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Oztec Tips and Suggestions

     
Tips and Suggestions
"The benefits of even the finest concrete vibrator are lost if the proper operating technique is not followed".
     

Proper vibrating techniques will:

  • Produce concrete with the maximum strength and qualities designed in the mix.

  • Bond rebar to maximize strength.

  • Slow penetration of rust causing liquids by increasing density.

  • Eliminate rock pockets and lift lines.

  • Minimize patchwork, improving surface appearance by removing trapped air.

 

Proper consolidation techniques will not:

  • Cause segregation in well designed

  • Eliminate a significant amount of entrained air.

  • Normally damage the lower layers, as long as the concrete in these lower layers becomes plastic under the vibrating action.

 

For Quality Concrete, Oztec Suggests:

1.  Select the largest vibrator suitable for the job.

2.  Insert the vibrator vertically, allowing it to sink to the desired depth by its own weight.  Forcing it may lock it between

     rebars.

3.  Hold the vibrator 5 to 15 seconds then slowly lift vibrator up, staying behind the trapped air's upward movement.  Allow

     about 15 seconds for each 2 foot distance to avoid re-trapping air.

4.  A slight up and down movement will close the hole formed by the vibrator.

5.  Withdraw the vibrator quickly when near the top to prevent churning air into the top layer.

6.  Move vibrator and re-insert at a distance 1 ½ times the Radius of Action…As shown in the diagrams.

7.  Allow vibrator to pass 3 to 6 inches into the preceding layer to ensure knitting the two layers together, insuring a good

     bond and preventing "lift lines" when forms are removed.

8.  Try to limit pours to 2 to 3 feet high, so air has less resistance to escape.

9.  Do Not use vibrator to move concrete laterally…it causes segregation (use a shovel).  Place vibrator in the center of

     mounds to knock them down.

 
  Consolidation eliminates pockets of aggregate and air bubbles maximizing strength, eliminating surface voids bringing sufficient fine material to the surface and against the forms to produce the desired finish. Vibrators consolidate concrete by sending out shock waves which allows aggregate to “float” freely while pushing lighter trapped air up and out of the mix. Vibrators allow pouring stiff mixtures which are stronger, more economical and result in less segregation, less bleeding and less shrinkage cracks..

You know that you have consolidated concrete properly when a thin line of mortar appears along the form near the vibrator or the coarse aggregate disappears into the concrete.
  Proper Vibrating Technique

 

IMPORTANT: Trapped air moves upward in the mix from

 1 to 3 inches per second. (1 inch in near 0 slump; 3 inches

in 4 to 5 inch slump).

 
 
 

Extension Cord Wire Size Per UL Specifications:

Too light an extension cord can cause poor performance and motor burn out.

  Radius of Vibrator Action  
 
    One page is not sufficient to describe the full scope of vibrating concrete. A fine source for more complete information are publications from ACI.  
 

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