ATT ATT Deleterious Materials & Clay Content 2

Question 1

Which ASTM standard is used to determine lightweight pieces in aggregate (such as coal and lignite)?

Accepted Answer

ASTM C123

Answer

ASTM C123 is the standard test method for lightweight pieces in aggregate, used to identify coal, lignite, and other low-density particles.

Question 2

In ASTM C123, lightweight particles are separated from aggregate by:

Accepted Answer

Immersion in a heavy liquid of specified density

Answer

ASTM C123 uses a heavy liquid (such as zinc chloride solution) with a specific gravity between 1.95 and 2.0 to float out lightweight particles.

Question 3

What is the maximum allowable lightweight pieces (coal and lignite) in fine aggregate per ASTM C33 for concrete subject to surface wear?

Accepted Answer

0.5%

Answer

For fine aggregate in concrete subject to surface wear, ASTM C33 limits lightweight pieces (coal and lignite) to 0.5% by mass.

Question 4

Chert with a bulk specific gravity less than 2.40 is considered a deleterious substance in coarse aggregate because:

Accepted Answer

It has poor freeze-thaw durability and causes pop-outs

Answer

Low-density chert absorbs water and deteriorates rapidly during freeze-thaw cycles, causing surface pop-outs in concrete.

Question 5

When testing for lightweight pieces per ASTM C123, the test result is expressed as:

Accepted Answer

Percentage by mass of lightweight pieces

Answer

ASTM C123 results are reported as the percentage by mass of lightweight pieces in the aggregate sample.

(ATT) ACI Aggregate Testing Technician Practice Test