Bituminous materials are binders made from bitumen, the heavy residue of petroleum refining, or from coal tar, and they are the basis of asphalt pavement, sealcoats, and many waterproofing products.
- Also called
- Asphalt binder, bitumen
- Where you see it
- Surface lot paving, sealcoats, crack fillers, waterproofing membranes
- Key fact
- The maintenance ladder: crack seal, sealcoat, mill and overlay, then full reconstruction
In parking, bituminous materials are most visible as the asphalt surface of a surface lot: aggregate held together by an asphalt binder, laid hot, and compacted. They also appear in crack fillers, sealcoats, and modified bitumen membranes used under plaza decks and on roofs.
In surface lots
- Asphalt offers the lowest first cost of any durable parking surface, but it ages steadily. Sun and oxygen harden the binder, water enters through cracks, and freeze and thaw cycles widen them.
- The usual maintenance ladder is crack sealing, then sealcoat, then mill and overlay, and finally full reconstruction once the base has failed.
- Coal tar sealcoats, once common, are now restricted in several states and cities because of their environmental profile, so asphalt-based sealers are the default.
Pick a strategy for a surface lot and drag through 25 years. Watch which rung of the ladder the lot needs.
A lot that gets crack sealing and sealcoat every few years stays on the cheap rungs of the ladder and needs one mill and overlay. A lot left alone spends nothing for years, then passes through years of rough pavement and ends with full reconstruction. A lot that will be redeveloped should be kept safe and serviceable, with nothing spent that the next building will remove.
Illustrative condition curves and timing, not engineering data. Dollar signs show the relative cost of each rung, not prices.
In structured parking
- Asphalt is rarely used as the wearing surface on an elevated concrete deck. It adds dead load, can hold water against the slab, and hides cracking and corrosion from the condition surveys that a garage depends on.
- Structured decks are more often protected with sealers and traffic-bearing membranes.
The Parkonomics view
A surface lot’s pavement is a capital liability that rarely appears in the operating budget until it fails. Owners who schedule crack sealing and sealcoating spend far less than those who wait for reconstruction, and for lots held for future development, the right strategy is often the opposite: keep the surface safe and serviceable, and spend nothing that the next building will tear up.
Related terms: Albedo, Foundation Systems, Heat Island Effect, Life Cycle Cost
Further reading: The Evolution of U.S. Parking Structures in 2026