The Ultimate Glossary of Commercial Asphalt Paving Terms
When you hire a paving contractor, you are making a massive capital investment. Unfortunately, many "fly-by-night" paving companies rely on their customers not understanding the technical terminology of the trade, allowing them to cut corners on materials and execution.
As a 4th-generation paving company, Blue Ridge Estate Paving believes in total transparency. Here is the ultimate glossary of commercial asphalt paving terms you need to know.
Base and Subgrade Terminology
Subgrade
The native soil beneath the pavement structure. If the subgrade is soft (like clay), it must be excavated or stabilized before any stone or asphalt is laid. A failing subgrade guarantees a failing parking lot.
Aggregate Base Course (ABC)
The compacted layer of crushed stone that sits on top of the subgrade and beneath the asphalt. In Virginia, the standard for heavy-duty commercial paving is #21A Crushed Stone. This stone contains a mix of large rocks and fine dust, allowing it to compact into a concrete-like density.
Compaction / Density
The process of removing air voids from the subgrade, stone base, and hot mix asphalt using vibratory rollers. Asphalt must achieve 95%+ density. If it doesn't, water will penetrate it and destroy it.
Asphalt Mix Terminology
HMA (Hot Mix Asphalt)
A highly engineered mixture of liquid asphalt cement binder and heated aggregate. It is mixed at a plant at roughly 300°F to 350°F and must be laid down and compacted while it is still hot.
Asphalt Cement (Binder)
The black, sticky petroleum byproduct that acts as the "glue" holding the aggregate rock together in HMA.
PG (Performance Grade) Binder
A rating system that dictates the temperature extremes the asphalt binder can handle before deforming or cracking. A common grade in Virginia is PG 64-22, meaning it resists rutting at 64°C (147°F) and resists thermal cracking down to -22°C (-7°F).
VDOT Mix
Asphalt mixes that meet the strict engineering specifications of the Virginia Department of Transportation. Blue Ridge Estate Paving exclusively uses VDOT-approved mixes for commercial and heavy-duty residential applications.
Pavement Failure Terminology
Alligator Cracking (Fatigue Cracking)
A series of interconnected cracks that look like the scales of an alligator. This is the ultimate sign of structural failure. It means the subgrade beneath the asphalt has failed, and the asphalt is flexing and shattering under the weight of traffic. Sealcoating will not fix this; full-depth reclamation or patching is required.
Rutting
Depressions in the wheel paths of the pavement. Rutting usually occurs when the asphalt mix was incorrect for the climate (too soft of a binder), or the subgrade was insufficiently compacted.
Raveling
The progressive disintegration of the asphalt surface from the top down. As the binder oxidizes from UV exposure, it loses its grip on the aggregate rock, causing the surface to become rough and loose.
Maintenance Terminology
Emulsion Sealcoat
A protective liquid barrier applied to the surface of cured asphalt. High-solids emulsions protect the asphalt binder from UV oxidation, water penetration, and chemical spills (oil/gas).
Hot-Pour Crack Sealing
The process of injecting 400°F rubberized asphalt sealant into structural cracks. The extreme heat chemically bonds the rubber to the crack walls, creating a permanent, flexible, waterproof seal that moves with the pavement during freeze-thaw cycles.