Mechanical behavior and microstructure evolution of slag-fly ash based geopolymer stabilized sand

Abstract

Geopolymers made from ground granulated blast-furnace slag and fly ash could effectively address the issues of high energy consumption and emissions associated with Portland cement, which is commonly used as a soil curing agent. In this study, the unconfined compressive strength and microstructure of geopolymer-solidified sand were presented and analyzed. The study focused on effect of the type and ratio of activator, the ratio of slag to fly ash, and the ratio of water to (activator and cementitious materials) (W/(A + C)) on the behavior of geopolymer stabilized sand. The results of computed tomography (CT), and scanning electron microscope (SEM) indicate that the variation in initial water content significantly affects the porosity of the specimen, which increased as initial water content increased. The cracks were mainly found at the joints between the individual aggregates and at the edges of the individual aggregates. The pore size distribution of the specimens was concentrated in the range 0.0761–5 μm, while the polymer particle distribution was concentrated in the range 0.0761–10 μm, with a concentration of over 90 %. A significant amount of cementing material was densely distributed around both the aggregates and the pores. CT and SEM testing techniques enable a thorough analysis and mutual verification of the self-compacting process, pore distribution, and size, as well as the distribution of cementing material within the specimens. The optimum ratio for B-S19 has been determined.

Keywords

• Geopolymer
• Stabilized sandy soil
• Computed tomography
• Microstructure
• Pore and crack