Modification mechanism of high modulus asphalt binders and mixtures performance evaluation

• The particle size of the high modulus modifiers increased with time.
• The relative viscosity of the modified asphalt increased with time.
• The high modulus modifiers improved the high temperature performance, moisture–heat synthesis property of mixtures.

To observe the micro-morphology of high modulus asphalt binders (HMABs), a scanning electron microscope (SEM) and a fluorescence microscope were employed. To evaluate the performance characteristics of mixtures using these binders, laboratory mixture tests were conducted. The binder morphology showed that the particle size of high modulus modifiers, PR PLAST S® (PRS) and PR PLAST Module® (PRM), and the relative viscosity of modified asphalt increased with time; PRS modifier droplets tended to form a network. The test results of the mixtures indicated that compared with the original asphalt mixture and the styrene–butadiene–styrene (SBS) mixture, the HMABs significantly improved the high temperature performance, water stability, moisture–heat synthesis property, and dynamic modulus of mixtures. The investigation results of test sections showed that the average rut depth and surface deflection observed in the test sections using the high modulus asphalt concretes (HMACs) were much smaller than those in the test sections using the SBS mixture after one year of service. Based on the colloidal system equilibrium and the lowest energy principle, the modification mechanism of the HMABs modified by PRS and PRM was analyzed in this paper by using the effects of swelling and interface layer. The effects of the HMABs on the performance of HMACs were evaluated. The test results of the mixtures confirmed the correctness of the analysis associated with the modification mechanism.