Section 7: Making and Curing Cylinders and Beams Flashcards
For cylinders with a diameter of 6 inches or greater, the tamping rod must have a diameter of?
5/8 inches
The minimum frequency of an internal vibrator when making cylinders?
9000 vibrations per minute
When casting cylinders, what is the maximum size to not have to wet screen?
2 inches
When casting cylinders and using vibration, how many layers must the cylinder be filled in?
2
For cylinders with a diameter of less than 6 inches, the tamping rod must have a diameter of?
3/8 inches
How long must the vibrator be when casting cylinders?
3 inches longer than the depth
What are the ratios used for cylinder mold size?
- Length must be twice the diameter
- Diameter must be x3 the max aggregate size
What are the ratios used for beam mold size?
- Length must be at least 2” greater than x3 depth
- Width to depth must not exceed 1.5
When do you vibrate a cylinder mold?
Only when the slump is less than 1 inch
When you fill a 4 x 8 inch cylinder, how many layers?
2
How many vibrations per layer for a 4 x 8 cylinder? 6 x 12?
1; 2
What do you use to tap cylinder molds?
Your hand
How many times do you rod a beam mold?
Once for every 2 in2
How many layers do you fill a beam mold in if you’re rodding?
2
What do you use to tap the sides of beam molds?
Mallet
What do you do after you tap a beam mold?
Spade the sides and end with a trowel or float
How many layers do you fill a beam mold in if you’re vibrating?
1
How often and where do you insert a vibrator in a beam mold?
At 6 inch increments along the centerline
Where you label molds?
On the side
How long do you have to move the molds to their initial curing location?
15 minutes
Can you refinish the surface of a cylinder after moving to the initial curing location?
Yes
How long must samples of a specified strength be stored prior to transportation to the laboratory?
48 hours
What is the temperature range that samples must be initial stored at for concrete with less than 6000 psi strength? 6000 psi or greater?
Less than: 60 to 80°F
Greater than or equal: 68 to 78°
What must specimens be protected from?
Sunlight and moisture loss
How long until regular specimens can be moved?
8 hours
How long can samples be transported for?
4 hours
