Rutting Behavior of Asphalt Surface Layers Designed for Solar Harvesting Systems.

Solar harvesting systems applied to asphalt roads consist of pipes or coils installed a few centimeters below the asphalt pavement surface. They work thanks to a circulating fluid able to collect the heat coming from solar irradiation of the pavement surface and convert it into thermal gradients that can be used for electric energy supply. Specific attention must be paid to the design of the asphalt mixtures comprising the system. In this sense, the high in-service temperature rutting potential is one of the main issues to be assessed in such applications since the thermal optimization of asphalt mixes could lead to excessively deformable materials. The present study is a part of a wider research area aimed at developing an efficient asphalt solar collector. Here, a laboratory mixture-scale investigation is proposed to verify the anti-rutting potential of specific asphalt layers that were initially designed based on thermal properties only. Repeated load axial and wheel tracking tests are carried out on limestone- and steel slag-based bituminous mixtures. Overall, the tested layers were not fully able to satisfy the permanent deformation acceptance criteria; in this regard, possible improvements in terms of mix constituents and properties are ultimately addressed.

Direct ink writing of porous titanium (Ti6Al4V) lattice structures.

Ti6Al4V components, for biomedical and aerospace sectors, are receiving a great interest especially after the advent of additive manufacturing technologies. The most used techniques are Selective Laser Sintering (SLS), Selective Laser Melting (SLM) and Electron Beam Melting (EBM). In the current research, we developed 3D-printed Ti6Al4V scaffolds by Direct Ink Writing (DIW) technology. Appropriate ink formulations, based on water-titanium powder suspensions, were achieved by controlling the rheological properties of the developed inks. After printing process, and drying, the printed components were sintered at 1400 °C under high vacuum for 3 h. Highly porous titanium scaffolds (with porosity up to 65 vol%) were produced and different geometries were printed. The influence of the porosity on the morphology, compression strength and biocompatibility of the scaffolds was investigated.