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    Composite Modifiers to Improve the Rheological Properties of Asphalt Binders
    (Asce-Amer Soc Civil Engineers, 2024) Yalcin, Beyza Furtana; Bakir, Esma; Yalcin, Erkut; Yilmaz, Mehmet
    For the last 20 years, researchers have been looking for ways to modify asphalt binders to improve their rheological and thermophysical properties. The application of composite modifiers to enhance the rheological properties of asphalt binders offers a potential remedy for this significant issue. Because of this, this study looked at how composite modifiers affected the plain binder's rheological characteristics. This study examined the rheological properties of unmodified and modified binders using a variety of formulations to blend modifiers including linear styrene-butadiene-styrene (SBS), radial SBS, Elvaloy, and polyphosphoric acid (PPA). The effect of PPA on the properties of polymer-added binders at low temperatures was investigated. Additionally, modifications using PPA aim to reduce the polymer content. Based on traditional performance classification (PG) and multiple stress creep recovery (MSCR) systems, original, rolling thin film oven-aged, and pressure aging vessel-aged binders were divided into three groups using a dynamic shear rheometer (DSR). The performance of binders at low temperatures was also assessed using the bending beam rheometer (BBR). All of the study's additions were discovered to have enhanced the neat binder's high-temperature capabilities. The elastic property of the neat binder was increased by the addition of Elvaloy and PPA. Results showed that, although the PPA modifier reduced the hardness of neat asphalt binder at low temperatures, other additives did not show significant effects on the hardness of the binder. The MSCR procedure was successfully utilized to grade all of the binders, but it appears that some binders and conditions do not fit the MSCR protocol's percent difference criterion. According to the study's findings, SBS can be replaced by 611 elastomer to enhance the performance of binders at high and moderate temperatures.
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    Effect of Using Capsules with Waste Mineral Oil on Self-Healing of Long-Term Aged Hot-Mix Asphalt
    (Asce-Amer Soc Civil Engineers, 2023) Bakir, Esma; Yalcin, Erkut; Yilmaz, Mehmet; Kok, Baha Vural; Hernandez, Alvaro Garcia
    Capsules containing waste mineral oil can delay the maintenance of asphalt mixtures by preventing the spread of cracks. As a result of the encounter between the crack and capsule, the capsule breaks and releases the restorative material inside the crack area, resulting in healing. This experimental research demonstrated the rate at which oil is released from the capsules when the asphalt is subjected to cyclic loading and four different cures (24 h at 25 degrees C, 48 h at 25 degrees C, 24 h at 40 degrees C, and 48 h at 40 degrees C), and the capacity of asphalt to improve its inherent self-healing capacities in terms of cracks. In the study, the effects of capsule amount, curing time, and temperature on the mixtures were examined. Three-point bending fatigue tests and Fourier transform infrared spectroscopy (FTIR) tests were used in the study. It was determined that the capsules were broken and oil was released when cracks started to form in the hot-mix asphalt. The experiments showed that increasing the amount of capsules increased the oil release and the recovery rate, but decreased the mechanical performance by reducing the fatigue life. It was also found that the increase in curing time and temperature increased the recovery rate. Finally, the effects of capsule content and load characteristics on the healing index were defined by response surface method (RSM).