Micro and Nano Size Additives for Enhancing the Sustainability of Asphalt Concrete

Asphalt concrete mixture practices loading and environmental impacts which can render the distresses formation.Implication of micro and nano additives to the mixture as partial substitute of the filler can extend the fatigue life of the pavement and control the initiation of distresses.An attempt has been made in this assessment to implement micro and nano additives such as fly ash and fumed silica to enhance the sustainability of asphalt concrete mixture.The influence of such additives on the stiffness, permanent deformation, and dissipated energy was investigated.It was revealed that the modified mixtures with silica fumes and fly ash exhibits higher flexural stiffness of (7500 and 8000) MPa, (2000 and 3000) MPa, and (1600 and 1800) MPa as compared to that of the control mixture under 250, 400, and 750 microstrain levels respectively.Significant loss of energy could be detected at the initial stages of loading.For the control mixture, the flexural stiffness exhibits almost constant stiffness while it increases after 0.00001 MJ/m 3 loss of energy.When the silica fumes additive are implemented, the stiffness increase sharply as the loss of energy reaches 0.0001 MJ/m 3 , then increases gently.When the fly ash was introduced, a sharp increase in the flexural stiffness could be observed up to 0.00001 MJ/m 3 loss of energy, and then the increment in the stiffness was almost constant.It was concluded that the micro size additive (fly ash) exhibits superior behavior in supporting the flexural stiffness of asphalt concrete when compared with the Nano size additive (silica fumes).