Moisture Content Testing Flashcards

When drying aggregate in an oven for moisture content determination, what is the required drying temperature per ASTM C566?

Answer: 110 ± 5°C (230 ± 9°F)

ASTM C566 specifies a drying temperature of 110 ± 5°C (230 ± 9°F) to evaporate free moisture without decomposing the aggregate.

Total moisture content of aggregate is defined as:

Answer: The sum of absorbed moisture and surface moisture

Total moisture content includes both the absorbed moisture within pores and the free (surface) moisture on the outside of particles.

A coarse aggregate sample has a wet mass of 2,050 g and an oven-dry mass of 2,000 g. What is the moisture content?

Answer: 2.5%

Moisture content = (2,050 − 2,000) / 2,000 × 100 = 50 / 2,000 × 100 = 2.5%.

Which of the following conditions describes aggregate that has no surface moisture but has absorbed water filling its permeable pores?

Answer: Saturated surface-dry (SSD)

Saturated surface-dry (SSD) aggregate has all internal pores filled with water but no free water on the surface.

Why is it important to seal or cover the aggregate sample tightly immediately after sampling for moisture content?

Answer: To prevent evaporation of moisture before testing

Moisture can evaporate quickly from a sample, causing erroneously low moisture content readings if the sample is not sealed promptly.

For fine aggregate moisture testing, what is the minimum sample size recommended by ASTM C566?

Answer: 500 g

ASTM C566 recommends a minimum sample mass of 500 g for fine aggregate to ensure representative results.

In hot weather conditions on a job site, aggregate moisture content can change rapidly. What is the BEST practice to account for this?

Answer: Test moisture content at frequent intervals throughout the day

Hot and dry conditions can cause rapid moisture loss from aggregate stockpiles, so frequent testing ensures accurate water-cement ratio control.