Application of biopolymers for improving the strength characteristics of red mud waste

Abstract

In this study, the usefulness of two biopolymers (guar gum and xanthan gum) in improving the strength properties of two types of red muds was explored. Experiments were performed to determine the unconfined compressive strength and to establish the morphological and mineralogical compositions of stabilised samples cured for 7, 28, 45 and 90 d. The obtained results were interpreted to understand the red mud–biopolymer interactions. Considerable improvement in the compressive strength of stabilised samples, by four to five times, vis-à-vis that of the untreated samples was observed. Based on the results obtained for different admixture contents (i.e. 0·5, 1·0, 2·0 and 3·0%), the optimum dosage of biopolymers was found to be 0·5%. The morphological analysis revealed the formation of gels and their role in the aggregation of particles by the combined action of binding and pore filling. However, no changes in mineralogical compositions were identified from the diffraction patterns of stabilised samples. Both biopolymers proved effective in improving the strength characteristics, but the efficacy of xanthan gum was found to be superior over that of guar gum. Despite extreme alkalinity in the media, biopolymers were still able to impart reasonably good strength to the treated samples, demonstrating their usefulness and applicability.