CCIL Aggregate Gradation and Properties 4

Question 1

What is the definition of 'apparent specific gravity' of aggregate?

Accepted Answer

The ratio of oven-dry mass to the volume of the solid material excluding all permeable pores

Answer

Apparent specific gravity is the ratio of the oven-dry mass to the volume of the impermeable solid material only, excluding permeable pore space.

Question 2

Which gradation type typically produces the highest density and lowest void content in a compacted aggregate layer?

Accepted Answer

Well-graded (dense graded)

Answer

Well-graded (dense-graded) aggregate has particles distributed across a range of sizes so smaller particles fill the voids between larger particles, maximizing density and minimizing void content.

Question 3

What does the organic impurities test (ASTM C40) assess in fine aggregate?

Accepted Answer

The presence of organic matter that could interfere with concrete strength development

Answer

ASTM C40 uses a sodium hydroxide solution color comparison to detect organic impurities in fine aggregate that could retard cement hydration and reduce concrete strength.

Question 4

What aggregate characteristic does the 'sand equivalent value' (ASTM D2419) measure?

Accepted Answer

The relative proportion of fine dust or clay-like material to sand-size particles

Answer

The sand equivalent test measures the relative proportion of clay-like or plastic fines to sand-size material in fine aggregate or soil, with higher values indicating cleaner material.

Question 5

What is the nominal maximum aggregate size (NMAS) as defined in mixture design?

Accepted Answer

One sieve size larger than the first sieve to retain more than 10% of the aggregate

Answer

Nominal maximum aggregate size is defined as one sieve size larger than the first sieve in a standard series that retains more than 10% of the aggregate.

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL Aggregate Gradation and Properties 4