Stabilized bases with lower quality materials such as sand asphalt or soil cement are also possible. Stabilization practices or primary concern for this study are those in which the structural characteristics of the material are improved due to the cementing action of the stabilizing agent. Seal coats or porous friction courses are permitted on the surface but not in combination. Project selection included those constructed on both fine and coarse subgrades. Sampling design factors for this study are moisture, temperature, subgrade type, traffic rate, surface thickness, base thickness and binder type.
All factors have two levels.
One or more subbase layers may also be present but are not required. The joints may have either no load transfer devices or smooth dowel bars. Jointed slabs with load transfer devices other than dowel bars are not acceptable. A seal coat is also permissible above a granular base layer. Sampling design factors for this study are moisture, temperature, subgrade type, traffic rate, dowels, PCC thickness and base type.