Design of flexible pavement thickness using stabilized high plastic soil by means of fly ash-based geopolymer

This paper presents an approach for stabilising high plastic soil (HPS) with fly ash-based geopolymer and its application in flexible pavement. The mechanical performance of HPS with various proportions of fly ash (FA) (10, 15, 20, 25, and 30%) based geopolymer were evaluated through a series of experimental investigations. The soil was mixed with sodium hydroxide of 6 and 8 molar concentrations (6M & 8M) and a sodium silicate mixture of ratio 1.5 was used as alkaline activators for (FA). The results clearly indicate that the mechanical performance of (FA)-based geopolymer stabilised HPS increases up to 25% (FA) content and was less prone to swelling and shrinkage behaviour. Also, the microstructure of HPS was studied through the Scanning Electronic Microscope (SEM) with energy dispersive x-ray (EDX), X-ray Diffraction (XRD), and Fourier Transformed Infrared Spectra (FTIR), and results showed significant alteration of the microstructure of HPS due to the formation of geopolymeric gel. The application of stabilised HPS is demonstrated for the design of flexible pavement thickness for low and high-volume roads. It has been observed that there is a significant reduction in pavement thickness for stabilised HPS compared to HPS. Thus, it can be used as a sustainable alternative to conventional stabilisers.