The uses of bitumen

The vast majority of bitumen is used by the construction industry, as a con- stituent of products used in paving and roofing. Excellent waterproofing characteristics and thermoplastic behaviour make it ideal for a wide range of applications. At el evated temperatures (typically between 100 and 2008C) it acts like a viscous liquid, and can be mixed with other components and manipulated and formed as required. Once cooled, it is an inert solid that is durable and hydrophobic (repels water).

Various terms are used to describe conventional bitumen such as straight run, paving grade and penetration grade (or ‘pen grade’). When people use these terms they normally mean grades of bitumen that can be produced at a conventional refinery in a relatively simple way.

The vast majority of bitumen used in asphalt for road construction is conven- tional bitumen; that is why it is often known as paving grade. The term ‘pen grade’ is short for penetration grade, and reflects the fact that this type of product is often classified (in Europe and parts of Asia) using the penetration test. The term straight run refers to the fact that this type of bitumen is often produced direct from the vacuum distillation process, without any further modification.

Current estimates put the world use of bitumen at approximately 102 million tonnes per year (Eurobitume and the Asphalt Institute, 2011), and about

85% of all the bitumen produced is used in asphalt for the construction of roads and other paved areas. Typically, asphalt will contain approximately 5% by mass of bitumen, with the remaining 95% consisting of a mixture of mineral aggregates and much finer materials such as limestone filler

A note on terminology is worth making at this point – ‘asphalt’ is a generic term used to describe a range of road surfacing products containing primarily bitumen and mineral aggregates. A few alternative terms exist including hot mix asphalt (HMA) and asphalt concrete (AC). In this book the term ‘asphalt’ will be used throughout. Asphalt is often referred to incorrectly in the media and in common parlance as tarmac (short for tarmacadam). Tarmacadam is a road surfacing product using coal tar as a binder and has not been used in road construction for over 30 years.

A further 10% of global bitumen production is used in roofing applications, and the remaining 5% is used mainly for sealing and insulating purposes in a variety of building materials, such as pipe coatings, carpet backing, joint sealants and paint.

The extremely wide range of uses for bitumen is demonstrated by the number of registered uses in Europe under the requirements of the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulations, which require all chemical substances and associated uses to be registered. Table 1.2 provides an overview (Eurobitume, 2013).

Bitumen is available in a variety of grades. Specifications are used across the world to define these grades to meet the needs of the applications, climate, loading conditions and end use. They are usually based on a series of standard test methods that define the properties of each grade such as hardness, viscosity, solubility and durability.

Bitumens are also used to manufacture mixtures or preparations. In these products, bitumen is often the principal component, but they can contain significant proportions of other materials to meet end use requirements. These mixtures are chemically classified as bitumen preparations.

The most commonly used are as follows (Eurobitume and the Asphalt Institute, 2011):

Cut-back bitumen and fluxed bitumen. Cut-back and fluxed bitumen products are preparations in which the viscosity of the bitumen has been reduced by the addition of a solvent, normally derived from petroleum. Typically the solvents used are white spirit, kerosene and

Type	Application
Agriculture	Disinfectants Fence post coating Mulches Mulching paper Paved barn floors, barnyards, feed platforms Protecting tanks, vats Protection for concrete structures Tree paints (protective)
Buildings and industrial paving	Water and moisture barriers (above and below ground) Floor compositions, tiles, coverings Insulating fabrics, papers Step treads Building papers Caulking compounds Cement waterproofing compounds Glass wool compositions Insulating fabrics, felts, papers Joint filler compounds Laminated roofing shingles Liquid roof coatings Plastic cements Shingles Acoustical blocks, compositions, felts Bricks Damp-proofing coatings, compositions Insulating board, fabrics, felts, paper Masonry coatings Plasterboards Putty Soundproofing Stucco base Wallboard Air-drying paints, varnishes Artificial timber Ebonised timber Insulating paints Plumbing, pipes Treated awnings Canal linings, sealants
Hydraulics and erosion control	Catchment areas, basins Dam groutings Dam linings, protection Dyke protection Ditch linings Drainage gutters, structures Embankment protection Groynes Jetties Levee protection Mattresses for levee and bank protection Membrane linings, waterproofing Introduction Type Application Reservoir linings Revetments Sand dune stabilisation Sewage lagoons, oxidation ponds Swimming pools Waste ponds Water barriers Backed felts
Industrial Conduit	Conduit insulation, lamination Insulating boards Paint compositions Papers Pipe wrapping Insulating felts Panel boards Underseal Battery boxes, carbons Electrical insulating compounds, papers, tapes, wire coatings Junction box compound Moulded conduits Black grease Buffing compounds Cable splicing compound Embalming Etching compositions Extenders Explosives Lap cement Plasticisers Preservatives Printing inks Well drilling fluid Armoured bituminised fabrics Burlap impregnation Mildew prevention Sawdust, cork, asphalt composition Acid-proof enamels, mastics, varnishes Acid-resistant coatings Air-drying paints, varnishes Anti-corrosive and anti-fouling paints Anti-oxidants and solvents Base for solvent compositions Baking and heat-resistant enamels Boat deck sealing compound Lacquers, japans Marine enamels Blasting fuses Briquette binders Burial vaults Casting moulds Clay articles Clay pigeons Expansion joints Flowerpots Foundry cores Friction tape Gaskets Mirror backing Rubber, moulded compositions Shoe fillers, soles
Paving (see also agriculture, hydraulics, railways, recreation)	Airport runways, taxiways, aprons Asphalt blocks Brick fillers Bridge deck, surfacing Crack fillers Floors for buildings, warehouses, garages Highways, roads, streets, shoulders Kerbs, gutters, drainage ditches Parking lots, driveways Portland cement concrete underseal Roof-deck parking Pavements, footpaths Soil stabilisation
Railways	Ballast treatment Dust laying Paved ballast, sub-ballast Paved crossings, freight yards, station platforms
Recreation	Dance pavilions Drive-in movies Gymnasiums, sport arenas Playgrounds, school yards Race tracks Running tracks Skating rinks Swimming and wading pools Tennis courts, handball courts Synthetic playing fields and running track surfaces

Bitumen emulsions. Bitumen emulsions are products in which droplets of bitumen or bitumen preparation are dispersed in an aqueous medium. An emulsifier is used to stabilise the mixture. Bitumen emulsions permit the handling, transport and application of bitumen at lower temperatures, and are used mainly in road surfacing applications.