Research Pays Off: Effective Use of Chip Seals in Minnesota

In the early 1990s, chip seal use throughout Minnesota declined to a historic low. State and local agencies were not obtaining a consistent quality of performance from the technique; however, long-term data show that successful application of chip seals extended service life of the state’s asphalt pavements by an average of 6 years.

 To address the problem, the Minnesota Local Road Research Board (LRRB) funded a study by the Minnesota Department of Transportation’s (MnDOT) Office of Materials and Road Research to investigate state, national, and international chip seal design methods and best construction practices. With information from the field visits and from other agencies and the industry, MDOT researchers recommended a design procedure and construction requirements.

 Data from MnDOT’s Pavement Management office show that for all bituminous roads during the span of 1987 to 2007, those that received regular chip seals had a service life averaging 6 years longer than that of pavements that did not receive regular chip seals.

Chip seals offer additional benefits, such as improved safety from increased friction; improved roadway aesthetics; a uniform pavement surface with small imperfections such as popouts filled in; and protection of the structural integrity of the underlying bituminous pavement. MnDOT is continuing research into best practices for pavement preservation.