Chapter 1 (1) 2
Chapter 1 (1) 2
Chapter 1 (1) 2
2 PAVEMENT TYPES
1.2.1 Flexible Pavements
• Flexible pavements are usually surfaced with Asphalt Materials. These pavements are
called flexible because the pavement structures can flex or bend under a traffic
loading.
• A flexible pavement structure requires several layers of materials because these layers
are not stiff enough to distribute the wheel load to a large area (Figure 1.2).
• Beneath the asphalt layer, a crushed aggregate base layer is commonly seen. Below
the base layer, a subbase layer is also used based on the subgrade strength.
Tack Coat
Prime Coat Wearing Course (1”-3”)
Asphalt Wearing Course
Binder Course (2”-4”)
Asphalt Binder/Base Course
Crushed Aggregate Base - CAB Base Course (4”-12”)
• Dowel Bars are typically used at transverse joints to assist in load transfer.
• Transverse Joint spacing is selected such that temperature and moisture stresses do not produce intermediate
cracking between joints.
• Tie Bars are typically used at longitudinal joints or between an edge joint and a curb or shoulder
• Tie Bars are not load transferring device, but they transfer some loads.
• Tie Bars are about 0.5 in. (12.5 mm) in diameter and between 24 and 40 in. (0.6 and 1.0 m) long.
Pumping Prevention
➢ Provide granular subbase 4-6 inches.
➢ Increase distance between joints (especially expansion joints)
➢ Joints must be filled with joints sealants (silicone) or rubberized
bitumen fillers (accommodating movement and preventing water • Zero Load Transfer
infiltration).
➢ Provide good drainage system so that water can not be
accumulated in subgrade.
• Using reinforced slabs, transverse joint spacing can be provided longer than that for
JPCP and ranges from about 25 feet (7.5 m) to 50 feet (15 m).
• Temperature and moisture stresses are expected to cause cracking between joints.
• Reinforcing steel or a steel mesh is used to avoid these cracks or hold these cracks
tightly together.
Transverse Joints Spacing:
JPCP: 12 to 20 ft. • Dowel bars are typically used at transverse joints to assist in load transfer.
JRCP: as long as 50 ft.
1.2 Pavement Types (Rigid) Portland Cement
1.2 PAVEMENT TYPES Concrete (PCC)
1.2.2.3 Continuous Reinforced Concrete Pavement (CRCP)
• Continuous reinforced concrete pavement completely eliminates the transverse joints,
except as required at end-of-day construction and at bridge approaches and
transitions to other pavement structures, by providing continuous reinforcement as
shown in Figure 1.5.
• Prestressed concrete pavement is built using precast concrete pavement slabs that are
fabricated at manufacturers’ plant and transported to and installed at the project site.
• PCP is very applicable in busy areas where high traffic volume requires stronger
pavement and construction time is very challenging considering traffic controls.
• Panels (Figure 1.6) are manufactured in sizes to match the width of one, two, or three
lanes of the pavement permitting one or multiple lanes of an existing pavement to be
reconstructed at one time.
1.2 PAVEMENT TYPES 1.2 PAVEMENT TYPES
Joints in Concrete Pavements Contraction Joints
➢ Longitudinal Joints Contraction joints provide for an orderly arrangement
➢ Transverse Joints (Expansion and Contraction Joints) of the cracking that occurs when concrete undergoes
curing. If the joints are properly designed and spaced,
➢ Construction Joints a minimum of cracking outside the joints can be
Load Transfer Devices expected.