Microstructural evolution and mechanical property enhancement of red mud incorporated high strength concrete
Chava Venkatesh, Chereddy Sonali Sri Durga, Takkellapati Sujatha, Ramamohana Reddy Bellum, Bypaneni Krishna Chaitanya, Meseret Getnet Meharie
Abstract
This study investigates the effects of red mud (RM) incorporation on high-strength concrete through comprehensive assessment of mechanical properties, microstructural characteristics, and phase evolution over 180 days. Five concrete mixtures with RM replacement levels ranging from 0 to 20% were analyzed. Results demonstrate that 10% RM replacement achieves superior performance with 28.96%, 13.66%, and 15.45% improvements in compressive, split tensile, and flexural strengths respectively at 180 days. X-ray diffraction analysis reveals significant mineralogical transformation in this mixture, with progressive reduction in portlandite content and increased formation of strength-contributing phases. Scanning electron microscopy confirms enhanced matrix densification and improved interfacial transition zone characteristics, while Energy Dispersive X-ray analysis shows a favorable Ca/Si ratio of 0.9475 at 180 days, indicating formation of stable C-S-H gel structures. Novel prediction models for mechanical properties demonstrate greater accuracy compared to established code equations. This research establishes 10% as the most effective RM replacement threshold, balancing enhanced mechanical performance with sustainability benefits, thereby providing a robust framework for industrial-scale implementation of RM in high-strength concrete applications.