Material-specific coefficients C1 and C2 in Williams-Landel-Ferry equations and phase transition behaviors of asphalt binder reinforced by various basalt fibers

The Williams–Landel–Ferry (WLF) equation is critical for predicting the rheological behavior of viscoelastic materials. However, no research has reported the main parameters, C1 and C2, in WLF equations for fiber-reinforced asphalts (FRAs). To provide the fundamental information for designing FRAs, this study investigated the rheological behaviors of asphalts reinforced by flocculent basalt fibers (fBFs) and short basalt fibers (sBFs) with a content of 2–6 wt%. The glass transition behavior and shift factor of basalt fiber-reinforced asphalts (BFRAs) were obtained using dynamic shear rheometer (DSR) and dynamic mechanical analysis (DMA). Material-specific C1 and C2 in the WLF equation were carried out using the programming solver method. As a result, the functions for C1 and C2 concerning a chosen reference temperature (Tref) were developed so that the predicted master curves of BFRA on non-measured conditions can be precisely established. C1 and C2 for BFRA varied from 9.6 to 6.5 and ∼110 to ∼160, respectively, with the Tref increasing from 46℃ to 76℃. Additionally, the study revealed that flocculent fibers reduce Tg and lift the softening point (Ts) of the FRA, extending the service temperature range of BFRAs by more than 10℃. Meanwhile, short fibers shift the Tg and Ts upward without extension of the service temperature range.