Effects of two biomass ashes on asphalt binder: Dynamic shear rheological characteristic analysis

In this work, two kinds of biomass ashes (BA), rice husk ash (RHA) and wood sawdust ash (WSA) were used to modify asphalt binder. Fourier Transform Infrared (FT-IR) Spectroscopy was used to characterize the effects of biomass ashes on chemical properties of asphalt binder. Physical properties, such as dynamic rheological behavior, high temperature storage stability and aging properties of the modified asphalt were investigated. Test results indicated that there is no chemical reaction between asphalt binder and BA. The RHA and WSA particle effect during blending with asphalt binder under physical agitation dominated the modification. Compared with WSA, RHA showed better effect in improving physical properties of modified asphalt binder. The storage stability tests indicated that the asphalt binder modified with RHA and WSA is stable when ash content is less than 20%. With the enhancement of the content of RHA and WSA to asphalt binder, viscosity, complex modulus and rutting factor (G*/sin δ) of modified asphalt binders increased rapidly at high temperatures. As a consequence, the deformation resistance of these modified binders at high temperatures was especially improved. RHA and WSA can be considered as asphalt modifiers which were more helpful for the improvement of rutting resistance.