Valorization of EPS and LDPE plastic waste in concrete tiles: mechanical properties, thermal insulation, and building energy simulation of a social housing case study

Plastic waste management is a global environmental challenge. This research explores a sustainable solution through the development of concrete tiles incorporating recycled plastic aggregates. An experimental methodology was designed evaluating three mixtures: a control mix (B 1 ) without waste, and two mixes with partial replacement of traditional aggregates by Expanded Polystyrene (EPS) and Low-Density Polyethylene (LDPE) waste (B 2 and B 3 ). Properties in the fresh and hardened state (slump, flexural and compressive strength, water absorption, density, thermal conductivity, and impact resistance) were analyzed. Additionally, the energy impact at the building level was assessed through dynamic simulations (SIMEDIF) of a social housing unit, comparing a Base Case with a Strategic Case incorporating the B 2 tile, high-performance bricks, and double glazing. Experimental results indicate that B 2 and B 3 comply with IRAM standards, reducing density by up to 14% and thermal conductivity by up to 47% compared to the control. The thermal simulation revealed that during the critical winter period, the Improved Case raised minimum indoor temperatures by up to +2.4 °C and reduced heating demand by up to 35%. In summer, it lowered maximum indoor temperatures by up to 3.5 °C and reduced cooling demand by up to 38%. Mix B 2 exhibited the best overall balance. The study concludes that it is feasible to produce tiles with plastic aggregates that not only improve thermal insulation at the material level but also generate significant energy savings at the housing scale, offering a viable alternative for waste valorization in sustainable construction.