Influência do tipo de EPS e método de mistura nas propriedades de argamassas de revestimento

Abstract

This study aims to analyze the influence of EPS type and the mixing method on rendering mortars properties. Mortars were produced with three aggregates, one being natural sand and two types of EPS: virgin (pearls) and recycled (flakes). These were evaluated for particle size distribution, particle morphology, density, and water absorption capacity. The EPS replaced 50% of the sand volume, which corresponds to 30% of the total volume of mortar. Five mortars were produced, and the mix proportion was equal to 1:0.5:4.5:0.70 (cement: limestone filer: sand: water/binder ratio). The water content was kept constant, and a superplasticizer was used to achieve the pre-established flow table spread. Two mixing methods were evaluated in the production of mortars with EPS: partial homogenization of the cement paste and later addition of EPS (type A); and EPS wrapping by water and fine particles (type B). Mortars were evaluated in the fresh state according to superplasticizer content, bulk density, air content, water receptivity, and squeeze-flow test. In hardened state, mechanical, physical, and microstructural properties were evaluated. Bond strength tests were performed at 28 days to verify the mortar adhesion on a cementitious substrate. The results showed that virgin EPS particles are spherical, presenting lower surface roughness/open pores compared to recycled EPS. Due to the gridding process, the particles are angular, elongated, and with porous structures. Both EPS types can absorb water. The use of EPS reduced the bulk density and increased the mortar workability; the mixing method was not significant for the fresh state properties. In hardened state, EPS reduced mechanical properties and increased water absorption and porosity of mortars. The mechanical properties of recycled EPS mortars were higher than those of the virgin. Bond strength was 41% higher than those with virgin EPS, regardless of the mixing method used. There is a potential for the use of recycled EPS, both for the superior performance compared to virgin EPS and for the waste reuse.