Behavior of natural-fiber/thermoplastic sheet piling
Publication Name: Proceedings of American Composites Manufacturers Association (ACMA) Composites & Polycon 2009
This paper describes the flexural behavior of an innovative Natural-Fiber/Thermoplastic Composite (NFTC) also known as Wood Plastic Composite (WPC) sheet piling. Test methods were developed and full-scale bending tests were conducted to characterize the flexural performance of the piles as part of a larger effort to develop a structural design methodology. In this study, WPC sheet piling specimens were produced at the Advanced Engineered Wood Composites (AEWC) Center at the University of Maine. Tensile coupon tests were performed to identify material properties. Full scale four-point bending tests were conducted up to failure on 20 sets of joined pairs of Z-piles of four different span lengths. Following the static tests, cyclic loading with amplitude equal to 40% the mean ultimate strength was performed to assess residual deformation under repeated loading. Data analysis includes moment capacity, modulus of rupture, apparent modulus of elasticity, and failure modes. Test results indicate that the structural test method is adequate for WPC sheet piling and assures its reproducibility. Compression failures or buckling of the compression flanges were not observed, and the C-T joints did not restrict the rotation of joined piles with respect to one another. Specimens show a linear load- deflection behavior up to 40% of the ultimate strength. Short spans failed predominantly in shear while longer spans failed in flexural tension. Specimens fail without significant yielding, and the ultimate strength is reached at failure. The findings show significant promise for Natural-Fiber/Thermoplastic light duty sheet piling retaining wall structures.