Improving bituminous mixture performance by optimizing the design compaction energy – A cost effective approach for better pavements

•How design compaction energy affects the properties of the mixtures.•How design parameters can be used to optimize performance.•Choosing the relevant properties for a given set of in-service conditions.•Proposed methodology could improve performance compared to the existing ones. The design of bituminous mixtures has been improved with new analytical methods and enhanced laboratory tests. However, the adoption of these methods increases the complexity and cost of the design process and may not provide better bituminous mixtures nor improved pavement performance. The aim of this study was to analyse how a more flexible design method, which takes into account in-service conditions, can be a useful tool to improve the overall performance of the mixtures. Two mixtures, an AC20 and a SMA12.5, were designed using current design methods and a procedure based on volumetric design. The performance of the studied blends was characterized using laboratory tests. An analysis of the obtained results was made for the Portuguese in-service conditions, based on current pavement design guidelines. From this analysis values were proposed for the compaction energy levels necessary to design both mixtures, ranging from 45 to 85 gyrations for the AC20 and from 55 to 75 gyrations for the SMA12.5. A cost-benefit analysis was made to assess how mixtures designed with the proposed methodology performed when compared to those designed by the current design methods. For some applications, weighted performance variations were up to 40% while cost increase was below 5%. The results show this approach can be very cost-effective in increasing the performance of the bituminous mixtures and achieve better and more durable pavements.