Bituminous Materials
Asphalt and bitumen-based products used in paving, roofing and waterproofing.
Quick Answer
Bituminous materials are products built on bitumen, the dark, sticky, highly viscous hydrocarbon in asphalt. In construction they appear as the binder in asphalt pavement and in roofing and waterproofing products such as built-up roofing, modified bitumen membranes, shingles and damp-proofing coatings. Their performance depends on temperature, so selection and application matter.
The Full Picture
Bitumen is the heavy residue left from petroleum distillation. Pavement references describe asphalt as a dark brown to black, highly viscous hydrocarbon produced from petroleum distillation residue, formed either in natural deposits or in a refinery. In North American usage the words asphalt, asphalt cement and bitumen are often used loosely for the same binder, while in other regions bitumen is the common term. When a drawing or spec says bituminous, it usually means a product made with that binder.
In paving, the binder is heated and mixed with aggregate to make hot mix asphalt, then placed and compacted in layers. The same binder family appears in tack coat, prime coat and seal coat. The binder is not static: the same source notes that as it ages, its viscosity increases and it becomes stiffer and more brittle, which is why pavements crack over time. Highway agencies test and sometimes modify binders, and FHWA keeps technical briefs on binder modification and testing for that work.
In roofing and waterproofing, bitumen is used in several forms: built-up roofing with multiple plies and bitumen layers, modified bitumen sheets that include polymer additives, asphalt shingles, and brush- or spray-applied dampproofing and coatings. These systems are covered in the roof and waterproofing pages of this glossary. Application method matters: some are installed with hot asphalt, torches or cold adhesives, and each carries its own safety, fire-watch and weather requirements.
Estimators price bituminous work by the unit the trade uses: tons for asphalt paving mix, square yards or square feet for paving area at a given thickness, and squares (100 SF) for roofing. Quantities usually need thickness, compaction and waste assumptions, and the specification section defines the mix, the binder grade and the testing. A frequent mistake is pricing a pavement area without the base, tack coat and striping that the spec requires with it. Older roofing products can also contain asbestos, so renovation work should be checked against the building's survey.
Real Examples
Common Misconceptions
People assume: Asphalt and tar are the same thing.
Actually: They are different materials with different sources. Asphalt and bitumen come from petroleum, while coal tar is made from coal. Specifications and safety data sheets name which one is permitted.
People assume: A bituminous product is the same as an asphalt pavement.
Actually: Pavement mix is one use of the binder. Roofing membranes, shingles and coatings are separate product families with separate standards, installers and warranties.
People assume: Older asphalt roofing is just asphalt.
Actually: Some older roofing products contained asbestos. EPA's rule lists asphalt roofing products as Category I nonfriable ACM when they contain more than 1 percent asbestos, so renovation work should be checked against a survey.
Frequently Asked Questions
What does bituminous mean in construction?
It means made with or containing bitumen, the viscous petroleum-derived binder in asphalt. It is applied to paving mixes, roofing membranes and shingles, and waterproofing and dampproofing coatings.
Is bitumen the same as asphalt?
In much of the world bitumen is the term for the binder itself. In the United States, asphalt often refers to both the binder (asphalt cement) and the finished paving mix. Pavement references describe asphalt cement used for paving as consisting of almost pure bitumen.
What units are bituminous materials priced in?
Paving mix is usually bought by the ton and placed by area and thickness, so SY or SF with a thickness. Roofing is commonly priced by the square (100 SF). Coatings and damp-proofing are usually by SF of surface treated. The project spec and your supplier define the exact basis.
Why do bituminous materials crack or soften?
They respond to temperature and age. Cold conditions can make binder brittle and hot conditions can soften it, and over time the binder stiffens. Mix design, binder selection and maintenance address this.