KR20150091872A - High Durable Concrete Composition For Revealing High Early Strength Using Modified Fly Ash - Google Patents

Abstract

The present invention relates to a concrete composition having early strength development and high durability which solves problems of contraction or the like caused by premature curing due to including a modified fly ash as an admixture and can express high durability by providing a dense paste structure.

Description

TECHNICAL FIELD [0001] The present invention relates to a high durability concrete composition for use in a high strength concrete,

The present invention relates to a concrete composition capable of exhibiting high durability by solving the problem of shrinkage due to premature curing which may be present in the admixture contained in the concrete composition, .

Various policies and technologies are being developed due to global warming both domestically and globally. GHG reduction is becoming the biggest issue in the world. Domestic efforts to reduce greenhouse gas emissions by 30% are needed in all fields. In the industrial sector, such as thermal power plants and cement industries, where greenhouse gases are emitted in large quantities, stronger measures are needed. The cement industry is an industry that emits a considerable amount of greenhouse gas, which accounts for about 7% of the global CO ₂ emissions, and it is necessary to develop an admixture that can replace cement.

Among them, fly ash, which is a part of coal ash produced as a by-product in a thermal power plant, is known to contribute to the creation of added value and prevention of environmental pollution due to waste recycling. Fly ash is widely used as an admixture for cement reduction when manufacturing cement concrete. In addition, it is widely used for the improvement of concrete properties, cost reduction of concrete products, improvement of durability, and reduction of heat of hydration.

However, in spite of these advantages, the amount of fly ash is limited due to the reduction of the initial strength of concrete when a large amount of fly ash is added as an admixture. Therefore, there is a need for development that can increase the amount of fly ash.

Accordingly, Korean Patent Registration No. 0887943 discloses a technique of activating fly ash by adding an activator to fly ash to increase the amount of cement substitute as an admixture.

However, these techniques also have a problem in that the problem of initial strength reduction caused by using fly ash can not be sufficiently solved. Even if the initial strength problem is solved by an activator or the like, there is a problem in durability due to contraction due to early curing and the like.

Korea Patent No. 0887943

In order to solve the above problems, the present invention proposes a method of improving durability due to an increase in hydration heat and an increase in shrinkage due to early strength improvement while improving the early strength of the fly ash with an activator or the like, And to provide an economical and environmentally friendly concrete composition by enhancing durability and increasing cement replacement amount.

In order to achieve the above object, the present invention provides a high strength concrete composition for use in modifying fly ash, which comprises an admixture formed by mixing and grinding fly ash, an activator, and a durable additive. That is, the present invention solves the problem of initial strength reduction of fly ash chemically and physically by pulverizing the activator, and solves the problem that durability may be lowered due to increase in hydration heat and increase in shrinkage due to reinforcement of initial strength, The present invention also relates to a concrete composition for improving the strength and durability.

Fly ash is a by-product of industrial use such as SiO ₂ , CaO, Al ₂ O ₃ The polymerization reaction is one of the greatest reactions that can be induced in the present invention due to the formation of a geopolymer. In addition, the reaction for promoting the hydration reaction .

When the fly ash is used, it is necessary to prepare a concrete environment having a pH of 13.8 or higher as a means for removing the glassy coating on the surface. In order to ensure this, a high alkali activator is inevitably used. In addition, there is a problem that the fly ash has a low initial strength and a long period of high temperature curing period, which are disadvantages of fly ash.

In general, the polymerization reaction is a reaction of Si-Al-containing minerals with NaOH or KOH, and fly ash is a material that can be activated by polymerization reaction because of the relatively high contents of SiO ₂ and Al ₂ O ₃ . However, in the case of using fly ash, a glassy film is formed. Therefore, in order to accelerate the reaction by destroying this film, a highly alkaline environment with a pH of 13 or higher, a high temperature curing or other methods is required. In the prior art, the glassy film of fly ash was broken by high temperature curing in most cases to induce polymerization reaction.

In particular, the admixture added to the concrete composition of the present invention is characterized by being formed by mixing fly ash, activator and durable additive and pulverizing. When the compositions are produced by simple mixing, the initial strength of fly ash is supplemented There is a problem in that the function of performing the above-described operation is lowered. Accordingly, in the present invention, it is intended to increase the initial strength reinforcement efficiency by mixing the above compositions and pulverizing them using a vibrating mill or the like. That is, when the mixture is mixed and pulverized, uniform mixing is possible in the pulverization operation and the crystal structure can be simultaneously changed to activate the surface of the particles.

In the present invention, it is preferable that the admixture is blended by mixing 2 to 4 parts by weight of the activator and 2 to 8 parts by weight of the durable additive with respect to 100 parts by weight of the fly ash.

In the present invention, the activator is limited to 2 to 4 parts by weight with respect to 100 parts by weight of fly ash, which is obtained by activating fly ash by mixing a much smaller amount of the activator (20 to 30 parts by weight) This is due to the effect of mixed pulverization. If the weight ratio of fly ash is larger than the above range, Na and the like required for the reaction are insufficient. On the other hand, when the weight ratio of fly ash is smaller than the above range The Si or Al contributing to the strength is insufficient and the strength strengthening effect is lowered.

Preferably, the activator used in the present invention is a mixture of anhydrous gypsum, calcium hydroxide and calcium chloride. In addition, by adding anhydrous gypsum, ettringite acicular crystals are produced by the addition of calcium hydroxide and calcium chloride, and the initial strength can be supplemented by further adding calcium hydroxide and calcium chloride. Thereby providing a dense structure. That is, by adding anhydrous gypsum, it is possible to improve resistance to cracks while ensuring durability.

The activator which is a mixture of anhydrous gypsum, calcium hydroxide and calcium chloride is mixed in an amount of 100 to 200 parts by weight of anhydrous gypsum and 100 to 200 parts by weight of calcium chloride per 100 parts by weight of calcium hydroxide, In the case of exceeding the above-mentioned limited range, the amount of etch ringite is too large, which causes expansion of the structure rather than inhibiting cracking and strength development.

The reason why the calcium chloride is limited as described above is limited to the above range in order to solve the problem that the initial strength is complemented by calcium hydroxide but the long-term strength is lowered.

In addition, the admixture added to the concrete composition of the present invention improves the durability by reducing the heat of hydration and reducing the shrinkage by mixing the durability additive. In particular, the durability additive is a mixture of a silane flame and a polyoxyalkylene alkyl ether . The silicate flame retards the hydration reaction by reacting with the calcium hydroxide generated in the cement hydration reaction in the cement paste, thereby reducing the heat of hydration. In addition, the calcium hydrate is generated in the course of the reaction, The micropores are filled in the micropores to provide a closed structure, thereby improving durability.

However, sodium hydroxide (NaOH) is generated in the reaction of generating calcium hydrate. Since sodium hydroxide produced in such a manner is high in solubility in water, it is redissolved and eluted when moisture is present.

Therefore, it is insolubilized by reacting with sodium hydroxide, and polyoxyalkylene alkyl ether system which fills micro pores by chemically reacting with concrete components such as a silane flame is added to make the concrete structure completely closed. The incorporation of polyoxyalkylene alkyl ether systems as durability additives makes it possible to control the problem of cracking due to shrinkage by controlling the problem of concrete shrinkage which can be generated as the admixture of the present application complements the initial strength of fly ash will be.

In addition, triethanolamine is further added to the admixture added to the concrete composition of the present invention in order to promote the early strength of the concrete. The initial dispersibility is thereby manifested by the triethanolamine, So that the early strength is secured.

That is, in the modified fly ash modified with a chelate compound, the length of the main chain is short and the length of the side chain is long, so that the above-mentioned effect is exhibited. For this purpose, it is appropriate that the amount of triethanolamine added is 0.8-1.0 parts by weight of triethanolamine per 100 parts by weight of fly ash.

In addition, a filler can be added to the admixture added to the concrete composition of the present invention, and calcium carbonate (CaC ₂ ) is added as a filler to induce a pozzolanic reaction with calcium hydroxide (Ca (OH) ₂ ) Thereby enhancing the long-term strength. The calcium carbonate (CaC ₂ ) is a by-product generated in the production of acetylene (C ₂ H ₂ ) gas. Calcium hydroxide (Ca (OH) ₂ ) is produced by the reaction with water, , Fe, and CSH gel-like pozzolanic reaction, which is a long-term strength. It is preferable that the above-mentioned calcium carbonate is blended in an amount of 1 to 3 parts by weight based on 100 parts by weight of fly ash.

Further, in the present invention, in order to double the mixing and crushing efficiency of the above-mentioned compositions, the crushing aid may be further blended. The crushing aid is preferably limited to 0.01 to 0.03 parts by weight per 100 parts by weight of fly ash, When the amount is less than 0.01, the function of the milling aid is insignificant. When the amount of the additive is more than 0.03, the amount of air becomes excessive as compared with the reaction.

On the other hand, the pulverizing assistant is a mixture of diethylene glycol (DEG) and polyglycol (PG), and the use of such a pulverizing assistant can increase the pulverization efficiency.

More preferably, the ratio by weight of diethylene glycol (DEG): polyglycol (PG) is 2: 1.

More preferably, the admixture composition of the present invention is prepared by mixing and pulverizing fly ash, an activator and the like, and mixing and grinding the fly ash with an amount of powder of 4,000 cm 2 / g to 4,700 cm 2 / g, 4,700 to 5,300 cm < 2 > / g.

The reason why the fly ash powder has a viscosity of 4,000 cm 2 / g to 4,700 cm 2 / g is mixed is that when the powder having a particle size of less than 4,000 cm 2 / g is used, the energy requirement in the pulverization process after mixing is large, It is not sold as a normal product, so it is necessary to perform a separate grinding process in preparation of the material.

In addition, the reason why the degree of powder after mixing and grinding is limited to 4,700-5,300 cm2 / g is that the effect is insignificant in the case of less than 4,700 cm2 / g and the quality performance is improved such as poor workability in the case of exceeding 5,300 cm2 / g And the manufacturing cost only increases.

The above-mentioned admixture composition of the present invention suitably has a cement replacement ratio of 10 wt% or more and less than 50 wt%. When the content of the admixture composition is less than 10 wt%, the effect of reducing the amount of cement due to substitution is insignificant. %, There is a problem that the strength is lowered. That is, the present invention provides a concrete composition which can be physically and chemically modified to improve fly ash strength and initial strength and durability so that a fly ash with an excess of cement replacement ratio of 30 or more can be used.

Concrete composition of the present invention as described above is economical by the recycling of industrial by-products it is a problem of fly ash disadvantages of the early strength development of the cement may increase the degree of substitution by the resolved fly ash, much of the CO ₂ It is possible to reduce the generation of gas, which is advantageous for environment.

In addition, the concrete composition of the present invention has an advantage that high durability can be manifested by solving the problems such as shrinkage due to premature curing that may be present as initial strength is developed, and showing a tight paste structure.

Hereinafter, embodiments of the present invention will be described in more detail with reference to experimental examples.

<Experimental Example 1>

Active compounding ratio

Table 1 below shows the mixing ratio of mortar for deriving the optimum mixing ratio of activator.

Type of mortar cement Fly ash Standard yarn water standard 450 ± 2 0 1,350 ± 5 225 ± 1 Stimulant test 337.5 ± 1.5 112.5 ± 0.5

Table 2 shows examples in which samples were prepared by varying the compounding ratio of anhydrous gypsum, calcium chloride and calcium hydroxide as activators according to the mortar mixture ratio.

division Anhydrous plaster
(FA x%) Calcium chloride
(FA x%) Calcium hydroxide
(FA x%) standard - - - Reference Example 1-1 2 - - Reference Example 1-2 4 - - Reference Example 1-3 - 2 - Reference Example 1-4 - 4 - Reference Example 1-5 - - 2 Reference Example 1-6 - - 4 Example  1-1 2 One One Example  1-2 One 2 One Comparative Example 1-7 One One 2 Comparative Example 1-8 2 2 One Comparative Example 1-9 One 3 One Example  1-3 One 2 One

Table 3 shows the result of measuring the compressive strength of each sample.

Comparative Examples 1-1 and 2 show the case where only anhydrous gypsum is added as an activator. As the amount of anhydrous gypsum is increased, the strength increases after 28 days of age, but the initial strength is lower than the standard appear.

Comparative Examples 1-3 and 4 show the case where only calcium chloride was added as an activator. As the amount of calcium chloride was increased, the initial strength (1 day, 7 days strength) was increased, but the strength after 7 days was below the standard .

Comparative Examples 1-5 and 6 show the case where only calcium hydroxide is added as an activator. As the addition amount of calcium hydroxide is increased, the initial strength (day strength) is increased, but after 7 days, the strength is lower than the standard .

On the other hand, as in Examples 1-1 and 2, 4 parts by weight of an activator was added to 100 parts by weight of fly ash, and the mixture was mixed with an activator in a weight ratio of anhydrous gypsum: calcium chloride: calcium hydroxide = 2: 1: 1 or 1: The results exceeded the standard in both the initial strength and the long term strength.

On the other hand, in the case of Comparative Example 1-7, when 4 parts by weight of the activator was blended with 100 parts by weight of fly ash, and when the blending was carried out at a weight ratio of anhydrous gypsum: calcium chloride: calcium hydroxide = 1: 1: , 7 days) were not met.

In addition, in the case of Comparative Examples 1-8 and 9, 5 parts by weight of an activator was added to 100 parts by weight of fly ash, and examples in which the anhydrous gypsum or calcium chloride was further blended with Example 1-2, (1 day, 7 days) were not met.

From the results of this experiment, it is judged that 2 to 4 parts by weight of the activator is appropriate for 100 parts by weight of fly ash in terms of the initial strength reinforcement surface, and in the activator, mixing of anhydrous gypsum, calcium chloride, 100 to 200 parts by weight of anhydrous gypsum and 100 to 200 parts by weight of calcium chloride per 100 parts by weight of calcium hydroxide are considered to have a proper mixing ratio in terms of initial strength development.

In Examples 1-3, calcium carbonate (CaC ₂ ) was added as a filler in an amount of 2 parts by weight based on 100 parts by weight of fly ash in the same manner as in Example 1-2 As compared with Example 1-2, the expression of initial strength (1 day, 7 days) is similar, but it is found that it is more effective in the expression of long-term strength (28 days, 91 days). It is considered that the calcium carbonate produced by the calcium carbide is mixed with the calcium carbonate to cause synergy such as pozzolan reaction together with the polymerization reaction of fly ash.

division Compressive strength (%) 1 day 7 days 28th 91 days standard 100 100 100 100 Reference Example 1-1 88 95 101 105 Reference Example 1-2 92 96 110 109 Reference Example 1-3 105 101 95 99 Reference Example 1-4 115 105 94 97 Reference Example 1-5 104 98 93 102 Reference Example 1-6 110 99 89 95 Example  1-1 100 105 106 103 Example  1-2 103 102 101 107 Comparative Example 1-7 96 98 101 103 Comparative Example 1-8 97 99 100 102 Comparative Example 1-9 98 97 101 100 Example  1-3 104 102 104 109

<Experimental Example 2>

Of durable additive  effect

As shown in the following Table 4, the test was carried out in the same mixing ratio as in Example 1-2 in Experimental Example 1, while Examples 2-1 to 2-4 and Comparative Example 2-1 were combined with the same additives as the durability additive And a polyoxyalkylene alkyl ether-based mixture (each mixed at a weight ratio of 1: 1) were mixed in amounts of 2, 4, 6, 8, and 10 parts by weight based on 100 parts by weight of fly ash, And Comparative Example 2-3 were prepared in the same mixing ratio as Example 1-2 in Experimental Example 1, except that only 2 parts by weight of a silylation agent or a polyoxyalkylene alkyl ether alone was added as a durable additive.

division Silane flame + polyoxyalkylene
Alkyl ethers (FA x%) standard - Example 2-1 2 Example 2-2 4 Example 2-3 6 Examples 2-4 8 Comparative Example 2-1 10 Comparative Example 2-2 2 (only the flame of the flame) Comparative Example 2-3 2 (polyoxyalkylene alkyl ether type only)

As shown in the following Table 5, in the case of Examples 2-1 to 2-4, that is, a mixture of a silicate flame and a polyoxyalkylene alkyl ether is added as a durable additive, and the hydration heat generation amount and shrinkage amount .

As a result of these experiments, it is possible to control the cracking by decreasing the shrinkage and consequently to achieve a closed structure by retarding the hydration reaction by adding a mixture of a silane coupling agent and a polyoxyalkylene alkyl ether mixture as a durable additive. To be improved.

However, in the case of Comparative Example 2-1, when 10 parts by weight of a mixture of a silane coupling agent and a polyoxyalkylene alkyl ether is added as a durable additive, the effect of reducing hydration heat generation amount and shrinkage amount is insignificant.

In the case of Comparative Example 2-2, the effect of reducing hydration heat is similar to that of Example 2-1 in the case of adding only a silicic acid flame retardant as a durable additive, but the effect of reduction in shrinkage is not exhibited, In the case of Comparative Example 2-3, only the polyoxyalkylene alkyl ether system was added. Compared with Example 2-1, the shrinkage reduction effect showed similar results, but the amount of heat of hydration So that it is not possible to provide a closed structure due to delayed hydration, and thus it can be exposed to freezing and thawing.

Therefore, it can be seen from the results of this experiment that the effect of delaying the hydration reaction by the addition of the silane flame has an effect of reducing the shrinkage by adding the polyoxyalkylene alkyl ether system, It is preferable to use a mixture of a silane flame and a polyoxyalkylene alkyl ether as a durable additive to ensure the effect simultaneously. It is known that the amount of the additive is 2 to 8 parts by weight of the durable additive relative to 100 parts by weight of fly ash have.

division Hydration calorific value (cal / g) Shrinkage (μm) standard 60.02 -480 Example 2-1 55.07 -460 Example 2-2 47.56 -445 Example 2-3 41.26 -420 Examples 2-4 33.65 -395 Comparative Example 2-1 33.70 -396 Comparative Example 2-2 55.08 -470 Comparative Example 2-3 59.2 -458

<Experimental Example 3>

Proper grinding time

Table 6 shows the results of an experiment in which the specific surface area was measured at different grinding times by blending in the same manner as in Example 2-1 of Experimental Example 2. As shown in Table 6, it can be seen that the specific surface area increases as the grinding time becomes longer.

Grinding time (min) Grinding speed (rpm) Specific surface area (cm 2 / g) 3 2,000 4,837 5 4,984 10 5,294 15 5,574

Table 7 shows the results of measuring the compressive strength and the slump flow for each of the samples prepared in the same manner as in Example 2-1 except that the crushing time was varied.

Grinding time (min) Compressive strength (MPa) Slump (mm) 1 day 3 days 7 days 28th standard 100 100 100 100 210 3 103 102 101 107 225 5 107 108 109 113 220 10 113 115 118 119 210 15 114 120 122 124 200

As shown in Tables 6 and 7, as the grinding time is increased, the specific surface area is increased and the compressive strength is increased. However, when the grinding time is 15 minutes, the slump is significantly lowered at a specific surface area of 5,574 cm 2 / g . Therefore, it is understood that the proper grinding time is 3 to 10 minutes in consideration of the strength and the workability.

<Experimental Example 4>

Triethanol Amine  effect

The following Table 8 shows the results of measuring the slump and the compressive strength of the sample prepared by varying the addition amount of triethanolamine in the same manner as in Example 2-1 of Experimental Example 2. [ As shown in the following Table 8, when the addition amount of triethanolamine was increased, the initial strength was increased as compared with Example 2-1 (Example 1-2).

Also, it can be seen that the slump value increases as the amount of triethanolamine added increases. However, as shown in Comparative Example 4-1, when the addition amount of triethanolamine was 0.6 parts by weight (relative to 100 parts by weight of fly ash), the slump value was inferior to the standard. In Comparative Example 4-2, the addition amount of triethanolamine The addition amount of triethanolamine for increasing the initial strength while securing the workability was inferior to that of Example 4-2. In addition, the amount of triethanolamine added in the initial stage (day 1, 7 days) And 0.8 to 1.0 part by weight based on 100 parts by weight of ash.

division Unhardened concrete Hardening Properties Slump (mm) Air volume (%) Compressive strength (MPa) 0 minutes 60 minutes 0 minutes 60 minutes 1 day 7 days 28th 91 days standard 220 150 3.5 2.1 100 100 100 100 Comparative Example 4-1 (0.6%) 180 160 5.1 4.8 107 103 101 107 Example 4-1 (0.8%) 220 210 5.7 5.4 110 105 102 108 Example 4-2 (1%) 230 230 6.0 5.8 115 110 103 109 Comparative Example 4-2 (1.2%) 235 235 6.8 6.7 115 109 103 110

<Experimental Example 5>

Compressive strength according to cement replacement amount

The following Table 9 shows the results of measuring the compressive strengths of samples prepared in the same manner as in Example 4-2 and having different crushing rates with a crushing time of 10 minutes.

FA replacement ratio (%) Compressive strength (MPa) 1 day 3 days 7 days 28th 0 100 100 100 100 10 116 112 105 112 20 115 110 103 109 30 111 109 101 104 40 107 102 100 103 50 97 95 99 96 60 86 87 86 84

As shown in Table 9, the strength decreases as the substitution ratio increases, and the strength decreases significantly when 50% by weight is substituted. That is, when it is substituted by less than 10% by weight, it is judged that it is meaningless in terms of recycling of resources, and when it is substituted by 50% by weight or more, the strength is lowered to the reference value or less.

Therefore, in the case of the admixture of the present invention, the proper replacement ratio is 10 wt% or more and less than 50 wt%, and the optimum replacement ratio is determined to be 30 wt% considering resource recycling and strength. As a result, when the conventional fly ash is blended, there is a problem of initial strength deterioration and the replacement amount is insufficient. However, in the present invention, the initial strength is improved by modifying the fly ash so that the replacement amount can be reduced to less than 50 wt% The advantage is presented in terms of advantages.

<Experimental Example 6>

Depending on the amount of cement replaced Salt resistance

Table 10 below shows the result of measuring the diffusion coefficient to determine the resistance to salting after each sample was prepared in the same manner as in Experimental Example 5. [

FA replacement ratio (%) Diffusion Coefficient (× 10 ^-12 m2 / s) 28th 56 days 91 days 0 13.54 10.61 6.54 10 10.98 8.50 5.21 20 10.12 7.44 4.11 30 9.32 6.22 3.12 40 8.08 5.22 3.01 50 7.44 5.01 2.77 60 8.21 5.55 3.26

As shown in Table 10, according to the present invention, as the fly ash is physically and chemically modified to improve initial strength and durability, the resistance to freezing and thawing is improved up to 50% by weight Able to know.

As a result, in the case of the salt resistance test results, the proper replacement ratio of the admixture of the present invention is 10 wt% or more and less than 50 wt%.

<Experimental Example 7>

Freezing and thawing characteristics according to cement displacement

Table 11 shows the result of measuring the relative dynamic modulus of elasticity to determine the freeze-thaw characteristics after preparing each sample in the same manner as in Experimental Example 5. [

FA replacement ratio (%) Relative dynamic modulus (%) 0
(cycle) 150
(cycle) 300
(cycle) 0 100 96 78 10 100 97 85 20 100 98 83 30 100 96 84 40 100 97 79 50 100 96 78 60 100 93 70

As shown in Table 11, according to the present invention, as the fly ash is physically and chemically modified to improve the initial strength and improve the durability, up to 50% by weight of the fly ash has resistance to freeze- %, Which is greater than or equal to. As a result, in the case of the results of the freeze-thaw experiment, the proper replacement ratio of the admixture of the present invention is 10 wt% or more and less than 50 wt%.

<Experimental Example 8>

Depending on the amount of cement replaced Hydration heat  characteristic

Table 12 below shows the results of measuring the heat of hydration to determine the hydration heat characteristics after preparing each of the samples in the same manner as in Experimental Example 5.

FA replacement ratio (%) Hydration heat Maximum temperature (℃) 0 85 10 75 20 70 30 63 40 55 50 42 60 31

As shown in Table 12, according to the present invention, as the fly ash is physically and chemically modified to improve initial strength and durability, the heat of hydration is reduced as the replacement amount is increased.

This is because, as mentioned above, the addition of a silane coupling agent and a polyoxyalkylene alkyl ether-based mixture as a durable additive to the admixture of the present invention is attributed to the addition of a silane flame.

As a result, the higher the replacement ratio of the admixture of the present invention, the more reasonable results are obtained. However, in consideration of the strength, the salt resistance and the freeze / thaw resistance as mentioned above, the admixture of the present invention has a proper replacement ratio of not less than 10 wt% , And less than 50% by weight.

<Experimental Example 9>

Shrinkage Characteristics by Cement Replacement Amount

Table 13 below shows the results of measurement of shrinkage characteristics after preparing each sample in the same manner as in Experimental Example 5.

FA replacement ratio (%) Shrinkage (μm)
28D 0 -790 10 -785 20 -770 30 -765 40 -750 50 -741 60 -735

As shown in Table 13, according to the present invention, as the fly ash is physically and chemically modified to improve initial strength and durability, shrinkage is reduced as the replacement amount increases.

This is because, as mentioned above, the addition of a silane coupling agent and a polyoxyalkylene alkyl ether-based mixture as a durable additive to the admixture of the present invention is considered to be due to the addition of a polyoxyalkylene alkyl ether system in particular.

As a result, the higher the substitution rate of the admixture of the present invention, the more reasonable results are obtained. However, as mentioned above, in consideration of strength, salt resistance and freeze / thaw resistance, the admixture of the present invention has a proper substitution rate of 10 wt% , And less than 50% by weight.

In addition to the above, The admixture Filler  Can be further compounded A bar , As filler  Calcium carbide ( CaC ₂ ) To form calcium hydroxide (Ca ( OH ) ₂ )and Pozzolanic reaction  Thereby improving the long-term strength. The calcium carbide ( CaC ₂ ) Is acetylene ( C ₂ H ₂ ) Gas production Generated  As a by-product, calcium hydroxide (Ca ( OH ) ₂ ) Is created and made

Claims (6)

Wherein the fly ash is mixed with 2 to 4 parts by weight of activator and 2 to 8 parts by weight of a durable additive per 100 parts by weight of fly ash.
The method of claim 1,
The activator may comprise,
Wherein the mixture is a mixture of 100 to 200 parts by weight of anhydrous gypsum and 100 to 200 parts by weight of calcium chloride per 100 parts by weight of calcium hydroxide.
The method of claim 1,
As the filler, calcium carbonate (

By weight based on 100 parts by weight of fly ash, and further adding 1 to 3 parts by weight with respect to 100 parts by weight of fly ash.
The method of claim 1,
The durability additive may include,
Wherein the mixture is a mixture of a silane-based flame and a polyoxyalkylene alkyl ether-based high-durability concrete composition.
The method of claim 1,
Wherein the admixture is further blended with 0.8-1.0 parts by weight of triethanolamine per 100 parts by weight of fly ash.
The method of claim 1,
Wherein the admixture is further blended with 0.01 to 0.03 parts by weight of a pulverizing additive based on 100 parts by weight of fly ash, wherein the pulverizing aid is a mixture of diethylene glycol (DEG) and polyglycol (PG) High strength durable concrete composition.