Investigation of the long-term shear strength behavior of municipal solid waste fines stabilized with biopolymer: An experimental study

Abstract

Biopolymers are emerging as sustainable and eco-friendly soil stabilizers, but there is a lack of studies investigating their long-term effectiveness. Municipal Solid Waste Fines (MSWF), the portion of MSW that passes through a 4.75 mm sieve, were treated with two biopolymers, Xanthan Gum and Agar Gum, and cured at a constant moisture level and room temperature for 7–180 days. Triaxial tests were conducted to determine shear strength parameters at different curing periods and biopolymer concentrations. Results showed that the shear strength of the treated MSWF increased more than 2.5 times when treated with 1.5 % of Xanthan Gum and Agar Gum. The shear strength increased from 85.2 kPa to 307.1 kPa and 322.2 kPa for Xanthan Gum and Agar Gum, respectively. Both biopolymers also improved the angle of internal friction and cohesion of the MSWF with long-term curing. Xanthan Gum exhibited a slower rate of strength gain over a period of up to three months, while Agar Gum-treated MSWF gained the ultimate strength more quickly. Agar Gum showed better strength properties due to its better gel stiffness, and a microstructure study demonstrated that these biopolymers consistently tend to fill pores when used over an extended period. The long-term stability of biopolymer-treated MSWF reflects a green approach, emphasizing the potential for circularity, sustainability, and reduced emissions.