In Plant Production of Hot Recycled Mixtures with High Reclaimed Asphalt Pavement Content: A Performance Evaluation

Abstract

Nevertheless hot recycling process is nowadays a widespread technique, many doubts related to the in plant recycling process effects on the performance of recycled mixtures still exist and limit the maximum allowable amount of Reclaimed Asphalt Pavement (RAP). Therefore, the feasibility of an efficient production of plant hot recycled mixtures characterized by high RAP content and suitable performance should be properly addressed. To this aim, the overall performance of hot recycled asphalt mixtures produced in asphalt plant and containing high RAP content were assessed in this study. The mixtures were prepared with two different bitumens (high and low content of SBS polymer modifier) and 40 % of RAP only deriving from asphalt layers containing polymer modified bitumens. The aggregate grading curve was previously optimized through a specific laboratory study by applying the Bailey Method and using selected RAP. A third mixture, currently used for binder layers in motorway pavements, was also studied for comparative purposes. Compactability, stiffness, cracking and rutting resistance and fatigue behavior were investigated. Results of the mechanical tests suggest that mixtures containing 40 % RAP are suitable for the production of new asphalt pavements, especially when low modified bitumens are used. In fact, the performance of such mixtures were comparable or even higher than those of the reference mixture. In particular, the specific and accurate mix design allowed the potential drawbacks due to higher RAP content to be balanced.

Self-healing capability and thixotropy of bituminous mastics

“…This observation agrees with the results obtained through specific studies on fatigue performance of recycled HMAs (Hot Mix Asphalt) prepared with the same SBS modified bitumens [29], which showed improvements in terms of fatigue and cracking resistance when a given amount of RA is added.…”

Fatigue Performance of Recycled Hot Mix Asphalt: A Laboratory Study

“…Among the different waste materials investigated for recycling in the road pavements, the Reclaimed Asphalt Pavement (RAP) aggregates are widely considered a fundamental resource to implement the sustainability philosophy in the road construction [23][24][25][26][27]. Several researchers have demonstrated the beneficial effects given by the use of RAP aggregates in the lithic skeleton of the hot mix asphalt, for example, a higher resistance to permanent deformation in comparison with traditional bituminous mixtures [23-25, 28, 29].…”

Features of the hot recycling method used to repair asphalt concrete pavements

“…The heat from the compression surface of layers with the granular binder permeates into the lower layers. Excessive pressure appears, which causes the binder to penetrate the depth of the layer, leveling the temperature fields [2]. The curing process flows more evenly over the thickness of the layers, which improves the road strength characteristics.…”

“…A cost-effective, technological solution, which provides for quality road construction materials obtained from asphalt scraps, is to process them by their secondary products and industrial waste such as granulated slag, nepheline sludge, ash, ashand-slag mixtures of thermal power plants (TPP), phosphogypsum, cement kiln dust (CKD), etc. [2]. A promising technological solution is to obtain organomineral material from a semi-finished product without heating it by processing the crushed scrap with a mineral binder.…”