Assessing and understanding the interaction between mechanical and thermal properties in concrete for developing a structural and insulating material

Abstract

Highly thermal insulated building envelopes are the base of energy efficient buildings worldwide, however,concrete show poor thermal insulation properties. Developing a structural and thermal insulatingconcrete is challenging because improving thermal properties undermines mechanical properties. Thisstudy aims to understand the interactions between thermal and mechanical properties of concrete(conductivity-to-strength efficiency), when modifying the matrix and aggregate phases by adding flyash (FA) and coarse and fine lightweight aggregates (LWAs). Based on the ratio fc/k, the highest efficiencywas given by the addition of LWAs (0.017 [W/mK]/MPa) in comparison with the addition of FA(0.008 [W/mK]/MPa). Nevertheless, those efficiencies are highly dependent on the interaction betweenthe aggregate and matrix phases. The optimization of one phase only is not enough to obtain a structuralinsulating concrete because the thermal conductivity-to-strength efficiency is governed by both, theaggregate and the matrix.