Mechanical and Microstructural Properties of a Stabilized Sand Using Geopolymer Made of Wastes and a Natural Pozzolan

In this study, a combination of geopolymers including Rafsanjan Natural Pozzolan (RNP), Cement Kiln Dust (CKD), and an activator such as Calcium Carbide Residue (CCR) or NaOH was used to stabilize and improve the poorly graded sandy soil. Factors such as the activator type, activator concentration, CKD and RNP content were studied. Chemical compounds of the soil and abovementioned materials were investigated using X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) detection tests. Unconfined Compressive Strength (UCS) tests were carried out to evaluate the mechanical behavior of the specimens. The findings revealed that CKD, which is a hazardous byproduct, could be turned into an eco-friendly construction material through geopolymerization. The presence of CKD along with NaOH significantly increased the UCS of the samples compared to unstabilized specimens (control 1). Microstructural analyses using Scanning Electron Microscopy (SEM) confirmed the desirable distribution of the geopolymer gel in the stabilized soil. According to the SEM images, it was observed that the samples stabilized with CKD had a higher strength than those stabilized with CKD combined with RNP due to the formation of a greater amount of gel and a stable microstructure. The findings of this research promote sustainable ground improvement techniques using waste by-products.