Lightweight thermal insulating coating mortars with aerogel, EPS, and vermiculite for energy conservation in buildings

Mechanical, thermal, microstructural, and acoustic properties of optimized lightweight coating mortars were analyzed. The fine aggregate was partially replaced by insulant alternative aggregates: silica aerogel, expanded polystyrene, and vermiculite. The consistency index, incorporated air content, water retention, compressive strength, mass density, water absorption, voids index, thermal conductivity, SEM microstructure analysis, and acoustic absorption were investigated. As a case study, the thermal resistance parameters were calculated for Brazilian bioclimatic zones, for two ceramic bricks masonry systems. Silica aerogel reduced the mortar thermal conductivity by up to 60% (EPS 53%, vermiculite 48%), and reduced the coating thickness from 3.4 cm to 1.4 cm for the same thermal performance. Microstructural analysis suggests a chemical reaction between silica from aerogel and pore solution from the cement mortar forming C–S–H gel with a low Ca/Si ratio. EPS mortar obtained the best performance for the acoustic insulation, and the silica aerogel mortar obtained the lowest performance.