CCIL Concrete 2

Question 1

According to CSA A23.1, what is the minimum curing period for concrete exposed to freezing temperatures before it can be considered adequately cured?

Accepted Answer

7 days at 10°C

Answer

CSA A23.1 requires concrete to be maintained at a minimum of 10°C for at least 7 days to achieve adequate early strength before exposure to freezing.

Question 2

When performing a slump test per ASTM C143/CSA A23.2-5C, the concrete is rodded in how many layers?

Accepted Answer

3 equal layers

Answer

The slump test requires filling the mold in 3 equal layers, each rodded 25 times with a tamping rod.

Question 3

What does a bleeding rate in fresh concrete primarily indicate?

Accepted Answer

Excess mix water migrating to the surface

Answer

Bleeding occurs when excess mix water rises to the surface of fresh concrete due to settlement of heavier solids.

Question 4

In CCIL concrete testing, what is the purpose of the air content test performed per ASTM C231?

Accepted Answer

Determining entrained and entrapped air in fresh concrete

Answer

ASTM C231 (pressure method) measures the air content of freshly mixed concrete to verify adequate air entrainment for freeze-thaw durability.

Question 5

Which failure mode is expected during a standard compressive strength test of a properly made and tested concrete cylinder?

Accepted Answer

Diagonal shear cone fracture or columnar cracking with end cones

Answer

Acceptable failure patterns for concrete cylinders include diagonal shear cones, columnar cracks, or combinations; these indicate valid test results per ASTM C39.

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL Concrete 2