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<jats:p> The possibility of using commercial rheometers for comprehensive testing of asphalt binders, asphalt mastics, and hot-mix asphalts (HMA) is explored. Samples of one polymer-modified asphalt, its mix with fine mineral filler (mastic), and one HMA prepared with the same modified asphalt as binders were tested in the dynamic shear rheometer (DSR) and the bending beam rheometer (BBR). All tested materials can be characterized by their discrete relaxation and retardation spectra (under the condition of small deformations). DSR testing was performed in the plate–plate and the torsion bar geometry. From the obtained relaxation and retardation spectra, the shear compliance, J(t), was calculated and compared with the tensile creep compliance, D(t), measured in BBR (both creep and recovery experiments were run). A simple relationship between J(t) and D(t) was found for the asphalt binder and the asphalt mastic. In the case of HMA, the bulk compliance, B(t), contributes to D(t) at short and long times. Both the Boltzmann superposition principle and the time–temperature superposition principle hold very well for all tested materials at low temperatures. There are qualitative differences, in the rheological behavior, of the asphalt binder and asphalt mastic on one side and the HMA on the other. These differences can be seen in dynamic (DSR) as well as in transient (BBR) experiments. </jats:p>

<jats:p> A dynamic creep test was proposed as a new method for evaluating the ability of modified asphalt binders to maintain their elastic response. The test was readily proposed to evaluate the resistance to rutting of asphalt pavements. The authors are reporting the analysis of results of the dynamic creep test on several conventional and oxidized asphalts and blends of conventional asphalts with two polymers. The used polymers were styrene-butadiene-styrene and styrene-(ethylene-co-butylene)-styrene. The effects of temperature, material (base asphalt and polymer modifier), applied stress level, and oxidation were investigated. The possibility of using linear viscoelastic models for the description of the dynamic creep test was also studied. </jats:p>

<jats:p> The rheological properties of asphalt binders modified by styrene–butadiene–styrene (SBS) depend on formulation variables. The most sensitive of them may be listed as polymer amount, cross-linking agent amount (percentage), and other additives such as polyphosphoric acid (PPA). The dispersion of SBS in an asphalt binder depends on the time and temperature of blending and the base asphalt binder compatibility. In this study an incompatible binder and a compatible base asphalt binder were selected and modified with various amounts of SBS. Elemental sulfur was used as a cross-linking agent in different proportions. Other additives, such as PPA at 0.5% concentration, were also used. High shear blends of SBS-modified asphalt binders were made in the laboratory by varying blending time until an optimum dispersion of polymer was obtained. The dispersion of the polymer was studied with a fluorescence microscope. A multiple stress creep and recovery (MSCR) test was used to study creep and recovery behavior of these modified binders. MSCR test results ( J<jats:sub>nr</jats:sub> and percentage recovery) were able to characterize the extent of dispersion of SBS in these polymer-modified asphalts (PMA). This implies that a fundamental test method is now available to discriminate between the dump-and-stir types of PMAs and those that have been optimally dispersed. This presentation discusses the effect of SBS dispersion and other additives on the MSCR test results. </jats:p>

<jats:p> Chinese transportation agencies usually use the styrene–butadiene–styrene (SBS) modified binder and rejuvenators when applying higher reclaimed asphalt pavement (RAP) in surface courses. However, the rutting performance of RAP binder containing SBS binder and rejuvenators remains a problem. In order to better evaluate the rutting performance of asphalt binder, recently, a multiple stress creep recovery (MSCR) test (AASHTO T 350) was proposed and approved. This paper critically reviewed the AASHTO T 350 test method and AASHTO M 332 specification by carrying out a series of MSCR tests. A total of 18 types of SBS modified and modified RAP binders were tested. The effect of a rejuvenator on the rutting performance was analyzed. Three different MSCR tests were conducted considering different stress levels and creep recovery cycles, including test conditions of AASHTO T 350. The results indicated that AASHTO T 350 can grade the binders based on the nonrecoverable creep compliance and stress sensitivity parameters. Since SBS modified binders always have lower J<jats:sub>nr</jats:sub> values at lower stress levels, higher stress levels and more creep recovery cycles are recommended to better evaluate the rutting resistance of binder. The addition of RAP decreased the J<jats:sub>nr</jats:sub> values while the addition of rejuvenator had the opposite effect. The added SBS modified binder and rejuvenator have a negligible effect on the percentage recovery. It is suggested that a suitable rejuvenator dosage and virgin binder type should be chosen carefully to guarantee the rutting performance of RAP binder. </jats:p>