KR20070059040A - Fastener composition for viscosity increase shotcrete - Google Patents

Abstract

Accelerator composition containing magnesium alumino silicate as a thickener for shotcrete is provided to lower W/C ratio and to improve compression strength of concrete in pouring or feeding concrete cement, and to increase adhesiveness of the concrete, by comprising liquid type accelerator such as liquid aluminate or silicate, and alumino silicate or bentonite as the thickener. The accelerator composition contains 80-99wt.% of liquid accelerator and 1-20wt.% of magnesium alumino silicate thickener. The liquid accelerator is any one selected from liquid aluminate, liquid silicate and liquid alkali-free based accelerators. Alternatively, the magnesium alumino silicate thickener is attapulgite or bentonite. The liquid aluminate is liquid sodium aluminate or liquid potassium aluminate. The liquid silicate is liquid sodium silicate or liquid potassium silicate. The liquid alkali-free based accelerator is liquid aluminum sulfate.

Description

Compositions of accelerating agent for making shotcrete}

The present invention relates to a fastener composition for viscosity increasing shotcrete containing magnesium aluminosilicate as a liquid fastener and a thickener, and more particularly, a liquid fastener selected from any one of liquid aluminate, liquid silicate or liquid alkali free. The present invention relates to a fastener composition for viscosity increase shotcrete comprising a magnesium aluminosilicate thickener which is aluminosilicate or bentonite.

In tunnel construction, dam construction or underground structure construction, shotcrete is used as a work for preventing collapse by reinforcing a crack in a rock or ground. The shotcrete is used in such a way that it is sprayed through a ready-mixed concrete, a pump, a nozzle, and the like on the ceiling or the wall of the construction site to harden the property, and the shotcrete composition includes cement, aggregate, fastener, admixture, and the like.

Conventionally, in order to impart bonding strength to concrete, thickeners are added to the shotcrete composition in addition to the fasteners and admixtures, and as a result, the viscosity of the shotcrete composition is increased and fluidity is decreased, and water is added to improve the W / C. There is a problem that the rain is increased. Therefore, there is a need for reducing the W / C ratio while maintaining the viscosity of shotcrete.

W / C ratio is the ratio of water-cement (W / C), which is one of several factors that affect the design of shotcrete. According to H-Rusch, the amount of water required for cement to hydrate is 23 Percentage of water, the flow of water in the cement pool requires 10-13% more water. The remaining water used for hydration evaporates to form voids in the cement pool. As the W / C ratio increases, the voids in the concrete become larger, and the volume of the solid part of the concrete itself decreases, thereby decreasing the strength of the concrete. Therefore, when preparing a composition for shotcrete, it is possible to lower the W / C ratio by using only a quickener without a thickener, but in this case, the shotcrete is not well cured or has a poor coagulation ability. For example, if only the aluminate-based fastener is used without a thickener, the fastening ability is excellent, but hardening is difficult at the water-exuding site. If only the silicate-based fastener is used, the coagulation ability is weak depending on the temperature. When used, there is no deterioration in compressive strength and excellent ability to realize high strength, but there was a problem such as dropout rate at the underground elution site.

When the fastener is classified according to the shape, it is divided into a liquid type and a powder type. In Korea, liquid quickeners are used for wet shotcrete and powdery fasteners are used for dry shotcrete. However, this is not necessary. Absolutely, overseasly, powdery fasteners are used for wet shotcrete and liquid quickeners are used for dry shotcrete. In many cases. In particular, the liquid type may not exist due to the characteristics of the material, such as cement mineral fillers. In general, the liquid fastener has advantages of convenience and mixing, and dust generation amount less than that of the powder fastener.

However, in the preparation of the shotcrete composition, when the liquid quickener is used instead of the powdery quickener when mixed with the fastener, the moisture contained in the liquid quickener increases the W / C ratio of the concrete, thereby reducing the adhesive strength of the shotcrete composition. The dropout rate was increased, resulting in a faster reactivity compared to the case of using a powdery fastener, which adversely affects the long-term strength of the concrete structure. In addition, the specific gravity of the liquid fastener is higher than water at about 1.4, and produced and supplied at a critical concentration. When the liquid fastener is mixed with other materials to prepare the composition and stored for a long time, additives other than the fastener are added to the fastener. There is a problem such that a phenomenon that is separated into two layers.

Application No. 2000-53318 (cement mineral quickener for shotcrete and preparation method thereof) describes a cement mineral quickener for shotcrete comprising a thickener and calcium aluminate amorphous powder as a fastener, and Application No. 2005-7004485 (Spraying material and the spraying method using the same) describe a liquid fastener containing an aluminum source, a sulfur source and a fluorine source, and a spray material containing one or more kinds of quickening aids, each of which is in the form of a powder. It is an invention that uses a quickener or a quickener to improve the quickness of the fastener, and is different from the present invention in which magnesium aluminosilicate is used as a thickener to improve the thickening effect, and in particular, a liquid quickener No compositions containing thickeners, which are calcium aluminosilicates, have been reported.

As a result of intensive efforts to overcome the above problems, by using a thick agglomerate magnesium aluminosilicate in the liquid fastener to be used in the shotcrete composition, when the concrete is poured, the adhesion is increased, the W / C ratio is reduced and the strength of the shotcrete is improved The present invention was completed.

Accordingly, it is an object of the present invention to provide a fastener composition for viscosity increasing shotcrete containing magnesium aluminosilicate as a liquid fastener and a thickener.

Other objects and advantages of the invention will be apparent from the following examples and claims.

The present invention relates to a fastener composition for viscosity-increasing shotcrete containing magnesium aluminosilicate as a liquid fastener and a thickener.

In the present invention, 'fastener' refers to a fastener for shotcrete that is used in concrete production to accelerate the hydration reaction of cement to shorten the solidification time of the sprayed concrete and to promote the development of initial strength. Depending on the shape or shape can be classified as follows.

Commercially available shotcrete for shotcrete is silicate, aluminate, alkali-free, and cement mineral based fasteners depending on the ingredients, and liquid type and powder type depending on the shape. In general, liquid quickeners are used in wet shotcrete, and powdery fasteners are mainly used in dry shotcrete in Korea, and the fastener of the present invention is a liquid quickener, for example, liquid aluminate or liquid silicate. And liquid alkali-free fasteners, and any of liquid aluminate, liquid silicate or liquid alkali-free may be selected as the fastener for shotcrete of the present invention.

The aluminate-based accelerator (Alluminate Based Accelerator) contains the AlO ₂ ^- or AlO ₃ ^3- component, it is characterized by reducing the setting time by promoting the hydration reaction of the cement. Therefore, it is mainly used in the place where the initial strength is needed and the soft rock or the high flexural strength is required, and since it is directly involved in the coagulation and hydration reaction of cement, it has a higher degree of ordering effect than the silicate system in the place where a lot of groundwater flows out. It works. There are two types of liquid aluminate-based fasteners, sodium aluminate and potassium aluminate quickeners, and the aluminate quickener of the present invention may be selected from either liquid sodium aluminate or liquid potassium aluminate. ATEX-QL, Union Crete-A, and Econex Shot-L, which are commercially available liquid fasteners in Korea, are representative examples of sodium aluminate-based liquid fasteners, and Sigunit-L. (Cica Korea) is a potassium aluminate-based liquid fastener.

The silicate-based accelerator (Silicate Based Accelerator) is characterized by containing XM ¹ ₂ O · ySiO ₂ (M1 is a monovalent metal such as Na or K), the silicate is not directly involved in the hydration reaction of cement It combines with cement and water to increase the viscosity in concrete. However, there is a limit in increasing the viscosity of concrete, and several shotcrete operations are required for overbreak filling. The rate of initial strength development is similar to that of ordinary concrete. Commercially available liquid silicate quickeners in Korea can be divided into two types: sodium silicate and potassium silicate. Examples of liquid silicate quickeners include Delvo Crete Activator S 61 (Korea Master Builders) and TCC 768 (Korea Master Builders). , Sigunit L30X (Cica Korea), Union Crete-S (Yeon), Su-Crete TL (Ewha Corporation), Econex Shot-LS (Igan Industry).

The Alkali Free Based Accelerator contains Al (OH) xRy (x + y = 3), where R is a cationic component separated from an organic acid such as RHn, and in some cases an alkali free based accelerator. It may also be referred to as an organic fastener. The alkali-free fastener is a liquid having an alkali cation content of 1.0% by weight or less, and thus has a pH of 0-7, which is acid to neutral, so that it has little adverse effect on the human body due to environmental and alkali burns, and suppresses the occurrence of alkaline aggregate reactions. The reduction rate of strength is small. As the liquid alkali-free fastener of the present invention, aluminum sulfate alkali-free quickener is preferable, and examples of commercially available liquid alkali-free quickeners in the market include SA 145 (Master Builders) and SA 160 (Master Builders).

In the present invention, the 'thickener' is a liquid fastener to maintain the viscosity easy to install in the slurry state, giving a bonding force to the shotcrete concrete after construction to stabilize the coating layer before hydration bonding of the water-soluble binder in the construction surface As used to prevent sagging and to maintain a lining of a certain thickness, it refers to magnesium alumino silicate. The magnesium aluminosilicate may be represented by the formula M _p Al _q Si ₂ O _r (OH) _s A _{t u u 2 2} O, wherein M is an exchangeable alkali metal cation, A is a halide, p, q, r, s and t are in the range of 0.2 ≦ p ≦ 2.0, 0.5 ≦ q ≦ 2.5, 4.0 ≦ r ≦ 12, 0.5 ≦ s ≦ 4.0, 0.0 ≦ t ≦ 1.0, and 0.0 ≦ u ≦ 6.0, respectively. In addition, the magnesium aluminosilicate includes attapulgite or bentonite, wherein the attapulgite is composed of SiO ₂ , Al ₂ O ₃ and MgO (Mg, Al) ₂ SiO _{4 ·} O Palygorskite clay mineral, denoted as ₁₀ (OH) .4H ₂ O, may vary in chemical composition depending on the region of the mineral, and elastic, strong stick-shaped crystal particles are charged on the surface. When dispersed in a liquid phase, atapulgite particles and other charged particles are formed and gelated by forming an ion lattice in the cement of the liquid quickener and shotcrete composition by electrostatic attraction. In addition, the bentonite (Bentonite) is a clay consisting of Montmorillonite-based expandable three-layer plate (SI-Ai-Si), is formed of Al ₂ Si ₄ (OH), a pyrophylite chemical structural formula. have. The bentonite is formed in a tile-like shape capable of absorbing water, and confines water therein to block viscosity of water in the cement of the liquid quickener and the shotcrete composition. Bentonite is largely divided into calcium bentonite and sodium bentonite according to the type of cation present between the layers.Most of the bentonite produced in Korea is produced by the property alteration of tuff, and most of it is Ca-Mg type bentonite. The content of montmorillonite, the main mineral, is 45-95%, and it is known to contain minor minerals such as quartz and feldspar.

The attapulgite or bentonite is very stable in strong alkalis and strong acids, and when mixed with liquid quickeners or concrete cements, each particle forms a lattice, and is evenly mixed in the liquid quickeners or concrete compositions. In addition, it has a thixotropy that varies in viscosity depending on the flow rate of the liquid phase, and has a high viscosity at a low flow rate and a low viscosity at a high flow rate. When a rapid shift occurs, it is in a liquid sol state.

In the present specification, 'shotcrete (shot concrete)' refers to the mortar or concrete sprayed on the construction surface by using an injector by compressed air, the shotcrete is a concrete, pump and nozzle on the ceiling or wall of the construction site, etc. It is used in such a way that it is sprayed through and hardened to the property, and generally includes cement, aggregate, water, quickener, thickener, and the like.

Viscosity increasing shotcrete fastener composition of the present invention is a magnesium alumino silicate thickener of attapulgite or bentonite based on 80 to 99% by weight of the liquid fastener selected from any one of liquid aluminate, liquid silicate or liquid alkali free. It is preferred to include 20% by weight.

The viscosity increasing fastener composition may be prepared in a conventional stirrer, alumino silicate or bentonite in the state containing a liquid quickener selected from any one of liquid aluminate, liquid silicate or liquid alkali free according to the composition ratio in the stirrer It is preferable to gradually introduce and disperse the thickener selected by either.

At this time, with respect to 80 to 99% by weight of the liquid fastener, if the thickener is added to 20% by weight or more, the viscosity is too high to achieve a suitable viscosity, when put in less than 1% by weight has a disadvantage of weakening the adhesive strength of the shotcrete.

Another object of the present invention,

1) preparing a cement composition for shotcrete by mixing cement, aggregate and water;

2) 80-99% by weight of a liquid fastener selected from any one of liquid aluminate, aluminosilicate or liquid alkali free and magnesium alumino silicate thickener which is attapulgite or bentonite as a thickener to 1 to 20% by weight Preparing a fastener composition for viscosity increasing shotcrete; And

3) a shotcrete pouring method comprising the step of spraying a mixture of the cement composition for shotcrete of step 1) and the fastener composition for the shotcrete of step 2) in a weight ratio of 90 to 95 to 5 to 10 To provide.

Cement used in the step 1) of the present invention means all kinds of cement, such as Falkland cement, crude steel cement, blast furnace cement, sulfate resistant cement, after the excavation, such as for the surface finish of the structure, repair and rust prevention of steel Portland cement with high initial strength and homogeneity is desirable when it is necessary to place it as soon as possible.In case where it is necessary to express strength quickly after construction of water part, rock crushing zone, soft ground, etc., crude steel portland cement, cemented carbide portland cement In the case where the shotcrete is exposed to special conditions affected by salt, highly durable cement such as blast furnace cement is preferable.

The cement content used in the present invention is suitable to use a weight of 300 to 450 kgf per 1 m ³ of shotcrete, but can be changed according to design.

Aggregate used in the step 1) of the present invention, like general concrete, it is preferable to have a clean, excellent durability and a suitable particle size. In addition, it is free from harmful substances such as thin flakes, elongated flakes, clay lumps, and organic impurities, and it is also suitable for alkali aggregate reaction. Such aggregates are divided into fine aggregates and coarse aggregates according to size, and the aggregates of the present invention preferably include both the fine aggregates and coarse aggregates. In this case, the coarse aggregate used has a high content of coarse particles, which increases the compressive strength but increases the rebound, and when the content of intermediate particles or fine particles increases, the rebound is low but the compressive strength decreases, depending on the particle size and particle size distribution. And because it can greatly affect the rebound rate, by adding a fine powder of 0.2mm or less to be able to adhere well even in poor construction conditions, it is possible to construct a relatively thick layer with less rebound. However, the amount of fine powder increases, required quantity is so much to increase the drying shrinkage and it may clog inside the construction machine interior or tubing, the amount of fine aggregate for the shotcrete compositions using a 1,000 ~ 1,200 kgf weight per shotcrete 1m ³ Preferably, the blending amount can be changed according to design. In addition, coarse aggregates contained in the shotcrete compositions of the invention are available all gangjagal, crushed stone and a typical shotcrete aggregate material, a number of maximum value of the aggregate use of shotcrete 1m ³ 550 ~ 620 kg weight per a 10 to 15mm, the design Can be changed according to. At this time, if the maximum size of the coarse aggregate is too large, it is preferable to select a coarse aggregate within the above range because there is a large amount of rebound during shotcrete construction and the hose may be closed.

The water used in step 1) of the present invention should be clean and contain no substances harmful to concrete or steel such as oil, acid, alkali, salt, organic materials.

The shotcrete casting of step 3) of the present invention is a method of spraying by mixing the cement composition for shotcrete of step 1) and the rapid-acting shotcrete composition for shotcrete of step 2) in a weight ratio of 90 to 95 to 5 to 10 It can be poured, and each composition is preferably sprayed at the same time with the mixing through the nozzle of the end of the shotcrete equipment immediately before the pouring is attached to the surface to be deposited. The composition of shotcrete injected are per unit volume of (1m ³⁾ 450 ~ 480Kg cement content, 50 to 70% by weight of S / a, 5 ~ 10% by weight of 35 to 45% by weight of the W / C ratio and the cement weight of the It is preferable to contain a liquid fastener composition.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention in more detail, it is to those skilled in the art that the scope of the present invention is not limited by these examples in accordance with the gist of the present invention. Will be self-evident.

Preparation Example: Preparation of Fastener Composition for Shotcrete

To the liquid sodium aluminate, liquid sodium silicate or liquid aluminum sulfate alkali free fastener, attapulgite or bentonite as a thickener was mixed in the composition of Table 1 to prepare the viscosity increasing shotcrete fastener composition of the present invention.

As a liquid fastener used in the preparation, the liquid sodium aluminate is Al (Hongchang Co., Ltd.), the liquid sodium silicate is DB-S (Emerging Silica), the liquid aluminum sulfate alkali free fastener is L-LS (Co., Ltd.) Spear), attapulgite (Atapulgite Minugel 50, Engelhard) and bentonite (Volclay, Volclay Korea) were used as thickeners, and as a comparative example, a composition containing only liquid quickeners (Comparative Examples 1 to 3) And Comparative Examples 1 to 9, in which styrene butadiene copolymerized latex thickener (Kumho Petrochemical) was mixed with a liquid fastener as a control example.

division A quick payment Thickener Liquid Sodium Aluminate (wt%) Liquid Sodium Silicate (% by weight) Liquid Aluminum Sulfate Fastener Attapulgite Bentonite Styrene Butadiene Copolymer Latex Comparative Example 1 100 0 0 0 0 0 Preparation Example 1 95 0 0 5 0 0 Preparation Example 2 90 0 0 10 0 0 Preparation Example 3 85 0 0 15 0 0 Preparation Example 4 95 0 0 0 5 0 Preparation Example 5 90 0 0 0 10 0 Preparation Example 6 85 0 0 0 15 0 Comparative Example 1 95 0 0 0 0 5 Comparative Example 2 90 0 0 0 0 10 Comparative Example 3 85 0 0 0 0 15 Comparative Example 2 0 100 0 0 0 0 Preparation Example 7 0 95 0 5 0 0 Preparation Example 8 0 90 0 10 0 0 Preparation Example 9 0 85 0 15 0 0 Preparation Example 10 0 95 0 0 5 0 Preparation Example 11 0 90 0 0 10 0 Preparation Example 12 0 85 0 0 15 0 Comparative Example 4 0 95 0 0 0 5 Comparative Example 5 0 90 0 0 0 10 Comparative Example 6 0 85 0 0 0 15 Comparative Example 3 0 0 100 0 0 0 Preparation Example 13 0 0 95 5 0 0 Preparation Example 14 0 0 90 10 0 0 Preparation Example 15 0 0 85 15 0 0 Preparation Example 16 0 0 95 0 5 0 Preparation Example 17 0 0 90 0 10 0 Preparation Example 18 0 0 85 0 15 0 Comparative Example 7 0 0 95 0 0 5 Comparative Example 8 0 0 90 0 0 10 Comparative Example 9 0 0 85 0 0 15

In the preparation of the shotcrete fastener composition prepared according to the composition of Table 1, Comparative Examples 1 to 3 (composition consisting only of liquid phase fastener), Preparation Examples 1 to 18 (liquid fastener and thickener mixed composition of the present invention) and In Comparative Examples 1 to 9 (composition composition of the liquid fastener and the control thickener), Comparative Examples 1 to 3 in which styrene butadiene copolymerized latex, which is the control thickener, and the liquid sodium aluminate were mixed, and Comparative Examples 7 to 8, which were mixed with the liquid aluminum sulfate quickener. In the case of mixing, the mixture immediately agglomerated and floated on the surface, and the mixing failed. In addition, in Comparative Examples 4 to 6, in which styrene butadiene copolymerized latex and a liquid sodium silicate accelerator were mixed, they did not aggregate immediately upon mixing, but latex appeared on the surface about 10 minutes after mixing, and thus it was impossible to disperse evenly. This may be because the fastener is sodium aluminate or when aluminum trivalent metals, such as aluminum sulphate, are combined with the surfactant contained in the styrene butadiene copolymerized latex to form insoluble salts or agglomerate with latex. In addition, it can be seen that the liquid fastener having a specific gravity of about 1.4 cannot be uniformly dispersed due to the specific gravity difference with the styrene butadiene copolymer latex having a specific gravity of 1.1.

Test Example 1 Test for the Fastening Performance of Shotcrete Cement Paste Containing Viscous Increased Shotcrete Composition of the Present Invention

The shotcrete cement paste containing the same was prepared according to the composition method shown in Table 2 below by using the viscosity increasing shotcrete fastener composition of Preparation Example (Preparation Examples 1 to 18), and measuring the setting time of each cement paste, and testing the compressive strength. Flow values were measured and the results are shown in Table 3 for Comparative Examples 1 to 3, which included only thickeners. At this time, the setting time was measured according to KS L 5103 (Test method of setting cement's condensation time by Gilmore's needle), and the compressive strength test was tested according to KS F 2405 (Test method of compressive strength of concrete). After hitting five times by KS L 5111 (cement test flow table), the spreading was carried out by measuring the diameter (cm) of the hit cement. At this time, when the fastener is a silicate in the Examples, the amount of the viscosity increasing shotcrete fastener composition of the present invention was 10g. The cement paste used in the test was mixed within 10 seconds according to the composition of the shotcrete cement composition and shotcrete fastener composition within 10 seconds, and then the setting time, compressive strength and flow value were used in the measurement test.

Cement paste manufacturers water cement Polycarboxylic Acid Admixture Fastener composition for shotcrete of the present invention Setting time and compressive strength test 40 g 100 g 1 g 5 g Flow value test 50 g 100 g 1 g 5 g

division Flow value (cm) Setting time (minute: second) Compressive Strength (Kgf / cm ² ) First closing 1 day 3 days 7 days 28 days Comparative Example 1 22 3:30 9:45 84 153 178 204 Example 1 17 2:45 8:55 82 168 183 221 Example 2 15 2:25 7:58 90 188 198 234 Example 3 12 2:10 7:40 94 186 202 228 Example 4 17 3:10 9:30 80 162 189 221 Example 5 14 2:45 8:30 87 176 199 224 Example 6 12 2:35 8:10 89 182 201 241 Comparative Example 2 25 4:45 17:30 68 116 159 203 Example 7 14 4:15 14:15 76 133 169 204 Example 8 12 3:55 14:10 88 131 176 209 Example 9 12 3:45 12:45 88 128 172 204 Example 10 14 4:30 15:30 66 128 159 208 Example 11 12 3:50 14:45 69 148 184 205 Example 12 12 2:55 9:50 72 142 166 201 Comparative Example 3 25 2:55 7:50 104 203 316 334 Example 13 16 2:40 7:55 128 205 317 337 Example 14 14 2:30 6:45 138 215 331 373 Example 15 12 2:15 5:50 142 236 334 367 Example 16 16 2:45 7:15 103 207 316 347 Example 17 14 2:35 6:50 106 224 342 384 Example 18 12 2:15 6:10 110 234 345 376

As can be seen from the results in Table 3, Examples 1 to 27, which are shotcrete pastes containing the viscosity increasing shotcrete fastener composition of the present invention, have a flow value compared to Comparative Examples 1 to 3, which are shotcrete pools containing only the quickener. As a result, the viscosity increased to 4 to 10 cm, resulting in an increase in viscosity and a decrease in both the initial value and the final value, even at the setting time. In addition, also in the compressive strength test, Examples 1 to 18 of the present invention was similar or increased in strength value compared to Comparative Examples 1 to 3, and the strength value was increased in all cases when more than 5% of the thickener was used. Therefore, when attapulgite and bentonite were used as thickeners in the preparation of the shotcrete fastener composition of the present invention, it was tested to have an effect of decreasing the setting time and increasing the compressive strength, as well as the increase in point force by the thickening effect. However, as pointed out above, the viscosity of the solution does not increase when it contains more than 20% by weight of the thickener is impossible to use, even in the case of 15% by weight is very easy to transfer the product to the pump.

Test Example 2 Test for pouring shotcrete comprising the composition for increasing viscosity of shotcrete of the present invention

As an embodiment of the present invention, after preparing a concrete composition for shotcrete of water 180Kg, cement 440Kg, fine aggregate 1.006Kg coarse aggregate 679Kg and 2.2Kg polycarboxylic acid admixture, 22Kg of liquid sodium aluminate quickener contains 2.2Kg thickener. The shotcrete composition for shotcrete was prepared and mixed by spraying through a nozzle immediately before pouring, followed by a pouring test (Example 19 in Table 4). At this time, the casting equipment was placed on the wall and the ceiling using Meiko Suprema, and as a comparison test, water 180Kg, cement 440Kg, fine aggregate 1.006Kg, coarse aggregate 679Kg, polycarboxylic acid admixture 2.2Kg, Shotcrete composition (Comparative Example 5) prepared in the same manner as Comparative Example 4, except that 22 Kg of liquid sodium aluminate quickener and 2.2 Kg of thickener were mixed together and the thickener was replaced with water. It was prepared together with the concrete pouring test was carried out.

As a result, in Comparative Example 4 prepared by mixing and stirring the composition for the shotcrete fastener composition and cement composition at once, the slump value was 4cm showed a significantly inferior workability, the shotcrete for improving workability Increasing the amount of water used in the composition by 7.2Kg increased the flow value to 12cm, which improved workability, but the compressive strength of concrete was theoretically reduced by about 20% due to a 4% increase in the W / C ratio. In addition, in Comparative Example 5 in which the thickener was replaced with water, the slum value was 12 cm, and the workability was good, but the adhesiveness was poor, and the sagging property was observed at the attached surface of the top end. However, in the case of Example 19 in which the viscosity increase shotcrete composition for shotcrete and the shotcrete cement composition were sprayed by spraying the mixture with the shotcrete cement composition through a nozzle just before pouring, the flow value was 12 cm as well as good workability. The stickiness was exerted immediately after casting, and there was no sagging at the top end. In addition, the rebound ratio of shotcrete was 13%, 15%, and 6% in Comparative Example 4, Comparative Example 5, and Example 19, which was excellent in Example 19, and was about 2.5 times higher than that of Comparative Example 5, which is a conventional method. It became. In the case of 28-day compressive strength for core extraction, 213 Kgf / cm 2, 201 Kgf / cm 2, and 245 Kgf / cm 2 were found in Comparative Example 4, Comparative Example 5 and Example 19, respectively, and the compressive strength was also increased.

slump On-site core compressive strength (28 days strength) Rebound Rate Cm Kgf / ㎠ (%) Comparative Example 4 4 213 13 Comparative Example 5 12 201 15 Example 19 12 245 6

Therefore, when the shotcrete is poured by mixing and spraying the shotcrete liquid quickener composition and the shotcrete composition with the shotcrete through the nozzle immediately before pouring, the shotcrete cement composition and the shotcrete immediately before spraying the shotcrete composition Since the thickener is added to the concrete in advance, the amount of added water can be used in a smaller amount than the case where the fastener is mixed, so that the W / C ratio value and the flow value are lower. It can be seen that even stronger. In particular, the shotcrete strength could be improved to meet the "28-day strength" requirement, as well as the adhesive force was increased to reduce the rebound rate of the shotcrete.

The present invention relates to a fastener composition for viscosity increasing shotcrete containing magnesium aluminosilicate as a liquid fastener and a thickener, and more particularly, a liquid fastener selected from any one of liquid aluminate, liquid silicate or liquid alkali free. It relates to a viscosity increasing shotcrete fastener composition comprising aluminosilicate or bentonite thickener. When the concrete cementer is poured using the viscosity increasing shotcrete composition for the shotcrete, the amount of water added can be used in a small amount, so that the W / C ratio is lowered, thereby improving the compressive strength of the concrete and increasing the adhesive strength to the shotcrete. It is effective to reduce the rebound rate. In addition, the flow value of the cement is accelerated growth of the cement gel has a fast curing characteristics, there is an advantage that can maintain a high fluidity in operation when manufacturing the shotcrete composition compared to the fast curing properties.

Claims (9)

A fastener composition for viscosity increase shotcrete comprising magnesium aluminosilicate as a liquid fastener and a thickener. According to claim 1, wherein the liquid fastener is a viscosity increase shotcrete fastener composition, characterized in that any one selected from liquid aluminate, liquid silicate or liquid alkali free. According to claim 1, wherein the magnesium alumino silicate is attapulgite or bentonite, viscous increasing shotcrete composition for shotcrete. The method according to claim 2, wherein the liquid aluminate is a liquid sodium aluminate or a liquid potassium aluminate, the viscosity increasing shotcrete for the composition of the shotcrete. The method of claim 2, wherein the liquid silicate is a liquid sodium silicate or potassium potassium silicate, characterized in that the viscous shotcrete fastener composition. The method of claim 2, wherein the liquid alkali free is a viscosity increase shotcrete fastener composition, characterized in that the aluminum sulfate. The composition according to any one of claims 1 to 6, wherein the viscosity increasing shotcrete composition comprises 80 to 99% by weight of a liquid fastener selected from any one of liquid aluminate, liquid silicate or liquid alkali free, and attapulgite. Or Bentonite magnesium aluminosilicate thickener 1 to 20% by weight, characterized in that it comprises a viscous shotcrete fastener composition. 1) preparing a cement composition for shotcrete by mixing cement, aggregate and water; 2) 80-90% by weight of a liquid fastener selected from any one of liquid aluminate, aluminosilicate or liquid alkali free and magnesium alumino silicate thickener, which is attapulgite or bentonite, as a thickener, 10-20% by weight. Preparing a fastener composition for viscosity increasing cement shotcrete: and 3) the shotcrete cementing composition of step 1) and the viscosity increase shotcrete fastener composition of step 2) in the weight ratio of 90 to 95 to 5 to 10, comprising the step of spraying Method. 10. The method according to claim 8, wherein the step 3) is performed by mixing at the same time as the injection at the injection nozzle.