All factors have two levels except original pavement type which has three levels. The table below shows how a section may evolve to obtain such a designation. An interlayer used to prevent bonding of the two slabs is required. The overlaid concrete pavement may rest on most base and subbase types or directly on the subgrade. Sampling design factors for this study are moisture, temperature, overlay thickness, original pavement type and overlay type.
All factors have two levels except original pavement type and overlay type which have three.