Design of Concrete Slabs with Optimized Geometry and Built-in Curling Effect on Performance

A new methodology called TCP “Thin Concrete Pavements” has been developed to design the concrete slab thickness by optimizing the slab size given the geometry of the truck axles. The key principle of the design method is to configure the slab size so that not more than one set of wheels are on any given slab at any time, thereby minimizing the critical top tensile stress. Full-scale test sections were constructed and tested at Illinois under accelerated pavement loading conditions with concrete thickness of 8, 15, and 20 cm on both an aggregate (Subbase CBR 4% and 15 cm granular base) and asphalt base layer. Concrete slabs 8 cm thick on a 15 cm granular base withstood 75.000 ESALS, Slabs with 15 cm thickness showed cracks initiating at 12 million ESALs on average. The 20 cm slab thickness showed no fatigue cracking. A Mechanistic-based software, “OptiPave”, has been developed. The new methodology designs slabs that are on average 7 cm thinner than traditional pavements, AASHTO (1993), for the same traffic, with a thickness range of 8 cm to 20 cm thick. This new solution for designing concrete pavements has been used to build roads from local streets to high traffic highways and gives an alternative to asphalt in low volume roads and competes directly in direct cost Thickness design in Chile is very sensitive to climate variables. The AASHTO 93 method doesn’t consider built in curling conditions, which is especially sensitive to construction standards, making this design variable (BIC) extremely important in terms of pavement performance. Two cases are studied in this paper to show the benefits of the optimized designed slabs, in terms of thickness and sensitivity to climate conditions.