Design of flexible pavement Flashcards
What are the 3 components to determine pavements thickness?
Equivalent Single Axle Load (ESAL)
Resilient Modulus
Pavement layers
What is the equivalent single axle load (ESAL)?
the effect of any combination of axle load of a pav. = to the number of 80-kN (18000lbs) single-axle
What is resilient modulus test (Mr)?
dynamic test response
stress/strain
Mr [MPa] = 10.342CBR
Mr [psi]= 1500CBR
where CBR(california bearing ratio)= 100 * (Mb/Ms)
CBR test is strength test that compares the bearing capacity of a material (Mb) with that of a well-graded crushed stone (Ms)
What are the 4 pavement cases? describe each
- Full depth asphalt pavement (for temporary roads- 2 layer or 1 layer of asphalt- cheapest)
- Hot mix Asphalt concrete (HMA) over emulsified asphalt base (3 types of emulsified base –> Type 1: processed dense grade; Type 2: Semi-processed agg.; Type 3: sand)
- HMA over untreated agg. base
- HMA with emulsified asphalt mixes over untreated agg. base ($$$- long mixing design)
How do you determine the pavement case (thicknesses from the asphalt institute’s chart)?
Mr values along ESAL
What are the design steps to design asphalt pavement?
Calculate ESAL
Find the Mr
Use Asphalt Institute’s charts and minimum thickness guidelines related to the type of pavement base to determine pavement thickness
How do you design full depth asphalt pavement?
look at the chart with the full depth title (will give the thickness of the 2 thickness combined)
How do you design HMA over emulsified asphalt base?
look at the chart with the corresponding TYPE (will give thickness of the HMA surface AND emulsified base)
THEN, look at the minimum thickness of HMA over emulsified asphalt base with table
How do you design HMA over untreated agg. base
Look at the chart with the corresponding thickness of the agg. base (KNOWN) to find HMA thickness (UNKNOWN)
How do you design HMA and emulsified asphalt mix over untreated agg.?
