Chip seals are an effective maintenance tool for restoring a wearing course to a pavement. As a preventive maintenance tool, chip sealing prevents ingress of moisture into a pavement or base course and can prevent deterioration due to oxidative aging of a pavement. Emulsions for chip sealing include cationic polymer-modified formulations. Because many different geologic types and gradations of cover aggregate are used for chip sealing (single size, graded, hard, porous) the emulsion should be selected to accommodate the aggregate in a performance system.
Ideally, chip seals should be applied when a road is still in good condition, with only minor surface problems, such as loss of friction, drying surface or very minor cracking. They may also be applied as a wearing surface over a prepared base on rural roads. Chip seals are an excellent choice for keeping good pavements in good condition. The Strategic Highway Research Program found chip seals, which are a relative low cost treatment, to be one of the most cost-effective pavement preservation treatments