KR100635464B1 - Fiber reinforced mortar and repair-reinforcement method using thereof - Google Patents

Abstract

A fiber reinforced mortar comprising PVA fiber stable in matrix is provided to have improved rigidity and reinforcing ability and to noticeably enhance lowered durability such as chemical corrosion, fatigue and/or freezing and thawing state by homogeneously dispersing and distributing PVA fiber stables in matrix of mortar as reinforcing agent. The reinforced mortar comprises: 10-39.5wt.% of cement; 30-35wt.% of fine aggregate; 10-15wt.% of fly ash; 5-10wt.% of ceramic material in lightweight bead form having particle size of 60-150 micrometers and specific gravity of 0.8-1; 3-5wt.% of CSA expanding agent; 2-5wt.% of fumed silica; 0.2-0.5wt.% of fluidizing agent; 10-19.5wt.% of water; and PVA reinforced fiber with length of 8-12mm in 1-3vol.% relative to total volume of mortar.

Description

Fiber reinforced mortar and repair-reinforcement method using fiber

1 is a photograph showing the surface state of the mortar reinforced with fibers produced according to an embodiment of the present invention.

Figure 2 is a photograph showing the surface state of the mortar removing the light beads from the mortar shown in FIG.

Figure 3 is a photograph of the nailing on the mortar reinforced with fiber according to an embodiment of the present invention.

4 is a photograph after nailing mortar reinforced with the fiber shown in FIG.

Figure 5 is a photo of the impact test of the mortar reinforced with fibers (PVA short fibers) according to an embodiment of the present invention.

Figure 6 is a photo of the impact test with a mortar mixed with a conventional PP (polypropylene) short fibers.

Figure 7 is a photograph subjected to the impact resistance test with a conventional generally used polymer repair mortar.

Figure 8 is a photograph of a four-point bending test of the mortar reinforced with fiber according to an embodiment of the present invention.

The present invention relates to a reinforcing reinforcing method using a mortar reinforced with fibers and a mortar reinforced with the fibers, and more specifically, polyvinyl alcohol (PVA) fibers and fluidizing agents, fly ash, silica fume, etc. The present invention relates to a mortar reinforced with fibers having excellent crack resistance, tensile strength and flexural rigidity, and a repair reinforcing method using mortar reinforced with fibers.

Reinforced concrete structures are exposed to various loads, and their performance tends to deteriorate with time due to such loads or external influences such as acid rain. As a result, structural defects may occur, or durability may be degraded. Various maintenances are performed to suppress such deterioration of concrete.

One such maintenance method is the use of repair mortar, which is used to remove deteriorated parts of reinforced concrete structures and to fill in the removed parts, or increase the stiffness by increasing the cross section of existing reinforced concrete structures. Used to raise. In general, the deterioration of the reinforced concrete structure occurs near the surface exposed to the outside of the reinforced concrete, the repair reinforcement by the repair mortar is also made in the vicinity of the surface of the reinforced concrete and is usually constructed in a thin thickness on a wide surface. As the repair mortar is constructed with a thin thickness on the wide side, the moisture contained in the fiber-reinforced mortar evaporates at a rapid rate, so that microcracks occur during the curing process or cracks easily occur even after a light impact is completed. Or a problem that is destroyed is a common problem.

Epoxy mortar, polymer cement mortar, etc. have been developed to solve this problem, but such a repair mortar also has the following problems.

In the case of epoxy mortar, the difference in elastic modulus between the concrete and the epoxy resin is so large that peeling occurs at the interface, and since the epoxy resin itself is weak to ultraviolet rays, it is difficult to maintain the function by the ultraviolet rays. There is a drawback to not doing it right. In addition, since the epoxy resin contains various volatile substances harmful to the human body, its use is limited.

In the case of polymer cement mortar method, the polymer used as an additive is oxidized or weakened as time goes by, and the strength decreases.In addition, the dry shrinkage occurs due to the external temperature where the polymer cement mortar is in contact, and cracks occur. In particular, when the polymer cement mortar is applied to the upper plate of the bridge, it also has a problem that its function is not properly exhibited due to the fatigue phenomenon caused by the repeated vehicle load.

The present invention has been devised to solve the problems of the conventional repair mortar, including the fiber is strong tensile force, excellent workability and does not easily crack, reducing the amount of fibers exposed to the plaster surface, It is an object of the present invention to provide a reinforcing reinforcement method using mortar reinforced with fibers and mortar reinforced with fibers that have smooth fluidity suitable for spraying.

In order to achieve the above object, the present invention,

In mortar reinforced with fibers for repair and reinforcement of aged concrete structures,

10 to 39.5 weight percent cement;

30-35% by weight of fine aggregate;

10-15% fly ash;

5 to 10% by weight of ceramic material, specific gravity of 0.8 to 1, light weight beads having a particle diameter of 60 ~ 150μm;

3-5 wt% CSA expanding agent;

2-5% by weight of silica fume;

0.2 to 0.5% by weight of a glidant;

10 to 19.5% by weight of water; and

It provides a reinforcing mortar fiber, characterized in that it comprises; 1 to 3% of the total volume of PVA short reinforcing fiber.

The fine aggregate is preferably a mixture of No. 7 and No. 8 in a weight ratio of 3: 1.

In another aspect, the present invention, the chipping step of removing the deteriorated portion of the reinforced concrete structure;

A foreign material removal step of removing foreign substances in the chipped portion using high pressure water;

A mortar manufacturing step reinforced with fibers to produce mortar reinforced with the fibers described above;

It provides a reinforcing reinforcement method comprising a; mortar filling step of the fiber to fill the chipped portion using the prepared mortar reinforced fiber.

Mortar manufacturing step reinforced with the fiber,

A first step of mixing cement, fine aggregate, water, fly ash, lightweight beads, CSA expanding agent, silica fume, fluidizing agent and water of 70 to 80% by weight of the water used,

It is preferable to include a second step of re-mixing by dividing the remaining weight% of water and PVA short fibers into the mixture prepared by the first step.

After the foreign material removal step,

It is preferable to further include the step of reinforcing the corroded reinforcement of the chipped portion with the epoxy coating reinforcing bar is formed at both ends.

On the other hand, after the mortar filling step, it is preferable to further include a finishing step of applying a surface curing agent or surface treatment agent by spraying on the surface of the mortar filled with fiber reinforced with.

Hereinafter will be described in detail with respect to the configuration of the present invention.

Mortars reinforced with the fibers of the present invention include cement, aggregate, water, fly ash, lightweight beads, CSA expanding agents, silica fume, fluidizing materials and reinforcing fibers.

The cement may generally be a commercially available portland cement. The amount of cement is 10 to 39.5% by weight. If the amount of the cement is less than 10% by weight, the strength is expressed below the expected, and if the amount is more than 39.5% by weight, workability is inferior.

The fine aggregate accounts for 30 to 35% by weight of the total. The fine aggregate is preferably used that mixed No. 7 and No. 8 in a weight ratio of 3: 1. As already known, No. 7 means that the particle size is 0.1-0.25mm, and No. 8 means that the particle size is 0.075-0.1mm.

The water occupies 10 to 19.5% by weight of the total, tap water, etc. commonly available on the market can be used. If the water is less than 10% by weight may cause problems in the mixing process of mixing the material is less fluidity, if more than 19.5% by weight will result in a decrease in the overall strength.

The fly ash comprises 10 to 15% by weight of the total. When the fly ash is added below 10% by weight, the action of the fly ash does not occur properly, and when it is 15% by weight or more, the viscosity of the mortar reinforced with fibers is poor, resulting in a great drop in adhesion.

Light ceramic beads are made of 55 to 65% by weight of silica, 25 to 35% by weight of alumina, 1 to 5% by weight of iron oxide, and 0.5 to 1.5% by weight of titania. It is formed by sintering the materials. Specific gravity of the light bead is 0.8 to 1.0, the diameter is a spherical particle in the range of 60 to 150μm.

The light bead occupies 5 to 10% by weight of the total, when the light bead is less than 5% by weight does not occur the effect, when more than 10% by weight of the mortar reinforced with fiber is reduced adhesion The disadvantage of poor workability such as sex occurs.

It is preferable to use a mixture of aurine (3CaO.3Al ₂ O ₃ .CaSo ₄ ) and calcium oxide (CaO). The CSA expanding agent constitutes 2 to 5% by weight of the total. When the CSA expanding agent is less than 2% by weight, it is difficult to adhere mortar by spraying due to poor roughness, and when it is more than 5% by weight, cracks occur in the mortar reinforced with fibers due to excessive expansion.

The silica fume is preferably used that the average size of the particles of about 2μm. The silica fume is composed of 2 to 5% by weight of the total, when the silica fume is added less than 2% by weight it is difficult to expect the effect, if the addition of more than 5% by weight has a disadvantage that the long-term strength is too large.

It is preferable to use a polycarboxylic acid powder fluidizing agent or a melanin fluidizing agent as the fluidizing agent. The fluidizing agent occupies 0.2 to 0.5% by weight of the total, when the fluidizing agent exceeds 0.5% by weight, the fluidity becomes too large to significantly reduce the adhesion of the mortar reinforced with fibers, delaying curing There is a problem.

The reinforcing fiber is preferably a short fiber made of polyvinyl alcohol (PVA) material having a tensile strength of 1500 to 2600 MPa. The reinforcing fibers are added at 1-3% by volume of the total. When the reinforcing fiber is less than 1% by volume of the total, the crack resistance is lowered, and when the reinforcing fiber is less than 3% by volume, it is difficult to disperse the fiber when blending the mortar reinforced with the fiber, thereby causing fiber agglomeration phenomenon. have. The reinforcing fibers are difficult to be specified in weight% due to the remarkably small specific gravity compared to other materials of mortar reinforced with the fibers of the present embodiment, such as cement, water, aggregate, etc., and are generally mixed in the repair mortar containing reinforcing fibers. Since the amount of reinforcing fibers is specified by volume%, the amount added is also specified by volume% in this example.

Hereinafter, the operation and effects of the above components will be described in detail.

As is well known, the cement and aggregate are the basic components of mortar, and cement and aggregate are materials expressing the strength of mortar, and water is a component that mixes the cement and the aggregate and improves workability, and the details thereof. Effects are generally well known and will be omitted.

The fly ash is generally used as a mixture of mortar or concrete, and workability is increased due to the mixing of the fly ash, and the heat of curing generated during curing of the mortar is alleviated, and at the same time, the strength and water tightness are improved. Generates.

The lightweight bead serves to reduce the friction force between the pumping hose or plastering knife used in the repairing method using the fiber-reinforced mortar and the fiber-reinforced mortar in the fiber-reinforced mortar. For example, when the fiber is mixed in the mortar, the mixing process, which is a process of mixing the material by the incorporated reinforcing fibers, becomes difficult, and the pump or the pump for transferring the mortar is frequently blocked, so that the hose or nozzle for transferring the mortar is frequently blocked. When the distance between the place where the mixing process is performed and the part where the mortar is sprayed is more than a certain distance, it is almost impossible to apply mortar by spraying. On the other hand, in order for the mixed fibers to sufficiently suppress the cracks of the mortar or to disperse the cracks generated by the microcracks, fibers having a length of about 8-12 mm must be mixed, and some of the short fibers are mortars. There is also a problem of exposure to the surface after construction. This exposed fiber will hinder the aesthetics of the structure and cause a large amount of surface contamination, and the cleaning work will be hindered by the fiber even when cleaning the structure. Plastering works using mortar to bury the fiber in the mortar or to apply a thick coating to the coating wraps the fiber to prevent the fiber from being exposed to the outside, there was a problem that the light bead has a problem It will be solved. In the case of constructing the fiber-reinforced mortar by spraying the fiber-reinforced mortar with the spray according to the present embodiment, the work must be sprayed with the fiber-reinforced mortar through the pumping hose, when the pumping pressure is applied in the hose Under pressure, the fiber-reinforced mortar receives the compressive force, and the lighter bead, which is lighter than water, is located at the interface between the mortar and the pumping hose and lubricates similar to the ball bearings. It reduces the frictional force to make the fiber-reinforced mortar smoothly flow in the pumping hose.

In addition, the lightweight bead also serves to prevent the reinforcing fibers from being exposed to the surface of the mortar reinforced with fibers. In general, when mortar is applied and the finish of the plastering surface is finished, the bleeding of the water blended into the constructed mortar to the surface on which the mortar is applied is finished. This is because the surface of the mortar must be finished smoothly by the water exposed by the bleeding phenomenon to form a beautiful plaster surface state. However, the mortar on the surface is not completely solid at the time of this finishing process, so during the finishing process, the degree of exposure of fibers near the surface of the mortar to the surface is increased by the plasterer. By moving together, the phenomenon occurs that one side is oriented. Light weight beads have a specific gravity of 0.8-1.0, which is less than or equal to the specific gravity of water, and the diameter is larger than the diameter of the fiber, so the light beads on the mortar surface have the bearing surface between the finishing surface and the By reducing the coefficient of friction between the plastering knife and the mortar surface, it prevents the fibers from moving together even when the plastering knife moves on the mortar surface, and allows the exposed fiber to be immersed into the mortar. There is a significant effect of preventing exposure to the mortar surface.

The CSA expanding agent is added to reduce drying or impart expandability of the shrinkage of the mortar reinforced with fibers.

The glidant acts to improve the dispersibility of the incorporated fibers.

The reinforcing fibers are three-dimensionally dispersed in the mortar to increase the tensile strength of the mortar reinforced with fibers. The reinforced fiber in the mortar increases the tensile force of the mortar to suppress cracking, and exhibits a ductility characteristic that generates a plurality of microcracks when cracking occurs.

Hereinafter will be described the test results for the mortar reinforced with fibers according to an embodiment of the present invention.

Table 1 below is a table comparing the components of the two samples used in the experiment to confirm the inhibition of fiber exposure by light beads. In Table 1, Sample 1 is a sample that contains light beads, Sample 2 is a sample that does not contain light beads.

division Cement (wt%) Aggregate (wt%) Water (wt%) Fly ash (% by weight) Light Beads (wt%) CSA Expander (wt%) Silica fume (wt%) Glidants (wt%) Reinforcing Fiber (% by volume) Sample 1 35 30 14.7 10 5 3 2 0.3 2 Sample 2 35 34 15.7 10 0 3 2 0.3 2

The cement, aggregate, fly ash, CSA expanding agent, silica fume, fluidizing agent, and reinforcing fibers used in the samples were all made of the same material, but sample 2 did not contain lightweight beads.

1 is a photograph showing the surface of the mortar prepared from Sample 1, Figure 2 is a photograph showing the surface of the mortar prepared from Sample 2.

1 and 2, when compared with the observation, it can be seen that the reinforcing fiber exposure of the mortar reinforced with the fiber shown in FIG. 2 is much less than the surface of the mortar reinforced with the fiber shown in FIG. This is because, as described above, the light bead acts to suppress the movement of the fiber by the plastering knife at the surface finish and to allow the fiber to be immersed into the mortar. The reinforcing fiber exposed to the surface worsens the aesthetics of the surface, and contaminants are adsorbed to the reinforcing fiber exposed to the surface of the mortar reinforced with the fiber, thereby reducing the durability of the mortar. The problem caused by the present invention will be able to solve a large number by mixing light beads.

Table 2 is a test result of the performance of the mortar reinforced with fiber according to this embodiment.

Item KS F 4042 Quality Standard Mortar reinforced with fiber Polymer Cement Mortar Compressive strength (MPa) 20.0 or more 63.8 50.3 Flexural strength (MPa) 6.0 and above 13 8.2 Adhesion Strength (MPa) Standard condition 1.0 or higher 1.8 2.2 After hot and cold repeat 1.0 or higher 1.5 1.7 Alkali resistance Compressive strength over 20.0 MPa 62.7 47.4 Neutralization Resistance (mm) 2.0 or less 1.6 1.7 Permeability (g) 20 or less 2.3 1.3 Water Absorption Coefficient (kg / m ² h ^0.5 ) 0.5 or less 0.13 0.11 Moisture penetration resistance (Sd) 2m or less 0.3 0.3 Chloride ion penetration resistance (coulombs) 1,000 or less 528 805 Length change rate (%) ± 0.15 Within -0.021 -0.02 Sulfate resistance 99% -

Table 2 shows the results of the fiber-reinforced mortar and the polymer cement mortar in accordance with the KS F 4042 test method in order to show that the fiber-reinforced mortar is superior in various aspects to the conventional polymer cement mortar.

As shown in Table 2, the mortar reinforced with fibers according to the present embodiment showed high compressive strength and flexural strength, and showed excellent chemical resistance such as almost no change in strength even after alkali resistance test and sulfate resistance test. It can be seen that the performance is superior to the conventional polymer cement mortar.

3 is a photograph before nailing the mortar reinforced with fiber according to the present embodiment, Figure 4 is a photograph after nailing the mortar reinforced with the fiber shown in FIG.

In case of nailing the mortar reinforced with fiber, strong pressure is applied to the part where nail is nailed, which leads to stress concentration. If such cracking and impact resistance of mortar reinforced with fiber are weak due to the concentrated stress, the fiber Although the mortar reinforced with is broken, it can be seen that the nail is nailed without breaking at all as shown in Figure 4 it can be confirmed the excellent crack resistance and impact resistance of the mortar reinforced with the fiber according to this embodiment.

5 is a photograph of the impact resistance test by mixing the PVA short fibers in the mortar according to the present embodiment, Figure 6 is a photograph of the impact test by mixing PP (polypropylene) fiber generally used in the prior art, Figure 7 Is a photograph of an impact test with a conventional polymer repair mortar.

The impact resistance test was performed according to KS F 2221. As a result of dropping a weight of about 1 kg at a height of 50 cm, as shown in FIG. 7, the polymer repair mortar was completely broken in 18 drops, and the test body incorporating PP fiber as shown in FIG. Although it was broken due to the occurrence of reticular cracks in only 200 times, the present example of FIG. 5 shows the results of high impact resistance and fatigue resistance due to repeated loads.

Figure 8 is a photograph of the ductility ability through the four-point bending test mortar according to this embodiment. As shown in the picture, it can be seen that the ductility is exhibited by the deformation hardening behavior through the generation of multiple cracks.

Hereinafter, a repair reinforcing method using mortar reinforced with the above-described fiber will be described.

Repair reinforcement method according to an embodiment of the present invention includes a chipping step, foreign material removal step, fiber reinforced mortar manufacturing step, reinforcing reinforcement mortar filling step and finishing treatment step.

The chipping step refers to a step of removing a deteriorated portion of the reinforced concrete structure, that is, a portion that is structurally ineffective due to aging or external impact, by using a chipping machine such as a water jet, a leg hammer, or an electric hammer.

When the chipping step is completed, foreign substances in the chipped portion are removed using high pressure water.

When the deteriorated part is removed and the foreign material of the removed part is removed, the removed part is filled with reinforcement by mortar reinforced with the above-described fiber, which is filled by spraying or plastering.

At this time, if the cross-sectional area of the rebar in the chipped part is reduced due to the corrosion of the reinforcing bar, bend both ends of the epoxy coated reinforcing bar without fear of additional corrosion to form a fixing hook, and then bind to the reinforcing bar in the original structure and spray it. .

In order to fill the mortar reinforced with the above-described fiber, it is necessary to prepare the mortar reinforced with the fiber, the preparation of which is the first mixing cement, fine aggregate, fly ash, lightweight beads, CSA expanding agent, silica fume, fluidizing agent, water It is preferably made by a second step of remixing by adding the PVA short fibers to the mixture prepared by the first step.

At this time, in the first step, the powder components are mixed by using 70 to 80% of the water mixed in the mortar reinforced with fibers, and the PVA short fibers are added while appropriately adding the remaining% of water. It is preferable to divide into about 4 times. In other words, cement, fine aggregate, fly ash, lightweight bead, CSA expanding agent, silica fume, fluidizing agent, etc. 1 step of mixing using about 70-80% of water, and PVA short fiber divided into 3-4 times In addition, when the PVA short fibers are added, the remaining% of water is divided into two stages of mixing while mixing together 3-4 times at the same ratio to prepare mortar reinforced with fibers. When the fiber and water are mixed and mixed in the powder, the dispersibility of the fiber is improved by 10% or more than when the fiber and water are mixed at once.

When the mortar reinforced with the fiber is filled in the chipped portion, the surface curing agent or the surface treatment agent may be sprayed onto the surface of the mortar reinforced with the fiber.

To apply the mortar reinforced with fiber by spraying as described above, inject the compound of mortar reinforced with fiber into the mortar mixer and mix, and then spray the mortar reinforced with the blended fiber through a pressure hose with a mortar pump. It is possible to install in such a way that the mortar, which is injected to the gun and finally reinforced with fibers by the pressure supplied from the mortar pump, is sprayed through the nozzle of the spray gun.

When the sprayed mortar reinforced with fiber is applied by spraying, the repair work can be performed quickly. For this spraying operation, even when the reinforcing fiber is reinforced, proper fluidity must be maintained. The fluidity of mortar reinforced with fibers sufficient for spraying will occur.

In the above description of the preferred embodiment of the present invention, but the technical idea of the present invention is not limited to the above-described embodiment, mortar reinforced with various fibers within the range that does not violate the technical idea of the present invention and its It can be embodied by a repair method using mortar reinforced with fibers.

As described above, according to the present invention, the reinforcing fibers are mixed, so that the toughness and crack resistance, tensile deformation, impact resistance and fatigue resistance are strong, and also the bending strength, the compressive strength and the adhesion strength of the sphere are excellent, and the high workability is excellent. It is possible to spray even when the distance between the mixing place of mortar and the spraying plant is far, and the surface of mortar reinforced with hardened fiber and mortar reinforced with fiber and its fiber minimized exposure of reinforcing fiber. Provides repair method using mortar.

Claims (6)

In mortar reinforced with fibers for repair and reinforcement of aged concrete structures, 10 to 39.5 weight percent cement; 30-35% by weight of fine aggregate; 10-15% fly ash; 5 to 10% by weight of ceramic material, specific gravity of 0.8 to 1, light weight beads having a particle diameter of 60 ~ 150μm; 3-5 wt% CSA expanding agent; 2-5% by weight of silica fume; 0.2 to 0.5% by weight of a glidant; 10-19.5 weight% water; And Mortar reinforced with fibers, comprising; PVA reinforcing fibers each length of 1 to 3% of the total volume of 8 to 12mm. The method of claim 1, The fine aggregate is mortar reinforced with fibers, characterized in that the mixture of No. 7 and No. 8 in a weight ratio of 3: 1. Chipping to remove the deteriorated portion of the reinforced concrete structure; A foreign material removal step of removing foreign substances in the chipped portion using high pressure water; Mortar reinforcing step of manufacturing a fiber reinforcement mortar prepared by the fiber of claim 1; Reinforcing reinforcement method comprising a; reinforcing mortar filling step of filling the chipped portion using the prepared mortar reinforced with fibers. The method of claim 3, wherein Mortar manufacturing step reinforced with the fiber, A first step of mixing cement, fine aggregate, water, fly ash, lightweight beads, CSA expanding agent, silica fume, fluidizing agent and water of 70 to 80% by weight of the water used, And a second step of dividing and adding the remaining weight% of water and PVA short fibers to the mixture prepared by the first step to remix them. The method of claim 3, wherein After the foreign material removal step, Reinforcing reinforcement method characterized in that it further comprises the step of reinforcing the corroded reinforcement of the chipped portion with the epoxy coating reinforcing bar formed on both ends. The method of claim 3, wherein And a finishing treatment step of applying a surface curing agent or surface treatment agent by spraying the mortar-filled surface reinforced with fibers after the mortar filling step.

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