Influence of iron tailing filler on rheological behavior of asphalt mastic

Abstract

• Limestone filler (LF) was substituted by iron tailing filler (ITF) in mastics under different f/b ratios. • The interaction between ITF and asphalt matrix was primarily physical. • ITF possessed a superior stiffening effect on mastics than LF. • A new index Δ T d was proposed to quantify the low-temperature performance of ITF mastics. • The substitution of ITF should be controlled within 1.0 f/b ratio. Iron tailings, one kind of widespread solid waste, were preliminarily regarded as a potential substitute for mineral filler in asphalt mixtures. However, the overall rheological properties of asphalt mastics incorporating iron tailing filler (ITF) and the effect mechanism of ITF remain unclear, which is detrimental to the generalized utilization of ITF in asphalt pavement. To fill this gap, the present study selected ITF and limestone filler (LF) to fabricate mastics with four filler/asphalt weight (f/b) ratios (0.6, 0.8, 1.0, 1.2). The blending mechanism and surface morphology of mastics were revealed by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The rotational viscosity test, dynamic shear rheometer test as well as bending beam rheometer test, were conducted to comprehensively study the rheological behavior of mastics. A new index Δ T d was proposed to quantify the influence of ITF on low-temperature cracking performance. Results show that the interaction between ITF and asphalt matrix is predominantly physical, and ITF possesses a smaller particle size which is beneficial to stiffening the mastics. However, the worse infiltration and distribution uniformity of ITF in mastics than that of LF may result in poorer adhesion. Regarding the rheological behavior, the substitution of ITF can highly improve the viscosity, complex modulus, and creep stiffness while slightly decrease the phase angle, viscosity-temperature susceptibility, and m -value of mastics, indicating a higher stiffness and elasticity of ITF mastics. Notably, the plateau region of phase angle may appear in ITF mastics with high filler concentration at low frequencies, representing a more significant elastic response. Besides that, Δ T d remains between −3.5 and −1.1 ℃. These results prove that the substitution of ITF is advantageous for the anti-rutting performance of asphalt pavement but may jeopardize its workability and low-temperature cracking resistance in particular with the excessive incorporation (f/b ratio > 1.0) of ITF.