ATT Aggregate Sampling & Reduction 3

Question 1

Per ASTM C702, which reduction method is NOT recommended for fine aggregate because it can introduce segregation errors?

Accepted Answer

Miniature stockpile method

Answer

The miniature stockpile method is not recommended for fine aggregate because fine particles can segregate when formed into a small conical pile.

Question 2

What minimum sample mass of coarse aggregate (3/4-in. maximum size) is typically required for a field sample per ASTM D75?

Accepted Answer

25 kg (55 lb)

Answer

ASTM D75 specifies approximately 25 kg (55 lb) as the minimum field sample mass for coarse aggregate with a 3/4-in. nominal maximum size.

Question 3

When sampling freshly mixed concrete at a job site for aggregate content verification, which standard governs obtaining the composite sample of fresh concrete?

Accepted Answer

ASTM C172

Answer

ASTM C172 covers sampling freshly mixed concrete, from which aggregate-related tests such as unit weight and air content are then performed.

Question 4

What effect does over-drying an aggregate sample before splitting have on test results?

Accepted Answer

It prevents accurate moisture content determination of the field sample

Answer

If a field sample is oven-dried before splitting, its original field moisture is destroyed, making it impossible to determine the as-received moisture content.

Question 5

Which of the following best describes a 'composite sample' as defined in ASTM D75?

Accepted Answer

A sample made up of several increments combined together

Answer

A composite sample is formed by combining multiple individual increments collected from different points or times to represent a lot of material.

(ATT) ACI Aggregate Testing Technician Practice Test

(ATT) ACI Aggregate Testing Technician Practice Test

ATT Aggregate Sampling & Reduction 3