Impact of Mixing process on the physical and Rheological Characteristics of Asphalt Binder Modified with Nano- Silica Powder

Abstract

In Iraq pavements materials are exposed to various distresses due to the adverse environmental conditions and heavy traffic. The improvement of performance of flexible pavements is necessary for decreasing these distresses. The objective of this research is to improve the mixing efficiency of nano-silica particles with asphalt binder. Two mixer type (mechanical and high shear), rotational speeds (2000, 4000 and 6000 rpm), and mixing period (30 and 60 minutes) were assessed. Three nano-silica per cent 2%, 4%, and 6% by weight of asphalt were added and the asphalt binder mixtures were prepared by heating at mixing temperature 140 °C. Furthermore, comparisons were made to assess the modified asphalt binder characteristics such as penetration value, softening point, temperature sensitivity (penetration index), ductility and rotational viscosity. Results showed that the use of nano silica as an additive was useful in improving the asphalt binder characteristics. Generally, has been found that the penetration value decreased and softening point increased, as well as the viscosity, were increased and the temperature sensitivity was developed. Additionally, high shear mixing was more useful especially to obtain a good dispersion of nano silica powder in asphalt binder and got a homogenous composite material.

Nanosilica Agglomeration and Rheological Properties of Bitumen

“…After extensive literature reviews, Li et al 19) listed the most popular ranges of these factors for various nanoparticles in bitumen. For nanosilica, the dry mixing method and temperatures of more than 130 ℃ for 120 min at a speed of more than 3000 rpm are the most applied conditions 20) .…”

Performance Evaluation of Asphalt Mixtures Modified with Nanomaterials. (Dept. C)

“…nanomaterials positively affect AC mixtures by improving the cohesion and adhesion between aggregate and binder [10,11]. The nanomaterials improve the asphalt binder's stiffness, which increases the mixture's resistance to rutting [10,[12][13][14] Previous studies modified asphalt binder (60/70) by adding 2%, 4%, and 6% of NS using a high shear mixer at speeds ranging from 1800 rpm to 6000 rpm and a mixing temperature ranging from 140 o C to 180 o C for a period not less than 30 minutes [15][16][17][18][19]. Their results revealed an improvement in the properties of the asphalt binder and that the binder became less sensitive to temperature [15,17,18].…”