Solar roads are transportation infrastructures able both to generate electricity thanks to solar cells placed under a semi-transparent layer and to ensure heavy traffic circulation. In this paper, a novel transparent top layer made of glass aggregates bonded together using a polyurethane glue is presented. The goal is to design a composite material able to support traffic load, guarantee vehicle skid-resistance, allow the passage of sunlight, and protect the solar cells. For this purpose, the authors investigated the effect of different variables (thickness, glue content, and glass aggregate distribution) on the mechanical and optical performances of the material applying the factorial design method. The semi-transparent layer was characterized by performing the three-point bending test and measuring the power loss. Regarding the vehicle friction, experimental tests with the British Pendulum were conducted in order to measure the skid resistance of the surface and compare it with the specifications of a typical road infrastructure. According to the fraction factorial design and the British Pendulum test, the following mixture was developed: 42.8% of 4/6 mm; 42.8% of 2/4 mm, 14.4% of glue in volume, and a thickness of 0.6 cm. The first results are encouraging, and they demonstrate the feasibility of a semi-transparent layer for future applications in full scale.

Permeable removable urban pavement (RUP) is an innovative pavement system consisting of bimaterial permeable/plain concrete slabs, developed to mitigate climate change–related impacts. Whil...

Cement-based materials, regularly used in urban road base layers, must be sufficiently resistant to traffic but above all, easily excavated, even with a pick, to allow easy access to the underlying networks during maintenance operations. Unfortunately, bibliography shows that there is no satisfactory method for determining the ease of excavation. This paper presents the results of a large campaign in which manual excavations and Charpy tests carried out on scale 1 trenches were analyzed with an original laboratory punching test. It proposes a rational definition of an excavation difficulty scale by linking the feeling of workers and excavated volume per pick impact. The latter can be calculated from punching test thanks a classic soil failure model. A complete methodology to determine at the laboratory stage the excavation difficulty with a pick is finally proposed, opening the way of rational optimization of excavation ease, while keeping the bearing capacity constant..