Mechanical, physical and microstructural properties of a mortar with melted plastic waste binder

The feasibility of using plastic waste as a binding material to develop a new construction material (mortar with plastic waste binder (MPB)) is presented in this paper. Two types of plastic: high density polyethylene (HDPE) and low density polyethylene (LDPE), are combined in three blend (weight) ratios (HDPE/ LDPE of 40/60, 50/50, 60/40) and mixed with sand in four plastic contents (45%, 50%, 60%, and 65%). First, the plastic material is melted in an oven. Then, sand and the melted plastic are thoroughly mixed under a controlled temperature into an homogenous mixture. The mixture is then poured into standardized molds and cured for different periods of time. Mechanical, physical and water absorption tests are performed on the MPB samples after different curing times to assess the influence of the change in the plastic content and the blend ratio (HDPE/LDPE or H/L) on their mechanical and physical properties. Moreover, microstructural analyses and tests are performed on some of the samples for a better understanding of the behavior of this MPB at its microstructure level. The results show that samples with plastic contents of 50% and 60% and a blend ratio of 50/50 have the highest unconfined compressive strength. The same range of plastic content is found to provide the MPB with the highest splitting tensile strength when the H/L blend ratio is equal to 40/60 or 60/40. A relationship between the splitting tensile strength (ft) and the compressive strength is proposed. It is also found that the MPB is more ductile with greater plasticity than conventional mortar materials that use Portland cement. The plastic content and H/L ratio have significant effects on the water absorption, density and microstructure of the mortar. The microstructure of the MPB plays an important role in the development of its strength. This new material has good potential for use as a construction material to recycle plastic waste and reduce the impact of plastic on the environment.