FWD BackCalculation of Existing Pavement Structure
Slide 2
Pavement Structure
Slide 3
Critical Responses
Slide 4
Overlay Thickness Design (Critical Responses) RuttingVertical
strain on top of the subgrade, within the unbound/bound base and AC
layers Fatigue crackingHorizontal strain at the bottom of AC layers
Thermal crackingTensile stress at the surface of the AC layer
Slide 5
Structural Responses for AC/AC Overlays Critical structural
responses are: Tensile strain at the bottom of AC overlay Tensile
strain at the bottom of original AC layer Vertical stress at the
top of the subgrade
Slide 6
Structural Responses for AC/AC Overlays AC Overlay Existing AC
Pavement r Base Subgrade v r Bond Milling and Tack Coat
Slide 7
Structural Responses for AC/AC Overlays Other considerations:
Not all design procedures consider both strains at the bottom of
the overlay and existing layer Both strains should be examined as a
minimum If the existing layer is extensively cracked it may be
modeled as a granular layer, thus consider only strains at the
bottom of overlay