Calcined Clays as Binder for Thermal Insulating and Structural Aerogel Incorporated Mortar

Abstract

Partial replacement of ordinary Portland cement with calcined clay as binder in the aerogel incorporated mortars (AIM) was shown to decrease their thermal conductivities while maintaining the mechanical strength. It was found that at an aerogel loading of between 40 vol% and 80 vol%, replacement of cement with calcined clay lowered the thermal conductivity by up to 20% when <70 vol% aerogel was present (0.410 W/(mK) to 0.370 W/(mK)), and by up to 40% with >70 vol% aerogel (0.164 W/(mK) to 0.145 W/(mK)), driven mainly by the innate thermal conductivity of the binders. At replacement level of up to ∼30% by weight of binder (%bwob), the properties of the mortar was independent of clay types. When the replacement increased to above 40%bwob, calcined smectite enriched clays were favoured for lowering the thermal conductivities of the mortars as compared to those containing kaolinite.