What is Asphalt Pavement Preservation?
The FHWA describes it as “a program employing a network level, long-term strategy, which enhances pavement performance by using an integrated, cost-effective set of practices that extend pavement life, improve safety, and improve motorist expectations.”
Asphalt Road Preservation Treatments are an environmentally sound and cost-effective way to extend the life and the performance of and asphalt roadways while improving skid resistance on highways when compared to asphalt overlays.
It’s an important preventative maintenance program to keep roads and road structure in good condition to prevent additional base damage and unnecessary expenses.
Extending asphalt road life with ESCS (expanded slate, clay, or slate) materials is not only cost effective, but it also reduces road closure downtime. Simply said, ESCS materials are natural aggregate materials that have been exposed to temperatures of about 2,000° F. This exposure expands the material up to 40%.
ESCS aggregates are sustainable and have additional benefits:
ESCS is available throughout North America in different aggregate sizes, depending on the road surface application and can be applied with most standard dump vehicles, spreaders, and pneumatic rollers.
Before and After Comparison:
For example, a road experiencing alligator cracking can be sealed with a scrub seal treatment. The scrub seal process includes brooming the emulsion into the cracks, then applying a smaller grade ESCS (approximately 1/8″ diameter) chips via a chip spreader. Once the chips are placed, a pneumatic roller then embeds the chips into the asphalt extending wearing life 3–5 years while increasing skid resistance. It is not uncommon for road engineers to follow-up the new scrub seal a few weeks later with a similar chip seal process with larger (3/8″-5/8″ diameter) ESCS chips . This acts like a 1-2 punch for asphalt road preservation extending asphalt road life years and reducing lifecycle cost up to 25% when compared to HMA.
Effective treatment candidates include pavements that are moderate to highly cracked, oxidized, or smooth (polished surfaces with reduced friction). Bad candidates include pavements that are rutted or have structural damage. Treatments are typically used on state and county highways (and shoulders), local streets, and collector streets.
ESCS Scrub Seals are flexible and can be used as a stand-alone application or in combination with other treatment types such as: Fog Seals, Micro/Slurry (Cape Seals), Thin Lift HMA, Hot Mix Overlay (SAMI: Stress Absorbing Membrane Interlayer), and Standard Chip Seal Treatments.
Asphalt Preservation Treatments offer several options for asphalt life extenders. These include individual treatment with material ranging in size from 1/8″ to 5/8″. Treatments can also be used in combination with each other such as a 1/8″ scrub seal treatment to seal cracks to 5/8″ chip seals for pavement life extension.
Best Practices for a successful asphalt treatment:
Asphalt Preservation Scrub Seal Treatments are designed to extend asphalt road life at a fraction of the cost of milling followed by a hot mix overlay. It addresses issues that face many transportation engineers, such as fatigue cracking, transverse cracking, loss of friction, raveling, etc. Benefits include reduction in greenhouse gas emissions by up to 51% and reduced life cycle cost by 48% compared with HMA.
ESCS materials are available nearly anywhere coast to coast. Visit ESCSI.org for an ESCS Producer near you.