Development and Characterization of Alkali-Activated Red Mud - Slag Cementitious Material

Abstract

The alkali-activated material ‘geopolymer,’ is considered as the third generation cement after lime and ordinary cement for sustainable development considering global changes. Use of industrial by-products as the alkali-activated material is helping in energy conservation, reducing the CO2 emission and preserving the natural resources. But, the challenge lies in developing the alkali-activated material using a proper combination of base materials, activator solutions, curing temperature and curing conditions. Hence, the focus of the present thesis is to develop alkali activated material using less explored industrial wastes; red mud and ferrochrome slag. Development of alkali-activated material using iron-rich red mud is the main the objectives of the present work. The ground granulated blast furnace slag (GGBS) is used as the calcium base binder, and sodium hydroxide pellets and sodium meta-silicate powder as an alkaline activator. Effect of thermal curing on compressive strength is also studied. The compressive strength of alkali activated red mud – slag paste, mortar, and concrete are investigated at 3, 7, 28 and 60 days under ambient, water, acid and alkali curing conditions. The developed red mud – slag cementitious material has better compressive strength compared to Portland slag cement. Based on laboratory accelerated corrosion monitoring simulating the marine condition, the developed red mud – slag has better corrosion resistance compared to Portland slag cement. The chemical, morphological and mineralogical changes are studied using Fourier Transform Infrared (FTIR), scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques, respectively. Industrial wastes being used as the base material, the future challenge lies in leachate analysis, long-term strength, and development of design methodology for proportioning of base materials and activators for different uses.