ATT Moisture Content Testing 3

Question 1

The 'free moisture' (surface moisture) of aggregate is calculated as:

Accepted Answer

Total moisture content minus absorption capacity

Answer

Free moisture = total moisture content − absorption capacity; it represents the water that will add to the mix water in a concrete batch.

Question 2

Which ASTM standard governs the test method for total evaporable moisture content of aggregate by drying?

Accepted Answer

ASTM C566

Answer

ASTM C566 is the standard test method specifically for total evaporable moisture content of aggregate by drying.

Question 3

A stockpile of coarse aggregate is sampled at three locations: top, middle, and side. Why are multiple locations sampled?

Accepted Answer

Because moisture content can vary significantly at different points in a stockpile

Answer

Moisture tends to drain downward, making lower or interior portions of a stockpile wetter than the top or sides.

Question 4

When calculating the batch water for a concrete mix, the free moisture in the aggregate must be:

Accepted Answer

Subtracted from the design water content

Answer

Free moisture in aggregates will contribute water to the mix, so it must be subtracted from the design (added) water to maintain the correct water-cement ratio.

Question 5

An oven used for moisture content testing of aggregate must be checked for temperature uniformity. What tool is used to verify oven temperature?

Accepted Answer

A calibrated thermometer or thermocouple

Answer

A calibrated thermometer or thermocouple is placed inside the oven to verify it maintains 110 ± 5°C throughout the drying cycle.

(ATT) ACI Aggregate Testing Technician Practice Test

(ATT) ACI Aggregate Testing Technician Practice Test

ATT Moisture Content Testing 3