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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
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