SESSION 10
Special Design
Considerations for
Reinforced Concrete
Pavements
Objectives
 Identify design and construction aspects
unique to reinforced pavements
 Define reinforced pavement joint types
 Describe the amount and type of
reinforcement used in JRCP and CRCP
Introduction
 JRCP designs
 Jointed pavements
 Longer joint spacing
 Distributed steel in slabs (0.15 - 0.25%)
 CRCP
 No transverse contraction joints
 Heavy longitudinal steel carried through
the pavement (0.6 - 0.8%)
JRCP
7.6 to 18.3 m (typ)
(25 to 60 ft)
PLAN
VIEW
Welded Wire
Fabric Reinforcing
Transverse Joints
(with dowels)
Longitudinal Joint
(with tiebars)
CRCP
PLAN
VIEW
Continuous Longitudinal
Reinforcement
(Deformed Bars)
Typical Crack Spacing
(0.9 to 2.4 m)
(3 to 8 ft)
Longitudinal Joint
(with tiebars)
Special Considerations —
Foundation
 Subgrade characterization
 Same as JPCP
 Drainage and base type
 JRCP: same as JPCP
 CRCP: uniform base support
 CRCP: approach use of permeable
base with caution
Special Considerations —
Thickness
 Thickness design not differentiated by
pavement type
 Applicability of current procedures to
reinforced pavements
 1998 AASHTO supplement design:
 Use 9 m (30 ft) joint spacing for JRCP
 Assume 4.6 m (15 ft) joint spacing for
CRCP (for design purposes only)
Special Considerations —
Joints
 JRCP contraction joints
 Maximum spacings of 9.1 to 13.7 m
(30 to 45 ft)
 Doweled
 Properly designed reservoir
Special Considerations —
Joints (continued)
 CRCP
 No transverse contraction joints
 Construction joints
 Terminal joints
Lug anchors
Wide Flange (WF) steel beam
Lug Anchor
Permissible Raised Key
Construction Joint
Side
View
3 ft (min)
No. 5 Bars at
longitudinal
steel spacing
2 ft
Six No. 5
Bars
Wide Flange Steel Beam
1 in Expansion
Joint Material
WF Steel
Beam
Beam
Stiffener
Sleeper
Slab
10 in
10 ft
No. 4 Bars
@ 12 in c-c
No. 5 Bars
@ 6 in c-c
Side
View
No. 5 Bars
@ 8 in c-c
Special Considerations —
JRCP Reinforcement
 JRCP longitudinal steel reinforcing
 Holds cracks tightly together
 Deformed welded wire fabric (WWF)
or deformed bars recommended
 0.19% minimum steel content
JRCP Steel Design
 JRCP steel design often based on
“subgrade drag” theory
 “Subgrade Drag” theory considers:
 Friction between slab and base
 Slab length
 Working stress in steel
Key Factors for JRCP
Steel Design
 In addition to “subgrade drag” factors,
other research suggests:
 Expected crack widths
 Traffic loadings
 PCC/steel thermal properties
 Fatigue characteristics of steel
Typical JRCP Steel Layout
Longitudinal wires or bars on
152-mm (6 -in) centers (typical)
Traffic
Transverse wires or bars on 305m m (12 -in) centers (typical)
Special Considerations —
CRCP Reinforcement
 CRCP longitudinal steel reinforcing
 Induce the formation of transverse
cracks at desired intervals and hold
those cracks tight
 Only deformed bars
 Minimum 0.6% steel recommended
 For thick slabs, some agencies have
used double layers of steel
AASHTO CRCP
Steel Design
 Determines recommended steel content
assuming a given bar diameter
 Design criteria:
 Crack spacing between 0.9 and 2.4 m
(3 to 8 ft)
 Crack width < 1 mm (0.04 in)
 Steel stress < 75% of ultimate tensile
strength
Typical CRCP Steel Layout
Deformed longitudinal bars on
127 to 203 mm (5 to 8 in) centers
Traffic
Optional deformed transverse bars on
610 to 1220 mm (24 to 48 in) centers
Special Considerations —
Transverse Reinforcement
 Intended for control of longitudinal
cracking
 Generally included for JRCP because of
use of WWF
 Often used on CRCP as a means of
facilitating longitudinal steel placement
Special Considerations —
Shoulders
 Transverse joints in shoulder match
those of pavement
 Jointed PCC shoulders or ramps
adjacent to CRCP can be problematic
Special Considerations —
Construction
 JRCP steel
 Placed between lifts or vibrated into
fresh concrete
 CRCP steel
 Placed on chairs or placed using tube
feeders (chairs more precise position)
 Stagger steel splices
 Minimum 64 mm (2.5 in ) cover
CRCP Steel Placement
CRCP Steel Placement
Longitudinal Steel Laps
PLAN VIEW
Outside Pavement Edge
Lap
Spacing of
Longitudinal
Bars
Summary
DESIGN ITEM
TREATMENT IN
REINFORCED PAVEMENTS
Foundation
Same
Slab Thickness
Same
Joint Design
Special Considerations
Reinforcement Design
Special Considerations
Shoulder
Same/Some Special
Construction
Same/Some Special