TECHNICAL HINTS FOR VIBRATING SEPTIC TANKS AND BURIAL VAULTS

Some experimentation on the customers part is always necessary because the end result is determined by the way the forms react to vibration transfer, the concrete mix, the additives used, and the form oil. For casting septic tanks we recommend the use of two vibrators.

Start the pour as usual, and if a continuous and quick pour is planned, begin to vibrate when concrete is 1/2? above vibrator. If vibration is ample you should notice a leveling off of concrete and glossy surface and air bubbles rising to the surface. Continue vibrating for about a minute after pour is completed If placement of concrete is intermittent then vibrate for 1 to 2 minutes more after each pour.

When the concrete has been thoroughly vibrated a glossy surface and few (if any) air bubbles bursting on the surface will appear.

HELPFUL HINTS AND CORRECTIONS AFTER YOU STRIP FORM.

1. Separation of aggregate (too long vibration time or too much water in mix)
2. Bleeding of cement and water (tighten seals in form or use less water).
3. Honeycomb (often from bleeding, but if not, increase vibration time. If honeycomb on lower surface, move one vibrator lower).
4. Small pinholes in finish (often difficult to determine cause). Usually from: too wet mix; air entering, or other additives; possibly from form oil, or boiling in of air from action of form where form wall is too flimsy and flexes too much, weld on stiffeners to form wall).
5. Larger pinholes ? if all over, try reducing water content, vibrating longer after pour, adding additional vibrator, or re-vibration before initial set.

BURIAL VAULTS

Model VSP-510 Rotary Piston Vibrator used on Burial Vault. Same wedge brackets and vibrators as on septic tanks can also be used. Wedge brackets give a 90-100% vibration transfer. Pin brackets 60-75%.