Size Effect of Sub Nano-scaled Hydrated Lime on Selected Properties of HMA

Hydrated lime (HL) has been used as an additive in hot mix asphalt (HMA) mainly as an anti-stripping agent and mineral filler. The properties of the HMA added with the HL improve through the reaction of the HL with asphalt binder. This study investigates the size effect of HL on selected properties of HMA. First, an HL in HMA plant of Georgia, USA, was used for the production of sub nano-sized particles using an LA Abrasion machine in the laboratory. The particle size of the produced HL was measured through a microscope. Second, selected properties of asphalt binder and mixture were investigated through a dynamic shear rheometer and indirect tensile strength testing. The results from this laboratory study indicated that 1) the HL can be further grinded into sub nano-sized particles by the LA Abrasion machine, with the average HL decreasing to about 600 nanometers, a sub nano scale; 2) an increase of 10 percent in Tensile Strength Ratio (TSR) was observed for HMA incorporating the sub nano-sized HL over the HMA added with un-processed (control) HL; 3) the asphalt mastics containing HL in various sizes did not show much change in terms of phase angle and complex modulus from Dynamic Shear Rheometer (DSR) testing results.