Effect of Xanthan Gum Biopolymer on Fracture Properties of Clay

Abstract

Additives enhancing the fracture resistance of clay are of great importance to decrease cracking potential of earth structures. With the promotion of environmental protection, eco-friendly biopolymers have shown their competitiveness as additives in different engineering fields. This research deals with the findings of an experimental investigation carried out on single-edge notched beams manufactured from compacted clay. Three-point bending (flexure beam) tests were performed to evaluate the effect of xanthan gum biopolymer, a common fluid thickener biopolymer in the food industry, on fracture behavior of clay during drying. Particle size analysis (PSA) and scanning electron microscopy (SEM) were carried out to study the microinteractions of clay–xanthan gum mixtures. The results showed that although xanthan gum biopolymer has limited effects on nominal flexural strength and fracture toughness at high water contents, it increases clay fracture energy and final displacement at zero external load in all water contents. With the evaporation of water, the strength and fracture toughness of biopolymer-treated clay increases more significantly in comparison with the pure clay. In addition, although the fracture energy of clay reduces during drying, for biopolymer-treated clay the fracture energy not only does not decrease significantly but also increases at the dry state.