Surface Treatment is the application of an asphalt emulsion on either an existing asphalt road or a fresh, compacted granular surface immediately followed by the application of a cover aggregate.
It provides an economical all- weather surface for light to higher volume traffic depending on the emulsion and quality of aggregate used. It also provides a waterproof barrier that prevents the intrusion of moisture into the underlying materials and provide a skid resistant surface. It gives new life to a dry, weathered surface. A weathered, raveled pavement can be restored to useful service by application of a single or multiple surface treatment.
The asphalt emulsion is a mixture of asphalt cement, water, and an emulsified agent. It’s composition is approximately 66% AC, 33% water and 1% emulsifier. It is applied with a computerized distributor, at rates varying from 1.30kg/ m² to 2.00kg/ m² . The most commonly used emulsions are HF150, HF150P (Polymer), HFMS-2, and CRS-2. Other emulsions are available for specific applications.
The Aggregate is divided into six different classes.
- Class 1- washed chip
- Class 2-comparable to 5/8 crusher run
- Class 3- HL4
- Class 4-Commonly known as a sand seal
- Class 5-fine washed chip
- Class 6- HL3
It is applied with a computerized chip spreader at rates varying from 12kg/ m² to 22kg/ m² .
These operations are immediately followed by rubber tired rollers, and depending on the application, a steel drum roller.
Single Surface Treatment
Single Surface Treatment is a preventative maintenance tool that preserves and re-enforces existing pavements and surface treated roads, extending their life expectancy.
It is constructed by spraying a uniformed single application of asphalt emulsion on a clean surface with a Computerized Distributor Truck, followed by a layer of cover aggregate that is applied with a Computerized Chip Spreader. This is immediately followed by a minimum of two Pneumatic Rubber Tired Rollers, which seats the aggregate properly into place.
Sealant – Emulsion not only bonds aggregate, but creates a water proof barrier over the roads surface and fills cracks up to 6mm (¼ inch) preventing moisture and air penetration.
Restores Skid Resistance – Transforms a polished surfaced into a fresh wear course.
Time and Money – A Single Surface Treatment is a fraction of the cost of an asphalt overlay while achieving the same result in less time.
For high traffic volume applications polymer modified emulsions should be considered.
It is crucial that all necessary preparations such as pothole patching, leveling, and base repair are completed well in advance of surface treating. It is also recommended that all cracks larger than 6mm (¼ inch) be crack filled months in advance, ideally the season before.
*A Single Surface Treatment will not correct things such as cross fall imperfections and wheel rutting. These deficiencies must be corrected beforehand.*
Double Surface Treatment
Double or Multiple Surface Treatments are a cost effective alternative to Hot Mix Asphalt, generally constructed on a fresh, compacted granular surface.
They are constructed by spraying a uniformed application of asphalt emulsion with a Computerized Distributor Truck, followed by a layer of cover aggregate applied with a Computerized Chip Spreader. That is followed immediately by a minimum of two Pneumatic Rubber Tired Rollers (one Rubber Tire Roller may be substituted with a Steel Drum Roller on multiple surface treatment applications), which seats the aggregate properly into place.
Once the first lift is complete, the same process is repeated using an aggregate not less than ½ the size of the first application. It is completed with a Non-Vibrating, Steel Drum Roller following up behind.