Traditional Cementitious Materials for Thermal Insulation

The increasing requirement for indoor thermal comfort in the building sector leads to an increased demand for new thermal insulating materials. Developing materials capable to meet technical and environmental requirements are a hot topic. Thus, in this study, the authors tried to manufacture an insulating binder free from Portland cement (PC) or foaming agent. This insulating binder based on traditional cementitious materials such as metakaolin (MK), fly ash (FA), hydrated lime and gypsum. To increase its insulation efficiency, different proportions of expanded perlite (EP) and silica fume (SF) were incorporated. The bulk density, compressive strength, thermal conductivity, total porosity and thermal resistance were determined. X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used to analyze the results. The results showed that the combination of suitable ratios of FA, lime, gypsum and MK can produce good thermal insulating material with thermal conductivity of 0.331 W/mK associated with good compressive strength. The insulation efficiency of this material can be increased with the incorporation of EP. For more and more insulation efficiency, MK was replaced with SF. In short, these new insulation materials exhibited suitable compressive strength associated with low thermal conductivity (0.331–0.095 W/mK), low density (1275.1–417.3 kg/m³) and high porosity (54.67–81.25%). It is recommended to use these new type of insulation materials in different thermal insulation purposes, of which they satisfied the requirement of Egyptian Energy Code (ECP 306–2005).