This study investigates the mechanical performance of alkali-activated slag (AAS) under low-temperature curing conditions (2°C), focusing on the effects of activator modulus (1.2 and 1.5), alkali dosage (5, 7, and 9%), and Portland cement (PC) substitution rates (0, 10, and 20%). The research aims to develop a green binder suitable for cold weather applications by optimizing these parameters. The results show that increasing the alkali dosage enhances early-age strength but reduces 90-day strength. Higher activator modulus and PC substitution rates lead to lower strength due to shrinkage-induced cracking. The optimal mixture design includes using 10% PC with a 1.2 modulus or omitting PC with a 1.5 modulus. Despite low temperatures, PC significantly accelerates setting time. Modulus and alkali dosage changes affect FTIR spectrum peak intensity, indicating microstructural differences. Compressive strength at 7, 28, and 90 days was measured, with the highest 90-day strength achieved by M1.2/N5/P10 (79.2 MPa) and M1.5/N5/P0 (69.5 MPa). Ultrasonic pulse velocity (UPV) values showed a strong correlation with 28-day compressive strength but diverged at later ages due to crack development. SEM analysis revealed denser microstructures with higher modulus, while FTIR indicated consistent hydration product formation with denser gel structures at higher modulus. The study concludes that optimizing activator modulus, alkali dosage, and PC substitution is crucial for achieving optimal strength in AAS under low-temperature conditions. The findings suggest that AAS can be effectively used in cold weather applications when properly formulated, offering a sustainable alternative to traditional Portland cement.This study investigates the mechanical performance of alkali-activated slag (AAS) under low-temperature curing conditions (2°C), focusing on the effects of activator modulus (1.2 and 1.5), alkali dosage (5, 7, and 9%), and Portland cement (PC) substitution rates (0, 10, and 20%). The research aims to develop a green binder suitable for cold weather applications by optimizing these parameters. The results show that increasing the alkali dosage enhances early-age strength but reduces 90-day strength. Higher activator modulus and PC substitution rates lead to lower strength due to shrinkage-induced cracking. The optimal mixture design includes using 10% PC with a 1.2 modulus or omitting PC with a 1.5 modulus. Despite low temperatures, PC significantly accelerates setting time. Modulus and alkali dosage changes affect FTIR spectrum peak intensity, indicating microstructural differences. Compressive strength at 7, 28, and 90 days was measured, with the highest 90-day strength achieved by M1.2/N5/P10 (79.2 MPa) and M1.5/N5/P0 (69.5 MPa). Ultrasonic pulse velocity (UPV) values showed a strong correlation with 28-day compressive strength but diverged at later ages due to crack development. SEM analysis revealed denser microstructures with higher modulus, while FTIR indicated consistent hydration product formation with denser gel structures at higher modulus. The study concludes that optimizing activator modulus, alkali dosage, and PC substitution is crucial for achieving optimal strength in AAS under low-temperature conditions. The findings suggest that AAS can be effectively used in cold weather applications when properly formulated, offering a sustainable alternative to traditional Portland cement.