Development of a lightweight, eco-friendly self-compacting mortar based on polypropylene and limestone filler waste: Investigation of thermophysical and acoustic properties

The construction sector faces major environmental challenges due to the increasing accumulation of plastic waste and limestone by-products. This study investigates the use of sand derived from polypropylene waste (PPSW) as a replacement for natural sand (0, 20, 40, 60 and 100) % by volume, combined with limestone waste fines added as a filler, in self-compacting mortar (SCM). The objective of this study is to develop eco-friendly self-compacting mortars with enhanced thermophysical and acoustic properties, while aiming to design a lightweight mortar. The evaluation included physico-mechanical tests (density, strength, UPV, dynamic modulus), thermophysical properties (conductivity, diffusivity, heat capacity, thermal resistance), acoustic attenuation and SEM. Incorporating PPSW decreases mortar density by 27%, compressive strength by 68%, dynamic modulus by 68%, and UPV by 33%. However, it significantly enhances thermal performance, reducing thermal conductivity by 52%, and also improves acoustic behavior. SEM images reveal enhanced interfacial adhesion between the cementitious matrix and the MSPP 100 particles, indicating that the PPSW particles exhibit adequate interfacial bonding with the cementitious matrix. This research significantly contributes to the valorization of cement-based waste for the development of lightweight, eco-friendly self-compacting mortars, supporting a circular economy in the construction sector.