Let subsurface conditions help determine preservation candidates

Guidelines for systematic evaluation of subsurface conditions have been developed by the Indiana Department of Transportation (DOT) in the form of a project level evaluation for pavement preservation treatments applicability. These include micro surfacings, seal coats, 4.75-mm nominal maximum aggregate size (NMAS) hot mix asphalt (HMA) overlays, and ultra thin bonded wearing courses. The evaluation procedure comprises five steps, which include a preliminary assessment in the form of a checklist; evaluation level selection and core location determination; layer determination; laboratory tests and data analysis; and determination of applicability of the treatment.