KR101860528B1 - Light-weighted mortar compositions for repairing and repairing method of concrete structure therewith - Google Patents

Abstract

The present invention relates to lightweight mortar and a concrete repair method using the same. The object of the present invention is to provide lightweight mortar having rapid hardening, salt-resistance, and durability by mixing high-belite cement with attapulgite without addition of a methylcellulose thickener and a concrete repair method using the same. The lightweight mortar comprises: 30-40 wt% of high-belite cement; 1-5 wt% of attapulgite; 20-40 wt% of silica sand having a particle size of 2-1 mm; 10-30 wt% of silica sand having a particle size of 1-0.5 mm; 1-5 wt% of re-emulsification type powder resin; 0.1-1.0 wt% of defoamer; 1-5 wt% of siloxane-based rust inhibitor; and 0.1-1.0 wt% of polypropylene fiber. The high-belite cement (high belite sulphur aluminate cement, HB-SCA) is obtained by mixing and crushing bauxite, limestone, fly ash, and blast furnace slag in clinker fired at the temperature of 1,500-1,600 deg. C with phosphoric acid refinement type III beta-anhydrous gypsum. The lightweight mortar is used to repair concrete.

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a lightweight mortar and a concrete repair method using the same,

The present invention relates to a lightweight mortar and a concrete repairing method using the same, and is characterized by using Attapulgite and high-strength cement (HB-SCA) to maintain moisture retention and facilitate water movement, Lightweight mortar capable of realizing a large, fast and lightweight concrete, and a concrete repairing method using the same.

Concrete structures are deteriorated by chemical erosion, abrasion, and other deterioration due to various harmful environment and external factors. Therefore, when the performance of the concrete applied by the concrete deteriorates, it is possible to repair the bridge, the sewage box and the neutralized tunnel and the tunnel recovered after the fire, the repair of the underground road, repair of the concrete bridge pier of the railway bridge, Repair of concrete structures such as underground parking lots, water treatment plants, and sewage treatment plants is required.

Generally, lightweight mortar mixed with cement and aggregate can be used for repairing such concrete structures.

The lightweight mortar used conventionally includes: 1) polymer cement mortar + high tenacity polypropylene fiber + acrylic neutralization coating agent, 2) polymer cement mortar + high elasticity nylon fiber + urethane neutralization coating agent, 3) polymer cement mortar + high strength polyethylene fiber + Epoxy-based neutralization coating agent, 4) high-tenacity polymer repair mortar + neutralization coating agent,

All of these conventional lightweight mortar have improved adhesion and water resistance compared to general cement mortar by mixing EVA type resin, re-oil type powder resin, acrylic polymer, etc. with cement mortar and improve the tensile strength which is the weakest point in cement mortar To about 20%.

However, due to the improvement of the tensile strength, the reinforcing effect is also limited. All of the conventional mortar for sectional restoration has a dry specific gravity of about 1.9 to 2.1, which increases the self weight of the structure and inhibits the reinforcing function. There are various problems such as vibration resistance, fire resistance, heat insulation and dew condensation preventing performance.

Patent Registration No. 10-0886515 (Feb. 24, 2009) Patent Registration No. 10-1135018 (April 04, 2012) Patent Registration No. 10-1126189 (Mar. 23, 2012) Patent Registration No. 10-1609700 (Mar. 31, 201)

It is an object of the present invention to provide a lightweight mortar having quick-setting, salt-resistance and durability by mixing low-bite cement and attapulgite without addition of a methylcellulose thickener and a concrete repairing method using the same.

The present invention relates to a cement paste composition comprising 30 to 40 wt% of low-celite cement, 1 to 5 wt% of ataflite, 20 to 40 wt% of silica sand having a particle size of 2 to 1 mm, 10 to 30 wt% of silica sand having a particle size of 1 to 0.5 mm, The high-birefit cement (HB-SCA) is a high-brittle cement (HB-SCA), and the low-cure cement (HB-SCA) The concrete is to be repaired by lightweight mortar which is a mixture of crushed limestone, fly ash and blast furnace slag at 1,500 ~ 1,600 ℃ and phosphoric acid type Ⅲ type β anhydrite.

In the present invention, a high-brittle sulphur aluminate cement (HB-SCA) is added to form a mortar having a small shrinkage and a greater adhesive strength and crack resistance than general cement.

Since the fast curing is performed by using High Belite Sulfur Aluminate Cement (HB-SCA), the present invention has a great effect of crack resistance due to moisture release.

The present invention is characterized in that Attapulgite is added together with High Belite Sulfur Aluminate Cement (HB-SCA), and moisture resistance can be easily maintained while maintaining moisture retention, There is an effect to be improved.

By the addition of ataplite, the flowability of the mortar can be adjusted by a large amount of water without the use of the thickener, thereby realizing weight reduction.

The present invention provides a rustproofing and waterproofing effect even with the application of a quick-setting lightweight polymer mortar so that maintenance work can be performed without application of a rust inhibitor and an alkali remover, and the curing period is short, have.

1 is a block diagram showing a repair method according to the present invention;
2 is a graph showing an understanding of moisture transfer phenomenon according to the present invention

The lightweight mortar according to the present invention is characterized by comprising 30 to 40 wt% of high-bellite cement, 1 to 5 wt% of ataflite, 20 to 40 wt% of silica sand having a particle size of 2 to 1 mm, 10 to 30 wt% of silica sand having a particle size of 1 to 0.5 mm, 1 to 5 wt% of a powdered powder resin, 0.1 to 1.0 wt% of an antifoaming agent, 1 to 5 wt% of a siloxane-based antirust agent, and 0.1 to 1.0 wt% of a polypropylene fiber.

The above-mentioned High Belite Sulfur Aluminate Cement (HB-SCA) is prepared by adding boric acid, limestone, fly ash and blast furnace slag to 100 parts by weight of a cleaner baked at 1,500 to 1,600 ° C, 2 to 4 parts by weight of a powder mixture of 500 (m 2 / kg) is used, and the cleaner is composed of 15 to 25 wt% of boric acid, 40 to 60 wt% of limestone, 10 to 20 wt% of fly ash, To 15 wt%.

The phosphate type III-type? -Hydrous gypsum has a weak acidity of pH 5 to 6, so that when mixed with the above-mentioned cleaner, the workability of the low-brittle cement can be secured easily and the characteristic of increasing the strength development speed can be obtained. That is, when the natural anhydrous gypsum is mixed with the above-mentioned cleaner, the working time is only about 15 minutes, so that the workability is difficult to obtain and the speed of the strength development is delayed. However, when the phosphate- It is easy to secure workability and the strength development speed becomes high.

The bauxite has good heat conductivity and excellent compressive strength, and when used together with fly ash, it strengthens the weakening of strength.

The fly ash has a disadvantage in that the compressive strength of the mortar is weakened when the content of the fly ash is increased. Therefore, in consideration of the strength reinforcing effect due to mixing with the bauxite, the weight ratio of the bauxite: fly ash is 1: 0.7 to 1.0 It is preferable to mix them.

The blast furnace slag is intended for improving latent hydraulic characteristics, long-term strength development and durability. When the blast furnace slag is used in an amount exceeding 15 wt%, the early strength development is deteriorated. When the blast furnace slag is less than 5 wt%, the long-

In addition, the blast furnace slag satisfies the requirements of the blast furnace slag powder KS F 2562 for concrete.

Also, when the blast furnace slag is used at less than 5000 cm 2 / g of powder, the curing rate may be lowered and the strength may be lowered. Therefore, powder for the activation reaction is preferably 5000 cm 2 / g or more.

The above-mentioned Hybellite cement (HB-SCA) has characteristics of improved salt resistance, antistatic property and durability when compared with the conventionally used ultra fast cement or one kind of portland cement.

The attapulgite facilitates the flow of water, so that the flowability of the mortar can be adjusted by a large amount of water without using a thickener. The attapulgite forms a barrier film on the surface of water while holding a large amount of moisture , Moisture can be easily transported while maintaining the moisture retentivity, and crack resistance due to moisture release can be enhanced.

That is, the Hybellite cement (HB-SCA) according to the present invention has a characteristic that the workability can be ensured even with a small amount of water because the powdery degree is higher than that of general cement, However, when such a small amount of water is used, the light weight of the present invention can not be achieved. Therefore, in order to ensure workability such as spraying and plastering while having light weight, A thickener should be added.

However, the methylcellulose thickener, which is widely used as a thickener for adjusting the flowability of cement, can meet the flowability of a mortar using a large amount of water, but has a problem of poor workability due to tackiness, , The methylcellulose thickener has a gel-state shielding film formed on the surface of water as shown in FIG. 2 (a), thereby interfering with the flowability of water, So that a shrinkage stress is generated on the surface, which causes a crack phenomenon.

On the contrary, as shown in FIG. 2 (b), the ataflite according to the present invention does not form a moisture transfer blocking film, and moisture can be easily transferred. As a result, the surface of the hardened mortar There is no difference in the drying speed, and the cracking phenomenon is remarkably reduced.

In addition, the ataflite has no volume deformation even when absorbed, so that a stable cured product can be produced. That is, a bentonite-based inorganic thickener similar to ataplite has a property of expanding its volume during absorption and slowly returning to its original shape when water is released. As a result, it is mixed with Hybellite cement (HB-SCA) It can not be used for the purpose of easy use of moisture transfer, and an atomosphere must be used.

As described above, the present invention secures lightweight by mixing a large amount of water with Hybellite cement (HB-SCA), and ensures workability without addition of ataflite to add a thickener.

When the amount of attapulgite added is less than 1 wt%, the effect thereof is insignificant. When the amount of the attapulgite added is more than 5 wt%, the initial strength and the time of crispening are delayed, Is added in the range of 1 to 3 wt%.

The attapulgite is apparently similar to bentonite, but has more silicate component than bentonite, less alumina component, and has a function of absorbing and removing various heavy metals in mortar with porosity .

The silica sand serves as aggregate, and silica sand having a particle diameter of 2 to 1 mm and silica sand having a particle diameter of 1 to 0.5 mm are mixed and used. This is because the pores are reduced by the silica sand having a small particle size, thereby preventing infiltration of infiltration water and improving the strength of the mortar by the silica sand having a large particle size.

The silica sand is mixed with 20 to 40 wt% of silica sand having a particle diameter of 2 to 1 mm and 10 to 30 wt% of silica sand having a particle diameter of 1 to 0.5 mm. When the silica sand is mixed below the minimum range, The total strength of the mortar is lowered. When the mortar is mixed in excess of the maximum range, the strength is not lowered or the strength is not largely changed, but the workability is drastically deteriorated by affecting the mixing amount of other materials. Lt; / RTI >

The re-oiling type powder resin forms an integrated film in the mortar to provide adhesion with the concrete structure, prevents penetration of water and harmful substances by filling the gap, improves wear resistance, and prevents viscosity separation .

In addition, the re-oil type powder resin can obtain the effect of bonding hydrated cement with unreacted cement. After curing, high strength is exhibited early, the cross section of the member can be made small due to high strength, and adhesion, abrasion resistance, It has an effect of increasing fatigue resistance, chemical resistance and impact resistance, bending strength, adhesion strength and chemical resistance.

The re-melting type powder resin is not particularly limited in its kind but may be selected from the group consisting of ethylenevinyl acetate, styrene butadiene rubber, ethylene vinyl chloride, vinyl laurethate, vinyl acetate acetate, SBR powder resin, Acrylic esters, and polyacrylic esters, which are known in the art.

When the amount of the re-oiling type powder resin is more than 5 wt%, the hydration is hindered by the coating of the particles and the compressive strength may be lowered. When the amount is less than 1 wt%, the effect is insignificant. do.

That is, the re-oil type powder resin forms a film when the mortar is cured by hydration reaction, and acts as a bond to add the characteristics such as tensile strength and adhesiveness of the polymer to the mortar. High Belite Sulfur Aluminate Cement (HB-SCA) has a high water-solubility and high water-solubility when it has a high degree of hydration. Therefore, the addition of 1 ~ 5wt% re-oiled powder resin improves adhesion with concrete matrix.

The siloxane-based rust inhibitor is used for imparting rust-proofing property and water-proofing property to a mortar cured product, a reinforced concrete mortar and a mortar hardened product, and a powdery form encapsulated with polyvinyl alcohol and silane is used. Such siloxane-based rust inhibitors will dissolve the capsules when water is in contact with them, so that the polyvinyl alcohol and silane are uniformly distributed throughout the concrete, thereby enhancing the excellent antirust effect. The siloxane-based rust inhibitor may be a siloxane-based rust inhibitor sold in the market, and thus a detailed description thereof will be omitted.

The polypropylene fiber is added in order to compensate for shrinkage cracking and softening diffusion suppression, impact breakage and abrasion suppression, increase in resistance to fatigue load, flexural strength and tensile force of the mortar cured product, and the kind thereof is not particularly limited, Can be added. At this time, the polypropylene fiber has a standard length of about 5 to 8 mm, preferably a standard length of about 6 mm.

The lightweight mortar according to the present invention as described above has excellent durability while having anticorrosive property, waterproof property and quick hardness, and the curing period is as short as one day, so that the construction period can be shortened.

FIG. 1 is a block diagram illustrating a concrete repairing method according to the present invention.

A pretreatment step of chipping a concrete structure requiring maintenance;

A mortar applying step of applying lightweight mortar to the pretreated concrete structure;

Curing stage curing lightweight mortar;

And a surface treatment step of applying the neutralization coating material to the surface to which the lightweight mortar is applied,

The lightweight mortar is composed of 30 to 40 wt% of high-bellite cement, 1 to 5 wt% of ataflite, 20 to 40 wt% of silica sand having a particle diameter of 2 to 1 mm, 10 to 30 wt% of silica sand having a particle diameter of 1 to 0.5 mm, , 0.1 to 1.0 wt% of an antifoaming agent, 1 to 5 wt% of a siloxane-based antirust agent, and 0.1 to 1.0 wt% of a polypropylene fiber,

The above-mentioned High Belite Sulfur Aluminate Cement (HB-SCA) is prepared by adding boric acid, limestone, fly ash and blast furnace slag to 100 parts by weight of a cleaner baked at 1,500 to 1,600 ° C, 2 to 4 parts by weight of a powder mixture of 500 (m 2 / kg) is used, and the cleaner is composed of 15 to 25 wt% of boric acid, 40 to 60 wt% of limestone, 10 to 20 wt% of fly ash, To 15 wt%.

As described above, since the application of the rust inhibitor, the alkali remover and the primer can be omitted, the construction period can be remarkably shortened as compared with the conventional concrete repair method.

That is, in the conventional concrete repair method, concrete chipping, application of rust inhibitor, application of alkali remover, application of primer, application of polymer mortar, curing for 3 to 7 days, application of surface finish mortar, curing for 3 to 7 days, application of neutralization coating agent,

The concrete repairing method using the lightweight mortar composition according to the present invention can be applied to concrete chipping → light weight mortar composition according to the present invention, considering that the concrete is chipped, applied with antirust agent, applied with alkali remover, applied with primer, applied with polymer mortar, cured with 3 to 7 days, Mortar application, curing, and neutral fire application, the construction period is shortened by about two times as compared with the general construction method, and the construction process is simple, and the completion degree of the construction quality can be improved.

Hereinafter, the present invention will be described in detail with reference to the following examples.

Example 1

To 100 parts by weight of a clinker calcined at 20 to 60 wt% borax, 50 wt% of limestone, 20 wt% of fly ash and 10 wt% of blast furnace slag at 1,500 to 1,600 캜, 4 parts by weight of phosphoric acid- The specific surface area, coagulation time and physical properties of Hybellite cement thus prepared were compared with those of one kind of Portland cement (OPC) I was prepared. The results are shown in [Table 1] and [Table 2] below. At this time, the test method was carried out according to the standard of KS L 5201.

[Table 1]

[Table 2]

As shown in [Table 1] and [Table 2] above, Hybellite cement (HB-SCA) has a faster hardness, a larger specific surface area and a lightweight property compared with the one kind Portland cement (OPC) .

In addition, it can be seen that the low-impact cement (HB-SCA) according to the present invention has excellent compressive strength, bending strength and adhesion strength as compared with the one-component Portland cement (OPC).

Example 2

The mortar was prepared according to the mixing ratio according to Table 3, and the strength thereof was measured. At this time, the ratio of mortar to compounded water was fixed test with a flowability of 180 mm, and the results are shown in Table 4 below.

[Table 3]

[Table 4]

In Table 4, it can be seen that T1, T2, and T3 according to the present invention all exhibit excellent physical properties satisfying the criteria of KS F 4042. Especially, in T1 and T2, it shows that the dry specific gravity is 1.5 to 1.6 / the water absorption ratio is less than 2% / the compression strength is 35.0 Mpa or more / the adhesion strength is 2.0 MPa or more and the bending strength is 8.0 MPa or more.

Example 3

According to [Table 5], according to the mixing ratio, combination of HB-SCA and one kind of Portland cement, and maintenance mortar for repairing concrete using ordinary glutinous cellulose with Attapulgite were mixed and tested. Table 6]. At this time, in order to take similar conditions to the site of the curing condition, it was left in a place where the outdoor side was opened, so that only direct sunlight could be avoided.

In order to check the occurrence of cracks under external conditions, it was installed in outdoors by inserting 5mm thick wooden boards of 5m in thickness and 3m in width and 3m in width. The occurrence of cracks was judged visually by visual observation, and the results are shown in Table 7.

[Table 5]

[Table 6]

[Table 7]

(TE2), the test piece (TE3) and the test piece (TE4), when compared with the test piece (TE1) according to the present invention, as shown in the above [Table 6] and [Table 7] And the crack occurrence rate due to specific gravity and vibration is directly proportional.

Further, in the case of the test piece (TE3) to which the methylcellulose thickener was added, it was found that although it had comparatively excellent physical properties in terms of coagulation and strength, it was cracked due to vibration and wind. This shows that when a methylcellulose thickener is added, a gel-state shielding film is formed on the surface of water, so that water migration is not easy, thereby increasing the rate of cracking due to wind.

Example 4

Example 3 Lightweight mortar was compounded according to the materials TE1 and TE3 in Table 5, and the durability thereof was tested. The results are shown in Table 8.

[Table 8]

As shown in [Table 8] above, it can be seen that there is a large difference in durability when the AT1 added with ataplite is compared with the TE3 not added with ataplite.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims and their equivalents. Of course, such modifications are within the scope of the claims.

Claims (5)

For lightweight mortar for concrete repair;
The lightweight mortar is composed of 30 to 40 wt% of high-bellite cement, 1 to 5 wt% of ataflite, 20 to 40 wt% of silica sand having a particle diameter of 2 to 1 mm, 10 to 30 wt% of silica sand having a particle diameter of 1 to 0.5 mm, 0.1 to 1.0 wt% of an antifoaming agent, 1 to 5 wt% of a siloxane-based antirust agent, and 0.1 to 1.0 wt% of a polypropylene fiber,
The above-mentioned High Belite Sulfur Aluminate Cement (HB-SCA) is produced by mixing boric acid, limestone, fly ash and blast furnace slag at a temperature of 1,500 to 1,600 ° C in a cleaner, However,
The cleaner is composed of 15 to 25 wt% of boric acid, 40 to 60 wt% of limestone, 10 to 20 wt% of fly ash, and 5 to 15 wt% of blast furnace slag,
The light phosphate mortar according to any one of claims 1 to 3, wherein the phosphoric acid-treated type 棺 -form 棺 -hydrous gypsum is mixed and pulverized in an amount of 2 to 4 parts by weight per 100 parts by weight of a 500-㎡ / kg powder mill.
delete The method of claim 1,
Wherein the bauxite and the fly ash are mixed at a weight ratio of 1: 0.7 to 1.0.
The method of claim 1,
The siloxane-based rust inhibitor is in the form of powder in which polyvinyl alcohol and silane are encapsulated.
In the concrete repair method using lightweight mortar;
A pretreatment step of chipping a concrete structure requiring maintenance;
A mortar applying step of applying a lightweight mortar according to any one of claims 1, 3 and 4 to a pretreated concrete structure;
Curing stage curing lightweight mortar;
And a surface treatment step of applying a neutralization coating material to the surface to which the lightweight mortar is applied.

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