Proposal for an alternative thermal insulation material to be used in building thermal insulation applications

Environmental problems, whose importance is increasing day by day in the global sense, increase the interest in energy efficient use. While one of the leading sectors in energy consumption is the construction sector, most of the energy use in buildings is due to heating and cooling. Therefore, thermal insulation materials should prioritize products that minimize resource consumption and waste production throughout their entire life cycle, are sustainable, have limited adverse environmental impacts, and pose no risks to human health. Based on this approach, research and development efforts on alternative thermal insulation materials are ongoing. While one of the approaches to alternative heat insulation materials is to reintroduce products with natural content and proven themselves in vernacular architecture to building applications, another is to use high performance products developed with advanced technologies. The aim of this study is to propose an alternative thermal insulation material that combines natural fibers used in vernacular architecture with nanotechnology based product aerogel. Cement, although widely used in building applications, has significant environmental impacts; thus, reducing its usage is considered beneficial and forms the basis for its selection in this study. Goat hair was included due to its historical use in traditional tents and mats, while flax and hemp fibers were selected for their ease of production, recyclability, and eco-friendliness. Aerogel, a nanotechnology product, was chosen for its high performance and accessibility in the insulation field. The study was limited to 16 sample series produced by adding varying proportions of fibers and aerogel to cementitious mixtures. The samples were categorized into four groups based on the presence or absence of aggregates and aerogel. A consistent water-to-binder ratio of 0.5 was used across all mixtures, and natural fibers were added at a volume ratio of 30% of the binder. Aerogel was included at 2% of the aggregate volume as a replacement. The prepared samples underwent physical, mechanical, and thermal testing, and digital microscopy was used for morphological evaluations. The lowest thermal conductivity value (0.126 W/mK) was observed in the flax fiber sample without aggregate but with aerogel, while the highest (0.655 W/mK) was recorded in the control sample (Ç). Aerogel addition increased total porosity, resulting in reduced thermal conductivity but negatively impacting compressive strength. Among the fiber types, none achieved homogeneous distribution within the cement matrix, though goat hair demonstrated better matrix bonding than the others. All fiber types contributed positively to thermal insulation, albeit increasing water absorption due to higher porosity. No significant differences were observed between flax and hemp in terms of physical, mechanical, and thermal properties. The use of aggregates improved compressive strength but also led to higher thermal conductivity due to reduced porosity. This study is significant in combining natural fibers and aerogel to create an environmentally friendly alternative insulation product and in raising awareness among architects about sustainable material choices. In conclusion, the research demonstrates that cement-based mortars incorporating natural fibers and aerogel have potential for continued development as alternative thermal insulation materials.