Aspahlt exam Flashcards
Order in least to greatest moisture (OD, Air dry, Wet, SSD)
oven dry, Air dry, SSD, Damp and wet
Which moisture states have no external moisture (OD, Air dry, Wet, SSD)
SSD, Air dry, Oven dry
Which moisture states have no internal moisture (OD, Air dry, Wet, SSD)
Oven dry
How to get a volume from only a measurement of two weights
Boyant force, it is proportional to the volume displaced in water
What is the source of asphalt binder for roads
Residual from refining crude oil
What does PG 58 -28
Performance Grade, Max temp 58 degrees C, min temp -28 degrees C
If rutting is caused by asphalt binder what caused the problem
Max PG needs rasied, Viscosity is too low in high heat
What causes thermal cracking from the asphalt binder
Min PG needs lowered
What are the four Source properties
Tougness, Soundness, Deleterious Materials, Gradation
What is the test for toughness
LA abrasion test, measure resistance to abrasion and impact
What test is for soundness
Grow salt crystals in the aggregate, measures resistance to simulated freeze and thaw
What is the test for Deleterious materials
Clay lumps and friable particles, Breaks apart soft material and remove from sample (soft particles)
What is the test for gradation?
Sieve analysis, determines particle sizes
What are the four consensus properties?
Coarse aggregate angularity, Flat and elongated, Fine aggregate angularity, clay content
What is coarse aggregate angularity
Aggregate needs adequate friction
What is flat and elongated
an aspect ratio, the aggregate can be easily broken
What is Fine aggregate angularity
Low angularity sands have stability and surface rutting problems, round fine aggregate aren’t as stable and will compact later
What issues does clay content cause?
Fine particles have a large surface area, needs more binder
Does a lower Fineness modulus need more or less binder
It needs more binder
What is NMAS, and does a higher NMAS need more or less binder
Nominal maximum aggregate size, the bigger the NMAS the less binder needed
What is the goal of superpave mix design step one
Select materials, aggregate and PG binder
What is the goal of superpave mix design step two
Select aggregate blend
What is the goal of superpave mix design step three
Determine aspahlt content (binder). Graph at 4% air voids (Va)
What is the goal of superpave mix design step four
Moisture sensitivity test
How is the agg. blend determined in a batch plant
It is weighed in the batch tower
How is the agg. blend determined in a Drum mix plant
Cold feed bins, heigh of gate and speed of conveyer
How is the amount of binder controlled in a batch plant
Weighed in the batch tower
How is the appriorate amount of binder controlled in a drum mix plant
The weigh bridge knows the flow rate of agg. and a computer matches with the needed amount of binder
How is the agg. and binder mixed in a batch plant
In the pugmill
How is agg. and binder mixed in a Drum mix plant
In the mixing drum
What goes the same direction as airflow in a parallel mixing drum
Aggregate and air goes the same direction
What type of Drum mixing plant do air and aggregate go in opposite directions
Counterflow mixing drum
Where is RAP added in a mixing drum
After combustion
- List the follow in order of events
Paving machine
Vibratory compactor
Asphalt mix discharge from storage silo
Material transfer material
Tack coat
Mix agg. and asphalt binder
Smooth steel compactor
Haul truck
- Mix agg. and asphalt binder
- Asphalt mix discharge from storage silo
- Tack coat
- Haul truck
- Material transfer material
- Paving machine
- Vibratory compactor
- Smooth steel compactor
What is the purpose of a material transfer vehicle
Keeps HMA warm and ready from haul truck and will unload into paver
What are common sources of agg.
Gravel, crushed limestone, recycled concrete, and steel slag
What does the Sand equivalency test used for
To assess the amount of clay particles in a sample
Why does ASTM C33 limit the fines
An excessive amount of fines can give it a low abrasion resistance
