Air Void Asphalt Binder Aggregates Dense Graded Mixes Gap ...

siennatearfulUrban and Civil

Nov 25, 2013 (3 years and 6 months ago)

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PAVEMENTS

Pavement Types and Materials

Pavement Purpose


Load support


Smoothness


Drainage

DC to Richmond Road in 1919


from the Asphalt Institute

Pavement Condition

Pavement Condition

Pavement Condition

Pavement Types

Flexible

Pavements


Rigid


Pavements





Asphalt Concrete


Portland Cement Concrete




Composite




Pavements

(WSDOT, u.d.)

Flexible Pavement


Structure


Surface course


Base course


Subbase course


Subgrade

Asphalt Concrete Mix
Components

Air Void

Asphalt
Binder


Aggregates

Dense
Graded
Mixes

Gap
Graded
Mixes

Open
Graded
Mixes

Higher AV (%)

Higher Permeability

Higher Macrotexture

Types of Flexible Pavement

Dense
-
graded

Open
-
graded

Gap
-
graded

Flexible Pavement


Construction

Flexible Pavements


Adjusts to limited
differential settlement


Easily repaired


Additional thickness
added any time


Non
-
skid properties
do not deteriorate


Quieter and smoother


Tolerates a greater
range of temperatures



Loses some flexibility
and cohesion with
time


Needs resurfacing
sooner than PC
concrete


Not normally chosen
where water is
expected


Advantages

Disadvantages

Asphalt Mix


Dynamic Modulus, E*


Stiffness property


Function of


Temperature


rate of loading


Age


binder stiffness


aggregate gradation


binder content


air voids



Inputs


Asphalt mixture
properties


Asphalt binder


Air voids

Rigid Pavement


Structure


Surface course


Base course


Subbase course


Subgrade

Rigid Pavements


Good durability


Long service life


Withstand repeated
flooding and
subsurface water
without deterioration


May lose non
-
skid
surface with time


Needs even sub
-
grade with uniform
settling


May fault at
transverse joints


Advantages

Disa
dvantages

Types of Rigid Pavement


Jointed Plain Concrete Pavement (JPCP)









Jointed Reinforced Concrete


Pavement (JRCP)

Types of Rigid Pavement


Continuously Reinforced Concrete Pavement
(CRCP)

Rigid Pavement


Construction

Slipform

Fixed form

Rigid Pavement Terms


S’
c

(PCC modulus of rupture)


A measure of PCC flexural strength


Usually between 600 and 850 psi



J (load transfer coefficient)


Accounts for load transfer efficiency


Lower J
-
factors = better load transfer


Between 3.8 (undoweled JPCP) and 2.3 (CRCP with tied shoulders)



E
c

(PCC elastic modulus)


4,000,000 psi is a good estimate



k (modulus of subgrade reaction)


Estimates the support of the PCC slab by the underlying layers


Usually between 50 and 1000 psi/inch



Pavement Structure


Bedrock


Presence within 10 feet of the pavement
surface influences the structural response of
the pavement layers


Inputs


Layer thickness (infinite)


Unit weight


Poisson’s ratio


Layer modulus

Subgrade


Characterized by strength
and/or stiffness


California Bearing Ratio (CBR)


Measures shearing resistance


Units: percent


Typical values: 0 to 20


Resilient Modulus (M
R
)


Measures stress
-
strain relationship


Units: psi or MPa


Typical values: 3,000 to 40,000 psi

Subgrade

Some Typical Values

Classification

CBR

M
R

(psi)

Typical Description

Good

≥ 10

20,000

Gravels, crushed stone and
sandy soils. GW, GP, GM, SW,
SP, SM soils are often in this
category.

Fair

5


9

10,000

Clayey gravel and clayey
sand, fine silt soils.


GM, GC,
SM, SC soils are often in this
category.

Poor

3


5

5,000

Fine silty sands, clays, silts,
organic soils.


CL, CH, ML,
MH, CM, OL, OH soils are
often in this category.