Polyurethanes are versatile materials and, in civil engineering, they are implemented as bonding elements, injection material to stabilise soil condition, as well as insulating and coating foams. Because of their good adhesion, their transparency, and their mechanical and thermal properties, the idea of the present research is to use it as organic matrix in a glass aggregates/glue composite used as a semi-transparent pavement surface layer. This research takes part in a wider project aiming at designing a hybrid pavement system able to harvest energy from the sun. The aim of this paper is to characterise four different types of thermoset polyurethanes in terms of curing time and visco-elastic properties. For this purpose, an experimental campaign was conducted, performing tests in a dynamic shear rheometer and a dynamic mechanical analysis. Curing time kinetics, defined as the evolution of phase angle, were modelled according to the Arrhenius law. Temperature and frequency dependence on the complex modulus were finally measured. The results demonstrate the strong dependency of the polyurethanes behaviour, overall mechanical performance and especially glass transition temperature, on the curing temperature.

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.

Intelligent systems, the Internet of Things, smart factory, and artificial intelligence are just some of the pillars for the 4th industrial revolution. Engineering is the driving force behind this new industrial renaissance and transportation plays a leading role for the new challenges in mobility needs. In this scenario, intelligent transportation systems (ITS) represent an innovative solution for various transport issues, such as traffic congestion, air pollution, long travel time, and accidents. In parallel, transportation is going through a novel way of thinking for road pavements: a multi-functional infrastructure able to harvest energy and exploiting the solar radiation or the traffic load. As the main hurdle in ITS is to find reliable energy sources, the energy harvesting roads could be a great step in installing and managing ITS as an electricity supplier. The aim of this paper is to review the key elements of ITS and energy harvesting pavements, and investigate their coexistence. This paper describes different harvesting techniques that could be used to power various ITS solutions. A case study evaluates the power output of a road section equipped with a solar road, piezoelectric material, and thermoelectric generators. Finally, the coexistence between ITS and energy harvesting pavements is critically evaluated, taking into account the advantages and disadvantages.