Mechanical and Thermal Effects of Using Fine Recycled PET Aggregates in Common Screeds

The increasing consumption of plastics has necessitated the need to find a sustainable solution to reuse PET within common building materials. Recycled PET reinforcement would reduce plastic waste that is difficult to dispose of and CO2 emissions, representing a sustainable solution for generating lighter building materials. The goal of this work was to define a new cementitious mixture design and to study the mechanical and thermal behavior of three typologies of screeds with fine recycled polyethylene terephthalate (PET) aggregates. A weight percentage of PET of 1%, 2%, and 3% was used. The test results for sustainable screeds (S-Screeds) with waste PET were compared with a reference screed without the addition of plastic. In the fresh state, the workability and the air content were measured, while in the hardened state, the density, thermal conductivity, and compressive and flexural strength were investigated. These properties showed improvement for some tested S-Screeds after the introduction of fine (a few millimeters in size) and irregularly shaped waste plastic aggregates. Scanning electron microscopy (SEM) analysis showed the presence of a release surface between the cementitious mixtures and the plastic material, even if the mechanical interaction between the matrix and PET still existed