CONCRETE POKERS

The article discusses the development of electro-mechanical poker vibrators and their importance in achieving high-strength, quality concrete with the elimination of air voids. Optimum concrete density can be achieved by efficient compaction if the frequency of vibration coincides with the resonant frequency of the concrete grains. Current concrete mixes are said to require a working frequency of internal vibration of about 200 cps. Flexible shaft-driven internal vibrators originally consisted of a driving motor of optional energy form, a flexible shaft guided by A protective hose, and, interchangeable vibrating heads according to site requirements. Later high-frequency designs featured a built-in electric motor driving an eccentrically mounted, or rolling, weight to produce centrifugal forces. A simpler design is the compressed air internal vibrator which incorporates an out-of-balance mass rotating on a carriage and is similar to the flexible shaft equipment. This design has the disadvantage that the hose must be less than 4M long to maintain performance. Later types have higher operating speeds with automatic vibration control and produce 13000-18000 rpm according to concrete consistency. /TRRL/

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/oclc/10480594
• Corporate Authors:

  Morgan-Grampian (Professional Press) Limited

  Morgan-Grampian House, Calderwood Street
  London SE18 6QH,   England 
• Authors:
  • Maschmann, M
• Publication Date: 1976-5

Language

• English

Media Info

• Features: Figures;
• Pagination: p. 3-32
• Serial:
  • Civil Engineering
  • Publisher: American Society of Civil Engineers
  • ISSN: 0885-7024
  • Serial URL: http://www.pubs.asce.org/ceonline/newce/html

Subject/Index Terms

• TRT Terms: Admixtures; Air voids; Automatic control; Automation; Compaction; Compressed air; Concrete; Control; Control devices; Density; Design; Development; Electricity; Equipment; Frequency (Electromagnetism); High strength concrete; Quality control; Strength of materials; Vibration
• Uncontrolled Terms: Quality
• Old TRIS Terms: Air voids content
• ITRD Terms: 3882: Automatic; 3686: Compaction; 3814: Compressed air; 4755: Concrete; 3874: Control; 9011: Design (overall design); 9013: Development; 6954: Electricity; 3674: Equipment; 6997: Frequency; 9063: Quality; 5544: Strength (mater); 5558: Vibration
• Subject Areas: Design; Highways; Materials; Planning and Forecasting; I32: Concrete; I72: Traffic and Transport Planning;

Filing Info

• Accession Number: 00142110
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Report/Paper Numbers: Serial
• Files: ITRD, TRIS
• Created Date: Jun 17 1977 12:00AM