KR101815928B1 - Water-repellent Admixture for Reducing Shrinkage, Binder Composition for Repair Mortar with the Chemical Resistance Comprising the Admixture, Dry Mortar Composition Comprising the Binder and Concrete Repair Method Using the Mortar - Google Patents

Abstract

The present invention relates to a water-repellent shrinkage reduction admixture capable of improving water repellency and dry shrinkage reduction performance when being incorporated into cement mortar, a bonding composition for chemical resistant cross-section repair mortar preferably including the admixture, a dry mortar composition desirably including the bonding material, and a concrete cross-section repair construction method desirably using the dry mortar. The water-repellent shrinkage reduction admixture according to the present invention has a specific gravity of less than or equal to 2.20 and fineness of 5,500-9,000 cm^2/g by pulverizing and mixing the composition including a dispersing inorganic filler, an anti-aggregation agent, a water repellent agent, and a shrinkage reducing agent in a pulverizer. The bonding composition for chemical resistant cross-section repair mortar according to the present invention generally comprises: 30-80 wt% of Portland cement, 2-10 wt% of rapid hardening cement, 2-8 wt% of water-repellent shrinkage reduction admixture, 3-8 wt% of expansion agent, 2-10 wt% of anhydrous gypsum, 5-40 wt% of blast furnace slag fine powder, and 0.3-3 wt% of alkali sulfate.

Description

Technical Field [0001] The present invention relates to a water-repellent admixture for reducing shrinkage, a water-repellent admixture for reducing shrinkage, a chemical resistance mortar composition, a dry mortar composition, Comprising the Admixture, Dry Mortar Composition Comprising the Binder and Concrete Repair Method Using the Mortar}

More particularly, the present invention relates to a concrete repairing method for repairing and repairing damage caused by cracks and deterioration of a concrete structure, and more particularly, The present invention also relates to a dry mortar composition preferably containing the same, and a concrete section maintenance method using the dry mortar.

Various types of cracks occur in concrete structures due to the natural or anthropogenic action of materials, formulations, construction, structure and load, and environmental conditions. Cracks in these concrete structures cause deterioration in the performance of the concrete structures, which causes the concrete structures to fall short of the design use years. Also, even if artificial actions such as materials, formulations, construction, structure and load are excluded, the concrete deteriorates with time depending on the ambient conditions and the environment, and the performance is deteriorated. Therefore, concrete structures always need to maintain maintenance activities. In particular, when the problems of materials, construction, and structure are mixed with natural environmental factors, the demand for maintenance of concrete structures increases more.

In order to increase the service life of concrete structures, artificial defects should be minimized, but aggressive coping with degradation due to natural environment should be possible. Natural factors that cause deterioration of concrete structures are penetration of deteriorating factors such as temperature changes outside concrete, carbon dioxide, chlorine ion, sulfate ion, acid ion through the atmosphere and soil moisture. When deterioration occurs in concrete due to penetration of these deteriorating factors, a concrete section repair method is performed to remove the deteriorated portion and recover the removed concrete section.

For the concrete section repair method, section repair mortar is used. Sectional maintenance mortar is important for water repellency to prevent penetration of water, which helps natural deterioration factors penetrate into the concrete. As a method for imparting water repellency, it is common to incorporate a water repellent agent into the cross-section repair mortar.

However, since mortar generally uses more binder than concrete, it causes severe shrinkage and frequent cracking. If cracks are generated in the section repair mortar, the durability of the section repair mortar is lowered, and also the durability of the concrete to be restored is lowered. Moisture penetrates through the cracks. Moisture becomes a means for moving various harmful components, which causes freezing and thawing, resulting in a decrease in durability. Accordingly, it is also important to have a property that a single-sided repair mortar is not sufficient to have a simple water-repellent property and can form a dense cured body by suppressing cracks due to drying shrinkage.

Korean Patent No. 10-0913255 Korean Patent No. 10-1466823 Korean Patent No. 10-1616103

The present invention has been developed to provide a new cross-section maintenance mortar, and it is a technical problem to provide a chemical resistant cross-linked repair mortar composition for joint that exhibits excellent resistance to chloride ion penetration resistance as well as dry shrinkage resistance.

Another object of the present invention is to provide a water-based shrinkage reducing admixture which simultaneously exhibits water repellency and dry shrinkage and low sensitivity when mixed in a cement mortar.

Further, the present invention provides a dry mortar composition which can be easily applied on site, preferably including a chemical composition-resistant cross-linked mortar composition, and a concrete cross-section repair method using the dry mortar.

In order to solve the above-mentioned technical problem, the present invention relates to a process for preparing a composition comprising a dispersing inorganic filler, an anti-aggregation agent, a water repellent agent and a shrinkage reducing agent in a pulverizer to obtain a powder having a specific gravity of 2.20 or less and a powder viscosity of 5,500 to 9,000 cm2 / Wherein the shrinkage-reducing admixture is water-repellent.

The present invention also relates to a cement admixture comprising 30 to 80% by weight of ordinary Portland cement; 2 to 10% by weight of quick-setting cement; 2 to 8% by weight of a water shrinkage reducing admixture; 3 to 8% by weight of a swelling agent; 2 to 10% by weight of anhydrous gypsum; 5 to 40% by weight of fine blast furnace slag powder; And 0.3 to 3% by weight of an alkali sulfate, based on the total weight of the mortar composition.

Also, the present invention provides an epoxy resin composition of the present invention, which is obtained by mixing 50 to 200 parts by weight of an aggregate with 100 parts by weight of a binder composition for a chemical resistance cross-section repair mortar.

Further, in the present invention, 20 to 50 parts by weight of water is further blended with 100 parts by weight of the binder composition in the chemical-resistant single-side repair mortar composition to make wet mortar, and then the deteriorated portion is removed from the concrete structure and wet mortar The present invention provides a method for repairing a concrete section.

According to the present invention, the following effects can be expected.

Firstly, it is possible to provide a new concrete section repair mortar that exhibits excellent chemical resistance by effectively suppressing cracks due to drying shrinkage and forming a dense cured body, and also provides a water repellent shrinkage reduction admixture which can be advantageously used in such mortar can do.

Second, the cross-section repair mortar according to the present invention exhibits favorable performance in terms of compressive strength and freeze-thaw resistance as well as dry shrinkage resistance and chloride ion penetration resistance. Therefore, when the concrete section repair method is performed by using the section repair mortar according to the present invention, the durability of the repair part can be improved.

Third, since the section repair mortar according to the present invention exerts excellent chemical resistance, it can be advantageously used for repairing and reinforcing concrete structures requiring chemical resistance, such as road constructions frequently used in marine concrete and snow remover, and sewer pipes.

The present invention proposes a water-repellent shrinkage-reducing admixture, a binder composition and a dry mortar composition for a chemical resistant cross-section repair mortar, and a concrete cross-section repair method using the dry mortar.

The water-repellent shrinkage-reducing admixture according to the present invention is characterized in that a composition comprising an inorganic filler for dispersion, an aggregation inhibitor, a water repellent, and a shrinkage reducing agent is pulverized and mixed in a pulverizer. Preferably, the mixture is pulverized to have a specific gravity of 2.20 or less and a powder content of 5,500 to 9,000 cm 2 / g in consideration of usability and functionality.

Conventional shrinkage reducing agents are in the form of flakes having deliquescent properties and are difficult to be independently pulverized, and even if pulverized, they are agglomerated within a few hours, making them difficult to use in dry mortar products. In the present invention, the shrinkage reducing agent is pulverized and mixed with an inorganic filler for dispersion, an anti-aggregation agent and a water-repellent agent to prevent the agglomeration phenomenon due to the deliquescence of the shrinkage reducing agent and to be smoothly dispersed in the dry mortar product. Here, pulverization and mixing may be carried out in a disk type mill for about 30 minutes. Ball mills, vibration mills and the like are susceptible to agglomerating of the deliquescent material by the continuous friction grinding action. The disc mill is instantaneous (relatively much less persistent) and is continuously pulverized to facilitate the pulverization of the deliquescent material. In the pulverized mixed water-repellent shrinkage reducing admixture, the dispersion inorganic filler, the cohesion preventing agent, the water repellent agent and the shrinkage reducing agent are dispersed and mixed well.

In the present invention, the water-repellent shrinkage reducing admixture is constituted to contain 45 to 85% by weight of inorganic filler for dispersion, 1 to 10% by weight of an aggregation inhibitor, 2 to 20% by weight of a water repellent and 5 to 30% . Such a composition range is a result of considering performance performance together with grinding efficiency. In particular, when the shrinkage reducing agent is excessive, it is preferable that the shrinkage reducing agent is 5 to 30 wt. In the water-shrinkage-reducing admixture, the inorganic filler for dispersion uses fly ash, which can be expected to have a strength-enhancing effect by the pozzolanic reaction, magnesium hydroxide as the coagulation inhibitor, and stearic acid and wax, , And the shrinkage reducing agent is preferably glycol-based.

The above water-shrinkage-reducing admixture may be prepared in advance as a pre-mix binder with cement or the like, or may be further mixed with aggregate to prepare a premixed dry mortar. Since the water-shrinkage reducing admixture is uniformly dispersed in the binder or the dry mortar, when the binder or the dry mortar is stirred with water, the hardened body exhibits excellent water repellency and shrinkage reduction as well as strength improvement performance.

 A premix binder which preferably uses a water-repellent shrinkage reducing admixture is usually 30 to 80% by weight of Portland cement; 2 to 10% by weight of quick-setting cement; 2 to 8% by weight of a water shrinkage reducing admixture; 3 to 8% by weight of a swelling agent; 2 to 10% by weight of anhydrous gypsum; 5 to 40% by weight of fine blast furnace slag powder; And 0.3 to 3% by weight of an alkali sulfate. These composition materials and composition ranges are the result of simultaneously considering the performance and economical efficiency of the chemical resistance cross-section repair mortar application. In this case, the quick curing cement accelerates the curing rate and contributes to the shrinkage compensation due to the formation of etyne zeite and the densification of the cured body structure. The swelling agent contributes to the shrinkage compensation, while the anhydrite gypsum has the shrinkage- Contributes to densification. Blast furnace slag powder contributes to economic and environmental friendliness while contributing to long-term strength improvement. Alkali sulfite stimulates and activates blast furnace slag powder, contributing to densification of hardened structure and improvement of chloride ion penetration resistance.

The CSA-based ultrafast cement containing a specific gravity of 2.7 to 3.0, a powder of 3400 to 6000 cm < 2 > / g and Al2O3 of 36 weight% or more is preferable in the chemical composition resistant single-walled mortar composition. The swelling agent has a specific gravity of 2.8 to 3.1, It is preferable that the CaO-based swelling agent is 2500 to 4000 cm 2 / g, and the anhydrous gypsum has a specific gravity of 2.8 to 3.0 and a powder size of 3500 to 5000 cm 2 / g. It is appropriate that the blast furnace slag fine powder has a specific gravity of 2.9 and the powder has a powder density of 4000 cm2 / g or more, and at least one of K2SO4 and Na2SO4 is selected as the alkali sulfate.

The binder composition for chemical resistance cross-section repair mortar can be prepared by premixed dry mortar. It is suitable to blend 50 to 200 parts by weight of fine aggregate (silica) in 100 parts by weight of binder and 0.1 to 2 parts by weight of re- It is also possible to further blend 0.1 to 2 parts by weight of the fluidizing agent. Here, the re-oil type powder resin contributes to the improvement of adhesion, water resistance and elasticity, and the fluidizing agent contributes to improvement of fluidity. Further, various functional additives such as a dispersant, a thickener, and a retarder can be further mixed into the dry mortar composition.

Premixed chemical resistant single-walled mortar composition and cross-sectionally dried mortar composition are in the form of a dry powder, which can be packaged and commercialized. Particularly when water is added to the surface-repair mortar composition, wet mortar is formed. In this case, 20 to 50 parts by weight of water is suitable for 100 parts by weight of the binder composition when considering the workability. Such a wet mortar exhibits excellent performance in terms of strength, length change, freeze-thaw resistance, chloride ion penetration resistance, and therefore can be advantageously applied to a section repair method of a concrete structure requiring chemical resistance.

The concrete section repair method is carried out by removing the deteriorated part from the concrete structure and filling the removed part with wet mortar. Prior to filling the wet mortar, it is preferable to apply the concrete performance remover and the primer to improve the performance of the concrete matrix and to improve the adhesion of the absorption control type mortar. The concrete performance remediation agent is suitable for the alkali recovery agent of concrete, and the acrylic primer and the EVA primer are suitable as the primers. In addition, it is preferable for the concrete section protection to be repaired to apply the protective coating after filling the wet mortar, and the protective coating is applied as usual.

Hereinafter, the present invention will be described in detail with reference to Production Examples and Test Examples. However, the following Production Examples and Test Examples are provided only for illustrating the present invention, and the scope of the present invention is not limited thereto.

[Production Example] Water-repellent shrinkage reduction admixture

The materials shown in Table 1 below were prepared, and these materials were pulverized and mixed in a disk mill for 30 minutes to prepare a water-shrinkage reduction admixture. The water repellent shrinkage reducing admixture thus produced had a specific gravity of 2.11 and a powder density of 7800 cm 2 / g.

Water-shrinkage reduction Admixture composition (% by weight) material Furtherance characteristic Dispersing inorganic filler Fly ash 68 Specific gravity 2.21, powder degree 3600 Anti-aggregation agent Magnesium hydroxide 4 Weight 2.4 Water repellent agent Stearic acid 12 White solid, with formula C ₁₇ H ₃₅ COOH, specific gravity 0.87,
Melting point (℃) 69 ~ 72 Shrinkage abatement agent Neopental glycol 16 C ₅ H ₁₂ O ₂ , specific gravity 1.06, purity 99.2 or higher
Solubility 520g / H2O100g (20 ℃), water content 0.3% or less

[Test example] Chemical resistance Cross-sectional repair mortar characteristics

1. Mortar formulation

Using the water-shrinkage reduction admixture according to the above [Manufacturing Example], dry mortar was mixed with the composition shown in Table 2 below, and water was mixed with dry mortar to make wet mortar. Comparative Example 1 and Example 1 were mixed at a water-binding ratio (W / C) of 42 wt%, and Comparative Example 2 and Example 2 were combined at a water-binding ratio of 40 wt%.

Dry mortar composition (parts by weight) division Comparative Example 1 Example 1 Comparative Example 2 Example 2 Binders Usually Portland Cement 80 74.4 45 50 CSA based fast curing cement - - 12 12 CaO-based expander - - 5 5 Anhydrous plaster - - 8 8 Shrinkage reducing agent - 7 - 6.4 Fine powder of blast furnace slag 20 18.6 30 28 Alkali sulfate
(Na2SO4, specific gravity 2.69) - - - 0.6 sub Total 100 100 100 100 Resuspended Powder Resin Acrylic 0.2 0.2 0.2 0.2 aggregate Standard yarn 135 135 145 145 Fluidizing agent Naphthalene series 0.7 0.7 One One

2. Mortar characteristics test method

Fluidity, compressive strength, length change, chloride ion penetration test, and freeze - thaw test were applied to the wet mortar mixed above.

The flow test was carried out in accordance with the flow test of KS L 5105 and the circle diameter was expressed in mm. The compressive strength test was carried out according to KS F 2405 at 3 days, 7 days and 28 days. The specimens were prepared in accordance with KS F 2403.

 In the water repellency test, a 40 × 40 × 60 mm specimen was prepared, and after curing in water for 14 days at a certain age, a specimen was set up in a water tank of 30 mm in height. The height of the absorbed water was measured based on the upper part of the water tank height of 30 mm. For the accuracy of the measurement, the dark blue ink was dissolved in the water tank to check the height of the water.

For the length change test, the buried strain gauge was buried before the 40 × 40 × 160mm specimen was manufactured, and the length change was measured using a data logger immediately after the test piece was formed. The measurement conditions were 20 ± 2 ℃ and relative humidity of 60 ± 5%.

Chloride ion penetration tests were carried out in accordance with KS F 2711 "Concrete Chloride Ion Penetration Resistance Test Method by Electrical Conductivity". The specimen was prepared by curing a 100 × 200 mm specimen for 28 days and cutting it to 100 × 50 ± 3 mm. The side was then thinned and cured with silicone, held in a vacuum for 3 hours, then immersed in distilled water for 18 hours to saturate completely. The negative electrode of the Applied Voltage Cell was filled with 3.0% NaCl solution and the positive electrode was filled with 0.3N NaOH solution. The test cell was fixed to the test cell and the circuit was constructed. The total amount of charge passing through the circuit is measured by measuring with a data logger the voltage at 0.2 Ω for 6 hours every 30 minutes after the start of the test and converting the measured voltage into the current and calculating the current and charge by using the following equation Respectively.

(여기서, Q: 총통과전하량, I₀: 전압을 가한 시험시작 직후의 전류, I_t: 전압을 가한 후 t분 경과 후의 전류이다.)

(Where Q is the total current and charge, I ₀ is the current immediately after the start of the test with the voltage applied, and I _t is the current after t minutes after applying the voltage).

The freezing and thawing test was carried out in accordance with the water-melting test method after rapid freezing in air of KS F 2456. The temperature range of the freezing and thawing test was determined by measuring the primary resonance frequency and specimen mass up to 300 cycles every 36 cycles with the specimen center temperature of -18 ~ 4 ℃ and the cycle time of 3 hours and 30 minutes. Respectively.

(여기서, P_c : 동결융해 C사이클 후의 상대동탄성계수(%), n₀ : 초기의 1차 공명 진동수(Hz), n_c : 동결융해 C사이클 후의 1차 공명 진동수(Hz) 이다.)

(Wherein, P _c: sangdaedong modulus after freezing and thawing cycles C (%), n _0: the primary resonance frequency (Hz) after freezing and thawing cycles C: beginning of the first resonance frequency (Hz), n _c.)

3. Test results of mortar characteristics

The properties of the mortar were tested according to the test method described above, and the results are shown in Table 3 below.

Mortar characteristic test result division Comparative Example 1 Example 1 Comparative Example 2 Example 2 Flow (mm) 215 215 205 200 Compressive strength
(MPa) 3 days 24.2 22.9 33.2 32.8 7 days 44.7 41.8 42.7 41.8 28th 57.1 54.5 55.8 54.3 Water repellency
(Water absorption height, mm) 71 20 - - Length change (10 ^-6 ) -2010 -1370 -1087 -457 Chloride ion penetration test
(Coulombs)) - - 1970 796 Freeze-thaw resistance
(300 cycles, relative modulus of elasticity (%)) - - 91 92

Comparative Example 1 is an example in which a Portland cement and a blast furnace slag are combined with each other. In Example 1, the water-shrinkage reduction admixture is further mixed with cement and blast furnace slag in Comparative Example 1, Water repellent shrinkage reduction It is confirmed that mixing of admixture slightly reduces the compressive strength but greatly improves water repellency and length change. Comparative Example 2 is an example in which a binder is composed of ordinary portland cement, CSA-based ultrafast cement, an expanding agent, anhydrous gypsum and blast furnace slag. In Example 2, cement and blast furnace slag are replaced in Comparative Example 2, And the addition of the water-type shrinkage reducing admixture and the alkali sulfate showed a tendency that the change in length and resistance to chloride ion penetration were remarkably improved and the freeze-thaw resistance was also somewhat improved. Accordingly, the water-repellent shrinkage-reducing admixture according to the present invention exhibits excellent water repellency and shrinkage resistance, and when used with a specific binder, resistance to chloride ion penetration and freeze-thaw resistance can also be improved. Thus, it is expected that the mortar mixed with the water-shrinkage reducing admixture appropriately can be advantageously applied to the maintenance of the section of the concrete structure requiring chemical resistance.

Claims (8)

delete 45 to 85% by weight of an inorganic filler for dispersion; 1 to 10% by weight of an anti-aggregation agent; 2 to 20% by weight of a water repellent agent; And 5 to 30% by weight of a shrinkage reducing agent, wherein the composition has a specific gravity of less than 2.20 and a powder viscosity of 5,500 to 9,000 cm 2 / g. 3. The method of claim 2,
Wherein the inorganic filler for dispersion is fly ash,
The anti-aggregation agent is magnesium hydroxide,
Wherein the water repellent agent is at least one of stearic acid and wax and a melt,
Wherein the shrinkage reducing agent is a glycol-based shrinkage reducing admixture. 3. A binder composition comprising a water-repellent shrinkage reducing admixture according to claim 2 or 3,
Usually 30 to 80% by weight of Portland cement; 2 to 10% by weight of quick-setting cement; 2 to 8% by weight of a water shrinkage reducing admixture; 3 to 8% by weight of a swelling agent; 2 to 10% by weight of anhydrous gypsum; 5 to 40% by weight of fine blast furnace slag powder; And 0.3 to 3% by weight of an alkali sulfate, based on the total weight of the composition. A process for producing a corrosion resistant mortar composition, comprising the steps of:
And 50 to 200 parts by weight of an aggregate are mixed. The method of claim 5,
0.1 to 2 parts by weight of a fluidizing agent, and 0.1 to 2 parts by weight of a re-oiling type powder resin. According to the present invention, there is provided a concrete maintenance method using a repair mortar composition,
The mortar composition of the present invention is characterized in that 20 to 50 parts by weight of water is further blended with 100 parts by weight of the binder composition of the dried mortar composition to make wet mortar and then the deteriorated portion is removed from the concrete structure and the removed portion is filled with wet mortar Method. In claim 7,
Wherein a concrete performance restorer and a primer are applied before filling the wet mortar, or a protective coating agent is applied after the wet mortar is filled.