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Air-hardening organic polymer (AHOP), a new soil stabilizer, can form a cross-link among soil particles with high strength and toughness. In this study, the effect of the polymer content and density on the mechanical behavior of stabilized silty sand was investigated. The results indicate that the unconfined compressive strength and tensile strength of stabilized silty sand keep a prominent linear relationship with AHOP content that increases with the increment in density; the increment in AHOP content also leads to a higher elastic modulus of stabilized silty sand. The cohesion was also significantly enhanced by the increase in AHOP content and density; the internal friction angle of loose specimens (ρ≤1.50 g/cm3) keeps increasing with AHOP content; however, for dense specimens (ρ≥1.55 g/cm3), 3% polymer content is a turning point, at which the internal friction angle changes nonmonotonically. AHOP film can connect loose silty sand particles and adhere to the surface of particles, leading to silty sand with good strength properties. Based on failure modes, the failure of polymer–particle interactions can be divided into four modes, including (1) tensile fracture at membrane, (2) tensile fracture at polymer–particle interface, (3) shear at membrane, and (4) shear at polymer–particle interface. [ABSTRACT FROM AUTHOR]

This study focuses on the shear-strength properties of polyurethane polymer–treated sand stored at different temperatures. The triaxial test was performed at unconsolidated and undrained conditions on the specimen after 2 days of curing at room temperature and 1 day of curing at various temperatures. The effects of polymer content and dry density on strength properties were also considered. Polymer reinforcement mechanism was analyzed using scanning electron microscope images. Results indicated that the stress-strain relationship exhibited increasing ductility as temperature increased; the shear strength, energy absorption, and cohesion tended to decrease initially and then increase, while the friction angle remained stable at approximately 30°. The strength properties were in proportion to an increment in polymer content, and the trend became more apparent in a warmer environment. The shear strength, energy absorption, and cohesion increased up to about 2.4 MPa, 65 kPa, and 400 kPa, respectively. A higher dry density resulted in significant improvement in strength properties, except for a slight reduction in ductility, no matter the temperature. The presence of a polymer matrix formed a honeycomb and special net structures among sand via coating, bridging, and filling effects; hence, the treated sand turned into a whole system exhibiting favorable strength properties. This reinforcement effectiveness depended on polymer content, dry density, ambient temperature, soil grain, and polymer characteristics. [ABSTRACT FROM AUTHOR]