CT 524 - Flexural Strength of Rapid Strength Concrete

Question 1

Rapid Strength Concrete is used for short construction windows of ___ to ______ hours.

Answer 1

6 to 55 hours

Question 2

Rapid curing typically is ___ to ____ hours.

Answer 2

3 to 24 hours

Question 3

Molds should be coated with release agent before making specimens.

Answer 3

Yes

Question 4

What kind of release agent should be used for beam molds?

Answer 4

Any suitable release agent like Mineral oil.

Question 5

What are the dimensions of the beam molds?

Answer 5

6”x6” and at least 20” minimum length

Question 6

Rodding or vibrating should only be used?

Answer 6

Vibrating only.

Question 7

Vibrators should have a frequency of ______ vibrations per minute or ______ Hz.

Answer 7

7000 vibrations per minute or 150 Hz

Question 8

The diameter of the vibrator shall be how not bigger than_____.

Answer 8

One third the width of the beam mold.

Question 9

The length of the vibrator shaft and element shall exceed the depth of the form by at least _______.

Answer 9

3 inches

Question 10

Temperature of the lime saturated water should be__________.

Answer 10

73° F +- 3° F

Question 11

The span length of the beam breaker should be

Answer 11

18” +- 1/16”

Question 12

How many beams should be made for each set?

Answer 12

3 beams

Question 13

What should be done with the concrete composite sample before filling beam molds?

Answer 13

Remix concrete sample.

Question 14

Beams must be cast where in relation to the slab?

Answer 14

Immediately adjacent to the slab.

Question 15

Beams must be cast within how long of time?

Answer 15

Within 10 mins

Question 16

How many lifts are placed into the beam?

Answer 16

1 lift

Question 17

Placing concrete, vibrating, striking off should not result in _________.

Answer 17

Segregation

Question 18

Finish the surface of the specimens with a ___________ of manipulation necessary.

Answer 18

Minimum

Question 19

Record beam fabrication _________, ____________, __________, ________, and __________.

Answer 19

Fabrication time, date, weather, ambient temperature, and number of beams fabricated for each age tested.

Question 20

Apply what to the top of the beam?

Answer 20

Apply the same curing medium.

Question 21

Where do you place the beam on the slab?

Answer 21

When the slab can take foot traffic.

Question 22

Cover the beams with what?

Answer 22

Cover the beams with an insulating blanket.

Question 23

Cover the beams with what during transport for flex strength test greater than 7 days.

Answer 23

Wet towels

Question 24

Place the beams where for curing?

Answer 24

Lime bath, curing room, or sand pit.

Question 25

How long should the beam be in the water or moist cure room?

Answer 25

Between 5 and 10 times final set time or 24 hours, which ever is earlier.

Question 26

Specimens should be transferred from sand pit to water bath how long before testing?

Answer 26

24 +- 6 hours

Question 27

Keep the beams thoroughly __________ throughout the curing period.

Answer 27

Damp

Question 28

Span length of beam should be ____________.

Answer 28

18” +- 1/16”

Question 29

What rate is the beam broken at?

Answer 29

125-175 psi/min

Question 30

What is the formula if the fracture is in the middle third?

Answer 30

R=1.05(Pl/b(d^2))

Question 31

What is the formula if the fracture is outside of the middle third by no more than 5% of span length?

Answer 31

R=3.15(Pa/b(d^2))

Question 32

What happens if the fracture is outside of the 5% from the middle third?

Answer 32

Discard the test

Question 33

Round width and depth measurements to what?

Answer 33

Nearest 1/16”

Question 34

Round modulus of rupture to what?

Answer 34

Nearest 10 psi