cracks together, and faulting will result. The amount of reinforcing needed to hold cracks
together is traditionally calculated using a relationship based on the friction between
the subgrade and the bottom of the slab. This relationship assumes that for a crack to
open enough to fail the aggregate interlock, the slab will have to slide along the subbase.
The current AASHTO recommendation is based on this traditional approach (Guide
for Design of Pavement Structures, American Association of State Highway and
Transportation Officials, 1993).
The relationship can be expressed as follows: