Rheological Properties of Hot and Warm Asphalt Binder Modified with Nanosilica
Keywords:MSCR, nanosilica, rheological behavior, superpave rutting parameter, zycotherm
The impact of base and zycotherm binders modified with various proportions of nanosilica (i.e., 2 %, 4 %, and 6 %) based on the weight of the binder at high-temperature performance was investigated. Brookfield viscosity, penetration, softening point, and storage stability tests were all conducted on base and modified binders. Moreover, the Superpave rutting parameter (G*/sin δ) and Multiple stress creep recovery (MSCR) were utilized to assess the resistance of binders to rutting. By observing the outcomes of the modified binder tests, the incorporation of nanosilica into the base and zycotherm binders improved temperature susceptibility. Binders modified with nanosilica showed remarkable storage stability at elevated temperatures, as the variation in softening point between the upper and bottom parts was less than 2.5 °C for all binders. Based on the outcomes of the Superpave rutting parameter, the inclusion of nanosilica enhanced the stiffness of the modified binders up to 130 % for 6 % of nanosilica, while the improvement was caused by 6 % of nanosilica with zycotherm was nearly 92 % at 70 °C. The MSCR test revealed that the base and zycotherm binders' recovery (R%) was 27.72 % and 25.99 % for 6 % of nanosilica and 6 % nanosilica with zycotherm, respectively, while the nonrecoverable creep compliance (Jnr) decreased by 56.87 % for 6 % of nanosilica, and 43.23 % for 6 % nanosilica with zycotherm at 100 MPa. The results show that the incorporation of nanosilica is capable of improving the rutting potential regardless of the levels of stress. The rheological characteristics of modified base and zycotherm binders were improved at all concentrations of nanosilica, with the optimal concentration being 6% nanosilica.
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