So, which is it? I get asked this simple question more and more with the increased interest in Superpave. Superpave (SUperior PERforming Asphalt PAVEments) was developed by the Strategic Highway Research Program (SHRP) in the United States to help improve performance, efficiency, durability and safety of the highway system. As many more countries adopt Superpave or at least parts of it, there are many more individuals interested in understanding this new design system and all the new testing methods associated with it. Depending on what you search for, read in journals, or find on Google, you will most likely see all these terms are used interchangeably to describe the black sticky stuff used to hold the road together. I’ve found the following definition to be the most concise and thought it might be useful to share.
Bitumen is a semi-solid hydrocarbon product produced from refining crude oil but also occurs naturally. It is often referred to as asphalt (or asphalt binder/cement) and the terms are commonly used interchangeably; however, bitumen is the black oil product while asphalt is a combination of bitumen and aggregate stone. It is a very heavy, viscous material, is highly resistant to water and to environmental factors which requires storage and transportation at very high temperatures. It is primarily used by the construction industry, most notably for roofing and road surfaces, which accounts for approximately 85% of all bitumen use.
Since the introduction of Superpave, just 26 years ago in the United States, its use has been growing in popularity around the World with no apparent end in sight. While some Countries have adopted aspects of Superpave, predominantly the asphalt binder testing, others are using the entire system to AASHTO M320 and M332, in their entirety. Along with the increased use of this technology, the need and use of rheometers has also significantly grown; a problem I’m very happy to endure 😉
With globalization, asphalt/bitumen is traded like all other commodities around the World. For quality acceptance, rheological characterization has become the gold standard by many and Malvern Panalytical have a dedicated rheometer range for this application – the Kinexus DSR series. The Kinexus DSR is most user-friendly, precise and robust rheometer specifically designed for asphalt binder characterization, with additional capabilities and intelligence that provide a more complete picture of your asphalt materials – not just a number or grade!
If you want to see the system in action, then why not watch our demo at your desk, which I recorded last year
If you’re interested in bitumen (or asphalt), the following are excellent sources for information:
Also, here are some interesting facts about asphalt courtesy of the National Asphalt Paving Association.
- X-ray fluorescence to identify REOB/VTAE, sulfur and phosphorus in bitumen
- Laser diffraction for determining particle size and size distribution of asphalt emulsions
- Electrophoretic light scattering for assessing asphalt emulsion stability
- Capillary rheometry to optimize processing of highly filled asphalt mastics for roofing or pipe seals
- Gel permeation chromatography for evaluating molecular weight distribution of bitumen formulations