Performance of cementitious composites with bayer red mud as a partial cement replacement

Area of Science:

• Materials Science
• Civil Engineering
• Environmental Science

Background:

• Bayer red mud (BRM) is a major industrial byproduct of alumina refining.
• Sustainable utilization of BRM is crucial for waste management in the alumina industry.

Purpose of the Study:

• To evaluate Bayer red mud (BRM) from Shandong Xinfa Group as a partial cement replacement.
• To assess the impact of BRM on cementitious properties and microstructural development.
• To determine the environmental safety of BRM-blended mortars.

Main Methods:

• Cement replacement with BRM at 0.5%, 1%, 5%, 10%, and 15% by mass.
• Evaluation of setting times and compressive strength at 3 and 28 days.
• Microstructural analysis using XRD, TG/DTG, and SEM.
• Leachability testing via Toxicity Characteristic Leaching Procedure (TCLP).

Main Results:

• BRM addition slightly prolonged setting times within acceptable limits.
• Compressive strength was comparable to control up to 5% BRM replacement.
• Higher BRM content (10%, 15%) significantly reduced compressive strength.
• Microstructural analysis indicated BRM acted as a micro-filler and nucleation site.
• TCLP results confirmed heavy metal concentrations were below regulatory thresholds.

Conclusions:

• Xinfa Group's BRM can be effectively used as a supplementary cementitious material up to 10% replacement.
• BRM incorporation below 10% shows potential for sustainable solid waste management.
• BRM-blended mortars pose minimal environmental risk due to low heavy metal leachability.