric furnace, the process control of the melting process is based on the clinker CaO 46.0 ± 2.0%, electric furnace power 1700kwH or less, when the occurrence of the clinker CaO abnormal control Is controlled by the amount of quicklime input. When tapping the electricity, the tap is slowly loaded up after tapping.

The Tap refers to a terminal for adjusting the voltage of an electric furnace, and more power is input to a Tap having a higher value.

The A-10 process is an impurity extraction process that periodically extracts impurities from an electric furnace. Unlike the bauxite ore, alumina by-products contain a small amount of metal such as iron, which adversely affects calcium aluminate minerals, that is, 12CaO.7Al ₂ O ₃ . This is a process to remove impurities periodically by adding a tapping hole to the bottom of the electric furnace.

The A-11 process is a water cooling process for quenching by injection with compressed air and water to the melt introduced into the rotary cooler through the melting process, the pressure of the compressed air used in the water cooling process is 3 ~ 10kgf / cm2 The spraying amount of water is 60 to 300 kg / hr per melt per ton / hr.

The water cooling process uses a rotary cooler to spray high-pressure air together with water to the melt, which has undergone the melting process, to make small particles having a diameter of 10 mm or less, thereby increasing the cooling rate and completely maintaining the residual heat of the particles. It is a process of drying to make 12CaO · 7Al ₂ O ₃ beads in an amorphous state, and the glassy 12CaO · 7Al ₂ O ₃ beads have a uniform cooling state, so that the glass particles having black green transparency can be seen in appearance. X-ray diffraction analysis (XRD) results in an amorphous state in which crystal peaks do not appear.

In the case of air cooling without undergoing a water cooling process, slow cooling large chunks tend to be generated non-uniformly, and a problem of deterioration of quenching characteristics occurs due to a large amount of crystalline content.

The A-12 process is an intermediate inspection process for examining the chemical composition of the 12CaO · 7Al ₂ O ₃ clinker obtained through the A-11 process, and 12CaO · 7Al ₂ O ₃ (calcium aluminate) shown in Table 2 below. The 12CaO.7Al ₂ O ₃ (calcium aluminate) powder is Al ₂ O ₃ 42.0% or more, CaO 44.0 ~ 48.0%, SiO ₂ 5.0% or less, Fe ₂ O ₃ 1.0% or less, ₂ 0 0.5% or less, Na ₂ O 1.0% or less, TiO ₂ 4.0% or less should be managed.

The powder degree is preferably in the range of 5000 to 7000 brain (cm 2 / g), but managed so as to be 6300 to 6700 brain (cm 2 / g).

The A-13 process is a clinker coarse grinding process that coarsely grinds 12CaO · 7Al ₂ O ₃ clinker to have a particle size of 10 mm over 20% or less, to maximize the load reduction and grinding efficiency of the ball mill through coarse grinding before grinding. It should be done with a jaw crusher, and particles larger than 10mm should be less than 20%, and the particle size can be changed by adjusting the gap of the jaw.

The A-14 process is a screening process for sorting coarsely crushed 12CaO.7Al ₂ O ₃ , which is carried out by a vibrating screen to allow a predetermined size or more to be introduced into a jaw crusher.

The A-15 process is a work-in-process storage process for storing the coarse crushed 12CaO.7Al2O3, which has been screened through the A-14 process, and stored in a silo.

The step A-16 is a metering step for continuously metering in order to finely grind the stored coarse crushed 12CaO.7Al ₂ O _3. It is preferable to use a constant feeder weigher.

The A-17 process is a fine grinding process in which the pulverized coarse pulverization 12CaO.7Al ₂ O ₃ is put into a ball mill and finely pulverized so as to have a specific surface area of 5000 to 7000 brain (cm 2 / g). Pulverized Calcium Aluminate (12CaO.7Al ₂ O ₃ ) powder is separated by Cyclone Separator and stored in the lower tank.

Powder level control regulates RPM of Constant Feeder Weigher, fill rate of air session damper and steel ball, mill bearing temperature is below 80 ℃ and mill motor current is maintained.

The A-18 process is an intermediate inspection process for inspecting pulverized products, the intermediate inspection is analyzed by chemical components as XRF (X-ray fluorescence spectrometer), and powder level by a blain tester.

As shown in Table 2, the 12CaO.7Al ₂ O ₃ (calcium aluminate) powder is Al ₂ O ₃ 42.0% or more, CaO 44.0 ~ 48.0%, SiO ₂ 5.0% or less, Fe ₂ O ₃ 1.0% or less, K ₂ O 0.5% or less, Na ₂ O 0.5-2.5% or less, TiO ₂ 4.0% or less, the powder degree is in the range of 5000 to 7000 brain (cm2 / g), but the control value is controlled to be 6300 to 6700 brain (cm2 / g). It is preferable.

The A-19 process is a packaging process for packaging 12CaO.7Al ₂ O ₃ powder as a fastener raw material, packaging in a ton bag, the packaging weight is 1.3Ton ± 1%.

The process B is a fastener manufacturing process for producing a high strength cement mineral quickener as a main raw material and an auxiliary raw material (additive), and inspects 12CaO · 7Al2O3 powder as a main raw material, calcium sulfoaluminate as an additive, a curing accelerator, anhydrous gypsum, and fine powder pozzolan. B-1 process which is a raw material acceptance inspection process; A step B-2 which is a metering step of measuring 12CaO.7Al2O3 as a main raw material, calcium sulfoaluminate as an additive, a curing accelerator, anhydrous gypsum and fine powder pozzolan at a predetermined ratio; B-3 process which is the mixing process which mixes the measured main raw material and an additive; B-4 process which is a product storage process which stores the product which passed B-3 process; B-5 process which is a product inspection process which carries out product inspection; It consists of the detailed process of B-6 process, which is a packaging process for packing with a zone or ton bag, and the detailed process is described in detail as follows.

The B-1 step is a raw material acceptance test step of inspecting 12CaO.7Al ₂ O ₃ (calcium aluminate) powder as a main raw material, calcium sulfoaluminate, a curing accelerator, anhydrous gypsum, and fine powder pozzolan as a secondary raw material.

12CaO 7Al ₂ O ₃ (Calcium aluminate) powder is 42.0% or more of Al ₂ O ₃ , CaO 44.0-48.0%, SiO ₂ 5.0% or less, Fe ₂ O ₃ 1.0% or less, K ₂ O 0.5% or less, Na ₂ O 0.5-2.5% or less , TiO ₂ It should be confirmed that the powder is 4.0% or less and the powder is 6500 ± 200 cm 2 / g.

The calcium sulfo aluminate [4CaO3Al2O3CaSO ₄ (C ₄ A ₃ S)] is characterized in that the brain 4000 ㎠ / g ~ 8000 ㎠ / g and the coagulation characteristics are somewhat slower than the amorphous C ₁₂ A ₇ mineral, but Ethrinite Is formed stably, and when it is reacted with cement, it has the characteristics of improving strength and durability in the long term.

The curing accelerator in the group consisting of lithium carbonate (Li ₂ CO ₃ ), sodium carbonate (Na ₂ CO ₃ ), magnesium sulfate (MgSO ₄ ), sodium sulfate (Na ₂ SO ₄ ), aluminum sulfate (Al ₂ O ₃ SO ₄ ) Use one or more than one selected.

The fine powder pozzolan uses one of silica fume, metakaolin, Fly Ash or blast furnace slag, and compacts the tissue by the pozzolanic reaction to exert an excellent effect on enhancing the long-term strength, and has excellent chemical resistance and seawater resistance, thereby improving chlorine in the marine environment. It has the effect of suppressing the expansion collapse of the specimen due to ions and sulfates.

  The fine powder pozzolanic material used in the present invention was used blast furnace slag powder in consideration of economics and stability.

The B-2 process is a weighing process for measuring the 12CaO.7Al ₂ O ₃ (calcium aluminate) which is the main raw material, calcium sulfoaluminate, the curing accelerator, anhydrous gypsum and fine powder pozzolan as an additive (subsidiary material) at a predetermined ratio, Weigh by Constant Feeder Weigher and Hopper Scale.

The high-strength fastener 55-75% by weight of 12CaO.7Al2O3 powder as a main raw material; 0.1 to 10% by weight of calcium sulfoaluminate which stably forms Ettringite and improves strength and durability in the long term upon reaction with cement; 0.5 to 7% by weight of a curing accelerator for promoting curing; 15-35% by weight of anhydrous gypsum to improve the late curing rate and compressive strength; It consists of a 5 to 10% by weight fine powder pozzolanic mixture for densifying tissues to enhance organ strength, chemical resistance and seawater resistance.

Table 3 shows the condensation test and the mortar compressive strength test with the same formulation of high strength fasteners in order to check the properties of high strength fasteners. The change in penetration resistance and compressive strength according to the compounding amount of phosphorus additive was shown, and 1A-3 showed the best result at 28 days strength.

Calcium sulfoaluminate (C ₄ A ₃ S) used brain 4000cm2 / g ~ 8000cm2 / g, specific gravity 2.93, anhydrous gypsum was used Ⅱ anhydrous gypsum, and the curing accelerator used sodium carbonate. The fine powder pozzolan used three kinds of slag fine powder.

The B-3 process is a mixing process of mixing the measured main raw material and the additive (subsidiary material), it is preferable to use a double shaft mixer, which is a zero gravity mixer and the mixing time is 40 ± 10 minutes.

The B-4 process is a product storage process for storing a product that has undergone the B-3 process and is stored in a control screen hopper.

The B-5 process is a product inspection process for inspecting high-strength cement mineral quickeners using amorphous calcium aluminate minerals, and the chemical composition of the cement mineral quickener is Al ₂ O ₃ 32 ± 3%, CaO 38 ± 4% , Na ₂ O 3.0% or less, SO ₃ 10% or more, the physical components are penetration resistance of 1 minute 30kgf / ㎠ or more, 5 minutes 130kgf / ㎠ or more, 15 minutes 250kgf / ㎠ or more, compressive strength 1 day Examine whether 102 kgf / cm 2 (10 MPa) or more, 7 days 255 kgf / cm 2 (25 MPa) or more, and 28 days 408 kgf / cm 2 (40 MPa) or more.

The B-6 process is a packaging process that packs into a zone or ton bag when it meets the product standard.The packaging weight is 20kg ± 2% for the zone, 300kg ± 1% for the tonbag, and 400kg ± 1%. If the weight error exceeds the allowable limit, the basis weight of the packing machine should be readjusted.

The shotcrete composition of the present invention is composed of 17 to 24% by weight of cement, 64 to 74% by weight of aggregate, 6 to 12% by weight of water, and 1 to 2% by weight of high strength fastener.

The shotcrete composition may further comprise 0.1 to 1.0% by weight of a high performance water reducing agent in order to improve the dispersibility, workability, solid resistance and high strength of the cement particles, the high performance water reducing agent is 20-30%, Alkaaryl sulfonic acid type | system | group, melamine polymarine resin sulfonic acid salt type, or polycarbonate type | system | group is used.

The high performance sensitizer is significantly higher than the general sensitizer, and the dispersion performance of cement particles is significantly higher, and even when used in a large amount, there is no delay in condensation, excessive air entrainment, or a decrease in strength. It has low foaming and low coagulation delay, so it can be used in large quantities. It has a compressive strength of about 800kg / cm2 at around 30% of water cement ratio, and it is effective in improving durability because it has little shrinkage and tight shotcrete.

The shotcrete composition may further comprise 0.3 to 0.4% by weight of steel fiber in order to improve bending toughness, crack restraint and impact resistance, and the steel fiber may use a length of 30 to 35 mm and a diameter of 0.5 to 0.7 mm. In order to overcome brittleness, which is the biggest weakness of concrete, L FIBER increases tensile strength, flexural strength, resistance to cracking, shear strength, ductility, and impact resistance.

The steel fiber (STEE phase can be maintained.

In addition, the shotcrete composition may be additionally 0.3 to 0.7% by weight of polypropylene fiber (Polypropylene fiber) to improve the flexural toughness, cracking resistance and impact resistance instead of using the steel fiber (STEEL FIBER).

The aggregate consists of 55 to 65% by weight of fine aggregate and 35 to 45% by weight of coarse aggregate.

It is preferable that the granulation rate of the fine aggregate is 2.3 to 3.1, and that of the coarse aggregate is 6 to 8.

The assembly rate is a method of indicating the particle size of the aggregate, each sieve when the sieve classification test of the aggregate using a set of standard mesh sieve 80, 40, 20, 10, 5, 2.5, 1.2, 0.6, 0.3, 0.15 mm This is the sum of the cumulative weight percentage of the amount taken, divided by 100.

The particle size of the fine aggregate is based on the nominal size of the sieve and the percent by weight of the sieve, from 10mm to 100%, from 5mm to 95 to 100%, from 2.5mm to 80 to 100%, from 1.2mm to 50 to 85%, from 0.6mm to 25 to 60%. , It is preferably made of 10 to 30% at 0.3mm, 2 to 10% at 0.15mm.

The grain size of the coarse aggregate is preferably made of 100% at 13mm, 85 to 100% at 10mm, 0 to 10% at 2.5mm, 0 to 5% at 0.6mm based on the nominal size of the sieve and the percentage of weight passed.

Said shotcrete composition is 400 ~ 550kg of cement, aggregate 1470 ~ 1700kg, water 140 ~ 275kg, high strength fastener 20 ~ 44kg, high performance water reducing agent 2 ~ 20kg, steel fiber 32 ~ 55kg, 8 to 17 kg of polypropylene fiber, the weight of the shotcrete composition 1 ㎥ is based on an average of 2300 kg.

The steel fiber is preferably added to 8 to 10% based on the total weight of cement.

The polypropylene fiber is preferably added 2 to 3% based on the total weight of cement.

Table 4 shows the changes in penetration resistance and compressive strength (MPa) when the content of the high strength fastener is adjusted with respect to 100 parts by weight of cement by mixing 1A-3 in Table 3. The characteristics appeared quickly, so it was easy to use in the water and soft ground sections, and the strength was decreased due to the increase of the high strength fastener content.

In consideration of the results of Table 3 and Table 4, the strength test for each mixing condition was carried out by mixing the shotcrete compositions of Tables 5 and 6, and the test results are shown in Table 5 and the right side of the table.

However, Table 5 shows the amount of use of each material in weight%, Table 6 shows the amount of use of each material per 1㎥ of shotcrete in kg, the total weight per 1㎥ of shotcrete is shown in Tables 5 and 6, Table 5 and Table 6 show the same conditions for each category.

As shown in the experimental results in Table 5 and Table 6, it can be seen that the strength is increased as the amount of cement unit increases.In general, the conventional fasteners are made of plain concrete, which does not use the Whereas 1C-1, 2C-1, and 3C-1 do not use a fastener, they exhibit 70-85% strength. It can be confirmed that the intensity of 90% or more.

In the 3C-1 standard formulation of Table 5 and Table 6, that is, without the use of the fastener according to the Table 7 standard, when using the high-strength fastener of the present invention and when 5% of the powdered fastener is used, liquid alkaline free 8 Table 8 shows the compressive strength (MPa) when using% and using liquid aluminate 5%. Yellow in Table 7 represents the unit material amount (kg / ㎥) for each material per 1 ㎥ of shotcrete, and light green color represents the weight percentage of each material used.

As shown in Table 8 and FIG. 3, the shotcrete composition of the present invention has a strength of about 90% when the filler is not used, and has a strength of about 90%, and is higher than that of the shotcrete composition using the powdered or liquid alkaline free or liquid aluminate quickener. It can be seen that the strength is about 50% higher.

According to the shotcrete composition including the high-strength shotcrete cement mineral filler according to the present invention, it is possible to satisfy the early strength and the long-term strength without using the high-strength admixture as shown in Table 8, thereby reducing the thickness of the shotcrete.

In addition, there is no mixing path for mixing the concrete and the admixture can reduce the facility and simplify the construction.

In addition, the thickness of the shotcrete can be reduced to reduce the rebound amount, the curing time can be reduced, and the construction speed can be reduced, thereby reducing the construction cost and improving the construction efficiency and economic efficiency.

Claims (7)

In the shotcrete composition used as a temporary or permanent support for stabilizing the excavation section immediately after the excavation of the tunnel and underground space,
The shotcrete composition is composed of 17 to 24% by weight of cement, 64 to 74% by weight of aggregate, 6 to 12% by weight of water, 1 to 2% by weight of high-strength fastener,
The high strength fastener is added to the concrete mixture to improve adhesion and use a high-strength cement mineral powder type to accelerate the development of strength by rapid curing,
The high-strength fastener 55-75% by weight of 12CaO.7Al ₂ O ₃ powder is the main raw material;
0.1 to 10% by weight of calcium sulfoaluminate which stably forms Ettringite and improves strength and durability in the long term upon reaction with cement;
0.5 to 7% by weight of a curing accelerator for promoting curing;
15-35% by weight of anhydrous gypsum to improve the late curing rate and compressive strength;
It is composed of 5 ~ 10% by weight of fine powder pozzolanic mixture to increase the strength of organs and enhance chemical resistance and seawater resistance by densifying tissues,
The 12CaO · 7Al ₂ O ₃ powder is quenched by injecting water with compressed air into the melt introduced into the cooler through a melting process of melting 40 ~ 60% by weight of quicklime and 40 to 60% by weight of alumina byproducts and melting in a melting furnace. Aqueous 12CaO · 7Al ₂ O ₃ , a solid of liquid structure dried through a water cooling process, was made into a powder through a pulverization process. The powder is 5000 ~ 7000 brain (cm ² / g),
The calcium sulfoaluminate has a powder degree of 4000 to 8000 brain (cm ² / g),
The fine powder pozzolan uses one of silica fume, metakaolin, Fly Ash or blast furnace slag powder,
The curing accelerator uses at least one of lithium carbonate, sodium carbonate, magnesium sulfate, sodium sulfate or aluminum sulfate,
The quicklime is CaO 90.0% or more, SiO ₂ 3.5% or less, MgO 2.0% or less, Fe ₂ O ₃ 1.5% or less, loss on ignition (Lg. Loss) 3.0% or less,
The alumina byproduct is Al ₂ O ₃ 80.0% or more, SiO ₂ 10% or less, Na ₂ O 5.0% or less, Loss on ignition (Lg. Loss) 3.0% or less,
The high-strength quick-setting admixture is high strength for producing the main ingredient of the 12CaO · 7Al ₂ O ₃ powder, a manufacturing process of A step, a high-strength quick-setting admixture by mixing the said 12CaO · 7Al ₂ O ₃ powder and the additives in the additive prepared in A process Manufactured by B process, which is a manufacturing process
The step A includes a step A-1, which is a raw material inspection step of inspecting the appearance, composition, and loss of ignition of raw materials of quicklime and alumina by-products;
A-2 process which is a mixing process which adds a binder to an alumina by-product and mixes in order to produce a seed;
A-3 process, which is a process for making alumina byproduct into granules;
A-4 process which is a drying process of removing the moisture of the alumina by-products;
A step A-5 which is a granular alumina byproduct storage step of storing the dried granular alumina byproduct;
A step A-6, which is a weighing step of measuring the stored quicklime and granular alumina byproducts at a predetermined ratio;
A-7 process which is the mixing process which mixes measured quicklime and granular alumina by-product;
A-8 process, which is a mixed raw material input and flux addition process which inputs the mixed raw material to an electric furnace, and adds the flux which helps melt the granular alumina by-product;
A-9 process which is a melting process which melts the injected raw material at 1500-1700 degreeC in an electric furnace;
Step A-10, which is an impurity extraction step of periodically extracting impurities from the electric furnace;
A step A-11 which is a water cooling step of quenching by injecting compressed air and water together with the melt drawn into the rotary cooler through the melting step;
Intermediate inspection step of A-12 process for checking the composition of 12CaO · 7Al ₂ O ₃ clinker (Clinker) out through the A-11 and processes;
Step A-13, which is a clinker coarsely crushing step of coarsely crushing a 12CaO.7Al ₂ O ₃ clinker to have a particle size of 10 mm over 20% or less;
Pulverized with a screening step of A-14 a step of selecting a 12CaO · 7Al ₂ O ₃ and;
The A-14 jo completing the selection process after the grinding work-in-process storage 12CaO · 7Al ₂ O ₃ process is the step of storing the A-15 and;
A step A-16 which is a weighing step for continuously weighing the stored coarse crushed 12CaO.7Al ₂ O ₃ ;
Metered pulverized with a ball mill for 12CaO · 7Al ₂ O ₃ fine pulverization of A-17 were charged into a fine grinding step of (Ball Mill) and;
A-18 process which is an intermediate inspection process which examines a pulverized product;
It is composed of A-19 process, which is a packaging process for packing 12CaO · 7Al ₂ O ₃ powder as raw material of fastener,
The process B is a raw material acceptance test step of inspecting 12CaO.7Al ₂ O ₃ powder as a main raw material, calcium sulfoaluminate, a curing accelerator, anhydrous gypsum and fine powder pozzolan as additives;
A step B-2, which is a metering step of measuring 12CaO.7Al ₂ O ₃ as a main raw material, calcium sulfoaluminate as an additive, a curing accelerator, anhydrous gypsum and fine powder pozzolan at a predetermined ratio;
B-3 process which is the mixing process which mixes the measured main raw material and an additive;
B-4 process which is a product storage process which stores the product which passed B-3 process;
B-5 process which is a product inspection process which carries out product inspection;
Shotcrete composition containing cement mineral-based fastener for high-strength shotcrete, characterized in that produced by the process consisting of the B-6 process, which is a packaging process for packaging in a zone or ton bag
The method of claim 1,
The shotcrete composition is further composed of 0.1 to 1.0% by weight of a high performance water reducing agent to improve the dispersibility, workability, solid resistance and high strength of the cement particles,
The high-performance sensitizer has a 20 to 30% susceptibility, and shotcrete composition comprising a cemented mineral fastener for high-strength shotcrete, characterized in that it uses a polyalkaryl sulfonic acid type, melamine polymarine resin sulfonic acid salt type or polycarbonate type.
The method of claim 1,
The shotcrete composition is further composed of 1.4 to 2.4% by weight of steel fiber (Steel fiber) in order to improve the flexural toughness, crack restraint and impact resistance,
The steel fiber is shotcrete composition containing cement mineral-based fastener for high-strength shotcrete, characterized in that using a length of 30 ~ 35mm, diameter 0.5 ~ 0.7mm
The method of claim 1,
The shotcrete composition is a shotcrete composition comprising a cement mineral-based fastener for high-strength shotcrete, characterized in that 0.3 to 0.7% by weight of polypropylene fiber is further formed in order to improve the flexural toughness, crack restraint and impact resistance
The method of claim 1,
The aggregate consists of 55 to 65% by weight of fine aggregate and 35 to 45% by weight of coarse aggregate,
Assembly rate of the fine aggregate is 2.3 to 3.1,
Assembly rate of the coarse aggregate is 6-8,
The particle size of the fine aggregate is based on the nominal size of the sieve and the percent by weight of the sieve, from 10 mm to 100%, from 5 mm to 95 to 100%, from 2.5 to 80 to 100%, from 1.2 to 50 to 85%, from 0.6 to 25 to 60%. , 10-30% at 0.3mm, 2-10% at 0.15mm,
The particle size of the coarse aggregate is characterized in that the high strength consisting of 13% in 100mm, 10% in 85 ~ 100%, 2.5mm in 0 ~ 10%, 0.6mm in 0 ~ 5% based on the nominal size of the sieve and the percentage of the passing weight Shotcrete composition containing cement mineral quickener for shotcrete
delete The method of claim 1,
In the A-8 process, the flux uses graphite powder and aluminum powder,
The flux is a shotcrete composition comprising a cement mineral-based fastener for high-strength shotcrete, characterized in that to add 3 to 6% by weight relative to the alumina by-product

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