Fiber/Polymeric Compound for High Modulus Polymer Modified Asphalt (PMA)

The road construction sector has made a big research effort in recent decades, mostly aimed at better understanding the behaviour of the asphalt mixes contained in most such pavements. Hence the introduction of new binders, all based on bitumen as in the past but featuring polymers and reinforcements of various nature as well as innovative pavements. Moreover, newer regulations allow better predicting the behaviour of materials and their mixtures once laid, thanks to more rational testing methods. However both asphalt binder and asphalt-aggregate mixture show temperature and time-dependent behaviour. Rutting or permanent deformation is therefore the leading cause of pavement deterioration in temperate and warm climatic regions of the world while low-temperature cracking is a common problem in cold regions.The paper illustrates that the proposed innovative fiber/polymer compound may be potentially considered from now on as a relevant solution for sustainable long life pavements that do not deteriorate structurally, needing only timely surface maintenance and allowing reduced base course thickness (due to enhanced stiffness and fatigue properties) lead to a cost- effective and eco-friendly perpetual pavement design. Polymer Modified Asphalt (PMA) are modified asphalt concrete manufactured by feeding the fiber and/or the polymeric compound into the asphalt plant mixer after the aggregate has been loaded in to the mixer immediately before the bitumen is added. Fiber/polymeric compound asphalts may be preferable technology whenever a pavement is required to perform structural resistance, stiffness and resistance to rutting. One such application could be the manufacturing of ‘high-modulus’ mixes (EME), for laying heavy-duty base courses. These mixes are characterized by great coarse aggregate cohesion and high physical and chemical modified grade bitumens to obtain the EME2 specifications requirements, in particular high stiffness modulus value at 15 °C and high fatigue resistance, allowing for reduced pavement thickness and greater longevity.Fiber/Polymer modified Hot Mix Asphalt (PMA) has been claimed to resist rutting since they are less susceptible to reduction of the asphalt cement viscosity with high pavement temperatures during the summer months while the fiber component increase the resistance to tensile stresses and consequent cracking. Laboratory assessment of such materials consisted in the evaluation of the mix compactability, moisture resistance, rutting resistance at 60 °C, stiffness modulus at 15 °C and 35 °C and fatigue resistance at 10 °C.