1033 CETRA 2020* 20-21 May 2021, Zagreb, Croatia 6 th International Conferenceon Road and Rail Infrastructure COMPARATIVE STUDY ON THE DESIGN METHODS FOR FLY ASH- FLEXIBLE PAVEMENT Jacob A. Adedeji 1 , Samuel O. Abejide 2 , Mohamed M. Hassan Mostafa 3 1 Durban University of Technology, Civil Engineering Department Midlands, Kwazulu-Natal Province, South Africa 2 Walter Sisulu University, Faculty of Engineering Technology, Civil Engineering Department, Eastern Cape Province, South Africa 3 University of KwaZulu-Natal, School of Engineering, Sustianble Transportation Research Group (STRg), Civil Engineering, Kwazulu-Natal Province, South Africa Abstract Advancement in the design of pavement structures in the recent decade has brought about the use of fnite element modelling (FEM) tools. Numerical simulation of fexible pavement through these models are yielding positive results and enhancing pavement design year after year. Various factors contribute to this success; yet, material characterization model in FEM is a major/critical factor. However, in using FEM, there are various material charac- terization input methods which are; input through laboratory testing; secondly, through correlation and lastly a backward calculation from defection measurements. Overall, input methods are more realistic and give a better understanding of the mechanical behaviour of the material, nevertheless quite difcult to obtain. Although, the use of fy-ash stabilizer in pavement structure is not new yet its use has not been fully implemented in FEM design. As a result, a comparative study is considered based on input and correlation parameters on fy ash stabilized fexible pavement using Abaqus. Furthermore, the results show that the material input method provides better results and gives some amount of certainty on the design life of the pavement. Keywords: flexible pavement; finite element modelling; empirical design methods; material characterization; Non-linear model; fly ash 1 Introduction Flexible pavement design is based on load distributing characteristic of the component lay- ers. The asphalt surface depending on time and temperature behaves as a viscous material and the pavement foundation matrix (coarse-grained unbound granular materials in base / sub-base course and fne-grained soils in the sub-grade) exhibit stress-dependent non-line- ar behaviour [1]. Furthermore, with the introduction of soil stabilization resulting in alterna- tive materials, the design of fexible pavement has become more complex. Thou the analysis of pavement via empirical methods sometimes result in errors [2]. Therefore, this study pre- sents a comparative analysis of material characterization input methods for fy ash stabilized fexible pavement using FEM. FEM has been applied extensively in road engineering over the years [3]. So far, it is the most versatile of all analysis techniques, with capabilities for 2D and 3D geometric modelling, able to analyze stable (static), time-dependent problems, non-linear material characterization, large strains/deformations, dynamics analysis and oth- DOI: https://doi.org/10.5592/CO/CETRA.2020.979 ROAD SUPERSTRUCTURE: TESTING AND MODELLING