Xi’an, China – Alternatives to asphalt in road surfaces have been investigated by a team at Xi’an University of Architecture & Technology. The scientists, led by Qian Zhang, created two types of dense polyurethane mixtures, Stone Matrix polyurethane and Superpave polyurethane.
Asphalt mixtures are susceptible to permanent deformation as the asphalt itself can weaken at high temperatures. In the new materials, the asphalt binder was replaced by a polyurethane.
Dynamic modulus tests showed that both the new PU-based materials are viscoelastic materials, with elastic characteristics within the normal working temperature and loading frequency of the pavement. They also found that their mechanical properties are more stable than those of the asphalt-based material.
They also determined that there was a linear correlation between the dynamic and static moduli above 20°C. Its creep characteristics indicated that they also had a better resistance to permanent deformation than the asphalt material.
The work has been published in the journal Construction and Building Materials.