METHOD OF REMOVING MICROFRACTURES FROM CONCRETE SUBJECTED TO IMPACT METHODS OF CONCRETE DEMOLITION AND APPARATUS FOR PRACTICING THE METHOD

Abstract

A robot includes a movable vehicle to which is mounted a horizontal truss long enough to span the entire width of an area that has been demolished using impact methods. The truss extends laterally completely to one side of the robot and the robot travels on one side of a demolished area and the end of the truss has a wheeled support that can travel beyond the other side of a demolished area. A movable rotational lance device is traversed back and forth along the truss. With each pass the robot then moves perpendicular to the truss. The truss has a nozzle spraying water onto the area. In this way, an entire area is efficiently treated.

Claims

1. An apparatus for removing microfractures from an area of concrete that has been partially demolished using impact methods, comprising: a) a robot that is movable under control of an operator to one side of said area of concrete; b) a truss mounted to a side of said robot and extending horizontally; c) said truss having an end remote from said robot supportable on a surface at another side of said area of concrete that has been partially demolished; d) a lance movable along said truss over said area of concrete; e) a source of liquid supplying liquid to said lance, said lance carrying a nozzle through which said liquid is sprayed onto said area of concrete.

2. The apparatus of claim 1, wherein said robot is supported on movable wheels.

3. The apparatus of claim 2, wherein said robot is controlled by a controller whereby said robot's location is moved an incremental distance each time said lance moves a prescribed distance along said truss.

4. The apparatus of claim 3, wherein said prescribed distance comprises said lance moving along said truss from adjacent said robot to said remote end of said truss and back to a location adjacent said robot.

5. The apparatus of claim 1, wherein said nozzle is rotatable.

6. The apparatus of claim 1, wherein said remote end of said truss is supported on said surface by a rotatable wheel.

7. The apparatus of claim 3, wherein said incremental distance comprises one inch.

8. The apparatus of claim 5, wherein said nozzle is rotated by hydraulic fluid supplied under pressure to a motor to which said nozzle is attached.

9. The apparatus of claim 1, wherein said liquid comprises water.

10. The apparatus of claim 1, wherein said nozzle is angled about 25 with respect to a vertical axis.

11. The apparatus of claim 1, wherein new concrete poured over said area of concrete after said robot and truss have traversed said area of concrete has a 7-day tensile strength of at least 145 psi.

12. The apparatus of claim 9, wherein water pressure exiting said nozzle comprises up to 20,000 psi.

13. The apparatus of claim 5, wherein said nozzle is rotated from 75 to 300 rpm.

14. The apparatus of claim 12, wherein said nozzle is rotated from 75 to 300 rpm.

15. The apparatus of claim 13, wherein said nozzle is angled about 25 with respect to a vertical axis.

16. A method of removing microfractures from concrete subjected to impact methods of concrete demolition, including the steps of: a) providing an apparatus comprising: i) a robot that is movable under control of an operator to one side of said area of concrete; ii) a truss mounted to a side of said robot and extending horizontally; iii) said truss having an end remote from said robot supportable on a surface at another side of said area of concrete that has been partially demolished; iv) a lance movable along said truss over said area of concrete; v) a source of water supplying water to said lance, said lance carrying a nozzle through which said water is sprayed onto said area of concrete; b) moving said robot along said one side of said area of concrete; c) moving said lance along said truss; d) supplying water under pressure to said nozzle; e) rotating said nozzle while said nozzle sprays water under pressure onto said area of concrete.

17. The method of claim 16, wherein said step of moving said robot comprises moving said robot an incremental distance then stopping said robot, and, while said robot is stopped, moving said lance along said truss while water under pressure is supplied to said nozzle.

18. The method of claim 17, further including the step of supporting said end of said truss remote from said robot on a rotatable wheel.

19. The method of claim 16, wherein said supplying step comprises supplying water at a pressure of up to 20,000 psi.

20. The method of claim 16, wherein said rotating step comprises rotating said nozzle at 75-300 rpm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 shows a perspective view of a concrete surface, a portion of which has been treated in accordance with the teachings of the present invention.

[0028] FIG. 2 shows an end view of the portion of concrete illustrated in FIG. 1, also showing the inventive robot in place where it is performing the inventive method.

[0029] FIG. 3 shows a close-up view of the lance and shield along with a portion of the elongated truss that supports the lance and shield.

[0030] FIG. 4 shows a side view of the inventive robot, truss, and lance.

[0031] FIG. 5 shows a top view of the robot, truss, and lance shown in FIG. 4.

SPECIFIC DESCRIPTION OF THE PREFERRED EMBODIMENT

[0032] With reference first to FIG. 1, an area of concrete is generally designated by the reference numeral 1 and is seen to include a first region 2 where demolition has not yet taken place, and an area 3 where demolition has taken place and the inventive robot is in operation. The region 3 shows a reduced elevation portion of concrete 4 and the demolition has exposed a lattice work of reinforcing rebar 5 which will be reused in accordance with the teachings of the present invention.

[0033] With reference to FIG. 2, the same area 1 is shown but additionally, the inventive robot 10 is also visible.

[0034] The robot 10 is also seen in particular as an overview in FIGS. 4 and 5. With reference to FIGS. 2, 4 and 5, the robot 10 is supported on tires 11 and a drive mechanism (not shown in detail) is provided to allow controlled rotation of the tires 11 to move the robot 10 as desired. FIG. 2 shows a bundle 13 of conduits extending between the robot 10 and the lance which is generally designated by the reference numeral 15. The bundle of conduits 13 includes conduits supplying hydraulic fluid to a hydraulic motor on the lance 15 that facilitates rapid rotation of the nozzle 17 which is seen in FIG. 4 and is preferably angled at an angle of 25 with respect to a vertical axis 19 so that when the nozzle 17 is rotated, it emits water at high pressure over a wider area than would be the case if it was not angulated with respect to the axis 19. Another conduit within the bundle of conduits 13 supplies high pressure water to the nozzle 17 which is emitted as the lance 15 moves along the truss 21.

[0035] As best seen in FIG. 2, the truss 21 is attached to the robot 10 at a first end 23 and extends a considerable distance to a second end 25 remote from the robot 10 where a support post 27 and wheel assembly 29 are provided to support the end 25 of the truss 21 in a position beyond the edge of the area of concrete being treated in accordance with the teachings of the present invention. As shown in FIG. 2, the robot 10 is located to one side of the area of concrete and the end 25 of the truss 21 is located at another side of the area of concrete, the truss 21 suspended over the area of concrete.

[0036] As briefly explained above, the rotation of the nozzle 17 is accomplished through use of a pump supplying hydraulic fluid to a motor at the lance 15 that rotates the nozzle 17. High pressure water is supplied in one of the conduits of the bundle of conduits 13. The lance 15 travels back and forth along the truss 21 by virtue of wheels 31, 33 (FIGS. 2 and 3) which ride on respective tracks 35 and 37 at the top and bottom of the truss 21. These wheels are operated either by a hydraulic motor or an electric motor which is controlled by a computer to rotate back and forth.

[0037] The robot 10 is also programmed to coordinate with movements of the lance 15 back and forth along the truss 21. In this regard, the computer (not shown) can easily be programmed by one of ordinary skill in the art so that the position of the robot 10 along the area 3 where concrete is to be treated can be coordinated with movements of the lance 15 so that, for example, each time the lance 15 travels from one end 23 of the truss to the other end 25 of the truss, the wheels 11 are caused to move to index the position of the robot 10 by a desired distance, for example, one inch. If desired, this indexing of the position of the robot 10 can be adjusted each time the lance 15 goes back and forth along the truss 21 rather than just from one end to the other.

[0038] U.S. Pat. No. 7,080,888 to Hach, described above, includes a detailed disclosure of the manner by which a robot may be moved, nozzles may be rotated, and pressurized fluid may be supplied to a nozzle as well as the manner by which a nozzle may be moved along a beam. These aspects of the disclosure of this patent are fully incorporated by reference in the present specification and demonstrate that these details are well understood by those of ordinary skill in the art. In the present invention, the nozzle 17 can be rotated from 75 to 300 rpm and water pressure can be up to in the range of 20,000 psi. 25-33 gallons/minute of water may be supplied to the nozzle 17.

[0039] With the inventive robot being described in detail, the method of using it to great advantage will now be described in detail.

[0040] First, an area of concrete where replacement is necessary, is identified. As a first step, impact demolition methods are used to remove concrete. Sometimes this occurs by simply jackhammering to the appropriate depth. Sometimes, it involves a first pass of hydrodemolition which removes much of the old concrete and results in an erratic cut which causes a number of high spots that must be hammered out. It is often the case that the original steel placement varies dramatically from area to area and customers typically require inch bar clearances for the rebar and so after the hydrodemolition, impact hammers are employed to attempt to chip out concrete that remains in place. This hammering operation, either employed on its own or after a first pass of hydrodemolition, creates microfractures in the bonding surface.

[0041] Thus, the next step in the method is to sandblast the entire bonding surface to remove microfractures that would inhibit a strong bond between the new and old concrete. As noted above, however, the sandblasting method has been shown not to remove adequately all the microfractures necessary to achieve the required tensile strength.

[0042] Thus, the inventive robot is next accessed and it is located with the robot vehicle to one side of the area that has already been subjected to demolition and the truss is extended over that area with the wheels 29 supporting the far end 25 of the truss 21 beyond the portion that has been demolished on solid flat concrete. It is noted that Applicant's conventional hydrodemolition robot cannot traverse the area that has been demolished, because that robot is designed to be located on top of an uncut surface; using it on a demolished area would result in an unstable situation including erratic operation and the tendency of rebar to be bent by the heavy machine.

[0043] The inventive robot is activated and through use of a hydraulic pump, conduit, motor combination, the nozzle 17 is rapidly rotated while high pressure water is supplied to the nozzle 17. At the same time, the lance 15 is reciprocated back and forth along the truss 21 from the end 23 to the end 25, and then back to the end 23. As this reciprocation takes place, with each pass over the area to be treated, the position of the robot 10 is indexed in a desired direction by a desired increment, for example, one inch.

[0044] In this way, the entire area previously treated by chipping hammers and sandblasting is again treated with high pressure water to remove any remaining microfractures from the concrete material remaining in place. This is accomplished without doing any damage or bending in any way the rebar that is in place or overexcavating the sound concrete substrate.

[0045] Once this step is completed, the contractor may repair the area by adding forms that cover open areas at the bottom of the concrete such as shown in FIGS. 1-3 and replacement concrete is poured with the existing rebar 5 embedded therein.

[0046] Once this process is completed, and the concrete has appropriately cured, tensile strength bonding tests are conducted in accordance with ASTM procedure C-1583. Applicant has found that such tests will result in a reading of at least 145 psi for the 7-day tensile strength, significantly higher than it was ever before possible to achieve using conventional methods.

[0047] As such, an invention has been disclosed in terms of a method of removing microfractures from concrete subjected to demolition and the apparatus for practicing the method of great novelty and utility.

[0048] Of course, various changes, modifications, and alterations in the teachings of the present invention may be contemplated by those of ordinary skill in the art without departing from the intended spirit and scope thereof.

[0049] As such, it is intended that the present invention only be limited by the terms of the appended claims.