The characterization and analysis of the cementation properties of novel biopolymer binders in soils are essential for their potential application in geotechnical engineering. This study investigates the cementation effect of a novel zein biopolymer binder on sandy soils. Soil specimens are mixed with various contents of zein biopolymer ranging from 0 to 5%. The mechanical and microscopic characteristics of the treated specimens are evaluated using unconfined compression tests and scanning electron microscopy, respectively, after curing for 3, 7, and 28 days. The results show a consistent increase in compressive strength and elastic modulus of treated soils with increasing curing periods and biopolymer contents. A small amount (1%) of zein biopolymer increases soil strength and elasticity regardless of gradation. Additionally, the bonding force between the soil–zein biopolymer increases linearly with soil uniformity. Therefore, the application of zein biopolymer can be potentially used as a binder for fine- and coarse-grained soils in geotechnical engineering considering its stabilization and sustainability properties.

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The curing condition and solvent composition of biopolymer binders may impact their efficacy for soil stabilization. This study introduces a novel hydrophobic biopolymer, zein, and investigates the effects of solvent and curing conditions on the mechanical properties of zein-treated soils. The zein biopolymer is used to prepare cohesionless soil with various ethanol contents. Unconfined compressive strength and microscopic tests are used to investigate the treated specimens under two different curing conditions. The mechanical properties of the treated specimens are evaluated in terms of compressive strength and the secant elastic modulus. The experimental results show that the compressive strength and elastic modulus increase with the curing period under both curing conditions. Higher curing temperature improves the compressive strength of biopolymer-treated specimens. The linear relationship between compressive strength and the elastic modulus of zein-treated soils shows higher strength and a lower elastic modulus compared to rock. Furthermore, the zein biopolymer shows significant strength improvement compared to the existing biopolymers, including casein and lignin. Thus, the effects of solvent and curing conditions on the mechanical properties of zein-treated soil should be considered for its application to soil stabilization.