With internal or external vibrators, worker skill and concrete properties are critical.
Vibration plays a vital role in achieving the desired surface finish for manufactured concrete products. The difference between acceptable and unacceptable results is certainly affected by equipment choices that include vibrator type (internal or external) and vibrator characteristics (frequency and amplitude). But vibration equipment is only one factor that affects surface finish.
This article reviews both internal and external vibration. Internal topics are insertion spacing, penetration depth into previous lift, and vibration duration. Accompanying a discussion of external vibration are details on forms for both methods, mix considerations, and vibration tips.
KEYWORDS: precast production, external vibration, internal vibration