KR100861008B1 - Preparation method of crude steel fiber reinforced cement composites and composites prepared therefrom - Google Patents

Abstract

The present invention is excellent in the initial strength expression can exhibit a compressive strength of 20MPa or more and flexural tensile strength of more than 5MPa per day in a 20 ℃ environment can significantly shorten the construction period can be used in a single day after the concrete is placed The present invention relates to a method for manufacturing a crude steel fiber reinforced cement composite, wherein a strength promoting binder is prepared by mixing silica fume, sand, and anhydrous gypsum with a crude steel cement, and a triethanolamine, a naphthalene-based water reducing agent, and distilled water are mixed to form a coagulation accelerator. It is prepared by mixing the blending water and the binder and then adding the steel fiber or PVA fiber.

The crude steel fiber reinforced cement composite produced by the method of the present invention has excellent initial strength expression, and thus, the compressive strength of 20 MPa or more and flexural tensile strength of 5 MPa or more can be significantly reduced per day. The structure can be used in the bay, and the physical properties such as elasticity coefficient and thermal expansion coefficient are similar to those of general concrete, and dry shrinkage is small, resulting in excellent dimensional stability, and excellent durability such as salt resistance, neutralization resistance and freeze-thawing resistance. In addition, the advantages of applying them as repair materials can greatly increase the life of the structure.

  Crude steel fiber reinforced cement composite, strength expression promoting binder, condensation accelerator

Description

A method for preparing high-early-strength fiber reinforced cement composites and high-early-strength fiber reinforced cement composites preparing from the method}

1 is a graph showing the results of the elastic modulus test for each repair material;

2 is a graph showing the results of the thermal expansion coefficient test for each repair material;

Figure 3 is a graph showing the strength test results of the rough steel cement and super-steel cement, (a) shows the compressive strength, (b) shows the bending strength,

Figure 4 is a graph showing the dry shrinkage test results.

The present invention relates to a method for manufacturing a steel fiber reinforced cement composite and a composite prepared therefrom. More specifically, the construction period is extended by exerting the compressive strength of 20 MPa or more and the flexural tensile strength of 5 MPa or more in one day with excellent initial strength. The present invention relates to a method for manufacturing a crude steel fiber-reinforced cement composite that can be significantly reduced and that the structure can be used even after one day of placing concrete, and a composite prepared therefrom.

Recently, major defects in the concrete, such as subways, tunnels, cavities, bridges, port structures, and building structures, have caused many defects during construction or use due to quality errors in design and construction, environmental changes, and load conditions. Problems deteriorating lifespan and safety have arisen and have become of great social concern.

     In order to cope with such a situation, various repair materials and construction methods are used. However, the following faults have not been solved, resulting in only temporary measures. The cost of use is enormously increasing.

     First, defects occur due to physical property differences from existing concrete. Epoxy-based repair method has a large initial adhesive strength, but due to the difference between the existing concrete, elastic modulus and thermal expansion coefficient, dropout occurs due to film formation on the adhesive surface. In many cases, condensation and interfacial failure occur at the surface along with corrosion of rebar. In addition, the polymer-based repair method may cause problems in the integration of the mother body in the long term due to the mixing of organic and inorganic materials, and may cause interfacial failure, and in the case of prolonged exposure to ultraviolet rays, it hardens and damages the repair layer. There are many.

     Secondly, cement-based repair methods with the same properties as existing concretes are used, but curing periods of about 3 to 7 days are required to develop a certain level of strength, resulting in inconvenience in traffic and congestion. This burden is considerable.

Third, the existing cement-based repair methods have a poor adhesion strength and lack of tensile strength, resulting in large impacts, fatigue loads, or dry shrinkage, which can easily cause cracks. There are many cases.

Therefore, the inventors of the present invention, the problem caused by the difference in physical properties with the existing concrete in the conventional epoxy-based and polymer-based repair method, the problem of delayed strength expression in the cement-based repair method, the reduction of adhesion strength and impact fatigue load and drying The present invention has been completed by solving technical problems such as cracking caused by shrinkage as a technical problem.

First, the problem caused by the difference in physical properties with the existing concrete was solved by making the elastic modulus and the coefficient of thermal expansion equal to that of the general concrete using materials used in the general concrete.

The problem of delayed strength expression was solved by using a strength promoting binder composed of a crude cement, silica fume, anhydrous gypsum and the like, and a condensation accelerator containing water containing triethanolamine.

The problem of cracking due to impact load, fatigue load and dry shrinkage was solved by fibers such as organic fibers and steel fibers.

Since various materials are used to realize the above technology, if each material is weighed and used in the field, manufacturing time may be delayed and precision may also be problematic.

In view of these considerations as a whole, an object of the present invention is to provide a method for manufacturing a crude steel fiber reinforced cement composite based on the crude steel portland cement which can significantly shorten the air period.

According to the invention,

Silica fume, 10-20 parts by weight, 100-120 parts by weight, and 5, respectively, based on 100 parts by weight of the crude cement to be mixed later with sand and anhydrous gypsum having a particle diameter of 5 mm or less at 100 ± 5 ° C. A first step of mixing in an amount of -20 parts by weight;

Mixing the mixture with 100 parts by weight of the cement for producing a strength-expressing promoting binder; Simultaneously or sequentially

A third step of mixing triethanolamine, a naphthalene-based water reducing agent, and distilled water in an amount of 1-3 wt%, 1-3 wt% and 94-98 wt%, respectively, to prepare a coagulation accelerator blended water;

A fourth step of obtaining a cement composite by mixing so that the weight ratio of the condensation accelerator compounded water obtained in the third step and the strength expression promoting binder obtained in the second step satisfies 0.15-0.25; And

Provided is a fifth step of mixing by mixing 1-3% by volume based on 100% by volume of the steel fiber or organic fiber to the cement composite obtained in the fourth step, and provides a method for producing a crude steel fiber reinforced cement composite comprising a do.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The crude steel cement used in the present invention typically has a component ratio of 3,300 cm 3 / g or more, C ₃ S 67% or more, C ₂ S 9% or less, C ₃ A 8% or more, C ₄ AF 8% or more. .

First, silica fume, sand, and anhydrous gypsum are blended to produce a strength-expressing promoting binder. At this time, the content of each component is composed of 10-20 parts by weight of silica fume, 100-120 parts by weight of sand and 5-20 parts by weight of anhydrous gypsum, based on 100 parts by weight of crude cement to be added later.

In this case, the strength of silica fume is rapidly developed based on 15 parts by weight, and the calcium hydrate (Ca (OH) ₂ ), which is a cement hydration product, and silica react with pozzolanic reaction at 15 parts by weight or less to generate calcium silicate (CSH) hydrate. At 15 parts by weight or more, the amount of calcium hydroxide required for the pozzolanic reaction in the early age is small, the initial strength is expressed small, but the age is increased as the age is increased, and the content is preferably 10-20 parts by weight. . In addition, although performance is lower than silica fume, metakaolin may be used.

The smaller the content of the sand, that is, the greater the amount of cement, the strength is enhanced, especially when using a sand with a particle diameter of 5mm or less made in absolute dry at 100 ± 5 ℃ is preferable considering the homogeneous formulation. At this time, the reason of making it in an absolute dry state is that the water contained in the sand may react with the cement and become weathered. When using such a product, the strength may be reduced, and the particle diameter of 5 mm or less may be used to distinguish sand and coarse aggregate. Because it is a standard.

The anhydrous gypsum (CaSO ₄ ) is effective to increase the strength by reacting with the cement component C ₃ A to generate a large amount of ettringite (ettringite) from the early age, and also in the present invention using the anhydrous gypsum Minimize shrinkage as much as possible. On the other hand, instead of anhydrous gypsum, it is also possible to mix the hemihydrate gypsum in a trace amount of about 1-5 parts by weight. In addition, the mixing ratio is set in consideration of the workability, strength, economics and the like comprehensively.

The mixture obtained by mixing as described above is mixed with 100 parts by weight of the steel cement to prepare a strength-expressing promoting binder. At this time, for the purpose of mixing the mixture more homogeneously, it is preferable to mix for 10-12 minutes at a speed of 20-40rpm and then additionally mix for about 3-5 minutes at a speed of about 10rpm. At this time, the mixing condition is to perform the purpose of reducing the amount of dust scattered by the secondary mixing at a low speed since the first mixture at a high speed, such as dust is scattered in the mixture consisting of powder, etc. It does not have to be done.

Separately from this, simultaneously or sequentially, triethanolamine, a naphthalene-based water reducing agent, and distilled water may be mixed to prepare a coagulation accelerator blended water.

At this time, triethanolamine further promotes the formation of ettringite produced by the reaction of the cement component C ₃ A with gypsum, and furthermore, promotes the hydration by activating the resulting ettringite into monosulfate. The higher the amount of liethanolamine used, in particular, the initial strength is increased.

At this time, the triethanolamine substitutes are CaCl ₂ , Na ₂ CO ₃ , NaAlO ₂ And the like, which promotes the production of etringite, thereby increasing the initial strength. In addition, alkali silicate salts (Na ₂ O.nSiO ₂ (n = 2 to 4)) can also replace triethanolamine, and the reaction of alkali silicate salts with Ca (OH) ₂ , a cement hydrate, results in CSH (Calcium Silicate). Hydrate) Hydrate can be produced to increase initial strength.

In addition, naphthalene-based water-reducing agent is used to improve the fluidity of the cement composite, and has a slight effect on the initial compressive strength and bending strength, but its influence is not very large. In this case, in addition to the naphthalene-based water reducing agent, a polycarboxylic acid-based water reducing agent, a melamine-based water reducing agent, etc. may be used, but may have an effect of delaying slight strength expression.

In the present invention, distilled water is necessarily used, but general tap water may also be used. When tap water is used, there is little effect on concrete. However, chlorine or the like reacts with the water reducing agent and the like to precipitate or float, which may cause problems as a product.

At this time, the mixing ratio of each component is sufficient in the range of 1-3% by weight, 1-3% by weight and 94-98% by weight. The mixing ratio is set to 1-3% by weight to have a large influence on the strength promotion by using the triethanolamine, naphthalene-based water reducing agent is used to improve the fluidity (workability), if too much material separation is used Since it adversely affects the workability, performance, and the like also decreases the strength, it is preferable to mix in the content ratio.

Then, mixing the resultant condensation accelerator compounded water at a speed of 500-800 rpm for about 3-5 minutes to obtain a homogeneous compounded water is preferable. At this time, the mixing conditions should be mixed at high speed so that the high-performance sensitizer, triethanolamine and distilled water are mixed well, and the effect of using these materials is shown well, and if the mixing is not performed well, they may be separated again if stored for a long time. It is most desirable to have the above mixing conditions because it can greatly affect the quality of the concrete.

The cement composite is obtained by mixing the condensation accelerator compounded water thus obtained with the strength-expressing promoting binder. In this case, the mixing ratio is sufficient to mix the strength-promoting binder with respect to the condensation-promoting blended water to satisfy the weight ratio of 0.15-0.25, and when it exceeds 0.25, the blending binder is excessively added compared to the blended water, making it difficult to use later in the construction. It is also not preferable, and if it is less than 0.15, since the accelerator binder is added in a small amount compared to the blended water, it is also difficult to use later in the construction and it is not preferable because the desired physical property value cannot be obtained.

At this time, if the weight ratio of the condensation promoting compound / strength expression promoting binder exceeds 0.25, the promoting binder is less than that of the blending water, so that the target strength cannot be secured. It is not preferable because the fluidity is reduced and not only the construction property is secured but also the economic efficiency may be reduced.

On the other hand, the cement composite obtained at this time is also preferably mixed for about 5-7 minutes at a speed of 40-50rpm. The mixing condition is to take into account that the mixer of the general concrete is 40-50rpm, to mix for a certain time to play a role in ensuring the workability by uniformly preparing the cement composite.

Then, the steel fiber or organic fiber is added to the obtained cement composite to prepare a crude steel fiber reinforced cement composite.

The fibers are used to solve the problem of fracture due to impact load and fatigue load and crack due to dry shrinkage due to lack of tensile strength of cement composite, and compressive strength, especially flexural tensile strength, regardless of the type of fiber used. Is increased, and the input amount is about 1-3% by volume based on 100% by volume of cement composite. At this time, the fiber material has a significant dimensional stability of the repair material, and in order to securely adhere to the existing member, a material that does not occur shrinkage is used in the present invention serves to reduce the shrinkage as used in conjunction with anhydrous gypsum as possible.

At this time, the fibers can be used, in addition to steel fibers, PVA fibers, PE, PP, cellulose fibers and the like can be used. As mentioned above, the mixing of the fiber is to overcome the sudden fracture and brittle fracture of the concrete, and to give toughness by increasing the tensile strength, and the mixing effect of the fiber is exhibited from about 1%. The larger the amount of the admixture, the better the effect. However, when the amount of the admixture is increased, problems such as economical efficiency and workability are deteriorated. Therefore, it is most preferable that the amount of the admixture be in the range of 1-3% by volume of the fiber.

Hereinafter, a method for producing a crude steel fiber reinforced cement composite will be described in more detail with reference to a preferred embodiment of the present invention. The following examples are intended to illustrate the invention, but are not intended to limit the invention thereto.

<Example>

Example 1-Effect of Cement Type

This embodiment is to analyze the effect of cement type on the quality of the crude steel fiber reinforced cement composite.

To analyze the effect of cement types on the quality of crude steel fiber reinforced cement composites, 36 kg of silica fume based on 360 kg of crude steel or cemented steel cement, 396 kg of sand less than 5 mm made in absolute dry at 100 ± 5 ° C, 36 kg of anhydrous gypsum A mixture consisting of 11 minutes at a speed of 30rpm, and then mixed for 4 minutes at a speed of 10rpm to prepare a strength-expressing promoting binder.

Then, a condensation accelerator blended water was prepared by mixing triethanolamine with 2.8 kg, 2.8 kg naphthalene-based sensitizer, and 160 kg distilled water for 4 minutes at a speed of 700 rpm using a high-speed dispersion mixer.

The steel fiber 156kg / ㎥ was added to the cement composite prepared by mixing for 6 minutes at a speed of 50rpm so that the weight ratio of the condensation accelerator blended water and the strength-expression promoting binder was 0.2 so that the mixture was mixed for 1 minute and 30 seconds at 25rpm again. After the fiber-reinforced cement composites were prepared, the coagulation properties, compressive strength, and flexural tensile strength were measured, and the results are summarized in Tables 1-3 below.

< Example 2- Influence on silica fume >

This embodiment is to analyze the effect of the amount of silica fume on the quality of the crude steel fiber reinforced cement composite.

To analyze the effect of silica fume on the quality of crude steel fiber reinforced cement composites, silica fume was mixed in a mixture consisting of 396 kg of sand of less than 5mm and 36 kg of dry gypsum at 100 ± 5 ° C based on 360 kg of crude steel cement. To 0kg, 18kg, 36kg, 54kg, 72kg was added to 11 minutes at a speed of 30rpm, the strength-promoting binding material was mixed for 4 minutes at a speed of 10rpm again.

Then, a condensation accelerator blended water was prepared by mixing triethanolamine with 2.8 kg, 2.8 kg naphthalene-based sensitizer, and 160 kg distilled water for 4 minutes at a speed of 700 rpm using a high-speed dispersion mixer.

The steel fiber 156kg / ㎥ was added to the cement composite prepared by mixing for 6 minutes at a speed of 40-50rpm so that the weight ratio of the condensation accelerator compounded water and the strength-promoting binding material prepared in this way was 0.2-0.25 1 again at a speed of 20-25rpm 1 After mixing for 1 minute 30 seconds to prepare a fiber-reinforced cement composite was measured the coagulation characteristics, compressive strength, flexural tensile strength and summarized the results in Table 1-3.

Example 3 Influence of Sand Content

This embodiment is to analyze the effect of the sand content on the quality of the crude steel fiber reinforced cement composite.

To analyze the effect of the amount of sand on the quality of crude steel fiber reinforced cement composites, sand mixed with 36kg of silica fume and 36kg of anhydrous gypsum based on 360kg of crude steel cement was used. 324 kg, 360 kg, 396 kg, and 432 kg, respectively, were added for 11-12 minutes at a speed of 30-40 rpm, followed by mixing for 5-5 minutes at a speed of 10 rpm.

Separately or sequentially, a condensation accelerator compounded water was prepared by mixing the mixture consisting of 2.8 kg of triethanolamine, 2.8 kg of naphthalene-based sensitizer, and 160 kg of distilled water for 4-5 minutes at a speed of 700-800 rpm using a high-speed dispersion mixer. .

The steel fiber 156kg / ㎥ is added to the cement composite prepared by mixing for 5-6 minutes at a speed of 40-50rpm so that the weight ratio of the condensation accelerator blended water and the strength-expression promoting binder is 0.15-0.2 so that the speed of 25-30rpm 1 minute 30 seconds-2 minutes to prepare a fiber-reinforced cement composite and then measure the coagulation characteristics, compressive strength, flexural tensile strength and summarized the results in Table 1-3.

Example 4 Effect of Content of Anhydrous Gypsum

This embodiment is to analyze the effect of the content of anhydrous gypsum on the quality of the crude steel fiber reinforced cement composite.

To analyze the effect of the amount of anhydrous gypsum on the quality of crude steel fiber reinforced cement composites, a mixture of 36 kg of silica fume based on 360 kg of crude cement and 396 kg of sand of 5 mm or less made in absolute dry condition at 100 ± 5 ° C 0 kg, 18 kg, 36 kg, 54 kg, and 72 kg of gypsum were added, respectively, to prepare a strength-expression promoting binder mixed for 11-12 minutes at a speed of 30-40 rpm and then 3-4 minutes at a speed of 10 rpm.

Separately, a condensation accelerator blended water was prepared by sequentially or simultaneously mixing ethanolamine 2.8 kg, 2.8 kg naphthalene-based sensitizer, and 160 kg distilled water for 3-4 minutes at a speed of 600-700 rpm with a high-speed dispersion mixer. .

The steel fiber 156kg / ㎥ was added to the cement composite prepared by mixing for 5-6 minutes at a speed of 40-50rpm so that the weight ratio of the condensation accelerator compounded water and the strength-promoting binding material prepared in this way is 0.2-0.25 1 again at a speed of 25rpm After mixing for 30 seconds to prepare a fiber-reinforced cement composite was measured the coagulation characteristics, compressive strength, flexural tensile strength and summarized the results in Table 1-3.

< Example 5- Effect of Content of Triethanolamine >

This example is to analyze the effect of the content of triethanolamine on the quality of the crude steel fiber reinforced cement composites.

To analyze the effect of triethanolamine content on the quality of crude steel fiber reinforced cement composites, 36kg of silica fume based on 360kg of crude steel cement, 396kg of sand less than 5mm made of absolute dry at 100 ± 5 ℃ and 36kg of anhydrous gypsum The strength-promoting binder was prepared by mixing the mixture for 11 minutes at 30 rpm and 4 minutes at 10 rpm.

A mixture of 2.8 kg naphthalene-based sensitizer and triethanolamine 0 kg, 1.4 kg, 2.8 kg, 4.2 kg and distilled water 163.9 kg, 162.2 kg, 160.6 kg and 160 kg, respectively, was mixed with a high speed dispersion mixer at a speed of 700 rpm for 4 minutes. One coagulant blended water was prepared.

The steel fiber 156kg / ㎥ was added to the cement composite prepared by mixing for 6 minutes at a speed of 50rpm so that the weight ratio of the condensation accelerator blended water and the strength-expression promoting binder was 0.2 so that the mixture was mixed for 1 minute and 30 seconds at 25rpm again. After the fiber-reinforced cement composites were prepared, the coagulation properties, compressive strength, and flexural tensile strength were measured and the results are summarized in Table 1-3.

< Example 6- Effect of the content of the naphthalene-based water reducing agent>

This example is to analyze the effect of the content of naphthalene-based water reducing agent on the quality of the crude steel fiber reinforced cement composite.

To analyze the effect of the amount of naphthalene-based reducing agent on the quality of crude steel fiber reinforced cement composites, 36 kg of silica fume based on 360 kg of crude steel cement, 396 kg of sand less than 5 mm made of absolute dry at 100 ± 5 ° C, and 36 kg of anhydrous gypsum 11 minutes at a speed of 30rpm, the mixture was further mixed for 4 minutes at a speed of 10rpm to prepare a strength-promoting binder.

A mixture of 1.4 kg triethanolamine and 0 kg, 1.4 kg, 2.8 kg, and 4.2 kg distilled water, respectively, 163.9 kg, 162.2 kg, 160.6 kg, and 160 kg, was mixed with a high-speed dispersion mixer at a speed of 700 rpm for 4 minutes. A mixed condensation accelerator blended water was prepared.

The steel fiber 156kg / ㎥ was added to the cement composite prepared by mixing for 6 minutes at a speed of 50rpm so that the weight ratio of the condensation accelerator blended water and the strength-expression promoting binder was 0.2 so that the mixture was mixed for 1 minute and 30 seconds at 25rpm again. After the fiber-reinforced cement composites were prepared, the coagulation properties, compressive strength, and flexural tensile strength were measured and the results are summarized in Table 1-3.

< Example 7- Effect of the type and content of the fiber>

This embodiment is to analyze the effect of the type and content of fiber on the quality of the crude steel fiber reinforced cement composite.

To analyze the effect of fiber type and quantity on the quality of crude steel fiber reinforced cement composites, 36kg of silica fume based on 360kg of crude steel cement, 396kg of sand less than 5mm made of absolute dry at 100 ± 5 ℃ and 36kg of dry gypsum 11 minutes at a speed of 30rpm, the mixture was further mixed for 4 minutes at a speed of 10rpm to prepare a strength-promoting binder.

A condensation accelerator blended water was prepared by mixing the mixture consisting of 2.8 kg of triethanolamine, 2.8 kg of naphthalene-based sensitizer, and 160 kg of distilled water at a speed of 700 rpm using a high speed dispersion mixer.

The steel fiber was mixed into the cement composite prepared by mixing the coagulant mixture water and the strength-expressing binding material at a speed of 50 rpm for 6 minutes so that the weight ratio of 0.2 was 0.2 kg / m3, 76 kg / m3, 156 kg / m3, 232 kg / m3 or PVA. 0kg / ㎥, 12.6kg / ㎥, 25.2kg / ㎥, 37.7kg / ㎥ is added to the fibers and mixed for 1 minute and 30 seconds at a speed of 25 rpm to prepare fiber reinforced cement composites. Tensile strength was measured and the results are summarized in Table 1-3.

Example 8-Influence of Weight Ratio of Blended Water and Binder

This embodiment is to analyze the effect of the weight ratio of the blending water and the binder on the quality of the crude steel fiber reinforced cement composite.

To analyze the effect of weight ratio of blending water and binder on the quality of crude steel fiber reinforced cement composites, 36 kg of silica fume based on 360 kg of crude steel or cemented steel cement, 396 kg of sand of 5mm or less made in absolute dry condition at 100 ± 5 ℃ , A mixture of 36 kg of anhydrous gypsum was prepared for a strength expression promoting binder, which was mixed for 11 minutes at a speed of 30 rpm and 4 minutes at a speed of 10 rpm.

A condensation accelerator blended water was prepared by mixing the mixture consisting of 2.8 kg of triethanolamine, 2.8 kg of naphthalene-based sensitizer, and 160 kg of distilled water at a speed of 700 rpm using a high speed dispersion mixer.

156kg / ㎥ of steel fiber was added to the cement composite prepared by mixing for 6 minutes at a speed of 50rpm so that the weight ratio of the coagulation accelerator blended water and the strength-expressing binder was 0.15, 0.18, 0.2, 0.25, and again at 25rpm for 1 minute. After mixing for 30 seconds to prepare a fiber-reinforced cement composite, the condensation properties, compressive strength, flexural tensile strength was measured and the results are summarized in Table 1-3.

For reference, after removing the fiber with a 5.5mm sieve from the fiber reinforced cement composite, the initial setting and final setting time were measured by KS F 2436 using the cement composite, and the results obtained are shown in Table 1 below. In summary.

Type of material Setting time (hr) First Termination cement Crude steel 4.5 5.7 Rasp 3.1 4.3 Silica fume 0 kg 5.6 7.8 36 kg 4.5 5.7 54 kg 4.3 5.5 72 kg 4.7 5.9 sand 324 kg 4.3 5.6 360 kg 4.4 5.7 396 kg 4.5 5.7 432 kg 4.7 5.8 Anhydrous gypsum 0 kg 5.7 7.9 18 kg 4.6 5.9 36 kg 4.5 5.7 54 kg 4.3 5.6 72 kg 4.2 5.3 Triethanolamine 0 kg 5.3 7.8 1.4 kg 4.7 5.9 2.8 kg 4.5 5.7 4.2kg 4.2 5.5 Naphthalene Water-Resistant 0 kg 4.3 5.5 1.4 kg 4.4 5.7 2.8 kg 4.5 5.7 4.2kg 4.7 5.9   fiber  Steel fiber 0kg / m ³ 4.4 5.5 78kg / m ³ 4.5 5.6 156kg / m ³ 4.5 5.7 232kg / m ³ 4.6 5.7  PVA Fiber 0 kg 4.5 5.8 12.6kg / m ³ 4.5 5.7 25.2kg / m ³ 4.6 5.7 37.7kg / m ³ 4.6 5.8 Compound Water / Binder 0.15 4.1 5.4 0.18 4.3 5.5 0.20 4.5 5.7 0.25 4.7 6.0

Table 1 summarizes the test results of the condensation properties of crude steel fiber reinforced cement composites. In the coagulation property test, the fiber reinforced cement composite was removed with a 5.5 mm sieve and then the initial setting and final setting time were measured by KS F 2436 using the cement composite. Compared with the crude steel cement, the less crude steel cement had a faster setting time and the faster the silica fume at 54 kg, the higher the amount of sand was. And the higher the amount of anhydrous gypsum, the more condensation is promoted, because from the beginning of aging the anhydrous gypsum reacted with the cement component.

Triethanolamine, which acts to promote the reaction between cement and gypsum, has been shown to promote condensation. And the higher the amount of naphthalene-based sensitizer slightly delayed the condensation, the fiber has little effect irrespective of the type and amount, and the smaller the weight ratio of the condensation accelerator blended water and the strength-expressing binder, it was found that the condensation is promoted.

From the obtained steel-fiber-reinforced cement composite material, the compressive strength was tested by KS F 2405 using a column test specimen of 100 × 200 mm, and the results are summarized in Table 2 and FIG. 3A.

Type of material Compressive strength (MPa) 0.5 days 1 day 3 days 7 days 14 days 28 days 91 days cement Crude steel 13.4 22.3 35.5 39.5 43.8 46.7 48.9 Rasp 17.2 32.1 39.6 43.6 45.3 47.9 49.5 Silica fume 0 kg 6.8 17.8 28.7 36.5 40.3 43.5 46.7 36 kg 13.4 22.3 35.5 39.5 43.8 46.7 48.9 54 kg 14.2 23.1 36.5 40.5 44.3 47.5 49.8 72 kg 13.6 22.5 35.9 40.3 44.5 48.7 51.1 sand 324 kg 13.8 23.1 36.2 40.2 44.5 47.6 49.8 360 kg 13.6 22.7 35.9 39.9 44.5 47.1 49.5 396 kg 13.4 22.3 35.5 39.5 43.8 46.7 48.9 432 kg 13.1 21.8 34.6 38.7 42.5 45.1 47.6 Anhydrous gypsum 0 kg 7.1 18.1 29.2 36.9 39.8 43.2 46.5 18 kg 12.8 20.3 34.7 39.1 43.2 46.1 48.5 36 kg 13.4 22.3 35.5 39.5 43.8 46.7 48.9 54 kg 13.8 22.8 35.7 40.0 44.3 47.1 49.5 72 kg 14.1 23.5 36.1 40.2 44.1 46.9 49.1 Triethanolamine 0 kg 6.1 16.5 25.7 35.4 37.8 41.2 44.5 1.4 kg 12.6 20.5 35.1 39.9 44.7 47.1 49.4 2.8 kg 13.4 22.3 35.5 39.5 43.8 46.7 48.9 4.2kg 15.6 25.4 36.1 39.7 43.6 45.2 47.8 Naphthalene Water-Resistant 0 kg 13.6 22.3 34.2 38.6 43.1 45.2 47.6 1.4 kg 13.5 22.7 35.9 40.1 43.8 46.8 48.7 2.8 kg 13.4 22.3 35.5 39.5 43.8 46.7 48.9 4.2kg 13.1 22.1 35.6 39.7 44.1 46.8 49.1   fiber  Steel fiber 0kg / m ³ 12.2 20.1 32.5 36.7 40.2 44.7 46.9 78kg / m ³ 13.1 21.5 34.3 38.2 42.1 45.2 47.8 156kg / m ³ 13.4 22.3 35.5 39.5 43.8 46.7 48.9 232kg / m ³ 13.5 22.7 35.9 40.1 44.1 47.2 49.1  PVA Fiber 0kg / m ³ 12.2 20.1 32.5 36.7 40.2 44.7 46.9 12.6kg / m ³ 13.4 22.1 36.4 38.5 43.6 47.3 49.1 25.2kg / m ³ 13.6 22.5 36.9 38.9 44.1 47.9 49.7 37.7kg / m ³ 13.8 22.8 37.3 39.5 44.6 48.1 50.1 Compound Water / Binder 0.15 15.1 27.7 39.9 47.3 50.1 54.5 56.5 0.18 14.5 25.4 37.8 44.3 48.9 51.1 53.3 0.20 13.4 22.3 35.5 39.5 43.8 46.7 48.9 0.25 12.8 21.8 34.1 37.6 39.8 45.2 47.5

From the obtained steel-fiber-reinforced cement composites, flexural tensile strength was tested by a four-point loading method using a 100 × 100 × 400 mm square test specimen, and the results are summarized in Table 3 and FIG. 3B.

Type of material Flexural strength (MPa) 0.5 days 1 day 3 days 7 days 14 days 28 days 91 days cement Crude steel 3.1 5.7 6.5 7.1 7.7 8.1 8.5 Rasp 4.2 6.7 7.5 7.9 8.5 8.8 9.1 Silica fume 0 kg 2.8 4.9 5.8 6.7 7.4 7.8 8.2 36 kg 3.1 5.7 6.5 7.1 7.7 8.1 8.5 54 kg 3.3 5.9 6.8 7.4 8.1 8.4 8.9 72 kg 3.2 5.9 6.9 7.5 8.3 8.5 9.1 sand 324 kg 3.5 6.0 6.8 7.5 8.1 8.4 8.8 360 kg 3.3 5.9 6.7 7.3 7.9 8.3 8.7 396 kg 3.1 5.7 6.5 7.1 7.7 8.1 8.5 432 kg 2.9 5.4 6.2 6.8 7.4 7.9 8.2 Anhydrous gypsum 0 kg 2.1 4.3 5.2 5.9 6.7 7.1 7.5 18 kg 2.9 5.3 6.1 6.7 7.3 7.8 8.2 36 kg 3.1 5.7 6.5 7.1 7.7 8.1 8.5 54 kg 3.3 6.0 6.8 7.6 8.2 8.6 9.1 72 kg 3.5 6.3 7.2 7.9 8.6 9.0 9.4 Triethanolamine 0 kg 1.8 3.7 4.9 5.8 6.6 7.2 7.8 1.4 kg 2.9 5.2 5.9 6.8 7.5 7.9 8.2 2.8 kg 3.1 5.7 6.5 7.1 7.7 8.1 8.5 4.2kg 3.8 6.2 6.7 7.5 8.3 8.8 9.3 Naphthalene Water-Resistant 0 kg 3.2 5.9 6.8 7.3 7.8 8.3 8.7 1.4 kg 3.2 5.8 6.7 7.3 7.8 8.3 8.6 2.8 kg 3.1 5.7 6.5 7.1 7.7 8.1 8.5 4.2kg 2.9 5.3 6.2 6.7 7.3 7.8 8.2   fiber  Steel fiber 0kg / m ³ 1.1 1.8 2.5 2.9 3.3 3.6 3.4 78kg / m ³ 2.3 5.1 5.7 6.5 6.9 7.5 7.9 156kg / m ³ 3.1 5.7 6.5 7.1 7.7 8.1 8.5 232kg / m ³ 3.7 6.5 7.3 7.8 8.4 8.9 9.4  PVA Fiber 0kg / m ³ 1.1 1.8 2.5 2.9 3.3 3.6 3.4 12.6kg / m ³ 2.2 5.0 5.6 6.2 6.7 7.4 7.8 25.2kg / m ³ 2.8 5.5 6.4 6.9 7.5 7.9 8.4 37.7kg / m ³ 3.5 6.4 7.2 7.9 8.5 9.0 9.6 Compound Water / Binder 0.15 3.9 6.4 7.6 8.5 9.3 9.9 10.3 0.18 3.5 5.9 7.1 7.9 8.5 9.0 9.4 0.20 3.1 5.7 6.5 7.1 7.7 8.1 8.5 0.25 2.7 5.3 5.9 6.6 7.3 7.9 8.2

Table 2 summarizes the compressive strength test results of the crude steel fiber reinforced cement composites, and Table 3 summarizes the flexural tensile strength test results. The compressive strength was carried out by KS F 2405 using a 100 × 200 mm column test specimen, and the flexural tensile strength was performed by a four-point loading method using a 100 × 100 × 400 mm square test specimen. Ultra-low strength cement, which has a weaker initial strength, exhibits higher strength than the low-strength cement, and when the super-strength cement is used, the compressive strength per day is about 32 MPa, and the rough cement is about 22 MPa, which is 91 days. The strength is high, almost 50 MPa, regardless of the type of cement. In addition, the flexural tensile strength of 1 day was very high at 6.7 MPa and that of 5.7 MPa.

The strength of silica fume is the fastest at 54 kg. This means that the calcium hydrate (Ca (OH) ₂ ) and silica are pozzolanic to produce calcium silicate (CSH) hydrate at 55 kg or less. The initial strength was small due to the small amount of calcium hydroxide needed for the pozzolanic reaction, but the age was increased with increasing age.

The smaller the content of sand, that is, the greater the amount of cement, the higher the strength, but the difference was not confirmed that much.

Anhydrous gypsum (CaSO ₄ ) is effective in increasing the strength by reacting with C ₃ A, a cement component, to generate a large amount of ettringite from the early stage of re-entry. The strength was found to be particularly enhanced.

Triethanolamine further promotes the formation of ettringite produced by the reaction of the cement component C ₃ A with gypsum, and further promotes the hydration effect by promoting the transition of the resulting ettringite to monoosulfate. Exert. Also in the present invention, it was confirmed that the initial strength is increased especially as the amount of triethanolamine used increases.

Naphthalene-based water reducing agent is used to improve the fluidity of the cement composite, it has been confirmed that little impact on the initial compressive strength, bending strength, but ultimately little.

The fiber was used to solve the fracture caused by impact load and fatigue load due to lack of tensile strength of cement composite and crack by dry shrinkage.In this patent, the compressive strength is not only increased but also flexural tensile strength regardless of fiber type. As the strength is increased, it is confirmed that the problems occurring in the existing cement-based materials can be solved.

In addition, the compressive strength and the flexural tensile strength are different depending on the weight ratio of the condensation promoting agent mixture and the strength expression promoting binder, and this result can be selected according to the strength of the structure, the strength of the crude steel fiber reinforced cement composites, etc. To show that there is.

Furthermore, as can be seen from the above results, the content of the components used in the present invention is based on the content of 100 parts by weight of the steel cement, 10-20 parts by weight of silica fume, the particle size made in absolute dry state at 100 ± 5 ℃ is 5mm or less 100-120 parts by weight of sand and 5-20 parts by weight of anhydrous gypsum are preferred, and the condensation promoting compound is preferably 1-3% by weight of triethanolamine, 1-3% by weight of naphthalene-based water reducing agent, and 94-98% by weight of distilled water. It can be seen that it is preferable to add 1-3 vol% of steel fibers or organic fibers to the obtained cement composite and mix them.

Example 9 Physical Analysis

This embodiment is to analyze how the physical properties of the crude steel fiber reinforced cement composite produced by the method of the present invention is different from the physical properties of the existing concrete.

To analyze whether the properties of crude steel fiber reinforced cement composites are different from those of existing concrete, 36 kg of silica fume based on 360 kg of crude steel or cemented steel cement, 396 kg of sand less than 5mm made in absolute dry condition at 100 ± 5 ℃ A strength expression promoting binder was prepared by mixing the mixture consisting of 36 kg of gypsum for 11 minutes at a speed of 30 rpm and again for 4 minutes at a speed of 10 rpm.

A condensation accelerator blended water was prepared by mixing the mixture consisting of 2.8 kg of triethanolamine, 2.8 kg of naphthalene-based sensitizer, and 160 kg of distilled water at a speed of 700 rpm using a high speed dispersion mixer.

156kg / ㎥ of fiber steel fiber or 25.2kg / ㎥ of PVA fiber was added to the cement composite prepared by mixing for 6 minutes at a speed of 50rpm so that the weight ratio of the coagulant-producing blended water and the strength-expressing binder was 0.2. After mixing for 1 minute and 30 seconds to prepare a fiber-reinforced cement composite, the thermal expansion coefficient, the elastic modulus was measured and the results are summarized in FIGS. 1 and 2.

The modulus of elasticity of the repair material is very important because the stress is concentrated in the large elastic modulus when the member under load is repaired. The modulus of elasticity was measured in accordance with KS F 2438 by making a cylindrical specimen of 150 × 300mm, and it is important that the material itself with the smaller adhesion interface or strength is destroyed by temperature change when using materials with different thermal expansion coefficients. Accordingly, the thermal expansion coefficient of the test specimen was buried in a thermal couple using a column specimen of 100 × 200 mm, and measured at 7 days of age.

1 is a result of measuring the elastic modulus for each repair material. The elastic modulus of epoxy-based repair materials was 0.98 GPa, the elastic modulus of polymer repair materials was 1.63 GPa, and the elastic modulus of concrete was 2.75 GPa. As a result, it can be seen that defects are likely to occur.

On the other hand, the elastic modulus of the present invention is 2.65GPa ~ 2.87GPa, which is similar to that of general concrete.

2 is a thermal expansion coefficient measurement results for each repair material. The thermal expansion coefficient of epoxy-based repair materials is 28.5 × 10 ^-6 / ℃, the thermal expansion coefficient of polymer-based repair materials is 8.7 × 10 ^-6 / ℃, and the thermal expansion coefficient of concrete is 13.7 × 10 ^-6 / ℃. Is different from the coefficient of thermal expansion of ordinary concrete, so that failure may occur in ordinary concrete with low strength due to shrinkage expansion in structures subjected to adhesion interface failure or temperature history.

As a result, the coefficient of thermal expansion of the present invention was found to be about the same as that of general concrete at 12.5∼14.1 × 10 ⁻⁶ / ℃. For this reason, when used as a repair material in the existing concrete according to the present invention, the thermal expansion coefficient is almost the same, there is no possibility of defects.

Example 10 Strength, Dry Shrinkage and Durability Analysis

This embodiment is to analyze the strength, dry shrinkage and durability of the crude steel fiber reinforced cement composite.

Mixture consisting of 36kg of silica fume, 396kg of sand less than 5mm made in absolute dry at 100 ± 5 ℃ and 36kg of anhydrous gypsum based on 360kg of crude steel or supercemented cement for analysis of drying shrinkage and durability of crude steel fiber reinforced cement composite 11 minutes at a speed of 30rpm, and was further mixed for 4 minutes at a speed of 10rpm to prepare a strength-expressing promoting binder.

A condensation accelerator blended water was prepared by mixing the mixture consisting of 2.8 kg of triethanolamine, 2.8 kg of naphthalene-based sensitizer, and 160 kg of distilled water at a speed of 700 rpm using a high speed dispersion mixer.

156kg / ㎥ of fiber steel fiber or 25.2kg / ㎥ of PVA fiber was added to the cement composite prepared by mixing for 6 minutes at a speed of 50rpm so that the weight ratio of the coagulant-producing blended water and the strength-expressing binder was 0.2. After mixing for 1 minute and 30 seconds to prepare a fiber-reinforced cement composite, and then measured the strength, dry shrinkage and durability (salt resistance, neutralization, freeze thaw resistance, water tightness) and the results are summarized in Figure 3-4 and Table 4 below. .

3 is a result of the strength test. Regardless of cement type and fiber type, the daily compressive strength is more than 20MPa and the flexural strength is more than 5MPa. Therefore, it is judged that there is no problem even if enough structures are used after one day, and the strength increases as the age increases. The intensity expression also appeared to be no problem. In addition, the use of super-tensioned steel cement is much more accelerated than the use of steel-based cement, and the compressive strength is 17MPa at 0.5 days. Need to use

Repair materials have significant dimensional stability. In order to securely attach the existing member, a material that does not cause shrinkage is required. In the present invention, shrinkage is reduced as much as possible by the use of fibers and anhydrous gypsum. 3 is a dry shrinkage test result. In the case of cement composite without fiber, regardless of cement type, shrinkage occurred up to about 1,000 × 10 ⁻⁶ , but the final dry shrinkage of the present invention occurred at about 150˜350 × 10 ^−6. Deterioration in adhesion strength and cracking will not occur.

Table 4 summarizes the test results along with the durability measurement methods and conditions.

               Type Evaluation Item Moderate strength concrete High strength concrete Invention Remarks Crude steel Rasp Salt Resistance (Coulombs) 2,445 178 112 36 ASTM C 1202 Neutralization (Depth: mm, 91 days) 25 11 4 3 CO ₂ : 10% 60% RH 30 ℃ Freeze thawing (durability index) 83 92 100 100 ASTM C 666 Watertightness Speculative (× 10 ^-16 ㎡) 0.1335 0.0475 0.018 0.012 Torrent Permeability Tester Permeability (㎡ / secBar) 0.00362 0.00259 0.00077 0.00038 GWT

Table 4 shows the durability test results. The crude steel fiber reinforced cement composite of the present invention was shown to be much superior to high strength concrete and moderate strength concrete in terms of salt resistance, neutralization, freeze thawing and water tightness regardless of cement type.

This result is because the crude steel fiber reinforced cement composite is a cement composite having high strength, and the structure of the hardened cement body is very tight, making it difficult to penetrate the deterioration factor.

As described above, the crude steel fiber-reinforced cement composite obtained by the method of the present invention has excellent initial strength and exhibits a compressive strength of 20 MPa or more and flexural tensile strength of 5 MPa or more per day, thereby significantly reducing the construction period. It can be used in a day by pouring the structure, and also has similar properties to general concrete such as elastic modulus and thermal expansion coefficient, and it has small dry shrinkage, so it has excellent dimensional stability, salt resistance, neutralization resistance, freeze-thawing resistance, etc. The durability is shown to be very good, and when applied as a repair material, it has an excellent effect on significantly increasing the life of the structure.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art can be variously modified and changed without departing from the spirit and scope of the invention described in the claims below. Can be.

Claims (6)

Silica fume, 10-20 parts by weight, 100-120 parts by weight, and 5, respectively, based on 100 parts by weight of the crude cement to be mixed later with sand and anhydrous gypsum having a particle diameter of 5 mm or less at 100 ± 5 ° C. A first step of mixing in an amount of -20 parts by weight; Mixing the mixture with 100 parts by weight of the cement for producing a strength-expressing promoting binder; Simultaneously or sequentially A third step of mixing triethanolamine, a naphthalene-based water reducing agent, and distilled water in an amount of 1-3 wt%, 1-3 wt% and 94-98 wt%, respectively, to prepare a coagulation accelerator blended water; A fourth step of obtaining a cement composite by mixing so that the weight ratio of the condensation accelerator compounded water obtained in the third step and the strength expression promoting binder obtained in the second step satisfies 0.15-0.25; And And a fifth step of mixing 1-3% by volume of steel fibers or organic fibers with respect to 100% by volume of the cement composite, to the cement composite obtained in the fourth step. The method of claim 1, further wherein the mixed 10-12 minutes to a mixture of the mixture to produce the strength-promoting binder in step 2 to 20-40rpm next step of re-mixing between 3-5 minutes, and 10rpm; containing Method for producing a crude steel fiber reinforced cement composite, characterized in that. The crude steel reinforced cement according to claim 1, further comprising: mixing the condensation accelerator compounded water blended in the third step at a speed of 500-800 rpm for 3-5 minutes prior to the fourth step. Method for preparing a composite. The method of claim 1, further comprising mixing for 5-7 minutes at a rate of 40-50rpm prior to injecting the steel fiber or organic fiber to the cement composite prepared by mixing the condensation accelerator blending water and the strength expression promoting binder in the fifth step Method of producing a fiber-reinforced cement composite, characterized in that it comprises a ;. The method of claim 1, further comprising the step of adding a steel fiber or organic fiber to the cement composite in the fifth step and then mixing for 1-2 minutes at a speed of 20-30rpm; Manufacturing method. Crude steel fiber reinforced cement composite prepared according to the method according to any one of claims 1 to 5.

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