Factors affecting unconfined compressive strength of fly ash based geopolymer stabilized soil.

In this paper, based on the advantages of fly ash geopolymer-stabilized soil, two kinds of low-calcium fly ash was used as the raw material, sodium hydroxide and water glass as the exciter to study the factors affecting the unconfined compressive strength of the geopolymer stabilized silty soil through three kinds of sample preparation method. The results show that among the three influencing factors, sample preparation method has the greatest influence on the unconfined compressive strength, followed by the type of activator and the fineness of fly ash. At 7 days of curing, the unconfined compressive strength of fly ash-based geopolymer stabilized soil activated by NaOH demonstrated a greater increase compared to that activated by Na₂SiO₃. However, at the 28-day curing mark, the activation effect of Na₂SiO₃ on the soil's strength surpassed that of NaOH. Directly mixed components exhibit unconfined compressive strengths that are 30% to 50% higher than those of sequentially mixed components that have undergone soil confinement. Through SEM observation and pore analysis of the specimens under different factors, it was found that the gap in the material was mainly filled by the generated geopolymer gel material, to reduce the porosity and improve the compressive strength of the stabilized soil. [ABSTRACT FROM AUTHOR]