2023 - USA - Chip Seals for Roughness Mitigation in Cold Climates

Chip Seals are a type of pavement preservation treatment characterised by its ability to reduce pavement deterioration and restore surface condition. Chip seal performance, like other pavement preservation treatments, depends on several factors such as environmental conditions, traffic level and the condition of the existing pavement structure prior to treatment application. In cold regions, the presence of freeze and thaw cycles promotes the generation of thermal cracks and possible tenting distresses, consequently, pavement roughness has been a prominent parameter to assess treatment performance. The objective of this study was to evaluate the roughness progression on several chip seal configurations in a cold climate region, utilising a set of field performance data from the Pavement Preservation Group Study, a broader research study conducted by the National Center for Asphalt Technology and the Minnesota Department of Transportation’s Road Research Facility. The main findings indicate that chip seals provide a negligible effect on immediate roughness improvement; however, on a long-term basis, they provide a reduction in IRI progression over time. The magnitude of the IRI benefit is dependent on the type of chip seal implemented and the traffic level experienced.