Grit blasting instead of scabbling

The task

Constructing concrete structures.

The problem

A construction company was building one of the stations for the London Underground Jubilee Line extension. The main structure of the station is concrete which was being cast in situ in stages. The meeting surfaces of each section have to be prepared before the adjacent section is cast to ensure an effective bond. In some parts of the structure, this was done using a special expanded metal material which forms the bond itself. However, this material is not suitable for use on thin sections of concrete which meant the joints in these sections had to be prepared in some other way. They could have been prepared using impulsive scabbling tools such as needle guns, but workers would have been exposed to vibration magnitudes of about 18 m/s2 for up to 2 hours per shift. These tools also produce high noise levels.

The solution

The surfaces were prepared by grit blasting. A sub-contract gang was able to blast about 300 m 2 of the surfaces per day per worker. Before the work began, screens were erected around the area to be blasted to prevent dust from blowing around the site. The grit blasting method compares favourably with the use of impulsive scabblers which may prepare as little as 8 m 2 of the surface per day per worker.

The result

  • The operators are not exposed to any vibration with grit blasting.
  • Grit blasting is much faster than scabbling but may increase exposure to dust and noise which will require further assessment and control measures.

Case courtesy of Tarmac Bachy Joint Venture

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: 2021-11-09