Section 4: Density (Unit Weight) and Yield** Flashcards
What is the length of tamping rod?
4 inches taller than the equipment 16 to 24 inches
Minimum frequency of vibrator in density test?
9000 vibrations per minute
Size of vibrator in density test?
3/4 to 1 1/2 inches in diameter
What is the minimum thickness of a strike-off plate made of glass or acrylic?
1/2 inch
How much wider must a strike-off plate be?
1 inch on all sides
What is the minimum thickness of a strike-off plate made of metal?
1/4 inch
What is the weight of a mallet used for measures 1/2 ft3 or less?
1 1/4 lb +/- 1/2 lb (3/4 to 1 3/4 lb)
What is the weight of a mallet used for measures greater than 1/2 ft3?
2 1/4 lb +/- 1/2 lb (1 3/4 to 2 3/4 lb)
What method of consolidation must be used when the slump is greater than 3 inches?
Rodding
What method of consolidation must be used when the slump is less than 1 inch?
Vibration
If rodding during a density test, how many layers?
3
If using a vibrator during a density test, how many layers?
2
How accurate should density be recorded?
0.1 lb/ft3
What happens during each layer during a density test? (Rodding)
- Adding 1/3 of volume
- Rodding 25 times
- Tapping side 10 to 15 times, evenly distributed
What is the ideal amount of excess concrete above the measure during a density test?
1/8 inch