NETTCP Concrete Testing 5

Question 1

A concrete cylinder fails at 3,800 psi at 28 days when the specified f'c is 4,000 psi. What is the immediate required action?

Accepted Answer

Investigate per ACI 318 — core the structure or use other strength evidence

Answer

ACI 318 requires investigation when cylinders fall below f'c, which may include coring the in-place concrete before rejection.

Question 2

During a concrete pour in cold weather, the minimum concrete temperature as delivered is typically required to be at least:

Accepted Answer

50°F (10°C)

Answer

ACI 306 requires fresh concrete temperature to be at least 50°F (10°C) as delivered to maintain adequate strength gain in cold weather.

Question 3

What does a Type C fracture pattern (cone and split) in a 4×8-inch cylinder typically indicate?

Accepted Answer

An acceptable fracture pattern within normal test expectations

Answer

A cone-and-split fracture (Type 3 per ASTM C39) is a normal, acceptable fracture pattern for cylinder compression tests.

Question 4

For a concrete air content test using the volumetric method (AASHTO T 196), which aggregate type requires this method instead of the pressure meter?

Accepted Answer

Lightweight aggregate

Answer

The volumetric method is required for lightweight aggregates and highly porous aggregates that absorb pressure, making the pressure method unreliable.

Question 5

When transporting fresh concrete field samples to the testing area, the maximum elapsed time between obtaining the sample and starting tests is:

Accepted Answer

15 minutes

Answer

AASHTO R 60 requires that tests begin within 15 minutes of obtaining the composite sample.

(NETTCP) New England Transportation Technician Certification Program Practice Test

(NETTCP) New England Transportation Technician Certification Program Practice Test

NETTCP Concrete Testing 5