Study on the mechanical properties and water stability of steel slag-fly ash geopolymer for base Stabilisation

Modification of fly ash geopolymer with steel slag: Preparation of steel slag-fly ash geopolymer paste using steel slag andvarying dosages of NaOH-Na2SiO3 as variables. The study aims to investigate the workability, strength, and strengthening mechanismof this paste material, as well as to assess its mechanical properties and water stability in stabilized gravel. The results showed thatincorporating steel slag could decrease the fluidity and setting time of fly ash geopolymer while increasing its strength. When the steelslag and activator was 30% and 18%, respectively, the compressive strength at 7 and 28 days was the highest, reaching 19.3 and 24.9MPa, respectively. The strength of geopolymer-stabilized gravel was equivalent to that of cement-stabilized gravel. When thegeopolymer content is modified to 6%, the unconfined compressive strength at 7 and 28 days is 5.2 and 6.1 MPa, respectively. After28 days of curing, the water stability has significantly improved, with a water stability coefficient exceeding 0.9. The addition of steelslag can enhance the reactivity of the reaction system, facilitate the formation of C-(A)-S-H gel, increase the bonding strength, and fillthe internal pores, resulting in a 23.3% reduction in porosity, a denser structure, and improved strength.