Asphalt - Tarmac - Bitumen
Definition: Asphalt is a highly viscous or semi-solid sticky, black liquid that is present in crude petroleum, which is also found in some natural deposits.
It is a product which is also commonly referred to as bitumen.
Brief: The primary use of asphalt (bitumen) is in road construction, where it is used as a form of glue (binder) for the aggregate particles. The use of the words Asphalt and Bitumen causes a lot of confusion outside of the road or roofing construction industries. Asphalt or bitumen can also be confused with tar, which is a similar black thermo-plastic material, but one which is produced by the distillation of coals. During the early and mid twentieth century the Tar product was extensively used as the binder for road aggregates. The addition of tar to Macadam roads lead to the word Tarmac which is now used as a common term to refer to road making materials. However, since the 1970s asphalt (bitumen) has completely overtaken the use of tar in these applications.
Tarmac: Macadamized (Tarmac) roads & driveways were originally adequate for light usage by horse, carriage and car, but they are prone to erosion with heavy usage, high speeds, rain or heat. As petroleum production increased, the by-product asphalt became available in huge quantities and largely supplanted tar due to its reduced temperature sensitivity. The Macadam construction process also became quickly obsolete due to its high manual labour requirement; however, the somewhat similar tar and chip method, also known as bituminous surface treatment (BST) still remains a popular product.
Asphalt (bitumen) can be used for built-up-roofing situations, normally associated with flat roofs such as garages, or sloping roofs (more so in commercial environments).
This is achieved by impregnating and or sealing the surface of felt plies (cellulose, fibreglass, polyester screen or matting fabrics) with the asphalt in a useable form.
Basically, a modified form of bitumen which uses a polymer such as SBS (styrene-butadiene-styrene) or APP (atactic polypropylene), which can be applied by hot mopping (flame) or cold using a cutback asphalt (solvent-based asphalt adhesive). This process is referred to as Hot Mopping.
Oxidized asphalt is often used to manufacture roofing materials for a variety of roofing systems, which include asphalt shingles, reinforcing, roof-rolling products, polymer-modified bitumen roofing, and the underlaying of felts (as above). Other uses include membranes, hydraulic applications, undersealing specifics such as paving, pipe coatings and even some paint products.
ASPHALT & TARMAC