Locust Bean Gum–Stabilized Kaolin-Rich Earthen Composites (2025-10)¶

Additive manufacturing of bio-stabilized earthen materials offers a sustainable alternative to conventional carbon-intensive construction materials and methods, addressing growing environmental and resource concerns. This study investigates the potential of locust bean gum (LBG) as a bio-stabilizer for kaolinite-rich earthen composites, using it as a representative system to study mineral-mineral, mineral-biopolymer, and biopolymer-biopolymer interactions. Physico-chemical analyses show LBG’s strong binding affinity with clay particles, while rheological tests reveal three regimes driven by distinct particle interaction mechanisms. At low concentrations, LBG bridges particle networks, increasing yield stress and storage modulus. At intermediate concentrations, excessive adsorption disrupts clay self-assembly, reducing storage modulus and increasing creep compliance. At high concentrations, polymer overlapping enhances yield stress, storage modulus, and creep resistance. These results demonstrate that buildability in 3D printing is governed by the interplay of yield stress and viscoelasticity, rather than yield stress alone. Importantly, LBG not only improves rheology and mechanical strength for on-land printing but also has the potential to function as an anti-washout agent under water, enabling extrusion, cohesion, and shape retention. Together, these findings highlight LBG’s dual role as a rheology modifier and binder, advancing sustainable strategies for both terrestrial and underwater 3D printing of earthen materials.