Comparison of bitumen–rubber use in extreme conditions in Russia and South Africa

The development of the use of crumb rubber from used tyres in asphalt started in the USSR during the 1960s independently and in parallel with the research in the USA and Western world during the 1970s. The result is that different processes were developed for making bitumen–rubber (BR) asphalt. The objective of the paper is to present and compare the BR specifications and asphalt experience in Russia and in South Africa (which was derived from the USA approach). The focus is on the wet process even though more recently the dry method has been used. First, the properties of the constituent components are presented and discussed, thereafter the properties and manufacture of BR are compared. Finally, the properties of BR asphalt are compared and the experience and performance is presented. It was found that although the initial approach from the two schools differed, there are currently major similarities, even though the temperature ranges of use are vastly different. BR has been shown to cater effectively for a wide range of environmental conditions and is superior to unmodified bitumen.