Ultra thin lift asphalt is a hot mix asphalt mixture consisting of paving grade asphalt and fine aggregate. The ultra thin asphalt mixture is produced at a central hot mix plant and delivered to the job site. While there are many variations, ultra thin lift asphalt is typically applied at .75" to 1.0" depth and designed as a preservation treatment to extend the service life of the existing pavement and address minor distresses. After applying the bond coat, the ultra thin lift mixture is applied using traditional paving equipment and compacted to achieve optimum density. Milling may also be required prior to application at start up joints, tie backs, on curb and gutter sections and to level areas to facilitate compaction.
Ultra thin HMA typically uses standard hot mix paving equipment. There are a few variations to the process depending on location, treatment type, design and specifics of the project.
4.75mm Ultra Thin Lift asphalt is a dense graded asphalt mixture sometimes referred to as a "Sand Mix". This application is typically applied at 1" depth or less on low to moderate volume roads, but is used on higher traffic volume routes in some regions. These dense graded ultra thin lift mixes have low permeability.
Bonded Wearing Course is a unique type of ultra thin lift asphalt. Bonded Wearing Course is a gap graded mixture that is applied over a heavy application of polymer modified tack coat. This treatment is more expensive than traditional ultra thin lift, but bonded wearing course is a great choice for application on PCC pavements and high traffic asphalt pavements in good condition.
OGFC (Open Graded Friction Course) is a type of ultra thin lift asphalt. OGFC's has only a small percentage of fine aggregates and a high percentage of air voids in the mixture. This mix has a higher degree of friction and reduces splashing and overspray.