Experimental evaluation on high temperature rheological properties of various fiber modified asphalt binders

High temperature rheological properties of fiber modified asphalt binders and impact of the type and content on such properties were studied.Three types of fiber,including polyester(PET),polyacrylonitrile(PAN) and cellulose(CEL),a control content(0%) and four levels of fiber content(2%,4%,6% and 8% by total asphalt binder mass) were used with asphalt binders.The high temperature rheological properties,consisting of complex modulus(G*) and phase angle δ,were measured using SHRP's dynamic shear rheometer(DSR) between 46-82 ℃.Experimental results indicate that the changes of G* and tan δ of fiber modified asphalt binders with the increase of test temperature tend to slow down,and the temperature susceptibility is improved obviously compared to that of original asphalt binder.Fiber modification results in the increase of rutting parameter(G*/sin δ) at high temperatures,the decrease of temperature susceptibility,and further improved high temperature performance of asphalt binder.An excellent correlation exhibits between fiber content and high temperature performance of asphalt binder.Moreover,fiber type also has different influences on the improvement of G*/sin δ,G*/sin δ of PET and PAN fiber asphalt binders are both higher than that of CEL fiber,but G*/sin δ of CEL fiber is still higher than that of original asphalt.However,there is a critical fiber content when fibers start to interact with each other.Therefore,based on the critical fiber content and economic consideration,the optimum fiber contents for various fiber-modified asphalt binders are obtained.

High temperature rheological properties of fiber modified asphalt binders and impact of the type and content on such properties were studied. Three types of fiber, including polyester (PET), polyacrylonitrile (PAN) and cellulose (CEL), a control content (0%) and four levels of fiber content (2%, 4%, 6% and 8% by total asphalt binder mass) were used with asphalt binders. The high temperature rheological properties, consisting of complex modulus (G*) and phase angle δ, were measured using SHRP’s dynamic shear rheometer (DSR) between 46–82 °C. Experimental results indicate that the changes of G* and tan δ of fiber modified asphalt binders with the increase of test temperature tend to slow down, and the temperature susceptibility is improved obviously compared to that of original asphalt binder. Fiber modification results in the increase of rutting parameter (G*/sin δ) at high temperatures, the decrease of temperature susceptibility, and further improved high temperature performance of asphalt binder. An excellent correlation exhibits between fiber content and high temperature performance of asphalt binder. Moreover, fiber type also has different influences on the improvement of G*/sin δ, G*/sin δ of PET and PAN fiber asphalt binders are both higher than that of CEL fiber, but G*/sin δ of CEL fiber is still higher than that of original asphalt. However, there is a critical fiber content when fibers start to interact with each other. Therefore, based on the critical fiber content and economic consideration, the optimum fiber contents for various fiber-modified asphalt binders are obtained.