Recycled plastic aggregate in mortars composition: Effect on physical and mechanical properties

In this paper artificial aggregates based on recycled plastic materials, mostly polyolefin and polyethylene terephthalate waste, were used as partial replacement of natural aggregates for manufacturing hydraulic mortars. In particular, different amounts (10–50% by weight) of siliceous sand were substituted by the same weight of the above plastic waste, to obtain six mortars with different composition. The influence of plastic addition on physical and mechanical properties (density, porosity, compressive and flexural behavior and water vapour permeability) was studied. Moreover the thermal conductivity of the obtained mortars was evaluated. Recycled plastic substitution enhances the open porosity, causing a decrease in flexural and compressive strength, with an increase in water vapour permeability. Nevertheless, the presence of plastic aggregate leads to a significant reduction in thermal conductivity, which improves the thermal insulation performances of the mortar. For this reason the addition of recycled plastic aggregate in the manufacturing of hydraulic mortars can be considered a way to reduce the growing environmental impact of polymers and, at the same time, it allows the development of increasingly eco-sustainable building materials.