Warm Mix Recycled Asphalt – a sustainable solution

• The warm bitumen decrease in 40 °C the manufacture and application temperatures.
• The incorporation of RAP is a good alternative to the use of 100% mineral materials.
• The WMA compaction temperature is an important factor to ensure a good performance.
• The WMA with incorporation of RAP has a good fatigue resistance compared to the HMA.

The environmental issues raised over recent years, mainly the lowering of fuel consumption and the consequent emission of polluting gases, have led to a bigger concern with the environment. As a response to such concern, the asphalt road industry has developed warm mix asphalts. These are part of a set of new technologies that are being developed in order to reduce both the energy consumption and the gas emissions into the atmosphere, by lowering the mixing temperature. On the other hand, the incorporation of Reclaimed Asphalt Pavement (RAP) in these mixtures aims to improve sustainability by reducing the production of waste and the consumption of natural resources. The warm mix asphalt with RAP are environmentally friendly mixtures and have social, environmental and economic benefits in the production and application of asphalt mixtures. Thus, the main aim of this paper is to produce a comparative study of the mechanical behaviour of warm mix asphalt and of conventional hot mixtures. We also intend to study the applicability of these mixtures with and without incorporation of RAP. Initially, the optimal bitumen content for each mixture was determined and fundamental properties were calculated. The tests performed were the stiffness test by indirect tension to cylindrical specimens, water sensitivity and resistance to fatigue by four-point bending test on prismatic shaped specimens. The findings have confirmed the advantages and demonstrated good performance of warm mix asphalt compared to conventional hot mixtures. The result of the stiffness modulus to the mixture with RAP, of 4750 MPa, is very close to the hot mixture. The water sensitivity for the hot mixture and warm mixture is the same, of 97%, and the fatigue resistance of the three mixtures in analysis is very similar. However, it was also found that these mixtures require an increased care during the production and application phases, in particularly as far as the temperature control is concerned.