Long-term Performance of Silica Aerogel and Aerogel Based Composites: A Literature Review Highlighting Pathways for Further Studies
Paper in proceedings, 2019
Aerogels are promising to be used in building materials and insulation products. Among varioustypes of aerogel, silica aerogel is the most commonly type used for building applications.Untreated silica aerogel is hydrophilic, but it can be chemically modified to becomehydrophobized. According to the literature review performed in this paper, few studies reportingageing of hydrophobized silica aerogel under varying hygrothermal (relative humidity andtemperature) conditions have been published so far. Among those, studies focused onmicrostructural evaluation of aerogel during hygrothermal ageing in laboratory conditionsreported some reduction of specific surface area and the shift of pore size distribution. Thisresults in a noticeable increase in thermal conductivity of the silica aerogel composite. Theobjectives of this literature review are to summarize the state-of-the-art studies concerning theimpacts of ageing, both accelerated and real-life, in hygrothermal conditions on thermalperformance of silica aerogel and aerogel based composite material. The results show thatdespite the hydrophobic treatment of aerogel, ageing still occur and has, in most cases, anegative impact on thermal performance of aerogel. Relative humidity seems to be the moredominant factor than temperature, concerning the intensity of degradation induced by ageing.Furthermore, a lack of direct correspondence between artificial ageing in laboratoryenvironments and natural ageing is also highlighted.