Construction Materials Exam 1
Questions with Correct Answers
5. The shape and surface texture of aggregate particles are important for both portland
cement concrete and asphalt concrete. a. For preparing PCC, would you prefer round
and smooth aggregate or rough and angular aggregate? Briefly explain why (no more
than two lines). b. For preparing HMA, would you prefer round and smooth aggregate or
rough and angular aggregate? Briefly explain why (no more than two lines). -
ANSWERSPCC: round and smooth to increase workaability
HMA: Rough and angular to increase strength
6. Saturated Surface-dry condition of aggregate - ANSWERSsurface of aggregate is
dry, but all permeable voids are filled with water. Moisture Content = Absorption
6. Absorption of Aggregates - ANSWERSamount of water that can fill permeable voids
Free water on aggregates - ANSWERSdifference between the actual moisture content
and moisture content in SSD condition. Water outside of aggregate, when moisture
content > Absorption
15. The following laboratory tests are performed on aggregate samples: a. Specific
gravity and absorption b. Soundness c. Sieve analysis test What are the significance
and use of each of these tests? - ANSWERSspecific gravity and absorption tests:
important to determine water/cement ratio for mix.
Soundness: determines freeze-thaw and weathering resistance
sieve analysis: determines gradation which is important to ensure aggregate meets
ASTM standards and design specifications
6.1 What ingredients are used for the production of portland cement? -
ANSWERScalcium
silica
alumina
iron
6.2 What is the role of gypsum in the production of portland cement? - ANSWERSslow
down the rate of hydration once cement is mixed with water
6.5 Define the C-S-H phase of cement paste - ANSWERSCalcium Silicate Hydrates are
main products of the hydration of portland cement, which gives concrete its strength
6.6 What are the four main chemical compounds in portland cement? -
ANSWERStricalcium silicate: C3S
Questions with Correct Answers
5. The shape and surface texture of aggregate particles are important for both portland
cement concrete and asphalt concrete. a. For preparing PCC, would you prefer round
and smooth aggregate or rough and angular aggregate? Briefly explain why (no more
than two lines). b. For preparing HMA, would you prefer round and smooth aggregate or
rough and angular aggregate? Briefly explain why (no more than two lines). -
ANSWERSPCC: round and smooth to increase workaability
HMA: Rough and angular to increase strength
6. Saturated Surface-dry condition of aggregate - ANSWERSsurface of aggregate is
dry, but all permeable voids are filled with water. Moisture Content = Absorption
6. Absorption of Aggregates - ANSWERSamount of water that can fill permeable voids
Free water on aggregates - ANSWERSdifference between the actual moisture content
and moisture content in SSD condition. Water outside of aggregate, when moisture
content > Absorption
15. The following laboratory tests are performed on aggregate samples: a. Specific
gravity and absorption b. Soundness c. Sieve analysis test What are the significance
and use of each of these tests? - ANSWERSspecific gravity and absorption tests:
important to determine water/cement ratio for mix.
Soundness: determines freeze-thaw and weathering resistance
sieve analysis: determines gradation which is important to ensure aggregate meets
ASTM standards and design specifications
6.1 What ingredients are used for the production of portland cement? -
ANSWERScalcium
silica
alumina
iron
6.2 What is the role of gypsum in the production of portland cement? - ANSWERSslow
down the rate of hydration once cement is mixed with water
6.5 Define the C-S-H phase of cement paste - ANSWERSCalcium Silicate Hydrates are
main products of the hydration of portland cement, which gives concrete its strength
6.6 What are the four main chemical compounds in portland cement? -
ANSWERStricalcium silicate: C3S
