INFLUENCE OF HYDROXYPROPYL METHYLCELLULOSE ON THE THERMO-MECHANICAL PROPERTIES OF LIGHTWEIGHT MORTARS WITH SAND REPLACED BY EXPANDED POLYSTYRENE POWDER
Lightweight mortar, thermal insulation, energy efficiency, EPS, HPMC
With the growing demand for energy efficiency, the construction industry has encouraged the adoption of innovative materials capable of reducing energy consumption, especially in coatings applied to building envelopes. One promising alternative is the incorporation of industrial waste, such as expanded polystyrene (EPS) powder, into mortars. In addition to contributing to sustainability by preventing improper disposal of this waste, EPS can act as a lightweight aggregate, whose polymeric nature reduces the material's mass density and improves thermal and acoustic insulation due to its porous morphology. In this study, a reference mortar with a 1:3 ratio (cement:sand) was formulated, partially replacing natural sand with EPS powder in proportions of 10%, 20%, 30%, 40%, and 50%, to evaluate the impact of this change on mechanical and thermal properties with and without the use of hydroxypropylmethyl cellulose (HPMC) at 0.20% of the cement mass. Tests were performed in the fresh and hardened states to characterize the mechanical and thermal properties, as well as microstructural analyses by scanning electron microscopy (SEM). The formulation with 50% EPS and HPMC showed a 33.38% increase in thermal insulation compared to the same composition without HPMC and a 133.49% increase compared to the reference mortar. The results indicate that HPMC enhances thermal performance by inducing greater porosity in the matrix, which, in turn, compromises the material's mechanical strength.