Page 29 - SAPEM-Chapter-10-2nd-edition-2014

South African Pavement Engineering Manual
Chapter 10: Pavement Design

Pre- Post-cracked Equivalent Pre- Post-cracked Equivalent
cracked phase granular cracked phase granular
phase phase phase phase

Radius of
curvature

Water Water
Ingress Ingress
Good quality Elastic
material deflection
Effective Modulus
Poor quality
material

Time, traffic Time, traffic

Effective Lightly Cemented Layer Modulus Elastic Deflection and Radius of Curvature
Figure 12. Long-Term Changes in the Elastic Response of Flexible Pavements with Lightly
Cemented Layers

4000
Asphalt Mill &
3500
BSM
Equivalent Stiffness (MPa) 2500 Granular
Replace
Cemented
Asphalt
3000
2000
1500

1000
500

0
0 1 2 3 4 5 6 7 8 9 10
Years

Figure 13. Change in Stiffness of Different Materials with Time

3.5.3.2 Concrete Pavements
The structural performance of concrete pavements is defined in terms of the percentage of road with the following
types of distress:
• Shattered slabs
• Faulting
• Pumping
• Crack spacing in the case of continuously reinforced concrete pavements (CRCPs)

Shattering of slabs normally initiates at joints in plain jointed concrete pavements and jointed reinforced concrete
pavement, or at closely spaced transverse cracks in CRCP, resulting in punch-outs. The percentage of the road

Section 3: Design Considerations
Page 18