Patent Publication Number: US-2005120660-A1

Title: Plastic micro packer and construction method using it

Description:
TECHNICAL FIELD  
      The present invention relates to a plastic micro packer and a middle- or low-pressure crack repairing method using the same, and more particularly, to a plastic micro packer and a middle- or low-pressure crack repairing method using the same, which have a simple and improved structure to allow economical construction.  
     BACKGROUND ART  
      In general, cracks may occur in the outside or the inside of concrete structures or buildings due to various causes, i.e., dry contraction, temperature change, water leakage or others. Furthermore, in places where lots of loads are applied, such as floors of underground parking lots, or in places where waterproofing layer and finishing concrete layer of general floor slabs are constructed weakly, the finished concrete layers often come off even though they are not exposed to the outside of the structure or building. Most of cracks caused by normal dry contraction of concrete do not have any influence on the structure or building, but cracks occurring by excessive dry contraction or other causes may have severely bad influences on the structure or building.  
      Water and air may enter the cracks and the come-off portions of the structure or building, and the water and air entering facilitate efflorescence of concrete of the structure or building and incur corrosion of reinforcing rods, and thereby life of the structure or building is reduced and safety is deteriorated.  
      As a method for repairing the cracks formed in the surface of the concrete structures or buildings, packers have been used.  
      The method for repairing the cracks using the packer includes the steps of installing a tube-type metallic packer in the crack by press-fit, connecting the packer and an injector, which is filled with repairing solution, to a tube, and providing repairing solution through the tube at high pressure to fill the crack with repairing solution.  
       FIG. 1  of Korean Utility Model Registration No. 0172536 shows an example of a conventional packer for repairing cracks. In order to install the packer, first, a hole of a predetermined size is formed in a crack, and the packer is inserted into the hole as shown in  FIG. 1 . When a worker rotates an injection member  2 , an interval between a lock head  3  and a nut member  4  becomes narrower, and a sleeve  5  is expanded in a radial direction. The outer circumference of the expanded sleeve  5  is in contact with the inner circumference of the hole of the crack, and the crack is filled with repairing solution by connecting an injector  6  to the injection member  2 .  
      However, the conventional packer has a complex structure because of a check valve  1  for preventing backflow of the repairing solution.  
      Furthermore, work is difficult and inconvenient because tightening force generated when the worker rotates the injection member  2  expands the sleeve  5 .  
      Moreover, because the sleeve  5  expanded after the worker rotates the injection member  2  is contacted to the crack, the contact level or force is imperfect. For a wide contact area between the sleeve  2  and the cracked part, the sleeve  2  must be formed long and the hole for inserting the sleeve  2  must be formed deep. As a result, the conventional packer is not economical due to an excessive working period of time.  
      Additionally, if the crack formed in the hole where high pressure acts is filled with pulverized powder generated during the perforation by a drill, repairing solution provided by the packer cannot be injected smoothly, and excessive pressure is loaded inside the hole, and thereby, the concrete structure or building can be destroyed.  
     DISCLOSURE OF INVENTION  
      Accordingly, the present invention is directed to a plastic micro packer and a middle- or low-pressure crack repairing method using the same that substantially obviate one or more problems due to limitations and disadvantages of the related art.  
      An object of the present invention is to provide a plastic micro packer, which has a simple structure and is constructed conveniently, and a middle- or low-pressure crack repairing method using the same.  
      Another object of the present invention is to provide a plastic micro packer being favorable even on edged portions, which are hard to construct, and a middle- or low-pressure crack repairing method using the same.  
      A further object of the present invention is to provide a plastic micro packer, which prevents stop of cracks by pulverized concrete powder generated when holes are made for inserting the packer to inject repairing solution smoothly, and a middle- or low-pressure crack repairing method using the same.  
      A still further object of the present invention is to provide a plastic micro packer and a middle- or low-pressure crack repairing method using the same, which can allow construction even though the holes for inserting the packer are shallow so as to reduce damage of structure or building.  
      Another object of the present invention is to provide a plastic micro packer and a middle- or low-pressure crack repairing method using the same, which can allow a worker to check whether or not repairing solution is injected into cracks. Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.  
      The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
      To achieve the above objects, in one aspect of the present invention, there is provided a plastic micro packer, which is connected to a hole formed in a crack to inject repairing solution into the crack of a concrete structure, including: a hollow rubber sleeve inserted into the hole, the rubber sleeve having, a screw portion formed on the inner surface thereof; a hollow packer body having a screw coupling portion screwed with the screw portion and a nozzle portion connected to a repairing solution injector; and a cover member connected to the nozzle portion to prevent leakage of repairing solution.  
      Because the screw portion of the rubber sleeve has a wide top and a narrow bottom, the lower portion of the screw portion is closely contacted to the hole of the concrete structure while being expanded in a radial direction when the screw coupling portion is connected to the screw portion. As a result, separation of the rubber sleeve is prevented during a high pressure injection.  
      A wrench coupling portion is formed on the circumference of the center of the packer body to screw the packer body to the rubber sleeve using a tool, such as a wrench.  
      The cover member includes a stopper connected to the nozzle portion, a round connection ring coupled to the screw coupling portion loosely, and a flexible connection cord for connecting the stopper and the connection ring to each other.  
      In another aspect of the present invention, there is also provided a method for repairing middle or low pressure cracks using a plastic micro packer includes the steps of: first forming a number of holes in cracks of a concrete structure in uniform diameter and depth and at uniform intervals; second forming deeper holes in the first holes using a core drill having a hollow-type core bit to form a concrete core portion, which passes cracks, on the bottom surface of the hole; cutting the concrete core portion attached inside each hole by applying impact to the concrete core portion; cleaning pulverized concrete powder or dust along the holes and cracks; connecting a hollow rubber sleeve to the inner surface of the hole, the hollow rubber sleeve having a screw portion; connecting a hollow packer body to the rubber sleeve, the hollow packer body having a screw coupling portion screwed to the screw portion of the rubber sleeve and a nozzle portion connected to a repairing solution injector; injecting the repairing solution into the crack through the nozzle portion; stopping the nozzle portion with a cover member after the infection of the repairing solution; and cutting and finishing the packer body and the rubber sleeve protruding from the surface of the concrete structure after the injected repairing solution is hardened.  
      The method for repairing middle or low pressure cracks using the plastic micro packer further includes the steps of: mounting check windows communicating with the cracks between the holes after the connection of the packer body to the rubber sleeve, the check window having a repairing solution space; and sealing the cracks along the cracks between the check windows and the holes to prevent leakage of the repairing solution.  
      In the sealing step, a sealing tape is adhered along the cracks. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:  
       FIG. 1  is a sectional view showing a state in which a conventional packer assembly is constructed;  
       FIG. 2  is an exploded perspective view of a packer according to the present invention;  
       FIGS. 3   a  and  3   b  are sectional views of essential parts of the packer of  FIG. 2 ;  
       FIGS. 4   a  to  4   g  are briefly sectional views showing a method for repairing cracks according to the present invention;  
       FIG. 5   a  is an exploded perspective view of a check window according to the present invention;  
       FIG. 5   b  is a sectional view showing a state in which the check window is installed;  
       FIGS. 6   a  and  6   b  are plan views showing a state in which the packer and the check window are installed on the surface of a structure:  
       FIG. 7  is a block diagram showing the construction method according to the present invention. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      The present invention will now be described in detail in connection with preferred embodiments with reference to the accompanying drawings. For reference, like reference characters designate corresponding parts throughout several views.  
      As shown in  FIG. 4   b,  a plastic micro packer for repairing cracks of a concrete structure according to the present, invention is coupled to a hole  101  formed in a crack  110  to inject repairing solution  200  into the crack  110 . The crack  110  communicates with the bottom surface of the hole  101 .  
      Referring to  FIGS. 2 and 3 , the packer  10  is coupled to the hole  101 , and includes a hollow rubber sleeve  30  having a screw portion  31  formed on the inner surface, a hollow packer body having a screw coupling portion  11  screwed with the screw portion  31  and a nozzle portion  12  connected to a repairing solution injector  300  (see  FIG. 4   d ), and a cover member  20  connected to the nozzle portion  12  to prevent leakage of the repairing solution  200 .  
      The screw portion  31  of the rubber sleeve  30  has a wide top and a narrow bottom. As a result, as shown in  FIGS. 3   b  and  4   e,  when the screw coupling portion  11  is screwed, the lower portion of the screw portion  31  is closely contacted to the hole  101  of the concrete structure while expanding in a radial direction, and therefore, the rubber sleeve  30  is not separated from the hole  101  when the repairing solution is injected at a uniform pressure. Furthermore, a flange portion  32  is formed at the front end of the rubber sleeve  30  to prevent excessive insertion of the rubber sleeve  30  into the hole  101 .  
      A wrench coupling portion  13  protrudes from the circumference of the center of the packer body  15  to be screwed with the rubber sleeve  30  using a tool, such as a wrench (not shown in the drawings). The packer body  15  is made of plastic material.  
      The cover member  20  includes a stopper  21  connected to the nozzle portion  12 , a round connection ring  22  connected to the screw coupling portion  11  loosely, and a flexible connection cord  23  for connecting the stopper  21  and the connection ring  22  to each other.  
      As shown in  FIG. 4   c,  the packer  10  is installed in the hole  101  of the concrete structure  100  by inserting the rubber sleeve  30  into the hole  101  formed in the concrete structure  100  and connecting the screw coupling portion  11  of the packer body  15  to the rubber sleeve  30  using the wrench (not shown in the drawings). At this time, as shown in  FIGS. 3   b  and  4   d,  because the screw portion  31  of the rubber sleeve  30  has the wide top and narrow bottom, the lower end of the rubber sleeve  30  is expanded when the packer body  15  is inserted, thereby, being closely contacted to the inner surface of the hole  101 .  
      As shown in  FIG. 4   d,  after the connection of the packer  10  to the structure, the injector  300  is connected to the nozzle portion  12 , and the repairing solution  200  is injected to the crack  110  at middle or low pressure of about 100 kg/cm 2 . The packer maintains a stable state in the hole to the injected pressure.  
      As shown in  FIG. 4   e,  after the finish of the injection, the cover member  20  is connected to the nozzle portion  12  to prevent leakage of the injected repairing solution  200 .  
      As described above, the packer  10 , which is made of rubber or plastic material, is economical, and has a simpler structure than the conventional packer having a check valve because the packer  10  according to the present invention prevents leakage of the repairing solution  200  by the cover member  20 .  
      Moreover, because the screw portion  31  of the rubber sleeve  30  has the wide top and the narrow bottom, the rubber sleeve  30  is closely contacted to the hole  101  to prevent separation of the rubber sleeve  30  when the packer body  15  is connected to the screw portion  31 , and thereby, the packer  10  of the present invention has a stable structure.  
      A method for repairing cracks of the concrete structure using the packer  10  having the above structure will be described as follows.  
      Referring to FIGS.  4  to  7 , first, a worker checks width, size, state and location of the crack and thickness of the concrete structure, and then, checks a location to install the packer of the present invention.  
      Next, as shown in  FIG. 4a , the worker forms a number of first holes  101  in the crack  110  of the concrete structure  100 , the holes  101  having diameter of about 10 mm and depth of about 10˜15 mm and being formed at intervals of about 25˜45 cm by a drill  120 . At this time, the cracks  110  inside the holes  101  are stopped by pulverized concrete powder.  
      Then, as shown in  FIG. 4   b,  second holes  101  of about 15˜20 mm, which are deeper than the first holes, are formed in the first holes  101  by a hollow core bit  130  mounted on an electronic drill. At this time, a concrete core portion  102  is formed in the second hole  101 , and concrete powder pulverized by vibration generated during the second perforation is separated from the crack  110  passing the core portion  102 . The worker cleans the concrete powder using a blower (not shown).  
      In another method, when the crack  110  formed in the hole  101  is stopped by the pulverized concrete powder generated during the first and second perforations, as the injection of the repairing solution  200  is prevented, the concrete core portion  102  is cut by applying impact. In this case, the crack  110  shown in the section of the cut core portion  102  is not stopped by the concrete dust.  
      In the above condition, the worker cleans the pulverized concrete powder or dust along the hole  101  and the crack  110  formed in the surface of the concrete structure  100  using the blower (not shown).  
      After that, as shown in  FIGS. 4   c  and  4   d,  the hollow rubber sleeve  30  having the screw portion  31  formed on the inner surface thereof, which has the wide top and narrow bottom, is connected to the hole  101 , and the packer body  15  is screwed with the rubber sleeve  30 . As shown in  FIG. 2 , the packer body  15  include the screw coupling portion  11  screwed to the screw portion  31  of the rubber sleeve  30 , and the nozzle portion  12  connected to the repairing solution injector  300 .  
      When the packer body  15  is screwed with the rubber sleeve  30 , as shown in  FIG. 4   d,  the lower end of the rubber sleeve  30  is expanded in the radial direction so as to be closely contacted to the inner surface of the hole  101 .  
      After the packers  10  are connected to the holes  101  respectively, as shown in  FIGS. 4   c  to  6   a,  check windows  40  are mounted along the cracks  110  at regular intervals.  
      As shown in  FIGS. 5   a  and  5   b,  the check window  40  includes a transparent boss  41  having a repairing solution space  41   a  communicating with the crack  110  between the holes  101 , a flange  42  formed around the boss  41 , a double-sided adhesive  45  adhered to the bottom of the flange  42 , and a release paper  46 .  
      The check window  40  allows the worker to check whether or not the repairing solution  200  is provided into the crack  110  adjacent to the present crack  110  when the repairing solution  200  of middle or low pressure is injected into the present crack  110 . That is, when the repairing solution  200  is injected through the packer  10 , the repairing solution  200  is induced into the repairing solution space  41   a  of the adjacent check window  40  while being provided along the crack  110 . As a result, the worker can check whether or not the repairing solution  200  is injected through the check window.  
      As shown in  FIG. 6   a,  after the packers  10  and the check windows  40  are installed, the cracks  110  are sealed along the length of the cracks  110 .  
      As shown in  FIG. 6   b,  the cracks  110  can be sealed with a sealing tape  400  along the length of the cracks  110 . In this case, it is preferable that the sealing tape  400  is adhered also to the top surface of the flange  42  of the check window  40  to increase adhesive strength with an adhesive tape  45  of the check window  40 . When the repairing solution  200  is injected along the crack  110 , the worker can check through the check window  40  whether or not the repairing solution is injected. Additionally, the worker can check the injection of the repairing solution through deformation of the sealing tape  400  by pressure of the injected repairing solution  200 , as the sealing tape  400  adhered on the crack  110  of the surface of the structure has elasticity.  
      Furthermore, the cracks may be sealed with epoxy resin along the length of the cracks, and sealed doubly by adhering the sealing tape  400  onto the top surface of the sealed epoxy resin.  
      Additionally, the cracks can be sealed with epoxy resin or the sealing tape  400  after the circumferences of the cracks  110  are coated with liquid type urethane-based primer (not shown) to a uniform width of about 100 mm. In this case, the primer cleans the circumferences of the cracks  110  and makes adhesion of the epoxy resin or the sealing tape  400  smooth.  
      After the adhesion of the sealing tape  400 , the packers and the check windows are closely contacted to the floor surface of the concrete structure by a pressurizing tool (not shown).  
      After that, as shown in  FIG. 4   d,  the repairing solution injector  300  is connected to the nozzle portion  12 , and the repairing solution  200  is injected into the crack  110  at a middle or low pressure of about 100 kg/cm 2 . At this time, the repairing solution  200  is provided along the cracks  110  communicating with each other by the pressure, and is injected until the repairing solution  200  is provided into the repairing solution space  41   a  of the check window  40  mounted on the surface of the concrete structure  100 .  
      As described above, when the worker checks through the adjacent check window  40  that repairing solution  200  is provided into the repairing solution space  41   a,  as shown in  FIG. 4   e,  the worker stops the nozzle portion  12  of the packer assembly  10  with the cover member  20 , and then, injects the repairing solution  200  through the adjacent packer assembly  10  as described above.  
      Meanwhile, during the supply of the repairing solution  200  through the packer  10 , the repairing solution  200  can be injected until air inside the crack  110  is discharged through the adjacent packer  10 . In this case, the discharge of the air inside the crack  110  and the filling of the repairing solution  200  allows more stable repair.  
      When the injected repairing solution  200  is hardened after a predetermined period of time, the screw coupling portion  11  of the packer  10  is cut as shown in  FIG. 4   f,  and the sealing tape  400  is removed as shown in  FIG. 4   g.  Then, the packer body and the flange portion of the rubber sleeve protruding from the surface of the concrete structure  100  are cut by a cutter blade and grounded and finished.  
      In the method for repairing cracks as the above, it will be appreciated that the first holes  101  may be formed after attaching the check windows  40  and adhering the sealing tape  400 .  
      Furthermore, it will be appreciated that the cracks  110  may be sealed before the packer  10  is installed after the holes  101  are formed.  
      Industrial Applicability  
      As described above, the present invention has the following advantages.  
      First, the packer according to the present invention can be easily constructed onto edge portions or concavo-convex portions, where the construction is complex, when cracks occur, as it has a simple structure.  
      Second, the conventional packer has a check valve to prevent backflow of the repairing solution, but the present invention adopts the flexible cover member of plastic material, and hereby, the present invention has a simple and improved structure and enables economical construction.  
      Third, because the packer of the present invention is assembled with simple tools, such as a wrench, even non-skilled person can operate it easily, and working time period is reduced.  
      Fourth, because the holes  101  are formed in such a manner that the worker first perforates the holes with a general drill and second perforates the holes with the core drill, the working period of time is largely reduced and life of the core drill is extended.  
      Fifth, because the concrete core portion is formed and cut with the core drill to prevent stop of the cracks by the pulverized concrete dust, the repairing solution is injected smoothly, and thereby, the packer enables easy construction.  
      Sixth, because the method for repairing the cracks using the packer of the present invention forms the holes  101  to the minimum depth, strength of the concrete structure is not reduced and embedded electric wire pipes are little damaged. Additionally, because the floor surfaces of the holes  101  are maintained at a short distance from the surface of the concrete structure, the holes can be formed at exact places on cracked line with no error.  
      Seventh, the conventional packer adopts the check valve to prevent backflow of the repairing solution to the outside after the repairing solution is injected, thereby the air inside the crack cannot be discharged, and as a result, the crack cannot be repaired stably. However, the present invention allows discharge of the air from the inside the crack through the adjacent packer during the injection of the repairing solution.  
      While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.