Physical and mechanical performance of cement-based renders with different contents of fly ash, expanded cork granules and expanded clay

Abstract

In recent decades, there has been a demand for new cladding solutions with higher thermal efficiency. Mortars with an improved thermal performance are one such solution. The biggest challenge in developing these mortars consists in achieving a lower thermal conductivity, while still maintaining an appropriate mechanical and water resistance performance with a low environmental impact.The aim of this study is to analyse the physical and mechanical performance of 20 cement-based coating mortars (renders) with different contents of a SCM – supplementary cementitious material (fly ash) used to replace cement, and of two insulating aggregates (expanded cork granules, expanded clay or a mix of both) replacing sand.The reduction of cement binder and sand aggregate contents led to lower thermal conductivity and a decrease of the mechanical properties. However, the balance between the physical and mechanical performance allows different applications, reaching thermal mortars with distinct EN 998 classes: (i) thermal conductivity T1 or T2; (ii) compressive strength CSI or CSII; (iii) water capillary absorption W0 or W1.