Soil burial degradation experiments were carried out at ambient temperature under moisture controlled conditions. Triplicate specimens of each composite were placed in a series of perforated boxes containing moisturized soil. The specimens (30 × 10 mm) were buried 100 mm beneath the surface of soil which was regularly moistened with distilled water. The samples were removed at predetermined time points, carefully washed with distilled water several times in order to ensure the stop of the degradation, dried at room temperature to a constant weight and then were stored in darkness until testing. The specimens were weighed on the TG328-A model analytical balance in order to determine the average weight loss