ATT Los Angeles Abrasion Testing 2

Question 1

How many steel balls (charge) are used for ASTM C131 Grading A?

Accepted Answer

12 balls

Answer

Grading A in ASTM C131 requires a charge of 12 steel balls weighing 5,000 ± 25 g.

Question 2

What is the standard number of revolutions for the LA abrasion test on aggregates tested per ASTM C131?

Accepted Answer

500 revolutions

Answer

The standard test per ASTM C131 requires exactly 500 revolutions of the LA machine drum.

Question 3

The Los Angeles abrasion loss is expressed as:

Accepted Answer

The mass passing the No. 12 sieve divided by original mass × 100

Answer

LA abrasion loss (%) = (mass passing the No. 12 sieve ÷ original sample mass) × 100.

Question 4

ASTM C535 is used instead of ASTM C131 when aggregate is:

Accepted Answer

Larger than 1½ inch (37.5 mm)

Answer

ASTM C535 covers larger aggregates with particles greater than 1½ in. (37.5 mm), while C131 covers smaller sizes.

Question 5

After the LA abrasion test, the aggregate and charge are separated using a sieve with an opening size of:

Accepted Answer

No. 12 (1.70 mm)

Answer

The material is removed from the machine and sieved over a No. 12 (1.70 mm) sieve to determine loss.

(ATT) ACI Aggregate Testing Technician Practice Test