SEDL / STP / STP1348-EB / STP12858S

Effectiveness of Seal Coat Interlayers in Maintenance Overlays

Hossain, MS
Post Doctoral Fellow, Auburn University, AL

Parker, F
Director, Highway Research CenterAuburn University, AL

Pages: 17    Published: Jan 1998

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Abstract

During 1992, three one-mile (1.6 km) long test sections were constructed on each of fourteen maintenance overlay projects in Alabama. A mile-long control section represented the usual construction practice of asphalt concrete overlay with a seal coat interlayer. Two experimental sections had a same and a thicker overlay without seal coat interlayers. Milled and unmilled projects were included. Cracking (alligator, transverse, and longitudinal), rutting and an overall pavement condition rating were considered to evaluate the effectiveness of seal coat interlayers.

Seal coat interlayers reduced transverse reflection cracking, but milling was more effective. Milling increased alligator cracking, but reduced rutting. Overall, neither seal coat interlayers nor milling improved overlay performance. Cost wise, seal coat interlayers and milling adds approximately $0.40 and $0.33 per m², respectively, to overlay costs.