Smoothseal  is the industry name for ODOT Specification Item 424, Fine Graded Polymer Modified Asphalt Concrete, type A or B. Any asphalt concrete producer can produce Smoothseal to ODOT specification.

Smoothseal is blended of high-quality aggregates with polymer modified asphalt to produce one of the most durable, dense-graded paving mixtures available. These materials are especially well suited for thin, preventive maintenance overlays. Smoothseal is unique among paving materials in Ohio in that the ODOT spec requires sand having at least 50% silicon dioxide, SiO2 (quartz) to insure high skid resistance. No other ODOT specification material has this requirement. Because not all sands found in southwestern Ohio have the necessary percentage of SiO2, Flexible Pavements of Ohio issued an advisory letter to users and producers in southwestern Ohio. Read our Smoothseal Advisory.

For more information on how to use " Smoothseal" to best advantage refer to the following technical documents and specification:

FPO Technical Bulletin: Smoothseal

What Exactly Is Your Preventive Maintenance Program Preventing?

Find the latest revision of the specification for Item 424 in the 2013 ODOT Construction and Material Specifications book and at  .

The progress of Smoothseal™ has been chronicled in articles in the newsletters and magazines of Flexible Pavements of Ohio. See the following issues and articles on the Ohio HMA News page to learn more about the development and use of Smoothseal™.

June, 2001 - ODOT Issues Preventive Maintenance Guidelines
September, 2001 – Smoothseal - Gaining Acceptance
June, 2002 – Smoothseal – Gaining Acceptance, Part 2
October, 2002 – Smoothseal Rolls Over Microsurfacing in Alternate Bid Project
April, 2003 – Preventive Maintenance, A Good Idea Whose Time Has Come

Also, see the following related articles from Ohio Asphalt magazine on the Ohio Asphalt Magazine page

Winter, 2004 – Smoothseal Trickles Down
Fall, 2005 - A Report on Early Skid Findings for Smoothseal 
Fall, 2006 - Recycled Asphalt Pavement Now Permitted in Smoothseal

For information on the cost effectiveness of Smoothseal see the article on ODOT's study:

Winter 2006 - Analysis looks at Cost-Effectiveness of Preventive Maintenance Treatments