Conventional construction materials used in foundations can encounter serious durability problems
in contaminated subsurface or marine environments. Fiber-reinforced polymer (FRP) composites are potentially
suitable for these harsh environments due to their chemical and corrosion resistant properties. Quantification of
the interface behavior between FRP composites and soils is a necessary precursor to the adoption of these new
materials in geotechnical engineering practice. This paper describes the results of an experimental study that
was conducted to investigate the behavior of sand-FRP interfaces. Tests showed that the interface shear behavior
between FRP composites and granular materials depended on the relative roughness (surface roughness/particle
mean size), the normal stress level, the initial density of the soil mass, and the angularity of the particles. The
soil specimen preparation method, the rate of shearing, and the thickness of the soil specimen had little influence
on the measured interface friction coefficients. The characteristics of FRP-sand and steel-sand interfaces were
compared.