ASTM C 138 - DENSITY (UNIT WEIGHT) OF CONCRETE

Question 1

Volume of Concrete

What is the DEFINITION of YIELD

Answer 1

Volume of concrete produced from known weights of component materials.

Question 2

__ lbs

What must the scale for density measurments be accurate up to?

Answer 2

Accurate to 0.1 lbs

Question 3

__ lbs/ft^3

What is a scales required MAXIMUM measuring capablities for densities of concrete?

Answer 3

160 lbs/ft³

Question 4

5/8 inch +- __ inch

What is the DIAMETER of the tamping rod for concrete density?

Answer 4

5/8 inch

+- 1/16 inch diameter

Question 5

How much LONGER must the tamping rod be than the depth of the mold?

Answer 5

4 inches longer

Question 6

What is the TYPICAL AND MAXIMUM LENGTH of the tamping rod used for densities?

Answer 6

24 inches

Question 7

3/4 inch - __ inch

What must the outside diameter of the vibration rod be between?

Answer 7

3/4 inch - 1 1/2 inch

Question 8

9___ vibrations/minute

What is the MINIMUM vibrating frequency for an internal vibrator? (150 Hz)

Answer 8

9,000 vibrations/minute

Question 9

How much longer must the vibrator be vs. the depth of the density container?

Answer 9

3 inches

Question 10

Every __ years

How often must a vibrator be checked and verified?

Answer 10

Every 2 years

Question 11

What must a vibrator be verified by?

Answer 11

Tachometer

Question 12

If the Nominal Aggregate Size of the sample is 1 inch – What must the MINIMUM bucket volume be?

Answer 12

0.2 ft³

Question 13

If the Nominal Aggregate Size of the sample is 1 1/2 inch – What must the MINIMUM bucket volume be?

Answer 13

0.4 ft³

Question 14

If the Nominal Aggregate Size of the sample is 2 inch – What must the MINIMUM bucket volume be?

Answer 14

0.5 ft³

Question 15

If the Nominal Aggregate Size of the sample is 3 inches – What must the MINIMUM bucket volume be?

Answer 15

1.0 ft³

Question 16

If the Nominal Aggregate Size of the sample is 4 1/2 inch – What must the MINIMUM bucket volume be?

Answer 16

2.5 ft³

Question 17

If the Nominal Aggregate Size of the sample is 6 inch – What must the MINIMUM bucket volume be?

Answer 17

3.5 ft³

Question 18

M__, P__, G__

What are the THREE different types of materials that strike-off plates are made of?

Answer 18

1) Metal
2) Plastic
3) Glass

Question 19

What is the MINIMUM thickness for a METAL strike-off plate?

Answer 19

1/4 inch

Question 20

What is the MINIMUM thickness for a PLASTIC strike-off plate?

Answer 20

1/2 inch

Question 21

What is the MINIMUM thickness for a GLASS strike-off plate?

Answer 21

1/2 inch

Question 22

How much WIDER must the strike-off plate than the diameter of the density measure

Answer 22

2 inches

Question 23

__ lbs +- 0.5 lbs

What is the mallet size required for a 1/2 ft³ measure AND SMALLER?

Answer 23

1.25 lbs +- 0.5lbs

Question 24

__ lbs +- 0.5 ;bs

What is the mallet size required for a LARGER THAN 1/2 ft³ ​measure?

Answer 24

2.25 lbs

+- 0.5 lbs

Question 25

# Rodding, Vibration, or Both? What method of consolidation must be used when measuring a slump of **\>3 inches**?

Answer 25

Rodding

Question 26

# Rodding, Vibration, or Both? What method of consolidation must be used when measuring a **slump between 1 inch and 3 inches**?

Answer 26

Vibration OR Rodding

Question 27

# Rodding, Vibration, or Both? What method of consolidation must be used when measuring a **slump of \<1 inch**?

Answer 27

Vibration

Question 28

Do you wet sieve for denisty? YES OR NO?

Answer 28

NO

Question 29

What is the rodding procedure for a density measure of 1/2 ft³ or smaller?

Answer 29

Rod each layer 25 times

Question 30

What is the rodding procedure for a density measure of 1 ft³?

Answer 30

Rod each layer 50 times

Question 31

# 1 time for each __ in^2 of surface area What is the rodding procedure for a density measures of larger than 1 ft³?

Answer 31

Rod each layer: 1 time for each 3 in² of surface area

Question 32

# 3 -- when rodding --\> __ when vibrating What is the amount of lifts when rodding vs. when vibrating?

Answer 32

3 -- lifts when rodding 2 -- lifts when vibrating

Question 33

When vibrating a measure for density -- at how many DIFFERENT points do you insert the vibrator?

Answer 33

3 DIFFERENT points

Question 34

# \_/8 inch How much OVER the lip of the measure do you want your concrete to be? (Inch)

Answer 34

1/8 inches

Question 35

What do you do if you strike-off your measure and you DO NOT HAVE ENOUGH CONCRETE in your measure?

Answer 35

You MUST empty the measure and re-fill again

Question 36

# 2/\_\_ of measure When sawing excess concrete off of measure -- how far onto the plate do you place the strike-off plate onto the measure? (In Fraction)

Answer 36

Across 2/3 of the measure

Question 37

# Back/Forward/Clean Describe the strike-off procedure for density measure in 3 STEPS?

Answer 37

1) Place plate 2/3 onto measure and **SAW BACK** 2) Place place 2/3 onto measure and **SAW FORWARD** 3) Clean outside of the measure