Evaluation of the filler effects on fatique cracking and permanent deformation of asphalt concrete mixtures

Abstract

The addition of hydrated lime to asphalt has shown to be beneficial with an improvement in the Theological properties of the binder, as well as resistance to permanent deformation (rutting) and fatigue cracking of asphalt concrete mixtures. The addition of hydrated lime produces a filler effect where the result is a stiffening of the asphalt mixture, thus improving the resistance to permanent deformation. The fatigue characteristics of the asphalt mixtures did not worsen from this stiffening effect, but were either improved or similar. The Superpave Performance Grade was not significantly indicative of the filler effects induced by the hydrated lime. However, evaluation of the physical properties, G*/sin5 and G*sin5 were indicative of significant filler effects induced by the hydrated lime. Creep properties, stiffness and m-value showed no substantial change with the addition of lime. The use of 10 to 20% mass concentration of hydrated lime can effectively improve the rutting resistance of the unaged and aged binder with little practical effect on the low temperature and fatigue properties. The filler effects produced through the addition of hydrated lime to the asphalt yielded asphalt mixtures less susceptible to rutting. In most cases, the fatigue life of the asphalt mixtures improved as well. The reference modulus and creep compliance of the asphalt mixtures with lime had shown to have greater fatigue life. In most cases, Stone Matrix Asphalt (SMA) mixtures with lime showed greater resistance to rutting, as well as greater fatigue life. The filler effects from the hydrated lime, as well as the stone-on-stone contact and stiffening from the mastic (two characteristics of SMA mixtures) improved these properties. The addition of hydrated lime to asphalt improved the G*/sin5 and G*sin8 of the asphalt binders. The use of these asphalt binders in asphalt concrete mixtures increased the resistance to rutting and fatigue life. It is apparent that a correlation exists between the asphalt binder and mixture test results.