KR100572035B1 - Development of equipment and repairing mortar for shotcrete - Google Patents

Abstract

The present invention relates to a structure of a mortar injector, and in particular, a mortar injector that can significantly increase the mortar's pourable thickness, can be installed in short air with a large area, and can use a fastener to condense mortar within a short time. It is about the structure.

The structure of the mortar injector of the present invention includes a mixer for mixing mortar with water, cement, sand and the like; A mortar spray nozzle for spraying the mortar mixed in the mixer; A structure of a mortar injector having an air compressor for injecting compressed air into the mortar ejection nozzle, the apparatus further comprising a quickener injector capable of mixing a fastener with the mortar ejected from the nozzle of the mortar injector It is characterized by.

Description

Development of Shotcrete Injector and Repair Mortar {Development of Equipment and Repairing mortar for shotcrete}

1 is a view showing the structure of a mortar injector according to the present invention;

Figure 2 schematically shows the operation of the mortar injector according to the present invention; And,

3 is a view showing that the mortar, compressed air and the fastener in the mortar injector according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: mortar injector 11: air chamber

12: mortar spray nozzle 20: mixer

21: pressure pump 30: fastener injection device

31: Quick Payment Tank 32: Quick Payment Injection Nozzle

33: hose 40: air compressor

41 air compressor 42 compressed air nozzle

43: hose 50: control device

The present invention relates to a structure of a mortar injector. More specifically, the present invention relates to a structure of a mortar injector that can significantly increase the mortar's pourable thickness, can be installed in short air with a large area, and can use a fastener to solidify the mortar in a short time.

In general, concrete is composed of cement, coarse aggregate, fine aggregate, admixture, admixture, and thus, unlike other construction materials such as reinforcing bars, the composition of the material varies, and materials of different properties are combined. Therefore, the quality of the concrete is closely related to the quality of the constituent materials, and the quality of the concrete varies according to the mixing ratio, the pouring method, and the curing method.

High-quality concrete has been used for construction and civil engineering materials for a long time because it is economical and semi-permanent. However, when concrete is produced and used with low quality, or when the concrete structure is exposed to poor environment from the outside, the concrete is easily damaged.

For example, concrete structures exposed to the coast cause corrosion when chlorine ions in seawater penetrate into the concrete, eliminating the passivation film in the reinforcing bars. It acts as a hydrate to neutralize the concrete surface, eventually leading to corrosion of the rebar. In addition, sulfuric acid gas and bacteria penetrate into concrete due to wastewater and domestic sewage of factories, which is a direct cause of reinforcement corrosion and concrete deterioration.

Due to these causes, when the steel reinforces inside the concrete, the volume expands, leading to cracking and cross-sectional dropping of the concrete structure. In addition, the concrete expands due to various deterioration factors invading from the outside, and eventually, the cross section falls, which may cause the structure to collapse due to insufficient performance of the structure.

Mortar is widely used to repair damaged concrete, and organic polymers are used to improve the adhesion of mortar to improve adhesion. Recently, as the degree of deterioration of concrete is intensified, the repair area of concrete is widened and the depth of damage is also deepened. In the past, where the repair area was small and the labor cost was relatively low, the skilled workers mainly used cross-sectional recovery. However, as the labor cost of the plasterer increases and the repair area increases, the repair mortar casting using shotcrete equipment is becoming more common. It is a situation.

However, in general, it is difficult to pour a mortar more than about 30mm thick at once when repairing mortar using shotcrete. Therefore, if the damage cross section is deep and needs to increase the thickness of the repair mortar, it must be repeated several times, and if the mortar is placed several times in the same place, a layer is formed between the repair mortars and the quality of the mortar must be reduced and repeated construction. Therefore, there is a problem in poor workability. Therefore, in order to overcome such a problem, it is urgent to develop a repair mortar that can not only significantly increase the mortar thickness of the mortar compared to the existing mortar, but also can construct a large area in short air.

And railways, subways, and lower parts of bridges, which are extremely limited in working time, cannot be built with a large amount of shotcrete in a short period due to the long curing period. In order to improve these shortcomings, a thicker and faster mortar construction method is required. The conventional method of using a hand polish or a shotcrete equipment that cannot be overlaid more than 30mm thick is not suitable for large structures that need to repair a large cross-sectional area, and the quality and workability of mortar There was an uneconomical issue.

The present invention is to solve the conventional problems as described above, in the case of the need for a wide area or deep deep repair of large concrete structures such as port structures and airports, mortar with better cohesion and adhesion than the existing mortar It is also aimed at improving the construction and economic feasibility of the renovation work using the improved shotcrete equipment so that the mortar can be thickly poured.

The mortar with strong cohesive force is developed differently from the existing mortar so that the mortar can be over 250mm thick in one pouring, and the use of a fastener can make the mortar start and end in a short time. The purpose of the present invention is to provide a structure of a mortar injector capable of thickening the mortar at one time and constructing a wide cross section at the same time by modifying and adding major parts of the shotcrete equipment to increase the thickness of the casting.

In order to achieve the above object, the present invention is a mixer for mixing mortar with water and cement and sand; A mortar spray nozzle for spraying the mortar mixed in the mixer; A structure of a mortar injector having an air compressor for injecting compressed air into the mortar spray nozzle, further comprising a quickener injector capable of mixing a fastener with the mortar sprayed from the nozzle of the mortar injector. It is characterized in that it can be mixed by spraying mortar and a fastener.

Furthermore, the quickener injector includes: a quickener tank for storing the quickener; A quickener spray nozzle which is installed outside the nozzle of the mortar spray nozzle and sprays the quickener; It is preferred to have a hose connecting the quickener tank and the quickener spray nozzle so that the quickener can move from the quickener tank to the quickener spray nozzle through the hose.

In addition, the angle between the mortar injector nozzle and the quickener spray nozzle is about 55 ° ~ 65 °, characterized in that it can reduce the setting time of the mortar.

Furthermore, the rapid injection device further comprises a control device, characterized in that the control device can control the injection amount of the mortar, compressed air and the fastener.

The mortar includes cement, blended water, swelling agent, fiber, admixture, and admixture, and the admixture is aluminosilicate-based, and when the weight ratio of the cement is 100, the weight ratio of the admixture is 9.5 to 17.8, mortar It is characterized in that the height of the possible pouring.

Moreover, when the weight ratio of cement is 100, the weight ratio of compounding water is 40-50; The weight ratio of the expanding agent is 8-14; The weight ratio of the fibers is 1 to 3; The weight ratio of the admixture is preferably 0.5 to 0.8. Here, when the compounding number is 40 or less, the viscosity of the mortar is high so that shotcrete is impossible, and when it is 50 or more, the strength and durability of the mortar are remarkably inferior. In addition, the expansion agent, which is a kind of admixture for suppressing the contraction of mortar, does not sufficiently exhibit the effect at 8% or less, and when it exceeds 14%, the expansion is excessive and cracks are generated in the mortar. In addition, the fiber increases the tensile force of the mortar to suppress the crack as much as possible, and the admixture is to improve the workability of the mortar, and it is economical only when used within an appropriate range.

-Mortar Development-

In the present invention, in order to maximize the thickness of the cast mortar has developed a different mortar and physical properties. Mortars consist mainly of water, cement and fine aggregates (sand), but they are not easily used on site due to their high shrinkage and poor durability. Therefore, it is possible to recover the workability by using a swelling agent to reduce the shrinkage of the mortar, and a powdered fluidizing agent to increase the fluidity. In order to provide cohesion between particles, an aluminate-based admixture and a thickener were used, and a polymer was added to increase adhesion.

Although mortar is made of the same kind of material, the physical properties (strength and durability, etc.) vary considerably according to the mixing ratio. Therefore, it is necessary to identify the mortar through many tests in order to develop mortar that can be used in the field.

In the present invention, the experiment was conducted using a compounding ratio of 15 to 65, fiber 5 to 20, admixture 1.22 to 4.08, and silica sand 170 to 300 based on the cement weight ratio 100 through many test formulations. In the test method, the mortar of the above compounding ratio was first introduced into a mortar mixer, the mixture water (water) was poured slowly, and the mixture was spun for about 45 seconds at low speed, and then rested for about 60 seconds. The high speed is then mixed for about 60 seconds. The fasteners are formulated 30 seconds prior to mixing at high speed, taking into account the field conditions as much as possible. In order to easily check the adhesion and cohesion of the mixed mortar and to easily measure the thickness of the covering in the room, wet the plywood with a rough surface and then carry out a simple test to measure the thickness of the covering through the hand plastering. It was. Next, test specimens for the mortar setting time and strength test were prepared. And in order to confirm the performance of the mortar properties identified indoors, the test model was fabricated in the field, and then the field applicability of the mortar developed using shotcrete equipment was examined.

In the laboratory test, after the mortar was mixed, the thickness of the mortar covering on the wall was measured through hand-dressing. After recording the measured thickness, the initial and final mortars were measured, and the specimens were made to increase the compressive strength and the bending strength by 28 days. Measured. However, although all formulations had excellent results in terms of strength, the condensation time was long, and when the wall was polished, it was not possible to overcoat it with a thickness of 30 mm or more. The admixture was developed to increase the cohesion and adhesion, and it was decided to increase the overlay thickness.

Firstly, there are largely kinds of fasteners that can maximize the thickness of the overlay by appropriately reacting with the developed mortar, and include silicate, aluminate, and alkali-free. However, the silicate system is not used well at present, and the aluminate system induces an alkali aggregate reaction of concrete to inflate concrete, induces cracking and dropping, and has a problem of being harmful to the human body because it is composed of strong alkali components. Therefore, in the present invention, it is decided to shorten the setting time and maximize the thickness of the overlay by using an alkali-free fastener. Alkaline-free fasteners are not harmful to the human body, and because the price is relatively low, the usage is increasing over time. The fastener is a kind of admixture that hardens the mortar quickly, but here it is used separately from the admixture.

Table 2 shows the settling times of the mortars mixed with the selected alkali free system and the settling time according to the amount of the fasteners. The setting time was significantly reduced between 25 minutes and 5 hours and 35 minutes compared to the formulation before the addition of the fastener, and the compressive strength and the flexural strength were increased by the use of the fastener (Table 3 and Table 4). Condensation time, however, did not decrease much more than expected, with good results of about 30-50 mm in the thickness of the overlay. And it was found that the initial strength was significantly decreased due to the increase in the amount of the fasteners used.

Table 2. Condensation Time

product name Quick amount added (%) Setting time Remarks First closing mortar 0 7 hours 15 minutes 10 hours 45 minutes E company (alkaline free system) 3 4 hours 45 minutes 5 hours 35 minutes E company (alkaline free system) 5 25 minutes 1 hour 14 minutes

Table 3. Compressive Strength Test Results

product name Quick amount added (%) Compressive strength (kgf / cm ² ) Remarks 3 days 7 days 28 days mortar 0 252.0 298.2 406.9 A quick payment 3 286.8 340.2 462.1 A quick payment 5 103.3 409.3 426.1

Table 4. Bending Strength Test Results

product name Quick amount added (%) Flexural strength (kgf / cm ² ) Remarks 3 days 7 days 28 days mortar 0 66.1 94.2 92.5 A quick payment 3 69.0 77.2 93.0 A quick payment 5 29.8 76.6 93.6

As a result of analyzing the test results, it was judged that the use of the fastener alone could not greatly increase the mortar overlay thickness targeted in the present invention, and after thinking about a method of increasing the cohesive force of the mortar, the admixture was developed to improve the cohesion and strength of the mortar. We decided to improve and maximize the thickness of the overlay.

In the admixture, anhydrous gypsum is added to the aluminate-based mineral to enhance the curing speed and strength, and sodium carbonate is added to improve adhesion. Aluminate-based minerals are mainly by-products that are produced in the process of separating iron from iron ore, react with water to produce hydrates, and increase their strength. However, the commonly used aluminate-based minerals are less powdery and slow in chemical reactions. Therefore, it is judged that it is difficult to obtain the early strength improvement and thickening effect at the beginning of the compounding, which are necessary in the present invention. Therefore, in order to accelerate the reaction of the admixtures and to improve the function, a high-powdered aluminate mineral is used. By increasing the early activity of the mortar, and to increase the strength.

Table 5 shows the mortar setting time of the mortar using the admixture, and compared with Table 2, the initial time of the mortar was shortened by 16 minutes, and the termination time was shortened by about 1 hour. Mortar using admixtures in compressive strength and flexural strength were initially about 200kgf / cm ² , 45kgf / cm ² , and 100kgf / cm ² and 15kgf / cm ² higher on 28 days respectively. As a result of the overlaid test in the room, the thickness of the wall could be increased by about 50mm more than the mortar without the admixture. Therefore, when the mixed material pulverized by mixing gypsum and calcium carbonate in the aluminate-based mineral in the mortar for shotcrete can increase the thickness of the overlay, it can be seen that early compressive strength and flexural strength are improved.

Table 5: Settling Time

product name Quick amount added (%) Setting time Remarks First closing mortar 0 7 hours 35 minutes 10 hours 45 minutes A quick payment 5 9 minutes 15 minutes

Table 6: Compressive Strength Results

product name Quick amount added (%) Compressive strength (kgf / cm ² ) Remarks 3 days 7 days 28 days mortar 0 385.0 380.0 458.0 E company (alkaline free system) 5 345.0 384.0 526.0 Test construction

Table 7 Bending Strength Results

product name Quick amount added (%) Flexural strength (kgf / cm ² ) Remarks 3 days 7 days 28 days mortar 0 96.0 97.0 100.0 E company (alkaline free system) 5 76.0 86.0 113.0

The constitution of the preferred mortar derived by such an experiment includes cement, blended water, swelling agent, fiber, admixture and admixture, and the admixture is aluminosilicate-based, when the weight ratio of the cement is 100, the admixture The weight ratio of is preferably 9.5 to 17.8. Moreover, when the weight ratio of cement is 100, the weight ratio of compounding water is 40-50; The weight ratio of the expanding agent is 8-14; The weight ratio of the fibers is 1 to 3; The weight ratio of the admixture is preferably 0.5 to 0.8.

-Equipment Development-

In order to maximize the thickness of the cross-sectional recovery, it was necessary to develop equipment that not only improves the quality of the mortar itself, but also allows the fastener used in the field to be properly mixed with the mortar so that the mortar performance can be sufficiently exhibited.

Shotcrete equipment is largely divided into concrete equipment and mortar casting equipment, and concrete shotcrete equipment is mainly used for new structures such as tunnels. Existing ordinary shotcrete equipment is to be used wet or dry, and when working in confined spaces such as railway tunnels or subways, the use of dry spray is limited because of dust and other reasons.

When wet spray equipment is used for the construction of cemented carbide mortars, hardening takes place in the transport hose, depending on the distance between the mixer and the spray gun. Therefore, the disadvantage of hardening the mortar in the mixer and the hose can be improved by limiting the cemented carbide admixture to a small amount during the initial mixing and spraying the fastener from the ejected nozzle. And mortar shotcrete equipment is mainly used for repairing damaged concrete structures. Currently, the mortar shotcrete equipment used in Korea is a screw, squeeze, piston type.

The mortar cross-section recovery shotcrete equipment has been widely distributed since 2000 as concrete repair volume has come out through a large area such as concrete tunnels and port structures, and requires a thick mortar casting at one time to improve productivity over time. have. Therefore, the necessity of the use of a fastener is suggested as a method of rapidly condensing mortar in the early stages like concrete in the case of repair mortar pouring. However, the repair work has not yet been used to restore the mortar cross section.

In the present invention, the air compressor 41, the fastener tank 31, the nozzles (32, 42) as an additional equipment that can be applied to the fastener to the mortar shotcrete of the screw method that is used a lot as shown in FIG. It is attached and connected with the hoses 33 and 43. Therefore, the fastener can move to the nozzle 32 through the hose 33, and by installing the controller 50, it is possible to appropriately control the amount of the fastener is injected through the nozzle, and at the same time the mortar is poured In the previous section, an additional device was installed in the existing equipment so that it could be instantly mixed well and the shotcrete equipment was improved to mix well with the mortar sprayed from the existing nozzle.

In particular, alkali-free fasteners contain a large amount of suspended solids. When using a common fastener inlet pump, suspended substances may get stuck in pistons or valves, causing the operation to stop. It is recommended to use a mono pump or a hose pump. Doing. Alkaline-free fasteners are highly corrosive and must be thoroughly cleaned with large amounts of water after use. Therefore, it is preferable to use a material which does not cause corrosion, such as stainless steel, in order to prevent corrosion of equipment using alkali-free fasteners.

According to the present invention, the fastener hose 33 and the quickener spray nozzle 32 are installed in the mortar spraying apparatus 10 to be used externally, so that the clogging of the hose during the mortar pouring or the alkaline free quickener In order to prevent corrosion of the entire equipment, as shown in FIG. 1, the rapid injection device 30 was separately mounted to the outside of the mortar injection device 10.

Hereinafter, an embodiment of the structure of a mortar injector according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing the structure of a mortar injector according to the present invention, Figure 2 is a view schematically showing the operation of the mortar injector according to the present invention. 1 and 2, the structure of the mortar injector according to the present invention is largely the mortar injector 10, the mixer 20, the fastener injector 30, the air compressor 40 and the control device ( 50).

The mixer 20 may prepare mortar by mixing cement, water, and sand, and the pressure pump 21 connected to the mixer 20 moves the mortar manufactured in the mixer 20 to the mortar injector 10. .

The quickener injector 30 includes a quickener tank 31, a quickener spray nozzle 32, and a hose 33. The quickener tank 31 may contain and store a quickener, and the quickener spray nozzle 32 is configured to inject a quickener to the mortar sprayed from the mortar spray nozzle 12. The fastener moves from the fastener tank 31 to the fastener spray nozzle 32 through the hose 33.

The air compressor 40 includes an air compressor 41, a compressed air nozzle 42, and hoses 43 and 44. The air compressor 41 compresses air and supplies compressed air to the mortar injector 10 through the hose 43 and the compressed air nozzle 42. In addition, a hose 44 is installed between the air compressor 41 and the fastener tank 31, so that the fastener of the fastener tank 31 is compressed by the compressed air generated by the air compressor 41. Can be moved up to).

3 is a view showing that the mortar, compressed air and the fastener in the mortar injector 10 according to the present invention. The mortar manufactured in the mixer 20 and moved to the mortar injector 10 through the pressure pump 21 is sprayed to the outside through a mortar spray nozzle 12 formed at one end of the mortar injector 10.

An air chamber 11 is formed in the vicinity of the mortar spray nozzle 12, and a compressed air nozzle 42 is formed at one side of the air chamber 11 to be connected to the air compressor 41. The compressed air moved from the air compressor 41 through the hose 43 is moved into the mortar injector 10 through the compressed air nozzle 42. In addition, the mortar and the compressed air are mixed in the air chamber 11 to be easily sprayed through the mortar spray nozzle 12.

The quickener spray nozzle 32 is installed outside the mortar jet nozzle 12 as shown in FIG. 3 to inject the quickener. Therefore, immediately after the mortar mixed with the compressed air is injected from the mortar injection nozzle 12, it is mixed with the rapid agent injected from the rapid injection nozzle 32 to recover the damaged concrete structure. The distance between the quickener spray nozzle 32 and the concrete structure (not shown) is about 15 to 30 cm, and the mortar is mixed with the fastener before being sprayed on the surface of the concrete structure.

At this time, the setting time was investigated according to the angle (θ, see Fig. 3) formed by the rapid injection nozzle 32 and the mortar injection nozzle 12, the results are shown in Table 8. Referring to Table 8, when the angle θ formed between the mortar spray nozzle 12 and the quickener spray nozzle 32 is disposed at 55 ° to 65 °, the condensation time is shortened compared to the other angle. Able to know. When the angle θ formed between the mortar spray nozzle 12 and the quickener spray nozzle 32 exceeds 65 °, the fastener is not sufficiently mixed with the mortar, so that the performance of the fastener is not sufficiently exhibited. . These results are similar to the mixing of mortar with a mortar using a mixer in the laboratory, demonstrating that the nozzle's internal spraying method and the angle of the nozzle can be sufficiently mixed with mortar in the field.

Table 8.

product name Injection angle (°) Setting time Remarks First closing mortar 30 3 hours 15 minutes 5 hours 45 minutes mortar 45 50 minutes 2 hours 35 minutes mortar 60 10 minutes 18 minutes

After the indoor test, the test concrete was applied to the actual structure by using the alkali free accelerator in the shotcrete mortar. Box-shaped reinforced concrete structures were installed, and wall and ceiling areas were chipped and washed with water to achieve the same process as in the actual site. In order to mix the mortar with water and to add the fastener spray nozzle 32 next to the mortar spray nozzle 12 of the mortar injector 10, a fastener spray nozzle 32 is additionally installed. The quickener was allowed to mix with the mortar.

First, mortar was placed on the wall to examine the maximum thickness of shotcrete once the mortar was attached to the concrete surface. As a result of the inspection, it was determined that the thickness could be up to about 37cm, and more than that, the repair section was dropped due to its own weight.

Like the wall, the ceiling was sprayed with mortar to check the maximum spray thickness once. When the mortar was attached to a thickness of about 32cm or more, the self-weight increased as the cross section increased, and the weight of the concrete attachment surface could not withstand the attachment force, resulting in separation phenomenon.

Mortar incorporating the mortar injector 10 and the admixture developed in order to improve the workability of the repair mortar, the faster the setting time, but the strength decreased as the amount of the mortar and the fastener increased. As a result of the field test construction using the developed mortar, it was determined that the concrete wall can be placed up to about 37cm and the ceiling can be up to about 32cm.

As described above, the structure of the mortar injector of the present invention significantly increases the mortar's pourable thickness, can be applied in a short area with a large area, and a fastener can be used to condense mortar within a short time. It works.

The present invention is not limited to the described embodiments, and various modifications and changes can be made to those skilled in the art without departing from the spirit and scope of the present invention. Such modifications or modifications may be made to the present invention. It belongs to the claims of the.

Claims (6)

A mixer for mixing mortar with water, cement and sand; A mortar spray nozzle for spraying the mortar mixed in the mixer; As a structure of a mortar injector having an air compressor for injecting compressed air into the mortar spray nozzle, The fastener may be mixed with the mortar sprayed from the nozzle of the mortar injector, further comprising a quickener injector mounted separately to the outside of the mortar injector, The mortar injector nozzle and the fastener spray nozzle made of an angle of about 55 ° ~ 65 ° structure of the mortar injector, characterized in that. The method of claim 1, The quickener injector includes: a quickener tank for storing the quickener; A quickener spray nozzle which is installed outside the nozzle of the mortar spray nozzle and sprays the quickener; A hose connecting the quickener tank and the quickener spray nozzle, The structure of the mortar injector, characterized in that the fastener can move from the quickener tank to the fastener spray nozzle through the hose. delete The method according to claim 1 or 2, The fastener injector further comprises a control device, The structure of the mortar injector, characterized in that the control device can control the injection amount of the mortar, compressed air and the fastener. The method according to claim 1 or 2, The mortar includes cement, blended water, swelling agent, fiber, admixture and admixture , the admixture is aluminosilicate based, When the weight ratio of the cement is 100, the weight ratio of the admixture is 9.5 to 17.8, the structure of the mortar injector. The method of claim 5, When the weight ratio of cement is 100, the weight ratio of the compounded water is 40 to 50; The weight ratio of the expanding agent is 8-14; The weight ratio of the fibers is 1 to 3; The weight ratio of the admixture is 0.5 to 0.8 structure of the mortar injector.

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