Fatigue cracks form a pattern similar to an alligator’s skin. Such cracks are the result of repetitive traffic loads or high deflection often due to wet bases or sub grades.
Longitudinal cracks run longitudinally along the pavement. They are caused by thermal stress and/or traffic loadings.
Transverse cracks occur perpendicular to the centerline of the pavement, or lay down direction. They are generally caused by thermally induced shrinkage at low temperatures.
Block cracks form regular blocks and are the result of age hardening of the asphalt coupled with shrinkage during cold weather.
Reflective cracks are caused by cracks, or other discontinuities, in an underlying pavement surface that propagate up through an overlay due to movement at the crack.
Edge cracks are crescent-shaped or fairly continuous cracks intersecting the pavement edge and are located within 0.6m of the pavement edge, adjacent to an unpaved shoulder.
Slippage cracks produce a characteristic crescent shape and are caused when the top layer of the asphalt shears, often due to high deflections and a poor bond between the layers.