Micromechanical Analysis of the Stiffening Mechanism in Asphalt Mastic Containing Portland Cement

In the production of certain hot mix asphalt mixtures, Portland cement is used as a filler to enhance mechanical properties, performance, and durability. Asphalt mastic, composed of bitumen and filler, is recognized as the microstructure within asphalt mixtures. Predicting the viscoelastic properties of asphalt mastic is crucial for estimating the mechanical and performance characteristics of asphalt mixtures. In this study, frequency sweep tests were conducted using a dynamic shear rheometer (DSR) to measure the complex shear modulus (G*) and phase angle (θ) of the original bitumen and asphalt mastic containing different volume filling ratios of Portland cement (ranging from ۱۰% to ۴۰%) at temperatures between ۴۶°C and ۸۲°C. The results indicate that an increase in volume filling ratio leads to a stiffening effect in asphalt mastic. To predict the viscoelastic properties of asphalt mastic, micromechanical models, including the generalized self-consistent model (GSCS) and the inverse rule of mixtures, were employed. A comparison between experimental and analytical results from these models demonstrates that the GSCS model provides higher accuracy in predicting the viscoelastic properties of asphalt mastic compared to the Inverse rule of mixtures model. Specifically, increasing the filler volume ratio from ۱۰% to ۴۰% resulted in an increase of the complex shear modulus (G*) from approximately ۷۰۰ Pa to ۲۲۰۰ Pa, clearly indicating a pronounced stiffening effect. Moreover, the prediction error of the GSCS model remained within about ۶%, compared to nearly ۲۷% for the inverse rule of mixtures, confirming the superior accuracy of the GSCS micromechanical model.

کلیدواژه ها:

Asphalt Mastic ، Micromechanical Model ، Portland Cement ، Filler ، Stiffening