Mechanical Characterization of Thin Asphalt Overlay Mixtures with 100% Recycled Aggregates

Abstract

Asphalt pavements inevitably deteriorate over time, requiring frequent maintenance work to ensure the proper serviceability of the road network. Small interventions, such as resurfacing for pavement preservation, are preferable to reconstruction at the end of roads’ in-service lives as they limit environmental- and economic-related impacts. Thin asphalt overlay (TAO) mixture represents a suitable maintenance solution to restore the functional properties of road surfaces. Due to the increasing awareness of the depletion of non-renewable resources and the importance of promoting the circular economy, this study evaluated the possibility of using fully recycled TAO mixes by investigating their volumetric and mechanical properties. Two eco-friendly TAO mixes were designed using recycled aggregates from reclaimed asphalt pavements, a municipal solid waste incinerator, and steel slags in order to meet EN 13108-2 requirements. The TAO mixes differed in regard to the type of bituminous binder (neat/SBS-modified bitumens) and fibres (natural/synthetic) employed. The preliminary results demonstrated that the presence of recycled aggregates did not negatively affect the workability and the mechanical performances of the two sustainable mixtures in terms of stiffness, tensile resistance, rutting and moisture susceptibility. Of these, the TAO mix with neat bitumen and synthetic fibres showed enhanced mechanical performance highlighting the structural effects of the used fibres.

Experimental Analysis of Hot-Mix Asphalt (HMA) Mixtures with Reclaimed Asphalt Pavement (RAP) in Railway Sub-Ballast

“…As regards ITS values for Mi4k, Figure 7 shows how the compaction process affects ITS when varying the RAP content for OBC. The observed trend complies with [ 37 ], where ITS increases when using up to 50% RAP.…”

“…The use of reclaimed asphalt pavement (RAP) as recycled aggregate and rejuvenated binder has become popular worldwide, and RAP is one of the most reused building materials [ 25 , 37 ]. Its blending efficiency depends on several variables such as the effective binder content, the quality of the aged bitumen, and the production process [ 38 ].…”

“…Bernier et al [ 57 ] tested the rutting susceptibility. Kucera et al [ 37 ] surveyed trial sections with the asphalt trackbed layer with up to 70% of RAP. The structures provided resistance against lateral, longitudinal, and vertical movement of ties and rails, and protected the subgrade from temperature variation and rainwater run-off.…”

“…The use of RAP is a useful strategy for increasing the environmental sustainability of construction materials because it reduces the amount of virgin bitumen, the exploitation of quarries, and the disposal of waste from road pavement rehabilitation. Although the results in the literature highlight the suitability for hot mix asphalt with RAP, deep investigations are required to establish threshold limits of usable RAP [ 37 ] without decay of performances. In this study, the physical characteristics and compositions of both aggregates and milled material were studied to identify their mechanical, volumetric, and resistance properties.…”

Evaluating the Ageing Sensitivity of the Asphalt Binder via Distinct Ageing Methods

“…However, over time, asphalt pavements undergo oxidative ageing processes due to climatic volatility and chemical reactions. Consequently, the asphalt binder becomes increasingly stiff and brittle, leading to higher susceptibility to cracking and degradation of the pavement [3,4]. It is crucial to identify the ageing mechanism of asphalt binders to implement strategies that can extend the service life of the pavement.…”