Engineering Properties of Soil Stabilized with Cement and Fly Ash for Sustainable Road Construction

This study presents an experimental study of engineering properties of soil stabilized with cement and fly ash for layers in roadway construction. The fly ash was used in this study satisfies the requirement according to ASTM C618. Five proportion mixes were used in this work with varying quantities of ordinary Portland cement amounts of 8, 10% cement and combination of 8% cement with fly ash content of 2%, 4%, and 6%. Specified curing periods of 7, 14, 28 days were applied for all types of specimens. Some engineering tests were carried out, such as unconfined compressive strength (UCS), splitting tensile strength, stiffness of stabilized soil, SEM, and XRD techniques. SEM images, magnified 3000 times, showed that compacted soil structure was found as small and odd particles arranged without gel bound, while cement-fly ash stabilized soil was covered foam formation due to cement-fly ash crystal, and small particles cannot be observed. The peak intensity of silicon oxide was seen in the region 26-28° with an angle of 2. In addition, cement and fly ash significantly improved the mechanical properties of stabilized soils. Finally, the specimen containing 8% cement and 2% fly ash at 14-day curing had a splitting tensile strength greater than 0.45 MPa, satisfying the base layer of road construction requirement according to current Vietnamese standards. The obtained results provided a shred of evidence for capable of using fly ash for road construction in the context of an increase in the fly ash generated in thermal power plants.