Nanobased rejuvenators for polymer-modified bitumen under long-term ageing conditions

Abstract

Effective and efficient bitumen rejuvenation is the key factor that affects the long-term performance of recycled asphalt pavement. This paper aims to extend the rejuvenation of standard polymer-modified bitumen (PMB) by incorporating nanomaterials into traditional rejuvenators. In particular, the objective of the study is to evaluate the efficiency of nanoSiO2 and nanoTiO2 to improve common rejuvenators - soft bitumen V12000 and aromatic oil - by restoring the chemical and rheological properties of aged PMB. The experimental program was composed of three steps, namely, (1) determination of the optimal dosage of rejuvenator, (2) evaluation of the effects of nanomaterials and rejuvenators on the properties of long-term aged PMB and finally (3) investigation of the increase in rejuvenated bitumen resistance to long-term ageing. In addition to standard tests of physical properties (penetration and softening point), the functional composition of bitumen was evaluated by performing the tests with a Fourier transform infrared (FTIR) attenuated total reflection (ATR) spectrometer, and the rheological properties were determined with a dynamic shear rheometer (DSR). The traditional rejuvenators changed asphaltene-matlene ratio of the aged base PMB resulting changes in bitumen rheology but chemical composition was not restored. The most promising results were obtained after rejuvenating aged PMB with an improved soft bitumen with 6% nanoTiO2. This approach allowed us to assess the durability of rheological properties during long-term ageing; however, it abilities to restore or protect styrene–butadiene–styrene (SBS) from ageing and further degradation was not validated.