Laboratory Compaction Study and Mechanical Performance Assessment of Half-Warm Mix Recycled Asphalt Mixtures Containing 100% RAP

Influence of a Rejuvenator on Homogenization of an Asphalt Mixture with Increased Content of Reclaimed Asphalt Pavement in Lowered Technological Temperatures

The most technologically advanced form of road construction uses a high content of reclaimed asphalt pavement (RAP) as a component of its asphalt mixture (AM). However, there is a real problem with the effective interaction of RAP and MA. The research herein described presents an effective use of RAP originating from the recycling process of old pavements thanks to the application of an original rejuvenator. Two types of AM were designed concerning the base course of pavement as well as the wearing course and the binder course for various traffic categories. The achieved results show that the rejuvenator improved the homogenization of RAP with the asphalt binder and aggregate in each mixture type. On the basis of the research, the possibility of using paving AM with an increased content of RAP in lowered technological temperatures received a favorable assessment. Mixtures of asphalt concrete containing 40% RAP meet both Polish and German requirements for mixtures intended for heavy traffic pavements. Thanks to use of the rejuvenator, it is possible to compact AM layers containing RAP in a final compaction temperature lowered by about 20 °C. The achieved AM lab test results were confirmed on trial road sections. The rejuvenator used in tested AMs improved the homogenization of RAP with both binder and virgin aggregate. Moreover, the study proved that it is possible to use 20%, 40%, and even 100% RAP contents in the mixtures thanks to the use of the rejuvenator based on plant resin and the creation of conditions enabling the effective homogenization of AM components.

Performance of High Rap Half-Warm Mix Asphalt

The current global situation regarding climate change makes it necessary to promote the circular economy and the use of more environmentally friendly technologies in the construction sector. To that end, it is of interest to deepen our understanding of the performance of half-warm mix asphalt (HWMA) manufactured with high proportions of reclaimed asphalt pavement (RAP). Thus, in the present study, a laboratory analysis was carried out in which the behavior of HWMA manufactured with 100% RAP and without rejuvenators was compared with that of a control mix, i.e., an HWMA manufactured with 0% RAP. In particular, we analyzed the compaction energy with a gyratory compactor, mixing time and temperature, volumetric properties, moisture damage resistance through indirect tensile tests after immersion (ITS), stiffness based on the resilient modulus, resistance to permanent deformation using wheel tracking tests, and fatigue resistance through indirect tensile fatigue tests (ITFT). Both mixtures displayed adequate volumetric and mechanical properties, but the performance of the high-RAP HWMA was better than that of the control mixture in terms of resistance to permanent deformation in hot areas. In addition, the high-RAP HWMA without rejuvenators could provide energy and material savings, thus promoting sustainable development.