Section 7: Making and Curing Cylinders and Beams

Question 1

For cylinders with a diameter of 6 inches or greater, the tamping rod must have a diameter of?

Answer 1

5/8 inches

Question 2

The minimum frequency of an internal vibrator when making cylinders?

Answer 2

9000 vibrations per minute

Question 3

When casting cylinders, what is the maximum size to not have to wet screen?

Answer 3

2 inches

Question 4

When casting cylinders and using vibration, how many layers must the cylinder be filled in?

Answer 4

2

Question 5

For cylinders with a diameter of less than 6 inches, the tamping rod must have a diameter of?

Answer 5

3/8 inches

Question 6

How long must the vibrator be when casting cylinders?

Answer 6

3 inches longer than the depth

Question 7

What are the ratios used for cylinder mold size?

Answer 7

• Length must be twice the diameter
• Diameter must be x3 the max aggregate size

Question 8

What are the ratios used for beam mold size?

Answer 8

• Length must be at least 2” greater than x3 depth
• Width to depth must not exceed 1.5

Question 9

When do you vibrate a cylinder mold?

Answer 9

Only when the slump is less than 1 inch

Question 10

When you fill a 4 x 8 inch cylinder, how many layers?

Answer 10

2

Question 11

How many vibrations per layer for a 4 x 8 cylinder? 6 x 12?

Answer 11

1; 2

Question 12

What do you use to tap cylinder molds?

Answer 12

Your hand

Question 13

How many times do you rod a beam mold?

Answer 13

Once for every 2 in2

Question 14

How many layers do you fill a beam mold in if you’re rodding?

Answer 14

2

Question 15

What do you use to tap the sides of beam molds?

Answer 15

Mallet

Question 16

What do you do after you tap a beam mold?

Answer 16

Spade the sides and end with a trowel or float

Question 17

How many layers do you fill a beam mold in if you’re vibrating?

Answer 17

1

Question 18

How often and where do you insert a vibrator in a beam mold?

Answer 18

At 6 inch increments along the centerline

Question 19

Where you label molds?

Answer 19

On the side

Question 20

How long do you have to move the molds to their initial curing location?

Answer 20

15 minutes

Question 21

Can you refinish the surface of a cylinder after moving to the initial curing location?

Answer 21

Yes

Question 22

How long must samples of a specified strength be stored prior to transportation to the laboratory?

Answer 22

48 hours

Question 23

What is the temperature range that samples must be initial stored at for concrete with less than 6000 psi strength? 6000 psi or greater?

Answer 23

Less than: 60 to 80°F
Greater than or equal: 68 to 78°

Question 24

What must specimens be protected from?

Answer 24

Sunlight and moisture loss

Question 25

How long until regular specimens can be moved?

Answer 25

8 hours

Question 26

How long can samples be transported for?

Answer 26

4 hours