CCIL - Canadian Council of Independent Laboratories Advanced Aggregate Characterization Questions and Answers

Question 1

According to CSA A23.2-15A, what is the primary objective of conducting a petrographic analysis on a coarse aggregate sample?

Accepted Answer

To identify the mineralogical composition and physical characteristics of the rock types present.

Answer

To determine the aggregate's resistance to abrasion and impact.

Answer

To measure the aggregate's resistance to freeze-thaw cycles.

Answer

To calculate the bulk specific gravity and absorption of the aggregate.

Question 2

A laboratory performs a Magnesium Sulfate Soundness test (CSA A23.2-9A) on a new source of coarse aggregate. The result is a weighted average mass loss of 15%, which exceeds the project specification limit of 12%. What does this high percentage loss primarily indicate about the aggregate?

Accepted Answer

The aggregate has poor resistance to weathering and is susceptible to degradation from freeze-thaw action.

Answer

The aggregate has a high potential for alkali-silica reactivity.

Answer

The aggregate contains an excessive amount of flat and elongated particles.

Answer

The aggregate has a very high absorption capacity, making it unsuitable for high-strength concrete.

Question 3

A petrographic examination of a granite aggregate source reveals the presence of strained quartz and chert, which are known to be potentially alkali-silica reactive. To further quantify the risk of this aggregate causing deleterious expansion in concrete, which of the following tests would be most appropriate?

Accepted Answer

Accelerated Mortar Bar Test (CSA A23.2-14A).

Answer

Micro-Deval Abrasion Test (CSA A23.2-29A).

Answer

Magnesium Sulfate Soundness Test (CSA A23.2-9A).

Answer

Los Angeles Abrasion Test (CSA A23.2-17A).

Question 4

What property of a fine aggregate is primarily assessed by determining its uncompacted void content, as described in CSA A23.2-11A?

Accepted Answer

The particle shape, angularity, and surface texture.

Answer

The fineness modulus and overall grading.

Answer

The potential for alkali-aggregate reactivity.

Answer

The resistance to degradation during handling.

Question 5

The Micro-Deval abrasion test (CSA A23.2-29A) is performed on an aggregate sample to assess which of the following properties?

Accepted Answer

Hardness, toughness, and durability against abrasion and degradation.

Answer

Resistance to degradation from freeze-thaw cycles.

Answer

Potential for alkali-carbonate reactivity.

Answer

The amount of clay lumps and friable particles.

Question 6

A technician is determining the percentage of particles with crushed faces in a coarse aggregate sample according to CSA A23.2-12A. Which of the following correctly describes the basis for this calculation?

Accepted Answer

The mass of particles meeting the specified crushed face requirement (e.g., one or two faces) as a percentage of the total mass of the test fraction.

Answer

The volume of particles with at least one crushed face as a percentage of the total sample volume.

Answer

The count of particles with at least one crushed face divided by the total number of particles in the sample.

Answer

The surface area of the crushed faces as a percentage of the total surface area of all particles.