Studies on Evaluation of Structural Properties of Mixed Multi-layered Recycled Plastic Lumber

Severe burdening of landfills due to non-degradable plastic waste deposition is a major environmental hazard. Although there have been initiatives to use recycled plastic as a building material, it has been successful only as a non-structural material or as a partial replacement of aggregate in concrete. Further, as far as the use of recycled plastic as construction materials is concerned, the present design standards do not mention anything regarding the matter. In the present study, an experimental program is developed to evaluate the mechanical properties of recycled plastic lumbers (RPL) developed using mixed multi-layered plastic (MLP). First, the specific density and coefficient of thermal expansion of RPL-MLP are evaluated. Compression, tension, flexure, and shear tests are also carried out on the RPL-MLP using displacement-controlled and load-controlled testing machine. All tests are carried out using pertinent ASTM standards. It is observed that the material exhibits a compressive strength of about 25 MPa. The flexural modulus is determined to be about 6 MPa and 12 MPa for the specimen kept in plank position and joist position respectively. The initial compression modulus was found to be only about 325 MPa. MLP exhibits excellent deformation capability, although the ultimate failure is a brittle mode. The paper also discusses the challenges involved in testing such a material and ideas to improve its structural performance. It can be concluded that RPL-MLP lumber can be used in low stress building applications.