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Category Archives: Technical
Performance Grade Systems for Asphalt Binders
Background Asphalt binders are most commonly graded by their physical properties. An asphalt binder’s physical properties directly describe how it will perform as a constituent in asphalt concrete (AC) pavement. Although asphalt binder penetration and viscosity grading are still commonly used worldwide, new binder tests and specifications have been developed to more accurately characterize asphalt Read more
Willows for Soil Stabilization
With winter comes the cool crisp air and the occasional unexpected erosion problem from heavy rains. Repairing an erosion gully or streambed can seem like a headache, however there is a natural remedy that requires little to no machinery to install: Willows. The willow species, Salix, has over 400 species of deciduous trees and shrubs Read more
An Overview of Asphalt Sealer Systems
Asphalt sealers are not slurry seals (Caltrans section 37.2 specifications) but a lot of people refer to asphalt sealers as slurry seals. Asphalt sealers have been in use for over 40 years and today there are basically three different sealer systems: Asphalt emulsion based sealers, clay emulsion based sealers and coal tar based sealers. The Read more
Hot Mix Asphalt Tennis Courts: Material Selection, Construction, Repair and Maintenance
Hot mix asphalt can be used for tennis courts to provide a durable, flat surface with good traction for players, clear defined boundary lines and consistent ball movement. Asphalt surfaces are not susceptible to rain unlike other types of courts and will not require much maintenance. Asphalt can be placed and compacted to develop one Read more
Warm Mix Asphalt Update
New Technologies Offer Opportunity for Improved Roadways Warm Mix Asphalt (WMA) is the name given to conventional Hot-Mix Asphalt (HMA) that is modified by additives or changes in manufacturing processes that allows asphalt mixes to be produced and placed at low temperatures. Reductions of 50 to 100 degrees Fahrenheit have been documented. WMA technology has Read more
Permeable Aggregate Systems for Playing Fields
It’s no doubt that synthetic athletic fields are becoming more popular. Organizations that decide to install synthetic fields have realized lower maintenance costs and better playability. Using a sophisticated system of drainage channels, filter fabrics and specialized aggregate, a well-designed field draws water quickly from the turf layer allowing year-round play and reliable playability in Read more
Tender Asphalt Mixes – Causes and Cures
A“tender” asphalt mix usually refers to a mix that is difficult to compact. It may have a tendency to shove under the roller wheels and/ or leave longitudinal cracks at the edge of the steel drums. Either a lack of friction between particles or a lack of shear strength in the mix essentially causes tenderness. Read more
Fog Sealing Older Pavements
In its “A Basic Asphalt Emulsion Manual”, the Asphalt Emulsion Manufacturers Association and the Asphalt Institute describe a fog seal as a “light application of slow-setting emulsion sprayed on an existing asphalt surface.” Properly applied and applied at the right time, a fog seal can be a valuable aid in the maintenance of an asphalt pavement. Read more
Tender Pavements
A tender or slow-setting asphalt pavement is defined as one that scuffs under horizontally applied shearing loads after compaction has been completed, such as when power steering turns are made by a stationary vehicle. There are several causes of “tender pavements” including a faulty mix design, low compaction, and liquid asphalt saturation. Although each of Read more
