Effect of blending conditions on nano-clay bitumen nanocomposite properties

Nanoclay/bitumen nanocomposites have been prepared using a commercial organically modified nanoclay (Nanomer), and two different penetration grade bitumens under a range of different blending conditions. Simple paddle stirring and high-shear mixing for different times at different shear speeds were investigated in order to determine whether expensive and time-consuming blending was necessary to achieve significant changes in the properties of the bitumen composites. Longer blending times and/or higher shearing speeds resulted in increased dispersion and exfoliation of the Nanomer particles, but this was not necessarily beneficial to the physico-chemical properties of the final material. Rheological analyses showed insignificant differences in properties between the samples blended for different times and speeds of shear mixing. Simple paddle mixing was sufficient to disperse the Nanomer to generate nanocomposites with improved physical properties. Dispersion of Nanomer into the softer of the two bitumen grades caused larger apparent changes than blending into the stiffer grade. These results suggest that the use of simple, low-cost blending techniques should be possible to manufacture effective clay-bitumen nanocomposites.