Rock-like strength enhancement of Indian desert sand using commercially available polysaccharide biopolymers

Biopolymers are a nature-friendly solution that can impart rock-like strength in sand by developing bonds between grains. In this study, we assessed the behaviour of desert sand treated with commercially available pectin (P), acacia gum (AG) and sodium alginate (SA) polysaccharide biopolymers (1%, 2% and 3% concentrations) applied at 0.75 and 1 pore volume (PV). Non-destructive ultrasonic pulse velocity (UPV) tests recorded maximum values of 1579 m/s for AG samples, 1490 m/s for SA samples and 1400 m/s for P samples, all showing rock-like behaviour. Unconfined compressive strength (UCS) and split tensile strength (STS) tests showed that the strength level generally increased with biopolymer concentration. The minimum UCS value was 173 kPa for the P (1%) 0.75 PV composition, and the maximum was 1287 kPa for the AG (2%) 0.75 PV composition. The UCS value for the AG (1%) 0.75 PV was 1178 kPa, with optimal results compared with other compositions. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) tests were performed for microstructural analysis. SEM revealed a strong bond between sand particles and biopolymers. EDX and XRD showed that the strength stemmed from gel formation in the pores, rather than mineralogical changes. The study results indicate the level of strength attained with varying biopolymer percentages and PVs and are useful for desert sand stabilization.