Quantifying the impact of reclaimed asphalt pavement on airport asphalt surfaces Greg White School of Science and Engineering, University of the Sunshine Coast, 90 Sippy Downs Drive, Sippy Downs, Queensland 4556, Australia highlights  RAP is no more variable than new quarried crushed rock sources.  RAP is more finely graded than the asphalt it is recovered from.  Asphalt containing RAP is moderately stiffer than asphalt without RAP.  Asphalt containing RAP has significantly lower surface friction than asphalt without RAP.  Inclusion of RAP from temporary ramps is not detrimental to airport asphalt. article info Article history: Received 6 March 2018 Received in revised form 19 September 2018 Accepted 15 November 2018 Keywords: Airport Asphalt RAP Quantified abstract Airports desire sustainable infrastructure solutions and airport pavements provide an opportunity for increased reuse and recycling of materials. The recycling of reclaimed asphalt pavement (RAP) in airport pavement surfaces is attractive and viable, but has been resisted by many airports. Two asphalt mixtures, both produced with and without RAP, were compared based on Marshall mixture design properties, lab- oratory performance-indicative test results and full-scale asphalt production properties. No testing indi- cated any detrimental effect associated with the inclusion of low-risk RAP sources at 5–10% RAP content. However, the surface friction was significantly reduced by the inclusion of RAP. It is recommended that further research consider the cause of the reduced surface friction associated with low-risk RAP inclusion, as well as the influence of other RAP sources on airport asphalt surface performance. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction Flexible airport pavement surfaces are predominantly com- prised of dense graded, Marshall designed asphalt. The aggregates are usually fully crushed, newly quarried hard rock and the bitumi- nous binder is usually a premium or modified product. Impor- tantly, the binder content is high compared to road and highway asphalt, typically 5.4–5.8% by mass of the asphalt mixture. In addi- tion, some jurisdictions and airports have developed alternate air- port surface types. For example, some European countries use stone mastic asphalt [5], open graded friction course [8] or gap graded mixtures [23]. However, the USA, Australia, New Zealand, the Middle East and South Africa continue to favour dense graded mixtures designed using the Marshall approach. Regardless of the asphalt mixture type, increased environmen- tal sustainability is desired by many airports [14,6]. Environmental sustainability can be achieved by recycling, reduced emission generation or increased surface life [20]. The incorporation of recovered asphalt, known as reclaimed asphalt pavement (RAP) is arguably the most common and well-established sustainability initiative in asphalt production and construction. However, some airports have resisted the use of RAP, citing concerns regarding performance. The research aims to quantify the impact of incorporating low- risk RAP into asphalt for runway surfacing. The low-risk RAP was sourced from the texturing of the underlying asphalt surface and the removal of temporary ramps by cold planing machines. The RAP was therefore produced to the same mixture design and as part of the same surfacing project. Asphalt was sampled and tested from two different Australian airport resurfacing projects and the findings are intended to be extended to other RAP sources in the future. https://doi.org/10.1016/j.conbuildmat.2018.11.131 0950-0618/Ó 2018 Elsevier Ltd. All rights reserved. E-mail address: gwhite2@usc.edu.au Construction and Building Materials 197 (2019) 757–765 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat