Towards a novel magnetic asphalt mixture containing ceramic ferrites for intelligently encoding road traffic sign information

•A novel magnetic asphalt mixture for encoding traffic sign information is designed.•Ceramic ferrites greatly enhance magnetic properties of magnetic asphalt mixtures.•Magnetic coding units have excellent corrosion resistance and thermal stability.•Mechanical response of magnetic coding units is close to original asphalt mixtures. With the development of smart road transport, the use of magnetic coding units (MCU) to store and transmit road traffic sign information is a novel technical solution that emerged in recent years for advancing the V2I communication. In this work, MCU was prepared by partly replacing the aggregates and mineral powder in the AC-13 asphalt mixture (AM) with ceramic ferrites (CF). It was found that the MCU was able to produce a stable and detectable magnetic field after magnetization, while its spatial distribution pattern is programmable. In order to provide technical guidance for MCU design, environmental impacts including erosion and thermal cycling on the magnetic performance of MCU were explored over in further. The following conclusions were obtained: (1) The experimental measurements show that CF has a remanence of more than 20 emu/g and a coercivity of more than 1 k Oe, and as a result, the addition of CF effectively improves the magnetic flux density and detectable range of MCU. (2) Satisfactory corrosion resistance of MUC is observed, which is mainly attributed to the stable hexagonal magnetoplumbite-type crystal structure and large binding energy of Fe3+ within the mixture. (3) Little irreversible flux density loss of the MCU is observed in a large number of thermal cycles in a range of 20–60 °C, which is attributed to the high curie temperature of the CF. Increasing the CF doping can enhance the Fe-O exchange interaction, thus reducing the reduction ratio of the MCU magnetic field at 60 ℃. (4) MCU material has typical viscoelastic response characteristics under mechanical loading, while its dynamic modulus is close to that of ordinary AC-13 AM. (5) The economic cost of using MCU to encode traffic sign information is merely 20.25% of that of conventional traffic signs, which supports further its application potential.