Abstract
Reclaimed asphalt (RA) mixtures have been extensively studied over the last decade, but there is no common procedure for producing high RA mixtures in the laboratory. This study evaluates the effect of asphalt mixing parameters, including rejuvenator incorporation method, mixing temperature, mixing time, and mixer equipment on properties of high RA content mixtures. The asphalt mixtures containing 60% RA material were evaluated using the indirect tensile strength test and the stiffness modulus test. In parallel, a stage extraction method was developed to obtain four layers of bitumen from loose mixtures and then further analyzing them using the dynamic shear rheometer and the Fourier transform infrared spectroscopy. The results identified mixing and heating temperature as an important parameter that must be carefully controlled to avoid excessive aging of the binder. It was also found that laboratory mixer equipment could affect the degree of blending and hence should be taken into account for comparing mixtures. Based on this study, a mixing procedure is recommended for producing high RA mixtures using the rejuvenator in the laboratory.
Highlights
Researchers generally agree that the reclaimed asphalt (RA) binder does not behave as a ‘‘black rock”; rather, but the extent of active blending between RA binder and virgin binder depends on the mixing parameters
Blended: The virgin binder was heated at a temperature of 155 °C for 2 h followed by addition of the rejuvenator and mixing them for 5 min using a high rate mixer
Laboratory mixing parameters can play an important role in evaluating the performance of high RA mixtures in the laboratory
Summary
Imaging techniques have shown the existence of a partial black rock effect and a layered structure surrounding the RA aggregates, and the thickness of RA binder was found to be affected by mixing temperature [7] This indicates that the chemical and physical properties of RA bitumen film may change as a result of the mixing process which needs to be taken into account for the mixture design. It should be noted that longer mixing time in the laboratory may be accompanied by extra oxidation of binder and consequential stiffening of the mixture As seen from this summary, some studies have shown that mixing parameters could have an important impact on evaluating the performance of high RA mixtures in the laboratory. There is no common procedure for preparing mixtures containing RA in the laboratory, and the results from different research projects might be difficult to compare or replicate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
