SIMULATION OF FLEXIBLE PAVEMENT UTILIZING FLY ASH AS ALTERNATIVE STABILIZER

Abstract

The stabilization process in pavement construction is not a new process, but hitherto this process has not been fully implemented in the design methods for pavement structure. Its partial implementation in design has contributed to the failures experienced in pavement structure, which result in such pavement needing excessive maintenance and rehabilitation, thereby increasing the operational cost of the roads. Additionally, the use of an empirical design method for pavement structure has led to the over-design of pavement, resulting in wasteful design and construction of pavement structure. Nevertheless, Mechanistic-Empirical seems to be the way out. Consecutively, with the advent of powerful design software based on different methods such as the Finite Element (FE), Discrete Element, Finite Difference, Boundary Element Methods, the possibility of design and construction of quality pavement structures are enhanced. Therefore, the main focus of this study is to provide a modelling tool for using fly ash as alternative stabilizer for base layers of flexible pavement. To achieve the aim of the study, various objectives were set in place based on literature reviews which are documented in this study.Considering the fact that FE is the method most adopted in pavement analysis and with the ability to obtain stresses and strains at the bottom of the surface layer, and compressive stress/strain within the base layer and at the top of sub-grade, it was considered in this study. Validations of a 3D FE model over 2D were conducted for fly ash stabilized base layer. Thereafter, the importance of an asphalt layer on a stabilized base layer was checked, and the efficiency of non-linear model for material characterization was also checked. Overall, a comparative analysis of FE modelling and an empirical method of pavement design was conducted. The results show that the use of 3D FE models is more efficient than 2D axisymmetric models; use of a non-linear material characterization model is more efficient than linear material characterization, and the use of empirical design methods results in the over-designing of pavement structure. Thus, the overall results suggest the use of 3D FE models, coupled with a non-linear material characterization model are suitable for the design of flexible pavement with a stabilized base layer.