CT 521 Compressive Strength

Question 1

What is the rate of loading for cylinders?

Answer 1

35+-7 psi/s

Question 2

Compressive Strength is rounded to what?

Answer 2

Nearest 10 psi

Question 3

For averaging multiple compressive strength results, do you average the unrounded result or rounded?

Answer 3

Unrounded

Question 4

Average compressive strength is rounded to what?

Answer 4

Nearest 10 psi

Question 5

What is the formula for calculating compressive strength?

Answer 5

fcm= (4Pmax)/(πD^2)

Question 6

In the Compressive strength formula identify the variables? Fcm, Pmax, D

Answer 6

Fcm = compressive strength, Pmax=max force pounds, D=diameter

Question 7

Will the compressive force pounds change with different size samples?

Answer 7

Yes

Question 8

Specimens shall not be tested if any individual diameter of a cylinder differs from any other diameter of the same cylinder by more than ___%.

Answer 8

2%

Question 9

How long should sulfur mortar be allowed to harden before testing if expected to break below 5000psi?

Answer 9

2 hours

Question 10

How long should sulfur mortar be allowed to harden before testing if expected to break above 5000psi?

Answer 10

16 hours

Question 11

Sulfur mortar should be brought to what temperature range?

Answer 11

265-290°F

Question 12

What is the tolerance for the uncapped end of a cylinder?

Answer 12

1/8 inch

Question 13

What must be done if the tolerance is outside of 1/8”?

Answer 13

The end shall be cut, lapped, or ground prior to capping.

Question 14

Sulfur mortar caps should be within what tolerance for planeness?

Answer 14

0.002 inches

Question 15

How do you check for planeness on sulfur mortar caps?

Answer 15

Using a straight edge and a feeler gauge.

Question 16

A cap must be replaced if a void or steam pocket is larger than _____.

Answer 16

1/4 inch

Question 17

If sulfur mortar catches fire, how do you put it out?

Answer 17

Cover and snuff out.

Question 18

Unbonded caps should be used between what psi?

Answer 18

1500-12000 psi

Question 19

How thick should be the neoprene pads for unbonded caps?

Answer 19

1/2 +- 1/16”

Question 20

The diameter of the neoprene pad shall not be more than ______ smaller than the inside diameter of the retaining ring.

Answer 20

1/16”

Question 21

The height of the retaining ring shall be how tall?

Answer 21

1.0 +- 0.1”

Question 22

The inside diameter of the retaining ring shall be not less than_____ or greater than _______ of the diameter of the specimen.

Answer 22

102%, 107%

Question 23

How thick should the retainer ring be for 4” diameters or less?

Answer 23

0.35”

Question 24

What is the thickness of the baseplate for 4” diameter or less?

Answer 24

0.30”

Question 25

How thick should the retainer ring and baseplate be for 4" diameters or greater?

Answer 25

0.47"

Question 26

Specimens with depressions under a straight edge across any diameter shall not exceed what?

Answer 26

0.20"

Question 27

What must happen to a specimen that has depressions greater than 0.20"?

Answer 27

The specimen must be corrected by sawing or grinding.

Question 28

Unbonded cap tested cylinders must be within what percent of the capped cylinders?

Answer 28

Within 98% of the average.

Question 29

Cylinders being tested shall not have strengths greater or lower than what percent of the high level strength and low level strength level specified in the durometer table?

Answer 29

10% higher than the high and 10% lower than the low

Question 30

When establishing the number of reuses for the pads, only those tests which are within _________ of the highest strength level to be qualified will be included in the reuse count.

Answer 30

2000 psi