Impact of the Aggregate Skeleton in the Compaction Energy Economy

Compaction is the most essential and energy-intensive technique for implementing pavement structures in a road construction project. In pavements coated with bituminous asphalt, the energy expended during their compaction can be linked to several parameters including the properties of the materials mix design. The purpose of this article is to measure the impact of the gravelly skeleton on the compaction ability of bituminous mixtures and their energy expenditure. For this purpose, compaction tests at the gyratory shear compactor (GSC or PCG in French) were carried out on several mixtures with dense–dense, dense–fine, and dense–coarse gravelly skeleton. The results showed that dense–dense skeleton asphalt is more manageable and compactable than fine and coarse mixtures. Indeed, this is the case for all turning cycles. For example, at 80 turns, dense–dense skeleton asphalt has a 5% void percentage while dense–coarse skeleton asphalt has a 9% void percentage and dense–fine skeleton asphalt has a 7% void percentage. This translates into a lower stability Index of the Mixture (SIM = 55% void cycle) and a higher resistance index of the mixture (RIM = 425% void cycle) for dense–dense skeleton. In terms of energy expenditure, these results result in a lower mix energy index (MEI1 = 54.79 kj/kg) during implementation and a higher mix energy index (MEI2 = 438, 705 kj/kg) resulting in greater resistance to secondary compaction due to road traffic.