Stress path investigation of fatigue characteristics of cement stabilized macadam

Fatigue strength is the core of pavement structure design. For semi-rigid base asphalt pavement, the anti-fatigue design of cement stabilized macadam is the key to the entire pavement design process. However, the structural layer of cement stabilized macadam is in a complex stress path, and the traditional S-N fatigue equation is various in different stress paths. Single S-N fatigue equation cannot truly reflect the actual pavement's stress path (three-dimensional structure), thus bringing challenges to make selections in engineering design. This study aims to accurately perform the cement stabilized macadam's fatigue characteristics in structural design. First, the specimens were prepared under vibration mixing and vibration molding, and the uniaxial compression, bending, and indirect tensile mechanical properties were studied. Then, based on test results and Miller yield criterion, the strength yield surfaces of cement stabilized macadam were established with an increase in loading rates. Finally, the generalized shear stress strength ratio is proposed to unify fatigue performance under different test methods. The results show that the strength rises with an increase in loading rates, and the yield surface is a parabola. Miller yield surface referrings as fatigue damage surface comprehensively describes the failure characteristics of cement stabilized macadam. The new fatigue equation curves based on the Miller yield surface are significantly closed in different stress paths and pass-through points (1, 1). Using one equation can represent the fatigue feature of cement stabilized macadam thoroughly. It realizes the unified characterization of fatigue performances and eliminates the effect of test methods and conditions on fatigue results. This study solves the long-standing problem: the fatigue equations obtained by different test methods are various, which improves the design accuracy of the semi-rigid base pavement. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study presents a new method to characterize the fatigue performance of cement stabilized macadam uniformly using experiments and mathematical analysis, which effectively solves the problem in engineering design.