Investigation on reinforcing mechanisms of semi-flexible pavement material through micromechanical model.

Graphical abstract Highlights • The 2S2P1D model is suitable for SFP. • A larger porosity in PA means a greater effect of skeleton interlock on loss modulus. • Grouting cement had a negative effect on the loss modulus at low temperatures. • Physiochemical stiffening effect and imperfect interface exist between PA and cement skeletons. • A larger porosity leads to a more stable interlock effect with the frequency increasing. Abstract Semi-flexible pavement (SFP) has been promoted to apply in pavement engineering mainly for its excellent performance in rutting resistance. Since the reinforcing mechanism of its stiffness and strength is still ambiguous, this paper aims to investigate the reinforcing mechanisms of SFP at meso-scale. SFP was regarded as a double skeleton structure (open graded asphalt skeleton and grouting cement skeleton) and three main reinforcing mechanisms were characterized on the basis of the Mori-Tanaka model (M-T), including matrix modulus, cement filling effect and double structure interlock. During the process, the matrix of SFP was redefined as asphalt mixture without effect of cement-filling air voids. The behavior of the imaginary matrix was obtained through back-calculation in M-T model. The two springs, two parabolic elements, and one dashpot (2S2P1D) model was utilized to characterize viscoelastic behavior and two interlock factors were established to amend interlock effect. The results may demonstrate the existence of physiochemical stiffening effect of grouting cement and imperfect interphase between the two skeletons. SFP with matrix of three different original porosities were compared during the prediction process. It was found that the reinforcing rate was positively related with original porosity. While the dynamic modulus value of SFP, meaning specially storage modulus value, depended more on the matrix gradation than porosity. And grouting cement had a negative effect on the holistic loss modulus at high frequencies. [ABSTRACT FROM AUTHOR]