For the design and construction of waterfront structures made of wood plastic composite (WPC) materials, time-dependent mechanical properties and the hygrothermal response of the material under various environmental conditions need to be characterized. In this thesis, durability studies of an innovative WPC sheet pile are presented. The effect of strain rate on the mechanical properties of the WPC material was characterized. Water absorption experiments on the WPC material were conducted and the moisture diffusion behavior and the resulting degradation in mechanical properties were quantified. The effect of temperature on tensile properties of the WPC material was established experimentally. The time dependent behavior of the WPC material was investigated through short-term creep tests in tensile mode. This experimental response was used to predict the long-term creep behavior by implementing the time-temperature superposition principle