CCIL Concrete 4

Question 1

The rebound hammer test (Schmidt hammer) per ASTM C805 is best used for:

Accepted Answer

Assessing uniformity and relative strength differences in-place

Answer

The rebound hammer is an in-situ non-destructive test for assessing concrete uniformity and identifying relative variations in strength, not an absolute strength measurement.

Question 2

What is the term for the phenomenon where concrete continues to gain strength beyond 28 days due to continued cement hydration?

Accepted Answer

Long-term strength gain

Answer

Concrete continues to hydrate and gain strength well beyond 28 days, a process known as long-term strength gain, especially with SCMs present.

Question 3

In mix design, the term 'nominal maximum aggregate size' refers to:

Accepted Answer

The smallest sieve through which 100% of aggregate passes but larger than the sieve retaining more than 15%

Answer

Nominal maximum aggregate size is defined as the smallest sieve size through which 100% of aggregate passes, with the next larger sieve retaining more than 15%.

Question 4

Alkali-silica reaction (ASR) in concrete is characterized by:

Accepted Answer

Expansive gel formation causing cracking and map cracking (crazing)

Answer

ASR occurs when alkalis in cement react with reactive silica in aggregates, forming a hygroscopic gel that absorbs water and expands, causing internal cracking and map cracking.

Question 5

When performing the splitting tensile strength test (ASTM C496), the load is applied along:

Accepted Answer

A diametral plane along the length of the cylinder via bearing strips

Answer

In the splitting tensile test, load is applied through two narrow bearing strips along a diametral plane of the cylinder, inducing tensile stresses perpendicular to the load.

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL Concrete 4