Dynamic Characteristics of Fly Ash Treated with Xanthan Gum Biopolymer

Dynamic instability is often cited as a significant issue while using fly ash for landfilling and land reclamation. Even though traditional cementitious binders have the potential to mitigate this problem, they may result in substantial negative impacts on the environment and ecological systems. This study presents the innovative application of an environmentally friendly biopolymer, xanthan gum (XG), to augment the dynamic response of fly ash and its sustainability. A series of cyclic triaxial experiments were conducted on untreated and XG-treated fly ash samples under various XG dosages, curing periods, and cyclic shear strains to assess the effectiveness of XG treatment in terms of dynamic properties, excess pore pressure (EPP) response, and stress–strain response. The findings demonstrate that XG has the potential to significantly reduce the accumulated EPP through its hydrophilic nature, densification through pore clogging, and particle bonding and bridging mechanisms, thereby substantially improving the dynamic properties against cyclic loading. After a curing period of 28 days, an optimal dose of 0.75% XG resulted in a 346% increase in dynamic shear modulus and a 173% increase in damping ratio. Also, the inclusion of XG significantly hindered the escalation of EPP generation in fly ash, as evidenced by the reduction in the maximum EPP ratio to 0.70. Furthermore, scanning electron microscopy images provide valuable insights into the reinforcing mechanism of XG through the bridging, bonding and aggregation of fly ash particles.