Interaction between crumb rubber modifier (CRM) and asphalt binder in dry process

The objective of this study is mainly to investigate the interaction between CRM and asphalt binder in asphalt mixtures added with CRM in dry process during the time period after mixing and before paving, including the storage in silo. High pressure-gel permeation chromatographic (HP-GPC) and Fourier transform infrared spectroscopy (FTIR) tests were used on extracted binders from the asphalt mixtures stored in the oven at four time phases of 0, 30, 60, 90 min at the temperature of 160 °C. The results showed that (1) the percentage of the large molecular size (LMS) from GPC test increased as the storage time of the mixtures in dry process increased, and could reach that from wet process; (2) the ratio of bonding at C[dbnd]O, an aging index from FTIR, had a sharp increase from storage time 0–30 min, and kept less change for further storage; (3) increase in LMS as storage time increase could be mainly caused by the interaction of CRM with the asphalt, not by aging.