Influence of Thermoplastic Polyurethane on the Properties of Asphalt Cement and the Elastic Behavior of Asphalt Mixtures

Abstract

The useful life of pavements determines the design of asphalt mixtures. However, premature structural failures and low durability are one of the main problems in pavement engineering today. The action of loads produced by traffic, exposure to environmental factors and the inadequacy of conventional designs of asphalt pavements are some of the main problems associated with the durability of the pavement. The modification of asphalt binders is an alternative that has been used for some years to improve the properties of bituminous material. Among the modifying materials are elastomers, a class of polymers with elastic properties that can be heat-treated. In this study, the asphalt was modified by wet means by adding 5, 10 and 15% of Thermoplastic Polyurethane (TPU) by weight of the binder. Subsequently, standard samples were prepared with the characterized constituents and mixtures with the modified asphalt cement. Consequently, tests were carried out to obtain the optimal mixture that improves the properties of conventional pavement. The results show that the optimal TPU addition content is 5%. With this percentage, the modified binder presented a greater elastic recovery of up to 5.60% and a reduction of up to 42.6% in penetration compared to conventional asphalt. In addition, using the Marshall method, it was determined that the stability of the modified mixtures was much higher than that of standard mixtures for light, medium and heavy traffic; so, they will have a higher resistance to deformation and better fatigue behavior.