Mechanical and compaction properties of graphite nanoplatelet-modified asphalt binders and mixtures

This paper presents an experimental investigation of the properties of asphalt binders and mixtures modified with graphite nanoplatelets (GNPs). The focus is on studying the effects of GNP addition on low-temperature rheological and fracture properties of asphalt binders and mixtures and on compaction effort of asphalt mixtures. This is the first time that these effects are investigated and significant findings are reported. The study considers three types of GNP materials, including graphite nanoplatelets and sub-microscale graphite flakes. The cost of these materials is reasonably low, which makes them suitable for large-scale applications, unlike other types of graphite and graphene materials. The experimental results indicate that the addition of GNPs leads to considerable improvements of low-temperature strength and fracture properties of asphalt binders and mixtures. While the properties of asphalt binders at intermediate temperatures are minimally affected, for some combinations of binders and GNPs the increase in low-temperature strength is over 100%. A similar effect is observed for some of the asphalt mixtures investigated, in which the low-temperature fracture energy almost doubles. The laboratory compaction experiments show that the number of gyrations required for achieving a target density can be reduced by as much as 20-40% by adding a small percentage of GNPs into asphalt binders. The results of this experimental study indicate that GNP-modified asphalt binders and mixtures have significant potential for increasing the durability of asphalt pavements in cold regions, by reducing the compaction effort and improving the low-temperature strength and fracture properties of asphalt materials.