KR101246114B1 - Concrete composition for manufacturing by the use of tbm method and the high-performance concrete segment - Google Patents

Abstract

PURPOSE: A segment concrete composition applied to TBM method is provided to reduce the number of steel reinforcement of segment using high tensile steel reinforcement and enhances rigidity and fire-resistance efficiency of concrete which is between high tensile steel reinforcement. CONSTITUTION: A segment concrete composition applied to TBM method comprises a binding material 500-600kg/m^3, a fine aggregate 800-900 kg/m^3, an aggregate 800-1000 kg/m^3, water 140-180 kg/m^3, an early strength expression agent 2.52-5.04 kg/m^3, a fireproof fiber 0.414-0.972 kg/m^3 and a reinforcing fiber 10-60 kg/m^3 about a concrete unit volume. The binding material comprises cement 250-550kg/m^3 and blast furnace slag micropowder 50-300kg/m^3 about a concrete unit volume. A replacement ratio of blast furnace slag micropowder is 10-50% in the binding material, a water weight ratio(%) of binding material is 28-38, and a fine aggregate ratio of whole aggregate is 45-55 volume%. [Reference numerals] (AA) Compressive intensity(MPa); (BB) 12 hours; (CC) 3 days; (DD) 7 days; (EE) 28 days; (FF) Replacement rate of blast furnace slag(%)

Description

Concrete composition for segment applied to TBM method and high-performance concrete segment manufactured by the present invention {Concrete composition for manufacturing by the use of TBM method and the high-performance concrete segment}

The present invention relates to a concrete composition for the segment applied to the TBM method and a concrete segment manufactured thereby, more specifically TBM improved rigidity and fire resistance while reducing the number of reinforcing bars used in the segment by using high tensile steel It relates to a concrete composition for the segment applied to the process and to the concrete segment produced thereby.

In recent years, cement-based composite materials such as concrete and mortar have mostly been developed to improve compressive performance, thereby enabling the production of high-strength mortar and concrete capable of expressing very high compressive strength.

However, these concrete and mortars have very low flexural strength and tensile strength, and also due to their strong brittleness, a sudden stress drop occurs after fracture, and even when reinforced by reinforcing bars, the cracks are limited to a part. There are many problems in the structural performance and durability.

On the other hand, various fiber reinforced concretes have been recently developed to compensate for this, but most of them are intended only to improve the bending and tensile performances, and thus do not impart high bending and tensile performances to concrete structures. For some reason, only part of the situation has been used.

Particularly, the segment applied to TBM method used in Korea is manufactured at 30 to 45 Mpa, and the utilization of high tensile reinforcing bars of SD400 to SD600 is increasing according to the design standard of concrete. Done. However, it is necessary to increase the concrete strength so that the cross section of the concrete does not increase.

Although the cross-section of the segment does not increase due to the increase in concrete strength, when the number of used reinforcing bars is reduced, the spacing between the reinforcing bars becomes wide, which causes problems such as cracking in concrete. In addition, in the case of precast concrete segments to which high-strength concrete is applied, the occurrence rate of defects of the products is high due to problems such as end bumps during assembly or deterioration of product quality such as end fracture cracking during transportation.

Republic of Korea Patent Publication No. 10-2009-0036952

The present invention improves the stiffness and fire resistance of concrete between high tensile reinforcing bars while reducing the number of reinforcing bars using high tensile steel, and satisfies design standard strength, and prevents cracking and breakage of concrete. It is an object of the present invention to provide a concrete composition for segments and concrete segments produced thereby.

The present invention, in the concrete composition for the segment to be applied to the TBM method, 500 to 600 kg / m ³ binder containing cement and blast furnace slag fine powder with respect to the concrete unit volume; For aggregate concrete volume, fine aggregate 800 to 900 kg / m ³ ; For concrete unit volume, coarse aggregate 800 to 1000 kg / m ³ ; For a concrete unit volume, 180 kg / m ^{3 in} water 140; With respect to the concrete unit volume, the early strength expression agent 2.52 to 5.04 kg / m ³ ; Per unit volume of concrete, refractory fibers 0.414 to 0.972 kg / m ³ ; And with respect to the concrete unit volume, to provide a concrete composition for the segment applied to the TBM method comprising a reinforcing fiber 10 to 60 kg / m ³ .

The present invention, the binder, the cement unit with respect to the concrete unit 250 to 550 kg / m ³ ; And it provides a concrete composition for the segment applied to the TBM method comprising the blast furnace slag fine powder 50 to 300 kg / m ³ with respect to the concrete unit volume.

The present invention provides a concrete composition for segments to be applied to the TBM method wherein the weight ratio of the water to the binder is 28 to 38.

The present invention, the binder, the cement unit with respect to the concrete unit 250 to 550 kg / m ³ ; For the concrete unit volume, the blast furnace slag fine powder 50 to 300 kg / m ³ ; And with respect to the concrete unit volume, it provides a concrete composition for the segment applied to the TBM method comprising fly ash 50 to 60 kg / m ³ .

The present invention provides a concrete composition for segments applied to the TBM method, the fine aggregate ratio is 45 to 55%.

The present invention, the early strength expression agent, 80 to 99 parts by weight of a polycarboxylic acid-based water reducing agent; And it provides a concrete composition for the segment that is applied to the TBM method comprising 1 to 20 parts by weight of a thiosulfate-based compound.

The present invention, the refractory fiber is applied to the TBM method is a sponge paper obtained by dispersing wet steel paper in a water-soluble medium, sheeting the dispersion and drying to prepare a dried sheet, and dry sponge the dried sheet. It provides a concrete composition for the segment.

The present invention, the reinforcing fiber provides a concrete composition for the segment is applied to the TBM method comprising a steel-fiber (steel-fiber).

According to another aspect of the present invention, the present invention provides a concrete segment that is applied to the TBM process produced by the concrete composition.

Concrete composition for the segment applied to the TBM method according to the present invention has the following effects.

The use of high-strength reinforcement can reduce the number of reinforcing bars in segmented concrete, preventing the increase in the size of the concrete cross section, and reduce the amount of steel used in the segmented concrete. Problems that may arise due to widening of the gap may be solved by using steel fibers. And it can have the effect of improving the stiffness and fire resistance of the concrete by the early strength expression agent, refractory fibers and reinforcing fibers.

In particular, when the blast furnace slag fine powder, which is an industrial by-product in the precast concrete field, is used, it is possible to solve the problem that the early strength is insufficient and the demolding strength is not provided by including the early strength expression agent. It may have the effect of improving the strength of the concrete by preventing cracks that may occur during curing.

And by applying the refractory fiber to the concrete can satisfy the fire resistance performance standard that is applied to the concrete more than 50Mpa can prevent the concrete explosion phenomenon by heat. In addition, the reinforcing fiber is included to meet the concrete design criteria in terms of concrete strength and usability. As described above, the number of reinforcing bars is reduced due to the use of high tension reinforcing bars, thereby increasing the rigidity of the concrete between the high tensile reinforcing bars. It can have the effect of producing a complementary high strength concrete.

1 is a graph showing a change in compressive strength of a concrete segment according to the substitution rate of the blast furnace slag fine powder when manufacturing the concrete segment according to the present invention.
2 and 3 are experimental results showing the chloride penetration depth of the concrete segment according to the substitution rate of the blast furnace slag fine powder when manufacturing the concrete segment according to the present invention.
Figure 4 shows the results of the test of the fire resistance performance of the concrete produced by the concrete composition for the segment applied to the TBM method.
Figure 5 is a graph showing the change in tensile strength of the concrete segment according to the steel fiber mixing ratio when manufacturing the concrete segment according to the present invention.

Prior to the detailed description of the present invention, the segment currently applied to the TBM process that is commercially available in Korea is manufactured at 30 to 45 Mpa. In addition, SD400 to SD600 may be applied to the reinforcing bar according to the design standard of the concrete. As the utilization of the high tensile rebar increases, the cross-section of the concrete is predicted to increase.

On the other hand, in order to apply high tensile reinforcing bars without increasing the cross-section of concrete, concrete strength should also increase with increasing reinforcing bar strength. Recently, when the strength of concrete is 50Mpa or more, it is reported that the utility of high tensile reinforcing bars (SD500, SD600) increases. Therefore, in the following detailed description, concrete strength of 50 or more and 60 Mpa, and by using a high-tensile reinforcement concrete composition for producing concrete with a reduced number of high-tensile reinforcement will be described as a representative example.

Concrete composition for the segment applied to the TMB method according to the present invention, the binder, fine aggregate, coarse aggregate, water, early strength expression agent, refractory fibers and reinforcing fibers. Segment concrete applied to the TBM method includes reinforcing bars in addition to the concrete composition. In particular, in the present embodiment, the reinforcing bar may be provided as high tensile reinforcing bars of SD500 and SD600, as mentioned in the foregoing description. However, the reinforcing bar need not be limited to the high-strength reinforcing bars of SD500 and SD600, and may be provided with the reinforcing bar of SD400 used in the related art. In particular, when the diameter of the reinforcing bar increases according to the amount of reinforcing bar, the number of reinforcing bar can be reduced, while including the above-mentioned concrete composition can be improved the rigidity and fire resistance of the concrete for the segment applied to the TBM method.

(1) binder

First of the above-mentioned concrete compositions, the binder comprises cement and blast furnace slag fine powder. By cement is meant the most commonly used common Portland cement (OPC). It consists of a mixture of oxides of calcium, silicon and aluminum and is used as the basis for cement, mortar and plaster. However, the cement need not usually be limited to Portland cement, and all kinds of cements which are commercially available may be used.

The blast furnace slag fine powder is used for the purpose of reducing cement heat of hydration, increasing hydration products, forming dense tissue and enhancing long-term strength. The kind of blast furnace slag fine powder is not specifically limited, Any blast furnace slag fine powder of 2 type-3 types can be used.

Blast furnace slag
Substitution rate
(%) Water / cement
(Weight ratio,%) Fine aggregate rate
(Volume ratio,%) water
(kg / m ³ ) OPC
(kg / m ³ ) Blast furnace slag
Fine powder
(kg / m ³ ) OPC + SP
(kg / m ³ ) Fine aggregate
(kg / m ³ ) Coarse aggregate
(kg / m ³ ) Early Strength Expression
(kg / m ³ ) division W / B S / a W C S / P B S G AD 10 28 46 140 450 50 500 803 947 4.5 20 28 46 140 400 100 500 803 947 4.5 30 28 46 140 350 150 500 803 947 4.5 40 28 46 140 300 200 500 803 947 4.5 50 28 46 140 250 250 500 803 947 4.5 60 28 46 140 200 300 500 803 947 4.5

Table 1 shows when the substitution rate of the blast furnace slag fine powder to be replaced in a part of the cement when manufacturing the concrete was different, Figure 1 shows the change in compressive strength of the concrete according to Table 1. Referring to Figure 1, it can be seen that the compressive strength of the concrete changes according to the blast furnace slag substitution rate. In concrete, the compressive strength does not change until the blast furnace slag fine powder has a substitution rate of 10 to 50%, and the compressive strength decreases after 28 days when the blast furnace slag fine powder has a substitution rate of 60%. This can be analyzed by the result of low amount of cement.

2 and 3 are experiments of salt durability of concrete, and as can be seen from FIGS. 2 and 3, when the blast furnace slag fine powder is not contained, the concrete penetration depth of chloride penetrates the deepest to 70 mm, and the blast furnace slag. When the fine powder is substituted by 30%, the penetration depth of chloride is 50mm, and when the blast furnace slag fine powder is substituted by 50%, the penetration depth of chloride is 30mm, and the larger the substitution amount of fine blast furnace slag powder, the smaller the penetration of chloride. . According to these experimental results, the substitution rate of the blast furnace slag fine powder is determined within the range of 10 to 50%.

The content of the binder including the cement and the blast furnace slag fine powder is included in the range of 500 to 600 kg / m ³ with respect to the concrete unit volume. In the above binder, the content of cement is included in the range of 250 to 600 kg / m ³ based on the unit volume of concrete, and the content of the blast furnace slag fine powder is in the range of 50 to 300 kg / m ^{3 based} on the unit volume of concrete. Included within.

Meanwhile, another embodiment of the binder may further include a fly ash together with the cement and the blast furnace slag fine powder. The fly ash refers to a by-product obtained by cooling and solidifying a non-combustible portion suspended in a molten state when burning coal in a coal-fired power plant. The chemical main component is SiO ₂ , Al ₂ O ₃ , CaO, or the like. The particle size of the fly ash is about 1 to 140 ㎛, and the shape is almost smooth spherical particles, the large particles are present in the form of empty center or filled with fine spherical particles inside to improve the fluidity of the concrete composition Can contribute to

In other words, fly ash is a ball bearing acting as a smooth spherical particle on the surface to improve concrete workability (flowability), and it slowly combines with calcium hydroxide dissolved in water in concrete at room temperature to produce insoluble compounds, reducing heat of hydration and long-term strength. And watertightness can be increased.

Therefore, the binder may be provided in an embodiment in which a part of cement is replaced with blast furnace slag fine powder, or in another embodiment in which a part of cement is replaced with blast furnace slag fine powder and fly ash. And in the case of the binder including the cement, the blast furnace slag fine powder and / or the fly ash to include a weight ratio to water in the range of 28 to 38. In the case of the binder including the cement, the blast furnace slag powder and the fly ash, the cement is in the range of 250 to 550 kg / m ³ with respect to the concrete unit volume, the blast furnace slag powder is 50 to 300 relative to the concrete unit volume The range of kg / m ³ , the fly ash comprises within the range of 50 to 60 kg / m ³ with respect to the concrete unit volume. On the other hand, when the fly ash is substituted with the blast furnace slag fine powder, the fly ash comprises a weight ratio to the cement in the range of 10 or less.

(2) fine aggregate and coarse aggregate

The fine aggregate and the coarse aggregate may be used as long as they are generally known for concrete, and the type does not need to be particularly limited. The fine aggregate can be used washing sand, artificial silica sand, crushed sand and the like having a constant particle size than the sand used in the general ready-mixed concrete, these can be used alone or mixed and the type and mixing ratio is not particularly limited. In general, the fine aggregate may have a particle diameter of 0.15 to 2.5 mm, an absolute dry density of 2.5 g / cm 3 or more, an absorption rate of 3% or less, and a stability of 10% or less. In addition, it is preferable to use the level of the assembly rate of 2.7 to 3.0 to ensure the fluidity of the concrete and to reduce the viscosity. The amount of the fine aggregate is preferably included in the range of 800 to 900 kg / ㎥ with respect to the concrete unit volume in terms of preventing material separation of concrete.

The coarse aggregate may have a particle diameter of 2.5 to 40 mm, an absolute dry density of 2.5 g / cm 3 or more, an absorption rate of 3% or less, a stability of 10% or less, and a wear rate of 40% or less. Generally, considering the strength of concrete, it is better to use aggregate of 25mm level like gravel. The amount of the coarse aggregate is preferably included in the range of 800 to 1000 kg / ㎥ with respect to the concrete unit volume in terms of preventing material separation of concrete.

(3) early strength expression agent

The early strength expression agent is to be added to sufficiently express the early strength and design strength of the concrete when the concrete for the segment to be applied to the TBM method using the above-described concrete composition as described above. The content of the early strength expression agent is included in the range of 2.52 to 5.04 kg / m ³ with respect to the concrete unit volume. The early strength expression agent includes a polycarboxylic acid-based sensitizer and a thiosulfate-based compound.

The polycarboxylic acid-based water reducing agent is commercially available as a concrete admixture in the form of copolymerizing the polyalkylene glycol monoalkyl ether monomer and maleic acid in US Patent Nos. 4,471,100, 4,808,641, 4,962,173, 6,939,935, acrylic acid and meso Copolymerization of three water-soluble vinyl monomers in the form of copolymerization of oxypolyethylene glycol methacrylate, acrylic acid, methoxypolyethylene glycol methacrylate and metaallylsulfonate, or esterification of maleic acid and maleic anhydride with alkylpolyethylene glycol And a method for producing the same in the form of polymerizing with acrylic acid are disclosed. In addition, a polycarboxylic acid compound having a copolymer of maleic acid and a monomer based on unsaturated polyalkylene glycol ethers disclosed in Korean Patent Publication No. 064529 is disclosed. The polycarboxylic acid-based water reducing agent to be applied to the present invention may be selectively applied as long as it does not deviate from the nature as the "polycarboxylic acid-based water reducing agent" as well as any of the foregoing matters.

The thiosulfate compound refers to a compound in which hydrogen ions of thiosulfate (an unstable acid in which one oxygen atom and a sulfur atom of a sulfuric acid group are replaced) are substituted with cations such as metal ions. These thiosulfate compounds are added to the blended water to increase the concentration of OH- and promote the latent hydraulic reaction of the blast furnace slag fine powder during steam curing of the concrete composition containing the blast furnace slag fine powder as a main component of the binder.

Such polycarboxylic acid-based sensitizer may be included in the range of 80 to 99 parts by weight in the composition of the overall early strength expression agent, the thiosulfate-based compound is in the range of 1 to 20 parts by weight in the composition of the total early strength expression agent Can be included in.

(4) refractory fiber

The refractory fiber is included to improve the fire resistance to prevent the concrete to be exploded due to the fire to be produced by the above-described compositions, and to be excellent in compressive strength as well as workability and economical efficiency required when placing the concrete. On the other hand, the refractory fibers used in the embodiment of the present invention is a spongy paper obtained by dispersing wet steel paper in a water-soluble medium, sheeting and dispersing the dispersion to produce a dried sheet, dry-drying the dried sheet It is a sponge paper, the refractory fiber is disclosed in detail in Patent No. 10-0899838. Therefore, in the present invention, a detailed description of the refractory fiber will be omitted.

Fireproof fiber
Mixing rate
(kg / m ³ ) Water / cement
(Weight ratio,%) Fine aggregate rate
(Volume ratio,%) water
(kg / m ³ ) OPC
(kg / m ³ ) Blast furnace slag
Fine powder
(kg / m ³ ) OPC + SP
(kg / m ³ ) Fine aggregate
(kg / m ³ ) Coarse aggregate
(kg / m ³ ) Early Strength Expression
(kg / m ³ ) Fireproof test
result division W / B S / a W C S / P B S G AD 0.275 28 46 140 350 150 500 803 947 4.5 Explosion 0.414 28 46 140 350 150 500 803 947 4.5 No explosion 0.55 28 46 140 350 150 500 803 947 4.5 No explosion 0.69 28 46 140 350 150 500 803 947 4.5 No explosion 0.83 28 46 140 350 150 500 803 947 4.5 No explosion 0.972 28 46 140 350 150 500 803 947 4.5 No explosion

Table 2 shows the results of explosive experiments made by varying the mixing rate of the refractory fibers when fabricating the concrete for the segment applied to the TBM method with the composition as described above. As shown in Table 2, when the mixing ratio of the refractory fibers is about 0.3 or less, the explosion occurred, but it can be seen that the explosion did not occur when the mixing ratio of the refractory fibers is 0.414 to 0.972. Therefore, based on the experimental results according to Table 2, the content of the refractory fiber can be determined within the range of 0.414 to 0.972 kg / m ³ with respect to the concrete unit volume.

And Figure 4 shows the results of the explosive test of the concrete containing the refractory fibers in the concrete composition and the concrete does not contain the refractory fibers. Figure 4 (a) is a concrete that does not contain refractory fibers, Figure 4 (b) is a concrete that contains a refractory fiber, as shown in Figure 4 concrete that does not contain a refractory fiber explosion occurs The concrete is partially broken, the concrete containing the refractory fibers can be confirmed that the concrete is not broken because of resistance to fire.

(5) reinforcing fiber

The reinforcing fiber is included to improve the rigidity of the concrete produced by the above-described compositions with the early strength expression agent and the refractory fiber. According to the recently revised concrete design standard, when SD400 to SD600 is applied to rebars included in concrete manufacturing, the cost of rebar can be reduced as the amount of rebar decreases, but the number of reinforcement of rebar decreases as the rebar diameter increases. When the reinforcing bar is reduced, the gap between the reinforcing bar and the reinforcing bar is widened, so that the problem of cracking and crack width increase occurs.

In this embodiment, the reinforcing fiber is provided with a steel fiber (steel-fiber). The steel fiber is disclosed in detail in Korean Patent No. 10-1073393, which is commonly used to improve the stiffness of concrete when concrete is manufactured. In addition, various steel fibers that are released as ready-made products may be added. The content of the reinforcing fiber is determined within the range of 10 to 60 kg / m ³ with respect to the concrete unit volume.

Steel fiber
Mixing rate
(kg / m ³ ) Water / cement
(Weight ratio,%) Fine aggregate rate
(Volume ratio,%) water
(kg / m ³ ) OPC
(kg / m ³ ) Blast furnace slag
Fine powder
(kg / m ³ ) OPC + SP
(kg / m ³ ) Fine aggregate
(kg / m ³ ) Coarse aggregate
(kg / m ³ ) Early Strength Expression
(kg / m ³ ) division W / B S / a W C S / P B S G AD 10 28 46 140 250 250 500 803 947 4.5 20 28 46 140 250 250 500 803 947 4.5 30 28 46 140 250 250 500 803 947 4.5 40 28 46 140 250 250 500 803 947 4.5 60 28 46 140 250 250 500 803 947 4.5 80 28 46 140 250 250 500 803 947 4.5

Table 3 shows when the mixing ratio of the steel fiber when the concrete is different, Figure 5 shows the change in tensile strength of the concrete according to Table 3. FIG. 5 illustrates the tensile strength of the concrete as the mixing ratio of the steel fibers is changed when manufacturing the concrete for the segment applied to the TBM method using the above-described concrete composition. Referring to FIG. 5, it can be seen that the tensile strength of the concrete is improved as the steel fibers are mixed during concrete production, and in particular, the tensile strength of the concrete is increased as the mixing ratio of the steel fibers is increased. However, as the mixing amount of the steel fiber increases, the manufacturing cost increases and the burden increases, so that the mixing amount of the steel fiber is determined in the range as described above.

If the concrete for the segment is applied to the TBM method by the concrete composition as described above, the number of rebars can be reduced while the number of rebars can be reduced by using high-strength reinforcement, but the rebar and the reinforcing bar between the reinforcing bar and the reinforcing bar It is possible to reduce cracking and crack width between bars. In addition, in the case of precast concrete segments made of high-strength concrete, it is possible to effectively prevent problems such as end dropouts generated during assembly and cracks generated during transportation and loading.

In particular, the early strength expression agent can enhance the strength during the curing of the concrete, can satisfy the design strength of the concrete, and by including the refractory fiber can improve the fire resistance performance of the concrete, The overall strength improvement effect can prevent the concrete from being damaged and destroyed.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (9)

In the concrete composition for the segment applied to the TBM method,
For the concrete unit volume, 500 to 600 kg / m ³ binder containing cement and blast furnace slag fine powder;
For aggregate concrete volume, fine aggregate 800 to 900 kg / m ³ ;
For concrete unit volume, coarse aggregate 800 to 1000 kg / m ³ ;
For a concrete unit volume, 180 kg / m ^{3 in} water 140;
With respect to the concrete unit volume, the early strength expression agent 2.52 to 5.04 kg / m ³ ;
Per unit volume of concrete, refractory fibers 0.414 to 0.972 kg / m ³ ; And
Per unit volume of concrete, comprising 10 to 60 kg / m ³ of reinforcing fibers,
The binder,
For the concrete unit volume, the cement 250 to 550 kg / m ³ ; And
For the concrete unit volume, the blast furnace slag fine powder comprises 50 to 300 kg / m ³ ,
Substitution rate of the blast furnace slag fine powder in the binder is 10 to 50%,
The weight ratio (%) of water to the binder is 28 to 38,
Residual aggregate ratio of the total aggregate is 45 to 55% by volume concrete composition for the segment applied to the TBM method. delete delete delete delete The method according to claim 1,
The early strength expression agent,
80 to 99 parts by weight of a polycarboxylic acid-based water reducing agent; And
Concrete composition for the segment applied to the TBM method comprising 1 to 20 parts by weight of a thiosulfate compound. The method according to claim 1,
The refractory fiber is a concrete composition for segments to be applied to TBM method, which is spongy paper obtained by dispersing wet steel paper in a water-soluble medium, sheeting and dispersing the dispersion to produce a dried sheet, and drying the dried sheet. . The method according to claim 1,
The reinforcing fiber is a concrete composition for the segment applied to the TBM method comprising a steel-fiber (steel-fiber). A concrete segment applied to the TBM process produced by the concrete composition of any one of claims 1, 6, 7 or 8.

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