NETTCP Concrete Testing 4

Question 1

For a concrete pavement project, the maturity method is used to estimate strength. What two quantities are measured continuously?

Accepted Answer

Temperature and time

Answer

The maturity method (ASTM C1074) tracks temperature and time to calculate a maturity index that correlates to strength gain.

Question 2

What is the minimum number of test cylinders that must be made from a single composite sample to represent one strength test result?

Accepted Answer

2 cylinders

Answer

A strength test result is the average of at least 2 cylinders made from the same composite sample and tested at the same age.

Question 3

Which AASHTO standard governs the making and curing of concrete test specimens in the field?

Accepted Answer

AASHTO T 23

Answer

AASHTO T 23 is the standard method for making and curing concrete test specimens in the field.

Question 4

A concrete mix has a design strength (f'c) of 4,000 psi. What minimum average strength (f'cr) must be targeted to account for variability?

Accepted Answer

4,700 psi or higher depending on standard deviation

Answer

ACI 318 requires the required average strength f'cr to exceed f'c by an amount based on the standard deviation of past test data, typically 700–1,200 psi or more.

Question 5

When striking off the top of a concrete cylinder mold, what tool is most appropriate?

Accepted Answer

A flat glass plate or steel plate

Answer

A flat glass or steel plate is used to strike off the cylinder top to achieve a smooth, level surface perpendicular to the axis.

(NETTCP) New England Transportation Technician Certification Program Practice Test

(NETTCP) New England Transportation Technician Certification Program Practice Test

NETTCP Concrete Testing 4