ATT Moisture Content & Specific Gravity 3

Question 1

An aggregate is described as 'oven-dry.' Which statement best describes this condition?

Accepted Answer

All evaporable moisture removed by heating to 110 ± 5°C

Answer

Oven-dry (OD) condition means all evaporable water has been removed by drying at 110 ± 5°C to constant mass per ASTM C566.

Question 2

The Le Chatelier flask method is an alternative procedure for determining specific gravity of which material?

Accepted Answer

Fine aggregate passing the No. 4 sieve

Answer

The Le Chatelier flask (volumetric flask) method can be used for fine aggregate specific gravity as an alternative to the pycnometer method.

Question 3

During the SSD cone test for fine aggregate, a properly SSD sample will:

Accepted Answer

Slump and lose its molded shape when the cone is lifted

Answer

At SSD, the fine aggregate cone slumps slightly when the mold is removed, indicating surface moisture is absent while internal pores are saturated.

Question 4

When computing the mix design batch weights, a technician must adjust aggregate quantities because stockpile moisture differs from SSD. Which quantity is adjusted upward when aggregates are wetter than SSD?

Accepted Answer

Aggregate batch weight is increased; mix water is decreased

Answer

Wet aggregates carry extra water, so aggregate batch weight increases to maintain the target SSD weight, and mix water addition decreases by the same free moisture amount.

Question 5

What is 'absorption capacity' of an aggregate as defined by ASTM?

Accepted Answer

The percentage of water the aggregate will absorb to reach SSD from oven-dry

Answer

Absorption is the increase in mass of oven-dry aggregate after soaking in water to reach SSD, expressed as a percentage of the OD mass.

(ATT) ACI Aggregate Testing Technician Practice Test

(ATT) ACI Aggregate Testing Technician Practice Test

ATT Moisture Content & Specific Gravity 3