Long-Term Field Performance Evaluation of Chip Seals

The optimal timing and long-term effectiveness of chip seal treatments on newly constructed pavements remain uncertain, particularly for local agency roads. This study was an evaluation of the field performance of chip seals applied at different postconstruction intervals (from immediately to after 4 years) across three local agencies in Minnesota: Cass County, Crow Wing County, and the City of St. Cloud. Performance was monitored from 2015 to 2025 using the International Roughness Index (IRI), manual crack counts, and surface ratings. Linear mixed-effects models were used to assess performance trends. Results show that early application, either immediately after construction or within 1 year, was associated with better surface condition. However, binder type and reclaimed asphalt pavement content in the original pavement mix design exerted greater influence on long-term durability than chip seal timing alone. While chip seals were associated with preservation benefits, baseline material design largely dictated performance outcomes. Cracking data and IRI alone were insufficient for optimizing chip seal treatment schedules. The integration of material, structural, functional, and environmental factors may improve treatment timing decisions and maximize preservation benefits.