Sustainable reuse of highway materials in hot and cold bituminous mixtures

In the last few years there has been growing concern about the increasing demand placed upon finite resources. Many organizations and types of industry now encourage the practice of sustainability. With the introduction of the landfill tax, aggregate lax and the increasing cost of bitumen, highway authorities must now consider other methods to achieve better value for money. In highway engineering, reduction in use of aggregate and bitumen resources can be achieved by better understanding of pavement design and choice of materials used. It may also be facilitated by the reuse of bituminous materials that have been removed from the pavement structure as part of a maintenance programme. This is termed reclaimed asphalt pavement (RAP) and is permitted in hot-mix asphalt in accordance with the Specification of Highway Works Clause 902. A combination of these two approaches will enable the maximum reuse of this type of material without urning the highway into what may he termed a waste disposal location. This paper shows how clients such as local highway authorities are maximizing reuse opportunities. It also gives an example of how suppliers are now collaborating with academic institutions to develop new technologies to solve the client's problem. Two experimental trial road sections are detailed which were designed and constructed to evaluate the use of RAP in a hot and a cold bituminous mixture. This as enabled the authors to quantify the benefit of using recycled materials and technologies.