Impact of Design Features On Jointed Concrete Pavement Performance

摘要

Jointed concrete pavement slab is designed to sustain fatigue failure. Fatigue life, which is characterized by the number of allowable repeat load, is a function of stress/strength ratio. Therefore, for slabs with same strength, maximum stress level on the slab decides the allowable number of repeat load. Westergaard pointed out that critical load conditions are located at the corner and the edge of the slab (Yoder & Witczak, 1975). Slabs curl and warp daily due to temperature changes. When relative stiffness of the base and the slab increases, field measurement showed that curing action lifts the slab from the base and causes these critical loading locations without support sometime during the day (Wu & Hearne, 1989). Maximum stress under these particular conditions will be greater than a fully supported slab. Therefore, base stiffness, i.e., base type, affects theoretical fatigue life of the slab. An experimental project, which was open to traffic in 1994, was constructed with different types of base and slab thickness. Data of slab response to dynamic loading was collected over the years. After five years of service, the weak sections begin showing sign of fatigue failure. This report summarizes this research effort and serves as an interim report on the effect of base type on slab performance.