Mechanical Characteristics of Silica Aerogel Mortar and Sandwiched Mortar with Silica Aerogel Mat Core

Due to increasing awareness of the indoor environmental quality, efforts to maintain human indoor thermal comfort have been intensely carried out worldwide in recent decades. Particularly, thermal insulating materials with good mechanical performance are of great interest to suit this functionality. In this respect, construction materials should be able to impede heat transfer while achieving the required mechanical strength. Silica aerogel (SA) is attractive to fit these criteria due to its favorable characteristics such as low thermal conductivity, lightweight, and sustainability. Therefore, the present work studies the mechanical properties of both mortar with sand replaced by silica aerogel and sandwiched mortar with silica aerogel mat core. First, the optimal mix design was determined for the mortars with 0%, 15%, 20%, and 25% sand replaced by volume with silica aerogel through compressive strength on Days 7 and 28. Flexural strength and modulus of elasticity were also assessed. In terms of sandwiched mortar with silica aerogel mat core, both edgewise and flatwise compressive characteristics were examined for 9-, 12-, and $15\text{-}\mathrm{mm}$ core thicknesses. Additionally, the optimal parameters of both specimen types were linked to their microstructures and failure modes. According to the result, 15% by volume of silica aerogel (by replacing sand) was determined as the optimum ratio for the SA powder mortar. Meanwhile, for silica aerogel sandwiched mortar, samples with 15- and $12\text{-}\mathrm{mm}$ core thicknesses achieved the highest flatwise and edgewise compressive strengths, respectively.