1. No category

I. Answer each of the following statements with either True or False (10
grades):
1. Interface deflection between two layers in a flexible pavement is
inversely proportional to the modulus of the underlying layer. T
2. The slope variance of a pavement is an indication of rutting occurring in
the pavement. F
3. As the vertical compressive strain on top of the subgrade layer decreases,
the number of load applications to rutting failure decreases. F
4. Fatigue cracking is a non-load related cracking pattern that occurs in
flexible pavements. F
5. The structural behavior of a pavement is related to the ability of the
pavement to satisfy the needs of the users of the pavement. F
6. The present serviceability index (PSI) of a pavement is an index
determined based on ride quality ratings made by a panel of raters. F
7. The performance index of a pavement is the PSI versus time. T
8. Transfer functions are distress models used to convert pavement
responses into pavement performance. T
9. Skid resistance of an asphalt pavement is affected by bleeding distress
occurring on the surface of the pavement. T
10. Distresses are considered the major correlation factor for computing the
PSI of a pavement. F
II. Please complete each of the following statements (20 grades):
1. The slope variance of a pavement is an indication of wheel path
roughness ……………………….. in the pavement.
2. According to research studies in the US, the pavement longitudinal
profile or roughness ………………………… provides the major correlation
variable for computing PSI.
3. As the tensile strain at the bottom of the HMA layer increases, the
number of load applications to fatigue failure decreases ………………….
4. As the vertical compressive strain on top of the subgrade layer decreases,
the number of load applications to rutting failure increases………………….
5. In flexible plate theory for flexible pavements, the pressure ………………. is
the same at all points on the plate but the deflection ……………….. is
different from point to point under the plate.
6. In case of a stabilized base layer used in an asphalt pavement, the critical
response for fatigue cracking is the tensile strain at the bottom of the
stabilized base layer ………………………….
7. Interface deflection between two layers in a flexible pavement is
inversely proportional to the modulus of the second (underlying)
…………………… layer.
8. A smoother pavement will have a higher ……………….. PSI.
9. Transfer functions are distress models used to convert pavement
responses into pavement performance or distress ………………………..
III. In a Marshall test, the percentage of asphalt binder by total weight of
aggregate is 5.2 percent. The bulk specific gravity of aggregate (Gsb) = 2.525,
the specific gravity of asphalt binder (Gb) = 1.000, and the density of water
w) = 1.000 g/cc. If the absorbed asphalt (P ba) is 1.8 percent by total weight
of aggregate, and the voids in total mixture (VTM) is 4.0 percent, answer the
following questions (30 grades):
Va = VV
Air
Vma
Asphalt
Vfa = Vbe
Vb
Vba
Vmb = VT
Vmm
Vsb = VAgg-bulk
Aggregate
Vse
Vsa
1. The effective asphalt content (Pbe), percent by total weight of mixture
equals to …………………3.23 %.
2. The bulk specific gravity of the compacted mixture (Gmb) is
……………….2.348.
3. The voids in mineral aggregate (VMA), percent by total volume of mixture
equals to ………………………..11.59 %.
4. The theoretical maximum specific gravity of the loose mixture (Gmm) is
……………….2.446.
5. The voids filled with asphalt (VFA), percent by volume of total voids is
…………………..65.49 %.
IV. A circular loading is applied on a three-layered asphalt pavement system as
shown in the figure below. If the radial tensile strain on the top of the
subgrade layer is 215 microstrains, the radial tensile strain at the bottom of
the asphalt layer is 304 microstrains, and the vertical compressive stresses at
the bottom and top of the base layer are 3.2 psi and 10.8 psi, respectively,
answer each of the following questions (30 grades):
a
q
HMA, E1 = 250,000 psi
h1
Base, E2 = 12,500 psi
h2

Subgrade, E3 = 6,250 psi
Note: Use –ve for tension and positive for compression. The required
stresses and strains are under the centerline of the wheel load.
1. The vertical compressive strain (in microstrains) at the bottom of the
asphalt layer is 608 …………………
2. The vertical compressive strain (in microstrains) at the top of the base
layer equals to 608 ……………………..
3. The vertical compressive strain (in microstrains) at the bottom of the base
layer is 430 …………………………
4. The vertical compressive strain (in microstrains) at the top of the
subgrade equals to 430 …………………………..
5. The radial tensile strain (in microstrains) at the top of the base layer
equals to 304 ………………………..
6. The vertical compressive stress (in psi) at the bottom of the asphalt layer
is 10.8 ……………………
7. The radial tensile stress (in psi) at the bottom of the asphalt layer is equal
to 141.2 ………………………..
8. The radial compressive stress (in psi) at the top of the base layer equals to
3.2 …………………………..
9. The radial tensile stress (in psi) at the bottom of the base layer equals to
2.2 ……………………………..
10. The radial compressive stress (in psi) at the top of the subgrade layer is
0.5 …………………………..