Enhancing the performance and durability of eco-friendly mortars: The role of calcium chloride in GGBS and glass powder-based mixtures

The use of calcium chloride (CaCl₂) in slag-based cementitious materials has been well documented over the past decades, particularly for enhancing the early-age strength of mixes. However, the effect of this chemical additive in mortars incorporating mineral additions such as ground granulated blast furnace slag (GGBS) and glass powder (GP) on properties like fluidity, long-term shrinkage, and durability against chemical attacks remains underexplored. This study investigates the incorporation of 1% CaCl₂ into eco-friendly mortars containing 30% GGBS and GP as partial cement replacements. The experimental methodology includes a comprehensive characterization of fresh-state properties (workability, density) and hardened-state properties (water absorption, flexural and compressive strengths, resistance to chemical attacks, total and autogenous shrinkage), along with microstructural analysis using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results reveal that adding CaCl₂ significantly enhances mortar properties. In the fresh state, the workability of mixes containing GGBS or GP increases by 4%. In the hardened state, the acceleration of pozzolanic reactions leads to a notable improvement in mechanical strength, with mixes containing GGBS reaching 37 MPa at 7 days (+60%) and retaining 73% of this strength at 28 days. The incorporation of GP also reduces total shrinkage deformations. Furthermore, formulations enriched with CaCl₂ exhibit improved durability against environmental aggressions. A life cycle-based environmental assessment also confirmed the reduction in carbon footprint and energy demand. This approach offers promising prospects for durable and high-performance cementitious materials, particularly for precast concrete, road pavements, and marine infrastructure. • CaCl₂ enhances early-age strength by 60%, improving durability of eco-mortars. • Workability increases by 3.8% with CaCl₂, optimizing fresh-state mortar behavior. • -CaCl₂ reduces weight loss under acid attack, improving long-term mortar resilience. • -Life cycle assessment shows that 30% cement replacement with slag or glass cuts environmental impacts.