Efficacy of Biopolymer Treatment in Improving the Dynamic Response of Fly Ash Deposits

Abstract

The utilization of biopolymer treatment presents a sustainable and environmentally friendly alternative to traditional binders such as cement, lime, and chemicals and has the potential to mitigate the carbon footprint significantly. The guar gum (GG) biopolymer used in this investigation exhibits viscoelastic behavior and establishes strong bonds with the fine fly ash particles, enhancing the dynamic response of fly ash. A comparative analysis was conducted between untreated fly ash (UFA) and GG-treated fly ash (GGFA) in terms of dynamic properties and excess pore pressure (EPP) response using cyclic triaxial testing, considering different GG dosages (0.50%, 0.40%, 0.30%, and 0.20%), curing periods (7, 14, and 28 days), and cyclic shear strains (0.45%, 0.75%, 1.125%, 1.50%, and 1.875%). Test results revealed that only 0.50% of GG was required for optimal performance, very small compared to conventional binders. At optimal dosage of GG, the 28-day dynamic shear modulus and the damping ratio exhibit increases of 284% and 364%, respectively, whereas the EPP exhibits a reduction of 32% compared with UFA. Also, the stress paths of UFA and GGFA were developed to understand the dynamic response better. Microanalysis of UFA, 7-day-cured GGFA, and 28-day-cured GGFA showed evidence of binding networks between the GG and fly ash particles through a pore-clogging mechanism.