CT 523 - Flexural Strength

Question 1

What type of loading is done to complete this test? 1st point loading, 2nd point loading, 3rd point loading

Answer 1

3rd point loading

Question 2

To what accuracy must the testing machine be accurate to of the maximum load?

Answer 2

1% accuracy

Question 3

When must the test machine be verified or calibrated? 5 part answer

Answer 3

1. Within 13 months of last verification, 2. On original installation, 3. After relocation, 4. After making repairs or adjustments that affect the operation of the force being applied, 5. Whenever there is reason to suspect the accuracy of the indicated forces.

Question 4

The flexural testing apparatus shall be capable of maintaining the span length and distance between the lines of loading within how much?

Answer 4

+- 0.05”

Question 5

The ratio of the horizontal distance between the line of application of the force and the line of the nearest reaction to the depth of beam shall be?

Answer 5

1.0 +- 0.03

Question 6

Loading blocks and support blocks shall not be more than ______ high.

Answer 6

2.50”

Question 7

Each block surface in contact with the specimen shall not depart from a plane by more than ___________.

Answer 7

0.002”

Question 8

Support blocks shall be _______ to _________.

Answer 8

Free to rotate.

Question 9

All surfaces shall be __________ and _______ of scars, indentation, holes, or inscribed identification marks.

Answer 9

Smooth and free

Question 10

The smaller cross sectional dimension of the beam is at least __________ times the nominal maximum size of the coarse aggregate.

Answer 10

Three

Question 11

What is the permissible tolerance in hours of when the specimen should be tested for 28 Day test age?

Answer 11

+- 20 hours

Question 12

What range of force is the specimen brought to for checking gaps with a feeler gage?

Answer 12

3-6% of ultimate force

Question 13

What feeler gage range is used to determine if shims should be used? Over how wide?

Answer 13

0.004” - 0.015”, 1”

Question 14

What are the dimensions of leather shims?

Answer 14

0.25” thick, 1-2” wide, and full width of specimen

Question 15

Is grinding allowed instead of shims?

Answer 15

Yes

Question 16

Is capping allowed to get rid of gaps?

Answer 16

Yes

Question 17

What range of psi/min should the specimen be loaded to?

Answer 17

125-175 psi/min

Question 18

What rate range in lbs/min should a 6”x6”x18” specimen be loaded to?

Answer 18

1500-2100 lb/min

Question 19

When should the six measurements be taken of the specimen and where?

Answer 19

After rupture and of the fracture face

Question 20

Where should the six measurements be taken?

Answer 20

3 for width, one at each edge with one in the middle, 3 for depth, one at each edge and one in the middle

Question 21

What should be done with the 3 measurements of taken from each depth and width?

Answer 21

Averaged

Question 22

What should be fractured face measurements be rounded to?

Answer 22

0.05”

Question 23

If the fracture occurs in the tension surface outside of the middle third of the span length by not more than ___% of the span length

Answer 23

5%

Question 24

Identify each of the formulas below:
R=PL/bd^2 R=3Pa/bd^2

Answer 24

R=PL/bd^2 is used for middle third rupture and R=3Pa/bd^2 is used for rupture outside of the middle third but within 5% of length.

Question 25

If fracture occurs outside of the middle third and not within 5% of the span length what should occur?

Answer 25

Test is discarded.

Question 26

What should the modulus of rupture be rounded to in psi?

Answer 26

5 psi