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Water jetting

The task

Removing damaged or weathered concrete surfaces.

The problem

The deck and side walls of a reinforced concrete road bridge had decayed to the extent that surface repairs were needed. The top few centimetres of concrete needed to be removed and replaced with new material. The traditional method of removing the old material is to use hand-held pneumatic breakers, which can expose workers to typical vibration magnitudes of 12 m/s2 for about 3 hours per day. The use of percussive tools can also damage the reinforcement bar, which then has to be repaired or replaced, and cause cracking in the base concrete which may weaken the structure. The operators work to a specified depth, often unnecessarily removing sound material and leaving areas of deep damaged material. The surface also requires thorough cleaning before new concrete can be applied. The job would have taken about 60 worker days with the breakers, as well as additional time to repair the reinforcement bar and other damage.

The solution

The job was done with a robot-mounted water jetting machine. This process uses an extremely high pressure water jet to wear away the old damaged concrete. The jet removes all concrete up to a certain strength, regardless of depth, leaving the good material and removing all of the damaged material.

 Robot machine water jetting a bridge side wall

Robot machine water jetting a bridge side wall

 Concrete surface after water jetting

Concrete surface after water jetting

The cost

The water jetting process was more expensive than the use of hand-held breakers. However, the cost of repairs to the reinforcement bar and base concrete was eliminated. These reinstatement costs often result in total project costs significantly higher than those for the water jetting method.

The result

  • Operators are not exposed to any hand-arm vibration.
  • The reinforcement bar was completely unaffected and there was no damage to the base concrete structure so it was immediately ready for the application of new concrete.
  • The new concrete adheres better to the jetted surface.
  • Airborne dust levels are very low as the debris is washed away by the water.

Link URLs in this page

  1. Vibrationhttps://www.hse.gov.uk/vIBRAtIon/index.htm
  2. Hand arm vibrationhttps://www.hse.gov.uk/vIBRAtIon/hav/index.htm
  3. About this websitehttps://www.hse.gov.uk/vIBRAtIon/hav/about.htm
  4. Key messageshttps://www.hse.gov.uk/vIBRAtIon/hav/keymessages.htm
  5. Worried about your handshttps://www.hse.gov.uk/vIBRAtIon/hav/yourhands.htm
  6. Overview - Advice for employershttps://www.hse.gov.uk/vIBRAtIon/hav/advicetoemployers/index.htm
  7. Employers responsibilitieshttps://www.hse.gov.uk/vIBRAtIon/hav/advicetoemployers/responsibilities.htm
  8. Assess riskhttps://www.hse.gov.uk/vIBRAtIon/hav/advicetoemployers/assessrisks.htm
  9. Overview - How to protect workershttps://www.hse.gov.uk/vIBRAtIon/hav/advicetoemployers/protect.htm
  10. Control riskhttps://www.hse.gov.uk/vIBRAtIon/hav/advicetoemployers/controlrisks.htm
  11. Information and traininghttps://www.hse.gov.uk/vIBRAtIon/hav/advicetoemployers/information.htm
  12. Health surveillancehttps://www.hse.gov.uk/vIBRAtIon/hav/advicetoemployers/healthsurveillance.htm
  13. Overview - Good practicehttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/index.htm
  14. Overview - Foundrieshttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/index.htm
  15. Eliminate fettling by improving casting qualityhttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/fettlingelimination.htm
  16. Machining as a substitute for fettlinghttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/machining.htm
  17. Automatic fettlinghttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/automaticfettling.htm
  18. Jig-mounting of grindershttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/jigmounting.htm
  19. Semi-automatic cut off machinehttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/cutoffmachine.htm
  20. Isolated casting cut offhttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/isolatedcasting.htm
  21. Installation of hydraulic cropping machinehttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/hydrauliccropping.htm
  22. Shell knockout 1https://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/castingshell.htm
  23. Shell knockout 2https://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/contactcastingshell.htm
  24. Hydraulic pushouthttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/furnaceliningremoval.htm
  25. Ladle slag chippinghttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/foundries/chippingslag.htm
  26. Overview - Constructionhttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/index.htm
  27. Preparing a code of practicehttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/tunnelling.htm
  28. Construction Industry Council guidancehttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/cicguidance.htm
  29. Mounted breakerhttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/mountedroadbreaker.htm
  30. Directional drillinghttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/directionaldrilling.htm
  31. Crushing concretehttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/crushingconcrete.htm
  32. Bursting concretehttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/burstingconcrete.htm
  33. Diamond wire cuttinghttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/diamondwire.htm
  34. Water jettinghttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/waterjetting.htm
  35. Codes of Practice from the Water Jetting Associationhttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/codeofpractice.htm
  36. Grit blastinghttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/gritblasting.htm
  37. Paint-on retarderhttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/paintonmaterial.htm
  38. Special formworkhttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/construction/specialformwork.htm
  39. Overview - Steel fabricationhttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/fabrication/index.htm
  40. Machininghttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/fabrication/cncmachining.htm
  41. Laser cuttinghttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/fabrication/lasercutter.htm
  42. Plasma cuttinghttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/fabrication/plasmacutting.htm
  43. Noise reduction in the ship repair industry – research report 1992https://www.hse.gov.uk/vIBRAtIon/hav/campaign/fabrication/noisereduction.htm
  44. Abrasive blastershttps://www.hse.gov.uk/vIBRAtIon/hav/campaign/fabrication/abrasiveblasters.htm
  45. Overview - Regulationshttps://www.hse.gov.uk/vIBRAtIon/hav/regulations.htm
  46. Inspector briefinghttps://www.hse.gov.uk/vIBRAtIon/hav/inspectorbriefing.htm
  47. Overview - Resourceshttps://www.hse.gov.uk/vIBRAtIon/hav/information.htm
  48. Publicationshttps://www.hse.gov.uk/vIBRAtIon/hav/publications.htm
  49. Researchhttps://www.hse.gov.uk/vIBRAtIon/hav/research.htm
  50. Statisticshttps://www.hse.gov.uk/vIBRAtIon/hav/statistics.htm
  51. Useful linkshttps://www.hse.gov.uk/vIBRAtIon/hav/links.htm
  52. Vibration calculatorhttps://www.hse.gov.uk/vIBRAtIon/hav/calculator-guide.htm
  53. Overview - Case studieshttps://www.hse.gov.uk/vIBRAtIon/hav/casestudies/index.htm
  54. (HAVS) in two motor companieshttps://www.hse.gov.uk/vIBRAtIon/hav/casestudies/enforceex.htm
  55. Monitoring exposure to Hand-Arm Vibrationhttps://www.hse.gov.uk/vIBRAtIon/hav/casestudies/mhav-carlwest.htm
  56. Overview - Supply project eventshttps://www.hse.gov.uk/vIBRAtIon/hav/project-events.htm
  57. Controlling vibrationhttps://www.hse.gov.uk/vIBRAtIon/hav/controlling-vibration.htm
  58. Q & A on hand toolshttps://www.hse.gov.uk/vIBRAtIon/hav/hand-tools-qa.htm
  59. Q & A on using a vibration consultanthttps://www.hse.gov.uk/vIBRAtIon/hav/qa-consultant.htm
  60. Q & A on health surveillancehttps://www.hse.gov.uk/vIBRAtIon/hav/qa-surveillance.htm
  61. Tunnelling and Pipejacking: Guidance for Designers https://www.hse.gov.uk/construction/pdf/pjaguidance.pdf
  62. Pile cropping. A review of current practice https://www.hse.gov.uk/vIBRAtIon/assets/docs/pilecrop.pdf
  63. Hand-arm vibration at work: A brief guide https://www.hse.gov.uk/pubns/indg175.htm
  64. Advice for employershttps://www.hse.gov.uk/vIBRAtIon/hav/advicetoemployers/index.htm
  65. Regulationshttps://www.hse.gov.uk/vIBRAtIon/hav/regulations.htm
  66. How to protect workershttps://www.hse.gov.uk/vIBRAtIon/hav/advicetoemployers/protect.htm
  67. Constructionhttps://www.hse.gov.uk/construction/index.htm
  68. Engineeringhttps://www.hse.gov.uk/engineering/index.htm
  69. Motor vehicle repairhttps://www.hse.gov.uk/mvr/index.htm
  70. Noisehttps://www.hse.gov.uk/noise/index.htm
  71. Quarrieshttps://www.hse.gov.uk/quarries/index.htm
  72. Agriculturehttps://www.hse.gov.uk/agriculture/index.htm

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Updated: 2021-05-20