Effect of crumb rubber and reclaimed asphalt pavement on viscoelastic property of asphalt mixture

Crumb rubber and reclaimed asphalt pavement have been widely used in the application of pavement engineering as they would greatly improve the high-temperature stability and rutting resistance of asphalt mixtures. This study aimed to give a comparative analysis of the viscoelastic improvement effect of crumb rubber and reclaimed asphalt pavement. In laboratory tests, 2 virgin binder contents, 2 crumb rubber contents, 2 sources of reclaimed asphalt pavement, and 2 reclaimed asphalt pavement contents were involved to produce 12 different types of asphalt mixtures with controlled aggregates gradation. Single axle creep test and dynamic modulus test were conducted to acquire stress-strain response under static and dynamic loading conditions. Creep performance was obtained under 20 °C, 35 °C and 50 °C, and dynamic modulus was obtained under 5 °C, 20 °C, 35 °C and 50 °C at 0.1 Hz, 0.5 Hz, 1 Hz, 5 Hz, 10 Hz and 25 Hz. Master curves were constructed for creep compliance, complex modulus, phase angle, storage, and loss modulus in the time and frequency domains, and an optimal fitting model was selected. As a result, it was found that both crumb rubber and reclaimed asphalt pavement had a positive effect on the elasticity of the asphalt mixture. In most scenarios, the elasticity improvement was dominated by reclaimed asphalt pavement but it was dependent on the aged binder content. The effect of incorporating crumb rubber and reclaimed asphalt pavement together was comparable to the sum of the effect when incorporating each of them solely.