Feasibility and Characterization Mortar Blended with High-Amount Basic Oxygen Furnace Slag

Prior research has explored the use of industrial byproducts in cementitious systems, but the feasibility of high-volume basic oxygen furnace slag (BOFS) as a cement replacement remains unclear. It was already known that BOFS contains reactive components like CaO and SiO₂, which may contribute to hydration processes. However, no prior work had resolved the effects of varying BOFS fineness and replacement levels on mortar properties. This gap motivated the current study to assess the mechanical and chemical behavior of BOFS mortars. The uncertainty around flowability, setting time, and expansion in high-BOFS mortars required further investigation. The challenge of balancing workability with structural performance in cement blends remains unresolved. No prior work had examined the formation of C-S-H and C-A-S-H colloids from BOFS hydration. This uncertainty drove the need for a detailed characterization of BOFS mortars.

The aim of this study was to assess the feasibility of using high proportions of basic oxygen furnace slag (BOFS) as a cement replacement in mortar blends. The specific problem addressed was the lack of data on how BOFS fineness and replacement levels affect mortar flowability, setting time, and mechanical properties. The motivation for this study was to determine if BOFS could serve as a sustainable alternative to cement. The researchers propose that BOFS may offer environmental benefits by reducing CO₂ emissions. The study also sought to clarify the hydration mechanisms of BOFS in mortar systems. The goal was to identify optimal replacement levels and fineness for mechanical performance. The researchers propose that BOFS may form hydration products like C-S-H and C-A-S-H colloids. The study aimed to provide a foundation for using BOFS in construction materials.

The study involved grinding basic oxygen furnace slag (BOFS) to three fineness levels and replacing cement at 10, 30, 50, and 70 wt.%. Mortar samples were prepared with these blends and tested for flowability and setting time. Mechanical properties were assessed using compressive strength tests. Scanning electron microscopy (SEM) was used to analyze the microstructure of the mortars. The researchers propose that SEM imaging may reveal hydration product formation. The study also monitored expansion behavior as a function of BOFS replacement levels. The researchers propose that expansion may increase with higher BOFS proportions. The methods included comparing BOFS mortars to ordinary Portland mortar as a control. The researchers propose that this comparison may highlight the viability of BOFS as a cement replacement.

The results showed that BOFS fineness and replacement levels significantly affected flowability and setting time of the mortars. The expansion of BOFS mortars increased with higher cement replacement proportions. The researchers propose that this expansion may exacerbate cracking in mortar systems. Optimal mechanical properties were observed at 10 wt.% cement replacement with BOFS of 10,000 cm²/g fineness. The compressive strength of BOFS mortar was similar to that of ordinary Portland mortar. SEM analysis revealed the formation of C-S-H colloids from CaO hydration. The researchers propose that SiO₂ and Al₂O₃ in BOFS may form C-A-S-H colloids. The study found that BOFS may be suitable as a partial cement replacement. The researchers propose that BOFS could reduce CO₂ emissions in cement production.

The authors suggest that BOFS may serve as a partial replacement for cement in mortar blends. They propose that BOFS could offer mechanical properties comparable to ordinary Portland mortar. The authors suggest that optimal performance occurs at 10 wt.% replacement with high fineness BOFS. They propose that BOFS hydration may produce C-S-H and C-A-S-H colloids. The authors suggest that BOFS may reduce CO₂ emissions in the steel industry. They propose that BOFS could contribute to sustainable construction materials. The authors suggest that flowability and setting time are affected by BOFS fineness and replacement levels. They propose that expansion increases with higher BOFS proportions, potentially leading to cracking.