Detecting the Impact of Micro and Nano Size Additives on Deformation of Asphalt Concrete

Abstract

Permanent deformation is considered as one of the major distress type of asphalt concrete pavement in the hot climate region. It can be controlled by the use of additives either for asphalt binder or for the asphalt concrete mixture. In the present assessment, the impact of micro and Nano size additives (fly ash and silica fumes) on the deformation behaviour of asphalt concrete mixtures was assessed. Such additives were implemented as partial substitute of mineral filler. Asphalt concrete slab samples were prepared in the laboratory with the aid of roller compaction. The optimum percentages of the additives are (2 and 4) % of silica fumes and coal fly ash respectively by the weight of the binder. Beam specimens were obtained from the slab samples and tested for fatigue life under three constant strain levels using four point bending beam technique. It was observed that for mixture treated with Nano additive (silica fumes), the reduction in the permanent deformation starts at 0.0001 MJ/m3 loss in energy for 750 microstrain level. However, for mixture treated with Micro size additive (fly ash), as the dissipated energy vanishes, the permanent deformation was in the range of (3 - 4.5) microstrain. It was concluded that as the dissipated energy vanishes, the permanent deformation was lower by (29.4 and 11.7) % for mixtures treated with silica fumes and fly ash additives respectively as compared with the control mixture.