Investigation of Mechanical and Durability Properties of Alkali-Activated Concrete Prepared with Ternary Blended Ground Granulated Blast Furnace Slag, Fly Ash, and Jajrood Trass

Alkali-activated concrete (AAC), an environment-friendly material, has attracted the attention of many researchers due to its unique features, such as good mechanical and durability properties. This research fabricated AACs that were a mixture of ground granulated blast furnace slag (GGBS), fly ash (FA), and Jajrood trass (JT) binders in three combinations with different SiO2-to-Al2O3 molar ratios, namely 70%GGBS-20%FA-10%JT (SiO2/Al2O3=5.4), 80%GGBS-10%FA-10%JT (SiO2/Al2O3=5.7), and 70%GGBS-10%FA-20%JT (SiO2/Al2O3=6.0). Subsequently, the mechanical and durability properties and the microstructure of the AACs were investigated. The results indicated that the 28-day compressive strength of the samples increased from 73.4 to 79.9 MPa when the SiO2-to-Al2O3 molar ratio decreased from 6.0 to 5.4. The same trend was observed for the tensile strength, water absorptivity, rapid chloride migration, corrosion resistance of rebars, pullout strength of rebars, and scaling resistance of concrete subjected to freeze-thaw cycles in the presence of deicers. Moreover, the 1-day corrosion of a steel rebar increased its pullout strength due to an increase in its surface roughness. However, an increase in corrosion time reduced the pullout strength due to cracking. Scanning electron microscopy images confirmed the results concerning the mechanical and durability properties of AAC.