ATT Sieve Analysis & Gradation 2 — Questions and Answers
Question 1: According to ASTM C136, what is the correct order of sieves when stacking them for a sieve analysis?
- Largest opening at the bottom, pan at the top
- Smallest opening at the bottom, largest at the top
- Largest opening at the top, pan at the bottom (Correct answer)
- Alternating large and small openings
Correct answer: Largest opening at the top, pan at the bottom
Sieves are stacked with the largest opening at the top and progressively smaller openings below, with the pan at the bottom to catch material passing the finest sieve.
Question 2: What is the fineness modulus (FM) of a fine aggregate if the cumulative percentages retained on the standard sieves are: No.100=95, No.50=80, No.30=55, No.16=30, No.8=10, No.4=2?
- 2.72 (Correct answer)
- 2.50
- 3.10
- 1.95
Correct answer: 2.72
FM = (95+80+55+30+10+2) / 100 = 272/100 = 2.72; fineness modulus sums cumulative percent retained on the six standard sieves divided by 100.
Question 3: When performing a washed sieve analysis per ASTM C117, after washing the sample over the No. 200 sieve, the material retained must be:
- Air-dried and immediately weighed
- Dried to constant mass in an oven at 230±9°F (110±5°C) (Correct answer)
- Dried at room temperature for 24 hours
- Dried in a microwave oven
Correct answer: Dried to constant mass in an oven at 230±9°F (110±5°C)
After washing, the retained material is oven-dried to constant mass at 110±5°C (230±9°F) before performing the dry sieve analysis.
Question 4: The nominal maximum size of an aggregate is defined as:
- The smallest sieve that retains any material
- The largest sieve opening through which 100% of the aggregate passes
- The sieve size one step larger than the first sieve to retain more than 10% (Correct answer)
- The largest sieve opening where more than 15% is retained
Correct answer: The sieve size one step larger than the first sieve to retain more than 10%
Nominal maximum size is the smallest sieve opening through which the entire amount of aggregate is permitted to pass, which is one sieve size larger than the maximum size.
Question 5: A sieve is considered overloaded during a sieve analysis when:
- Any single layer of particles covers more than 50% of the sieve area
- The mass of material retained exceeds the limits specified in ASTM C136 for that sieve size (Correct answer)
- More than 5% of the sample is retained on one sieve
- The sieve frame bends under the weight of the material
Correct answer: The mass of material retained exceeds the limits specified in ASTM C136 for that sieve size
ASTM C136 specifies maximum mass limits per unit area for each sieve size; exceeding these limits causes particles to stack and prevents accurate separation.
Question 6: Which gradation type is characterized by a gap or break in the particle size distribution, meaning certain intermediate sizes are absent or underrepresented?
- Well-graded
- Uniformly graded
- Gap-graded (Correct answer)
- Open-graded
Correct answer: Gap-graded
Gap-graded aggregate has a discontinuous particle size distribution where one or more intermediate sieve sizes have little or no material retained on them.
Question 7: If a coarse aggregate sample has an original dry mass of 5,000 g, and after washing and drying the mass is 4,925 g, what is the percent passing the No. 200 sieve by washing?
- 0.75%
- 1.50% (Correct answer)
- 1.52%
- 2.00%
Correct answer: 1.50%
Percent passing No. 200 = ((5000 - 4925) / 5000) × 100 = (75/5000) × 100 = 1.50%.
ATT Sieve Analysis & Gradation 2
According to ASTM C136, what is the correct order of sieves when stacking them for a sieve analysis?