ATT Materials Finer Than No. 200 Sieve (Washing Test) 3

Question 1

An aggregate sample has an original dry mass of 2,012 g. After washing over the No. 200 sieve and oven drying, the retained mass is 1,966 g. What is the percent finer than No. 200?

Accepted Answer

2.3%

Answer

1.9%

Answer

2.7%

Answer

3.1%

Question 2

Why is it important that the No. 200 sieve used in ASTM C117 be inspected and cleaned before each test?

Accepted Answer

To prevent blinding from previous tests from reducing the effective opening size

Answer

To ensure the sieve weighs the same as during calibration

Answer

To remove residual oven heat that could crack the wire cloth

Answer

To verify the frame serial number matches the laboratory record

Question 3

Which of the following best describes 'decanting' in the context of ASTM C117?

Accepted Answer

Pouring off the wash water carrying suspended fines over the nested sieves

Answer

Weighing the dried aggregate after washing

Answer

Agitating the aggregate under running water

Answer

Drying the No. 200 sieve to remove residual moisture

Question 4

Per ASTM C117, what must be done with any material retained on the No. 200 sieve after washing?

Accepted Answer

Returned to the main sample before oven drying

Answer

Discarded as it is considered contamination

Answer

Reported separately as a clay fraction

Answer

Weighed and recorded as the fine material mass

Question 5

For a combined sieve analysis (ASTM C136 + ASTM C117), where should the material finer than No. 200 obtained by washing be entered in the gradation calculation?

Accepted Answer

It is added to the No. 200 pan mass from the dry sieve analysis

Answer

It replaces the No. 200 sieve fraction entirely

Answer

It is reported only as a separate supplemental value

Answer

It is divided equally among the three finest sieves

Question 6

Which characteristic of aggregate makes the washing test particularly critical for evaluating concrete aggregate quality?

Accepted Answer

Presence of clay and silt that weaken the aggregate-paste bond

Answer

High moisture absorption capacity

Answer

Tendency to fracture under compaction

Answer

Reactivity with sodium chloride deicers

Question 7

If a technician accidentally loses some washed aggregate down the drain before drying, how does this error affect the calculated percent passing No. 200?

Accepted Answer

It increases the calculated percent finer than No. 200

Answer

It has no effect because the fines are already accounted for

Answer

It decreases the calculated percent finer than No. 200

Answer

It causes the test to be invalid and must be repeated with a new sample