ATT Soundness & Durability Testing 3

Question 1

The Los Angeles abrasion test (ASTM C131/C535) measures aggregate resistance to:

Accepted Answer

Degradation by abrasion and impact

Answer

The LA abrasion test measures an aggregate's resistance to degradation by abrasion and impact using steel balls in a rotating drum.

Question 2

In the Los Angeles abrasion test, after rotation the aggregate is washed over which sieve to determine percent loss?

Accepted Answer

No. 12 (1.70 mm)

Answer

Material passing the No. 12 (1.70 mm) sieve after washing is considered loss in the LA abrasion test.

Question 3

ASTM C131 applies to coarse aggregate with particles predominantly retained on which sieve?

Accepted Answer

9.5 mm (⅜ in.)

Answer

ASTM C131 covers smaller coarse aggregates predominantly retained on the 9.5 mm (⅜ in.) sieve, while C535 covers larger aggregates.

Question 4

In the Micro-Deval test (ASTM D6928), what abrasive medium is used with the aggregate sample?

Accepted Answer

Steel balls and water

Answer

The Micro-Deval test uses steel balls and water in a rotating drum to determine aggregate wear resistance.

Question 5

Which LA abrasion percent loss value represents BETTER aggregate quality?

Accepted Answer

25%

Answer

A lower LA abrasion percent loss indicates a harder, more wear-resistant aggregate; 25% represents better quality than higher values.

(ATT) ACI Aggregate Testing Technician Practice Test