Viscoelastic analysis and modelling of SBS modified bitumen: an insight from bitumen quality control test

Styrene–butadiene-styrene (SBS) is commonly used to improve the viscoelastic properties of bitumen and to enhance the service performance of asphalt pavements. A new method based on the bitumen quality control test (QCT) was used to evaluate the viscoelastic properties of SBS modified bitumen. The factors affecting the viscoelasticity of the SBS modified bitumen were analysed by maximum creep deformation (MCD), deformation recovery rate (DRR), and the average value of creep rate (AVCR). Furthermore, the viscoelastic properties of the bitumen were characterised by viscoelastic models. The dynamic shear rheometer (DSR) test and multiple stress creep recovery (MSCR)test were conducted to establish the correlation models between the QCT indexes (MCD, DRR, and AVCR) and other indicators (G*, δ, Jnr3.2, and R3.2). The correlation models were verified to evaluate the feasibility and generalizability of the QCT method. Results show that the LSBS and RSBS can reduce MCD and AVCR values, and increase DRR values. The creep and recovery behaviour of SBS modified bitumen can be better fitted by the Power law model. The 2S2P1D model can effectively characterise the viscoelastic properties of SBS modified bitumen, and β has a significant positive correlation with SBS content. The QCT indicators have a significant correlation with DSR and MSCR indexes, indicating that the QCT can be used as a complementary method to evaluate the viscoelastic properties of SBS modified bitumen.