Influence of hydroxypropylmethylcellulose (HPMC) on thermal and mechanical performance of cementitious rendering mortars

The application of insulating materials in the construction industry is an intelligent strategy that promotes energy efficiency by reducing energy consumption through enhanced thermal retention in indoor spaces, resulting in improved comfort and resource savings. The focus on enhancing thermal performance has led to the utilization of techniques involving cementitious materials and additives to impart insulation properties. In this study, we investigate the influence of Hydroxypropyl Methyl Cellulose (HPMC) on the thermal and mechanical properties of rendering mortars. Four different concentrations of HPMC (0.015, 0.030, 0.045, and 0.060%) were analyzed and compared with a reference mixture. Various tests were conducted to determine the fresh and hardened state properties of the mortars, including consistency index, bulk density, water loss through evaporation, compressive strength, flexural tensile strength, adhesive flexural strength, water absorption by immersion, and modulus of elasticity. The thermal performance was evaluated using a prototype that simulated heat incidence on a cementitious panel. The results indicate that the incorporation of HPMC allows for the production of lighter materials with a weight reduction of 11.76% due to the high porosity induced by the additive. This high void content contributes to thermal insulation by reducing the material’s conductivity by up to 30% while maintaining a fixed heat flux of approximately 49 W when subjected to the same heat flux. The resistance to heat transfer through the panel varies with the addition of HPMC, with the highest incorporation of the additive resulting in a 32.6% increase in thermal resistance compared to the reference mixture. These findings highlight the potential of HPMC as an effective additive for improving the thermal and mechanical performance of rendering mortars, thereby contributing to enhanced energy efficiency in building construction. The results have implications for the development of sustainable building materials that optimize thermal insulation and reduce energy consumption, thereby promoting environmentally friendly practices in the construction industry.