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The experimental investigation herein described is aimed at understanding the effects of cellulose-based fibers on the mechanical properties of bituminous mastics for paving applications. Three bitumen (two of which modified with SBS polymers), a calcareous filler and four different types of fiber with varying content were used to prepare the investigated mastics. The filler to bitumen ratio was maintained constant. The laboratory investigations were focused on empirical tests (Needle Penetration andRing and Ball -R&B -Temperature) and dynamic-mechanical tests, the latter performed in a wide range of temperatures. Results suggest that fibers improve the M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 2 behavior of mastics for hot mix asphalts, particularly with respect to the prevention of rutting phenomena at high service temperatures.

This paper reports the results of a laboratory investigation on the use of recycled fillers in bituminous mixtures for road pavements. The fillers were obtained by crushing and sieving (0.00-0.063 mm) Stabilized Bottom Ashes from municipal waste incinerators and Electric Arc Furnace Steel Slags. Moreover, a currently used calcareous filler was included in the research for comparative purposes. Two filler dosages were considered in the experiments. Laboratory tests aimed at investigating compaction properties, volumetric characteristics, and mechanical performance of the bituminous mixtures. The results suggest that both types of recycled filler are suitable to be used in bituminous mixtures, also demonstrating that in certain conditions the investigated fillers increase the performance of the corresponding mixtures in comparison to standard (calcareous) filler.

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The growing need for high quality bituminous mixtures in road construction, rehabilitation and maintenance is currently satisfied by means of techniques to produce polymer-modified bitumen, or by the addition of additives to mixtures during in-plant mixing operations. A rigorous rheological approach in the study of the bitumen modification process enables researchers to rationally compare different modifying agents and to evaluate their relative efficiency for specific field applications. As far as additives are concerned, the binder is not the only element involved in the evaluation; both binding mastics and bituminous mixtures must be evaluated to get a complete understanding of the characteristics. Moreover, the advantages that may stem from the use of fibers should be carefully taken into consideration since they may offer alternative strategies for the enhancement of bituminous mixtures. As a result of these observations, the authors have devised an experimental research project focused on the analysis of the effects of different types and dosages of cellulose-based fibers on the main performance-related properties of bituminous road materials: compaction properties, volumetric characteristics and mechanical performance. This paper provides an overview of the results obtained and some details of the specific protocols followed during the research project.